Proteins having a covalent warhead

Abstract

The present disclosure relates to proteins having a covalent warhead and compositions of same, as well as methods of making and using the proteins.

Description

[0001]Attorney Docket No.57891-0006WO1 PROTEINS HAVING A COVALENT WARHEAD CROSS REFERENCE TO RELATED APPLICATIONS This application claims the benefit of United States Provisional Application No. 63 / 672,421, filed on July 17, 2024, which is incorporated by reference in its entirety. 5 SEQUENCE LISTING This application contains a Sequence Listing that has been submitted electronically as an XML file named 57891-0006WO1_SL_ST26.xml. The XML file, created on July 16, 2025, is 44,670 bytes in size. The material in the XML file is hereby incorporated by reference in its 10 entirety. FIELD The disclosure relates to the technical fields of immunology, chemistry, and medicine. 15 BACKGROUND Antibody drug conjugates (ADCs) are a class of agents that include an antibody and a cytotoxic payload attached to the antibody via a chemical linker. Despite the increasing number of ADCs, many ADCs have not demonstrated a therapeutic benefit as compared to controls. Additional compositions and methods for inhibiting a target protein or inducing 20 cytotoxicity of a mammalian cell expressing a target protein are needed. SUMMARY Provided herein are proteins having a covalent warhead and compositions comprising the same, as well as methods of making and using the proteins and compositions, kits 25 comprising the protein or composition, and methods of screening. This disclosure also features biomolecules (e.g., a macromolecule, such as a polypeptide or a protein; or a smaller building block thereof (e.g., a peptide or an individual amino acid)), having one or more reactive groups (e.g., electrophilic reactive groups) e.g. a covalent warhead, compositions containing the same, as well as methods of making and using 30 the proteins and compositions, kits comprising the protein or composition, and methods of screening. 1 Attorney Docket No.57891-0006WO1 This disclosure also features chemical entities that are useful for preparing the biomolecules described herein. Said chemical entities include, but are not limited to, dually reactive spacer groups, e.g. chemical entities having the general formula (A) shown below: 5 Each of A and C is an independently selected electrophilic chemical moieties that can form one or more covalent bonds with one or more nucleophilic groups, e.g., nucleophilic groups that are typically present in a biomolecule, e.g., an optionally substituted amino (-NH2) group or a thiol (-SH) group. Said electrophilic chemical moieties described above are sometimes referred to herein as “reactive groups” or “convalent warheads.” B is an optional 10 spacer group (typically an organic moiety), of a desired length, that covalently connects A and C to one another. Examples of A and C include, without limitation, flurosulfates, (heterocyclyl)sulfates, hydroxyamines, azides, Au(III)-complexed aryl (e.g., phenyl) rings, and maleimides. For ease of reference, formula (A) chemical entities are sometimes referred to herein as “linkers.” Some non-limiting examples of formula (A) chemical entities are provided15throughout this specification, and for illustrative purposes only, are provided below: . In one aspect, this disclosure features gold-containing organometallic agents (gold is also referred to herein by its atomic symbol “Au”), e.g., Au(III). The gold-containing 20 organometallic agents described herein include, without limitation, gold complexes, e.g., Au(III) complexes, e.g., gold cyclometalated complexes, e.g., Au(III) cyclometalated complexes. The organometallic agents described herein can be used, for example, to (selectively) modify a biomolecule bearing one or more nucleophilic functional groups. Exemplary nucleophilic functional groups include protic functional groups, e.g., a thiol group,25e.g. a thiol group that is associated with a cysteine. While not wishing to be bound by theory, it is believed that the organometallic agents described herein form covalent linkages with the one or more of the nucleophilic groups present on the biomolecule, thereby modifying the biomolecule. 2 Attorney Docket No.57891-0006WO1 Accordingly, in another aspect, this disclosure features methods of modifying a biomolecule, e.g., a macromolecule, such as a polypeptide or a protein; or a smaller building block thereof (e.g., a peptide or an individual amino acid). The methods include contacting the biomolecule with a gold-containing organometalic agent described herein. In some 5 embodiments, modifying includes arylating a nucleophilic functional group, e.g., a protic functional group, e.g., a thiol group that is present on the biomolecule. In certain embodiments, the thiol group is associated with a cysteine. In one aspect, this disclosure features compounds having formula (I): 10wherein: Ring A is: ^ C6-14 aryl optionally substituted with 1-4 substituents independently selected from the group consisting of oxo, Ra, and Rb; or ^ heteroaryl of 5-12 ring atoms, wherein 1-4 ring atoms are heteroatoms, each 15 independently selected from the group consisting of N, N(H), N(Rc), O, and S(O)0-2, and wherein the heteroaryl is optionally substituted with 1-4 substituents independently selected from the group consisting of oxo, Ra, and Rb; each of R1and R2is independently selected from the group consisting of: 20 ^ C6-14aryl optionally substituted with 1-4 substituents independently selected from the group consisting of oxo, Ra, and Rb; and ^ C3-12 cycloalkyl optionally substituted with substituents independently selected from the group consisting of oxo, Ra, and Rb;25each of R3and R4is independently selected from the group consisting of: ^ C1-10alkyl optionally substituted with 1-4 independently selected Rd; and 3 Attorney Docket No.57891-0006WO1 ^ C3-12cycloalkyl optionally substituted with substituents independently selected from the group consisting of oxo, Ra, and Rb; R5is a coordinating anion; 5 R6is -*R61-R62-R63; wherein, the * indicates the point of attachment of R61-R62-R63to Au: R61is: ^ divalent C6-10 aryl optionally substituted with 1-4 substituents independently selected from the group consisting of oxo, Ra, and Rb; or 10 ^ divalent heteroaryl of 5-10 ring atoms, wherein 1-4 ring atoms are heteroatoms, each independently selected from the group consisting of N, N(H), N(Rc), O, and S(O)0-2, and wherein the heteroaryl is optionally substituted with 1-4 substituents independently selected from the group consisting of oxo, Ra, and Rb; 15 R62is absent or is C1-C16alkylene, C2-C16alkenylene, or C2-C16alkynylene, each of which is optionally substituted with 1-2 substituents independently selected from halogen and C3-C6 cycloalkyl; and wherein 1-8 alkylene units are optionally replaced with a group independently selected from the group consisting of: (i) -O-; 20 (ii) -NH-; (iii) -N(C1-C6 alkyl)-; (iv) -C(O)-; (v) -S-; (vi) –S(O)–; 25 (vii) – (viii) divalent C3-C10cycloalkyl, which is optionally substituted with 1-4 Ra; (ix) divalent C6-C10 aryl, which is optionally substituted with 1-4 Ra; 4 Attorney Docket No.57891-0006WO1 (x) divalent heteroaryl of 5-10 ring atoms, wherein 1-4 ring atoms are heteroatoms, each independently selected from the group consisting of N, N(H), N(Rc), O, and S(O)0-2; and which is optionally substituted with 1-4 Ra; and (xi) divalent heterocyclyl of 3-10 ring atoms, wherein 1-3 ring atoms are heteroatoms, 5 each independently selected from the group consisting of N, N(H), N(Rc), N(O-), O, and S(O)0- 2, and which is optionally substituted with 1-4 Ra; R63is a reactive group; 10 each occurrence of Rais independently selected from the group consisting of: halo; cyano; C1-10alkyl which is optionally substituted with 1-6 independently selected Rd; C2-6alkenyl; C2-6 alkynyl; C1-4 alkoxy; C1-4 haloalkoxy; -S(O)1-2(C1-4 alkyl); -S(O)(=NH)(C1-4 alkyl); -NReRf; –OH; -S(O)1-2NR’R’’; -C1-4 thioalkoxy; -NO2; -C(=O)(C1-10 alkyl); - C(=O)O(C1-4alkyl); -OC(=O)(C1-4alkyl); -C(=O)OH; -C(=O)NR’R’’; -NR’C(=O)(C1-4alkyl) 15 and –SF5; each occurrence of Rbis independently selected from the group consisting of: ^ L1-C3-12 cycloalkyl or C3-12 cycloalkenyl, each of which is optionally substituted with 1-4 substituents independently selected from the group consisting of oxo and Rd; 20 ^ L1-heterocyclyl or L1-heterocycloalkenyl of 3-12 ring atoms, wherein 1-3 ring atoms are heteroatoms, each independently selected from the group consisting of N, N(H), N(Rc), O, and S(O)0-2, and wherein the heterocyclyl or heterocycloalkenyl is optionally substituted with 1-4 substituents independently selected from the group consisting of oxo and Rd;25^ L1-heteroaryl of 5-12 ring atoms, wherein 1-4 ring atoms are heteroatoms, each independently selected from the group consisting of N, N(H), N(Rc), O, and S(O)0-2, and wherein the heteroaryl is optionally substituted with 1-4 substituents independently selected from the group consisting of oxo and Rd; and ^ L1-C6-10aryl optionally substituted with 1-4 substituents independently selected 30 from the group consisting of oxo and Rd; L1 is a bond or C1-4alkylene; 5 Attorney Docket No.57891-0006WO1 each occurrence of Rcis independently selected from the group consisting of: C1-6alkyl optionally substituted with 1-3 independently selected Ra; -C(O)(C1-4 alkyl); -C(O)O(C1-4 alkyl); -CONR’R’’; -S(O)1-2NR’R’’; - S(O)1-2(C1-4 alkyl); -OH; and C1-4 alkoxy; 5 each occurrence of Rdis independently selected from the group consisting of: –OH; - halo; –NReRf; C1-4 alkoxy; C1-4 haloalkoxy; -C(=O)O(C1-4 alkyl); -C(=O)(C1-4 alkyl); - OC(=O)(C1-4alkyl); -C(=O)OH; -CONR’R’’; -S(O)1-2NR’R’’; -S(O)1-2(C1-4alkyl); and cyano; each occurrence of Reand Rfis independently selected from the group consisting of: 10 H; C1-6alkyl optionally substituted with 1-3 substituents each independently selected from the group consisting of NR’R’’, -OH, halo, C1-4alkoxy, and C1-4haloalkoxy; -C(O)(C1-4alkyl); - C(O)O(C1-4 alkyl); -CONR’R’’; -S(O)1-2NR’R’’; -S(O)1-2(C1-4 alkyl); -OH; and C1-4 alkoxy; and 15 each occurrence of R’ and R’’ is independently selected from the group consisting of: H; -OH; and C1-4 alkyl. In a further aspect, this disclosure features a composition that includes a thiol containing biomolecule (e.g., a polypeptide or a protein) and a compound of Formula (I). 20 In a further aspect, this disclosure features a composition that includes a biomolecule having at least one cysteine residue and a compound of Formula (I). In a further aspect, this disclosure features a method for preparing a thiol-aryl conjugated biomolecule, the method comprising contacting a compound of Formula (I) with a biomolecule that includes at least one thiol group under conditions sufficient to prepare the 25 thiol-aryl conjugated biomolecule. The biomolecules can optionally include one or more reactive groups as described herein. In a further aspect, this disclosure features methods of preparing a cysteine-aryl conjugated biomolecule, the method comprising contacting a compound of Formula (I) with a biomolecule that includes at least one cysteine residue under conditions sufficient to prepare 30 the cysteine-aryl conjugated biomolecule. The biomolecules can optionally include one or more reactive groups as described herein. In a further aspect, this disclosure features methods of preparing a gold(III) aryl complex comprising contacting a compound of Formula (I) with an aryl halide under conditions 6 Attorney Docket No.57891-0006WO1 sufficient to prepare the gold(III) aryl complex. In certain embodiments, the aryl halide is an aryl iodide. Provided herein are proteins having a covalent warhead and compositions of same, as well as methods of making and using the proteins and compositions, kits comprising the protein 5 or composition, and methods of screening. Some embodiments provide a protein comprising an antigen-binding domain, wherein the antigen-binding domain comprising an oxime, the oxime having the structure: wherein: 10 * and ** represent the points of connection of the oxime to the antigen-binding domain; L1is a bond or a C1-C6 alkylene optionally substituted with 1-2 substituents independently selected from halogen and C3-C6 cycloalkyl, and wherein 1-2 alkylene units are optionally replaced by O, N, C3-C6 cycloalkyl, or phenyl; R1is azido, tetrazinyl, a C2-C3 alkyne, or an optionally substituted C8-C1215cycloalkyne. In some embodiments, L1is a bond or a C1-C6 alkylene optionally substituted with 1- 2 substituents independently selected from halogen and C3-C6 cycloalkyl, and wherein 1-2 alkylene units are optionally replaced by O, N, C3-C6 cycloalkyl, -C(O)-, or phenyl. Some embodiments provide a protein comprising an antigen-binding domain, wherein 20 the antigen-binding domain comprises a modified phenylalanine residue, the modified phenylalanine residue having the structure: wherein: * and ** represent the points of connection of the modified phenylalanine residue to25the antigen-binding domain; 7 Attorney Docket No.57891-0006WO1 L2is a C2-C16 alkylene optionally substituted with 1-2 substituents independently selected from halogen and C3-C6 cycloalkyl, and wherein 1-6 alkylene units are optionally replaced by O, N, S, C3-C10 cycloalkyl, phenyl, 5-12 membered heteroaryl, and 4-14 membered heterocyclyl; 5 , , X is O or NRX; RXis hydrogen, C1-C6 alkyl, or C3-C6 cycloalkyl;10R3is halogen or C1-C6 alkyl; R4is hydrogen or C1-C6 alkyl; R4Ais C1-C6 alkyl or C3-C6 cycloalkyl; R5Aand R5Bare independently hydrogen, halogen, or C1-C6 alkyl; or R5Aand R5Btogether with the carbon atom to which they are attached form a 15 cyclopropyl; Ring A is a 4-10 membered heterocyclyl. In some embodiments of Formula (B), L2is a C2-C16 alkylene optionally substituted with 1-2 substituents independently selected from halogen and C3-C6 cycloalkyl, and wherein 1-6 alkylene units are optionally replaced by O, N, S, C3-C10 cycloalkyl, phenyl, 5-1220membered heteroaryl, -C(O)-, and 4-14 membered heterocyclyl; and the other variables defined in Formula (B) are as defined above. In other embodiments of Formula B, L2is a C1-C16 alkylene optionally substituted with 1-2 substituents independently selected from halogen and C3-C6 cycloalkyl, and wherein 1-6 alkylene units are optionally replaced by O, N, S, C3-C10 cycloalkyl, phenyl, 5-12 25 membered heteroaryl, -C(O)-, and 4-14 membered heterocyclyl; and the other variables defined in Formula (B) are as defined above 8 Attorney Docket No.57891-0006WO1 Some embodiments provide a protein comprising an antigen-binding domain, wherein the antigen-binding domain comprises a modified cysteine residue, the modified cysteine residue having the structure: Formula (C), 5 wherein: * and ** represent the points of connection of the modified cysteine residue to the antigen-binding domain; , wherein a represents the point of connection of L to the sulfur atom of the modified cysteine10residue and “b” represents the point of connection of L to L2; n is 1 or 2; RL1, RL2, and RL3, are each independently selected C1-C10 alkyl; L2is a C2-C16 alkylene optionally substituted with 1-2 substituents independently selected from halogen and C3-C6 cycloalkyl, and wherein 1-6 alkylene units are optionally 15 replaced by O, N, S, C3-C10 cycloalkyl, phenyl, 5-12 membered heteroaryl, and 4-14 membered heterocyclyl; R2is a reactive group as described herein, e.g., , , 20 X is O or NRX; RXis hydrogen, C1-C6 alkyl, or C3-C6 cycloalkyl; R3is halogen or C1-C6 alkyl; R4is hydrogen or C1-C6 alkyl; 9 Attorney Docket No.57891-0006WO1 R4Ais C1-C6 alkyl or C3-C6 cycloalkyl; R5Aand R5Bare independently hydrogen, halogen, or C1-C6 alkyl; or R5Aand R5Btogether with the carbon atom to which they are attached form a cyclopropyl; 5 Ring A is a 4-10 membered heterocyclyl. In some embodiments of Formula (C), L2is a C2-C16 alkylene optionally substituted with 1-2 substituents independently selected from halogen and C3-C6 cycloalkyl, and wherein 1-6 alkylene units are optionally replaced by O, N, S, C3-C10 cycloalkyl, phenyl, 5-12 membered heteroaryl, -C(O)-, and 4-14 membered heterocyclyl; and the other variables defined 10 in Formula (C) are as defined above. In some embodiments of Formula (C), L2is a C1-C16 alkylene optionally substituted with 1-2 substituents independently selected from halogen and C3-C6 cycloalkyl, and wherein 1-6 alkylene units are optionally replaced by O, N, S, C3-C10 cycloalkyl, phenyl, 5-12 membered heteroaryl, -C(O)-, and 4-14 membered heterocyclyl; and the other variables defined 15 in Formula (C) are as defined above. In some embodiments of Formula (C), it is provided that the structure does not contain a GLP-1 peptide or variant thereof, optionally wherein the structure does not contain a modified GLP-1peptide, optionally wherein the structure does not contain a peptide as described in WO 2025 / 076010. 20 In some embodiments, R2 can further include -OSO2-HET as described herein. Some embodiments provide a pharmaceutical composition comprising a protein described herein and at least one pharmaceutically acceptable excipient. Some embodiments provide a kit comprising (a) a protein as described herein and (b) a pharmaceutically acceptable excipient. 25 Some embodiments provide a kit comprising the pharmaceutical composition described herein and instructions for administration of the pharmaceutical composition to a human subject. Some embodiments provide a method of treating in a subject in need thereof, comprising administering to the subject therapeutically effective amount of a protein described 30 herein, or a pharmaceutical composition described herein. Some embodiments provide a method of inducing or increasing internalization of the protein into a mammalian cell that expresses the target protein comprising contacting the mammalian cell with a protein described herein. 10 Attorney Docket No.57891-0006WO1 Some embodiments provide a method of inhibiting the activity of the target protein in a mammalian cell, comprising contacting the target protein with a protein described herein. Some embodiments provide a method of reducing the amount of the target protein in a mammalian cell comprising the target protein, the method comprising contacting the target 5 protein with a protein described herein. Some embodiments provide a method of inducing cell death in a mammalian cell comprising the target protein, the method comprising contacting the cell with a protein described herein. Some embodiments provide a method of screening for a protein that forms a covalent 10 bond with a target protein in a mammalian cell, the method comprising: contacting the target protein with a protein described herein; and determining whether a covalent bond has been formed between the protein and the target protein. Some embodiments provide a protein-protein conjugate comprising a first protein A 15 and a second protein B, wherein the protein-protein conjugate has the structure: Formula (D), wherein the first protein A comprises an antigen-binding domain, wherein the antigen- binding domain comprises a modified phenylalanine residue, wherein: * and ** represent the points of connection of the modified phenylalanine residue to20the antigen-binding domain of the first protein A; L2is a C2-C16 alkylene optionally substituted with 1-2 substituents independently selected from halogen and C3-C6 cycloalkyl, and wherein 1-6 alkylene units are optionally replaced by O, N, S, C3-C10 cycloalkyl, phenyl, 5-12 membered heteroaryl, and 4-14 membered heterocyclyl; 11 Attorney Docket No.57891-0006WO1 “a” represents the connection of R2Ato L2, “b” represents the connection of R2Ato 5 protein B, N* is a nitrogen atom of a lysine residue of protein B, S* is a sulfur atom of a cysteine residue of protein B, O* is an oxygen atom from a serine residue or a threonine residue of protein B, Nb is the nitrogen atom of a histidine residue of protein B and the connection of R2Ato protein B, and O** is an oxygen atom from a tyrosine residue of protein B; X is O or NRX; 10 RXis hydrogen, C1-C6 alkyl, or C3-C6 cycloalkyl; R3is halogen or C1-C6 alkyl; R4is hydrogen or C1-C6 alkyl; R4Ais C1-C6 alkyl or C3-C6 cycloalkyl; R5Aand R5Bare independently hydrogen, halogen, or C1-C6 alkyl; or15R5Aand R5Btogether with the carbon atom to which they are attached form a cyclopropyl; Ring A is a 4-10 membered heterocyclyl; wherein the antigen-binding domain of the first protein A specifically binds to the second protein B. 20 In some embodiments of Formula (D), L2is a C2-C16 alkylene optionally substituted with 1-2 substituents independently selected from halogen and C3-C6 cycloalkyl, and wherein 1-6 alkylene units are optionally replaced by O, N, S, C3-C10 cycloalkyl, phenyl, 5-12 membered heteroaryl, -C(O)-, and 4-14 membered heterocyclyl; and the other variables defined in Formula (D) are as defined above.25In some embodiments of Formula (D), L2is a C1-C16 alkylene optionally substituted with 1-2 substituents independently selected from halogen and C3-C6 cycloalkyl, and wherein 1-6 alkylene units are optionally replaced by O, N, S, C3-C10 cycloalkyl, phenyl, 5-12 12 Attorney Docket No.57891-0006WO1 membered heteroaryl, -C(O)-, and 4-14 membered heterocyclyl; and the other variables defined in Formula (D) are as defined above. Some embodiments provide a protein-protein conjugate comprising a first protein A and a second protein B, wherein the protein-protein conjugate has the structure: 5 (Formula E), wherein the first protein A comprises an antigen-binding domain, wherein the antigen- binding domain comprises a modified cysteine residue, wherein: * and ** represent the points of connection of the modified cysteine residue to the antigen-binding domain;10 , wherein “a” represents the point of connection of L to the sulfur atom of the modified cysteine residue and “b” represents the point of connection of L to L2; n is 1 or 2; RL1, RL2, and RL3, are each independently selected C1-C10 alkyl; 15 L2is a C2-C16 alkylene optionally substituted with 1-2 substituents independently selected from halogen and C3-C6 cycloalkyl, and wherein 1-6 alkylene units are optionally replaced by O, N, S, C3-C10 cycloalkyl, phenyl, 5-12 membered heteroaryl, and 4-14 membered heterocyclyl; 20 13 Attorney Docket No.57891-0006WO1 “a” represents the connection of R2Ato L2, “b” represents the connection of R2Ato protein B, N* is a nitrogen atom of a lysine residue of protein B, S* is a sulfur atom of a cysteine residue of protein B, O* is an oxygen atom from a serine residue or a threonine residue of protein B, Nb is the nitrogen atom of a histidine residue of protein B and the connection of 5 R2Ato protein B, and O** is an oxygen atom from a tyrosine residue of protein B; X is O or NRX; RXis hydrogen, C1-C6 alkyl, or C3-C6 cycloalkyl; R3is halogen or C1-C6 alkyl; R4is hydrogen or C1-C6 alkyl; 10 R4Ais C1-C6 alkyl or C3-C6 cycloalkyl; R5Aand R5Bare independently hydrogen, halogen, or C1-C6 alkyl; or R5Aand R5Btogether with the carbon atom to which they are attached form a cyclopropyl; Ring A is a 4-10 membered heterocyclyl, 15 wherein the antigen-binding domain of the first protein A specifically binds to the second protein B. In some embodiments of Formula (E), L2is a C2-C16 alkylene optionally substituted with 1-2 substituents independently selected from halogen and C3-C6 cycloalkyl, and wherein 1-6 alkylene units are optionally replaced by O, N, S, C3-C10 cycloalkyl, phenyl, 5-12 20 membered heteroaryl, -C(O)-, and 4-14 membered heterocyclyl; and the other variables defined in Formula (E) are as defined above. In some embodiments of Formula (E), L2is a C1-C16 alkylene optionally substituted with 1-2 substituents independently selected from halogen and C3-C6 cycloalkyl, and wherein 1-6 alkylene units are optionally replaced by O, N, S, C3-C10 cycloalkyl, phenyl, 5-12 25 membered heteroaryl, -C(O)-, and 4-14 membered heterocyclyl; and the other variables defined in Formula (E) are as defined above. In some embodiments of Formula (E), it is provided that the structure does not contain a GLP-1 peptide or variant thereof, optionally wherein the structure does not contain a modified GLP-1peptide, optionally wherein the structure does not contain a peptide as described in WO 30 2025 / 076010. Some embodiments provide a method of making a protein comprising an antigen- binding domain, wherein the antigen-binding domain comprises a modified phenylalanine residue, the modified phenylalanine residue having the structure: 14 Attorney Docket No.57891-0006WO1 the method comprising contacting (a) a compound having the structure Z-R2with (b) a protein comprising an antigen-binding domain, wherein the antigen-binding 5 domain comprising an oxime, the oxime having the structure: wherein: Z reacts with -L1- to form -L2-, wherein when R1is azido or tetrazinyl, then Z is a C2- C3 alkyne or an optionally substituted C8-C12 cycloalkyne, and when R1is a C2-C3 alkyne or 10 an optionally substituted C8-C12 cycloalkyne, then Z is azido or tetrazinyl; * and ** represent the points of connection of the oxime to the antigen-binding domain; L2is a C2-C16 alkylene optionally substituted with 1-2 substituents independently selected from halogen and C3-C6 cycloalkyl, and wherein 1-6 alkylene units are optionally replaced by O, N, S, C3-C10 cycloalkyl, phenyl, 5-12 membered heteroaryl, and 4-1415membered heterocyclyl; , X is O or NRX; RXis hydrogen, C1-C6 alkyl, or C3-C6 cycloalkyl;20R3is halogen or C1-C6 alkyl; 15 Attorney Docket No.57891-0006WO1 R4is hydrogen or C1-C6 alkyl; R4Ais C1-C6 alkyl or C3-C6 cycloalkyl; R5Aand R5Bare independently hydrogen, halogen, or C1-C6 alkyl; or R5Aand R5Btogether with the carbon atom to which they are attached form a 5 cyclopropyl; Ring A is a 4-10 membered heterocyclyl; L1is a bond or a C1-C6 alkylene optionally substituted with 1-2 substituents independently selected from halogen and C3-C6 cycloalkyl, and wherein 1-2 alkylene units are optionally replaced by O, N, C3-C6 cycloalkyl, or phenyl; and 10 R1is azido, tetrazinyl, a C2-C3 alkyne, or an optionally substituted C8-C12 cycloalkyne. In some embodiments of Formulas (F) and (G), L2is a C2-C16 alkylene optionally substituted with 1-2 substituents independently selected from halogen and C3-C6 cycloalkyl, and wherein 1-6 alkylene units are optionally replaced by O, N, S, C3-C10 cycloalkyl, phenyl, 15 5-12 membered heteroaryl, -C(O)-, and 4-14 membered heterocyclyl; and the other variables defined in Formulas (F) and (G) are as defined above. In some embodiments of Formulas (F) and (G), L2is a C1-C16 alkylene optionally substituted with 1-2 substituents independently selected from halogen and C3-C6 cycloalkyl, and wherein 1-6 alkylene units are optionally replaced by O, N, S, C3-C10 cycloalkyl, phenyl, 20 5-12 membered heteroaryl, -C(O)-, and 4-14 membered heterocyclyl; and the other variables defined in Formulas (F) and (G) are as defined above. In some of the foregoing embodiments of Formulas (A), (B), (C), (D), €, (F), and (G), R2 can further include -OSO2-HET. 25 Additional Definitions To facilitate understanding of the disclosure set forth herein, a number of additional terms are defined below. Generally, the nomenclature used herein and the laboratory procedures in organic chemistry, medicinal chemistry, and pharmacology described herein are those well-known and commonly employed in the art. Unless defined otherwise, all technical 30 and scientific terms used herein generally have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. Each of the patents, applications, published applications, and other publications that are mentioned throughout the 16 Attorney Docket No.57891-0006WO1 specification and the attached appendices are incorporated herein by reference in their entireties. The term “about” when referring to a number or a numerical range means that the number or numerical range referred to is an approximation, for example, within experimental 5 variability and / or statistical experimental error, and thus the number or numerical range may vary up to ±10% of the stated number or numerical range. The term “acceptable” with respect to a formulation, composition or ingredient, as used herein, means having no persistent detrimental effect on the general health of the subject being treated. 10 An “antigen-binding domain” is one or more protein domain(s) (e.g., formed from amino acids from a single polypeptide or formed from amino acids from two or more polypeptides (e.g., the same or different polypeptides) that is capable of specifically binding to one or more different antigen(s). In some examples, an antigen-binding domain can bind to an antigen or epitope with specificity and affinity similar to that of naturally-occurring antibodies. 15 In some embodiments, the antigen-binding domain can be an antibody or a fragment thereof. In some embodiments, an antigen-binding domain can include an alternative scaffold. Non- limiting examples of antigen-binding domains are described herein. Additional examples of antigen-binding domains are known in the art. In some embodiments, an antigen-binding domain can be a ligand for a target receptor protein. In some embodiments, an antigen-binding 20 domain can be a soluble receptor protein. In some embodiments, an antigen-binding domain can be a peptide substrate for an enzyme. The term “antibody” is used herein in its broadest sense and includes certain types of immunoglobulin molecules that include one or more antigen-binding domains that specifically bind to an antigen or epitope. An antibody specifically includes, e.g., intact antibodies (e.g., 25 intact immunoglobulins, e.g., human IgG (e.g., human IgG1, human IgG2, human IgG3, human IgG4)), antibody fragments, and multi-specific antibodies. One example of an antigen-binding domain is an antigen-binding domain formed by a VH -VL dimer. Additional examples of an antibody are described herein. Additional examples of an antibody are known in the art. The phrase “cytostatic to a cell” refers to a direct or indirect decrease in the proliferation 30 (cell division) of the cell (e.g., a cancer cell) in vivo or in vitro. When an agent is cytostatic to a cell, the agent can, e.g., directly or indirectly result in cell cycle arrest of the cell (e.g., a cancer cell). In some examples, an agent that is cytostatic to a cell can reduce the number of cells in a population of the cells that are in S phase (as compared to the number of cells in a 17 Attorney Docket No.57891-0006WO1 population of the cells that are in S phase prior to contact with the agent). In some examples, an agent that is cytostatic to a cell can reduce the percentage of the cells in S phase by at least 20%, at least 40%, at least 60%, or at least 80% (e.g., as compared to the percentage of cells in a population of the cells that are in S phase prior to contact with the agent). 5 The phrase “cytotoxic to a cell” refers to the inducement, directly or indirectly, in the death (e.g., necrosis or apoptosis) of the cell (e.g., a mammalian cell, e.g., a cancer cell). The term “pharmaceutically acceptable excipient” means a pharmaceutically- acceptable material, composition, or vehicle, such as a liquid or solid filler, diluent, carrier, solvent, or encapsulating material. In one embodiment, each component is “pharmaceutically 10 acceptable” in the sense of being compatible with the other ingredients of a pharmaceutical formulation, and suitable for use in contact with the tissue or organ of humans and animals without excessive toxicity, irritation, allergic response, immunogenicity, or other problems or complications, commensurate with a reasonable benefit / risk ratio. See, e.g., Remington: The Science and Practice of Pharmacy, 21st ed.; Lippincott Williams & Wilkins: Philadelphia, PA, 15 2005; Handbook of Pharmaceutical Excipients, 6th ed.; Rowe et al., Eds.; The Pharmaceutical Press and the American Pharmaceutical Association: 2009; Handbook of Pharmaceutical Additives, 3rd ed.; Ash and Ash Eds.; Gower Publishing Company: 2007; Pharmaceutical Preformulation and Formulation, 2nd ed.; Gibson Ed.; CRC Press LLC: Boca Raton, FL, 2009. As used herein, the “subject” refers to any animal, including mammals such as primates 20 (e.g., humans), mice, rats, other rodents, rabbits, dogs, cats, swine, cattle, sheep, horses, primates, and humans. In some embodiments, the subject is a human. In some embodiments, the subject has experienced and / or exhibited at least one symptom of the disease to be treated. As used herein a “therapeutically effective amount” means an amount of an entity (e.g, an ADC as described herein) that, when administered to a subject in need of such treatment, is 25 sufficient to (i) treat a particular disease, (ii) attenuate, ameliorate, or eliminate one or more symptoms of the particular disease, or (iii) delay the onset of one or more symptoms of the particular disease, as described herein. As used herein, terms “treat” or “treatment” refer to therapeutic or palliative measures. Beneficial or desired clinical results include, but are not limited to, alleviation, in whole or in 30 part, of symptoms associated with a disease, diminishment of the extent of the disease, stabilized (i.e., not worsening) state of disease, delay or slowing of cancer progression, amelioration or palliation of the disease state (e.g., one or more symptoms of the disease), and 18 Attorney Docket No.57891-0006WO1 remission (whether partial or total), whether detectable or undetectable. “Treatment” can also mean prolonging survival as compared to expected survival if not receiving treatment. Whenever a group is described as being “optionally substituted” that group may be unsubstituted or substituted with one or more of the indicated substituents. Likewise, when a 5 group is described as being “substituted” the substituent(s) may be selected from one or more the indicated substituents. If no substituents are indicated, it is meant that the indicated “optionally substituted” or “substituted” group may be substituted with one or more individually and independently selected group(s) that are stable and chemically acceptable for the group being substituted. Non-limiting examples of optional substituents are halogen, 10 cyano, hydroxyl, nitro, nitroso, azido, sulfhydryl, acyl, alkyl, hydroxyalkyl, aminoalkyl, alkoxyamino, haloalkyl, alkenyl, haloalkenyl, alkynyl, haloalkynyl, alkoxy, hydroxyalkoxy, alkoxyalkoxy, alkenoxy, alkynoxy, haloalkoxy, haloalkenoxy, haloalkynoxy, cycloalkyl, halocycloalkyl, cycloalkoxy, aryl, aryloxy, heteroaryl, heteroaryloxy, heterocyclyl, heterocyclyloxy, aralkyl, cycloalkylalkyl, heteroaralkyl, alkoxyalkyl, heterocyclylalkyl,15 thiocarbonyl, O-carbamyl, N-carbamyl, O-thiocarbamyl, N-thiocarbamyl, alkoxycarbonyl, C- amido, N-amido, S-sulfonamido, N-sulfonamido, sulfenyl, halosulfenyl, sulfonyl, sulfinyl, sulfoximino, sulfonimidamido, phosphine oxide, C-carboxy, O-carboxy, arylalkoxy, cycloalkylalkoxy, carboxaldehyde, iminyl, trihalomethanesulfonyl, trihalomethanesulfonamido, and ureido. 20 The term “halogen” refers to fluoro (F), chloro (Cl), bromo (Br), or iodo (I). The term “oxo” refers to a divalent doubly bonded oxygen atom (i.e., “=O”). As used herein, oxo groups are attached to carbon atoms to form carbonyls. The term "hydroxyl" refers to an -OH radical. The term “sulfhydryl” refers to a –SH radical. 25 The term "cyano" refers to a -CN radical. The term “azido” refers to a –N3 radical. The term “nitro” refers to a –NO2radical. The term “nitroso” refers to a –N=O radical. The term “alkyl” refers to a saturated acyclic hydrocarbon radical that may be a straight30 chain or branched chain, containing the indicated number of carbon atoms. For example, C1- C10 indicates that the group may have from 1 to 10 (inclusive) carbon atoms in it. Non-limiting examples include methyl, ethyl, iso-propyl, tert-butyl, n-hexyl. The term “saturated” as used 19 Attorney Docket No.57891-0006WO1 in this context means only single bonds present between constituent carbon atoms and other available valences occupied by hydrogen and / or other substituents as defined herein. The term “alkylene” refers to a bivalent alkyl group, as described herein, that may be a straight chain or branched chain, containing the indicated number of carbon atoms. Non- 5 limiting examples include methylene, ethylene, 1-propylene, 2-propylene, 2-methyl-2- propylene, tert-butylene, n-hexylene. An alkylene can optionally include one or more oxo (C=O) groups. When an alkylene group, as described herein, is substituted with, interrupted by, and / or has a methylene group “replaced” by a particular substituent or heteroatom, the substituent can 10 be connected in any appropriate way (e.g., valence, stability, and the like). For example, it is to be understood that an alkylene having two methylene groups replaced by oxygen atoms refers to two non-adjacent methylene groups (e.g., the oxygen atoms do not form a peroxide). In addition, the substitution of a cyclopropyl group on an alkylene refers to, for example, , while the replacement of a methylene of an alkylene refers to, for example,15 . As used herein, “alkenyl” refers to an alkyl group that contains in the straight or branched hydrocarbon chain one or more double bonds. As used herein, “alkynyl” refers to an alkyl group that contains in the straight or branched hydrocarbon chain one or more triple bonds. 20 The term “aryl” refers to a 6-20 carbon mono-, bi-, tri- or polycyclic group wherein at least one ring in the system is aromatic (e.g., 6-carbon monocyclic, 10-carbon bicyclic, or 14- carbon tricyclic aromatic ring system); and wherein 0, 1, 2, 3, or 4 atoms of each ring may be substituted by a substituent. Examples of aryl groups include phenyl, naphthyl, tetrahydronaphthyl, and the like.25The term “cycloalkyl” as used herein refers to cyclic saturated or partially unsaturated hydrocarbon groups having, e.g., 3 to 20 ring carbons, preferably 3 to 16 ring carbons, and more preferably 3 to 12 ring carbons or 3-10 ring carbons or 3-6 ring carbons, wherein the cycloalkyl group may be optionally substituted. Examples of cycloalkyl groups include, without limitation, cyclopropyl, cyclobutyl, cyclopentyl, cyclopentenyl, cyclohexyl, 30 cyclohexenyl, cycloheptyl, and cyclooctyl. Cycloalkyl may include multiple fused and / or bridged rings. Non-limiting examples of fused / bridged cycloalkyl includes: 20 Attorney Docket No.57891-0006WO1 bicyclo[1.1.0]butane, bicyclo[2.1.0]pentane, bicyclo[1.1.1]pentane, bicyclo[3.1.0]hexane, bicyclo[2.1.1]hexane, bicyclo[3.2.0]heptane, bicyclo[4.1.0]heptane, bicyclo[2.2.1]heptane, bicyclo[3.1.1]heptane, bicyclo[4.2.0]octane, bicyclo[3.2.1]octane, bicyclo[2.2.2]octane, and the like. Cycloalkyl also includes spirocyclic rings (e.g., spirocyclic bicycle wherein two rings 5 are connected through just one atom). Non-limiting examples of spirocyclic cycloalkyls include spiro[2.2]pentane, spiro[2.5]octane, spiro[3.5]nonane, spiro[3.5]nonane, spiro[3.5]nonane, spiro[4.4]nonane, spiro[2.6]nonane, spiro[4.5]decane, spiro[3.6]decane, spiro[5.5]undecane, and the like. The term “saturated” as used in this context means only single bonds present between constituent carbon atoms. 10 The term “heteroaryl”, as used herein, means a mono-, bi-, tri- or polycyclic group having 5 to 20 ring atoms, alternatively 5, 6, 9, 10, or 14 ring atoms; wherein at least one ring in the system contains one or more heteroatoms independently selected from the group consisting of N, O, S, P, B, and Si and at least one ring in the system is aromatic (but does not have to be a ring which contains a heteroatom, e.g. tetrahydroisoquinolinyl, e.g., 15 tetrahydroquinolinyl). Examples of heteroaryl include thienyl, pyridinyl, furyl, oxazolyl, oxadiazolyl, pyrrolyl, imidazolyl, triazolyl, thiodiazolyl, pyrazolyl, isoxazolyl, thiadiazolyl, pyranyl, pyrazinyl, pyrimidinyl, pyridazinyl, triazinyl, thiazolyl benzothienyl, benzoxadiazolyl, benzofuranyl, benzimidazolyl, benzotriazolyl, cinnolinyl, indazolyl, indolyl, isoquinolinyl, isothiazolyl, naphthyridinyl, purinyl, thienopyridinyl, pyrido[2,3-d]pyrimidinyl,20 pyrrolo[2,3-b]pyridinyl, quinazolinyl, quinolinyl, thieno[2,3-c]pyridinyl, pyrazolo[3,4- b]pyridinyl, pyrazolo[3,4-c]pyridinyl, pyrazolo[4,3-c]pyridine, pyrazolo[4,3-b]pyridinyl, tetrazolyl, chromane, 2,3-dihydrobenzo[b][1,4]dioxine, benzo[d][1,3]dioxole, 2,3- dihydrobenzofuran, tetrahydroquinoline, 2,3-dihydrobenzo[b][1,4]oxathiine, isoindoline, and others. In some embodiments, the heteroaryl is selected from thienyl, pyridinyl, furyl, 25 pyrazolyl, imidazolyl, isoindolinyl, pyranyl, pyrazinyl, and pyrimidinyl. For purposes of clarification, heteroaryl also includes aromatic lactams, aromatic cyclic ureas, or vinylogous analogs thereof, in which each ring nitrogen adjacent to a carbonyl is tertiary (i.e., all three valences are occupied by non-hydrogen substituents), such as one or more of pyridone (e.g., 21 Attorney Docket No.57891-0006WO1 imidazolone (e.g., wherein each ring nitrogen adjacent to a carbonyl is tertiary (i.e., the oxo group (i.e., “=O”) herein is a constituent part of the heteroaryl ring). The term “heterocyclyl” refers to a mono-, bi-, tri-, or polycyclic saturated or partially 5 unsaturated ring system with 3-16 ring atoms (e.g., 5-8 membered monocyclic, 8-12 membered bicyclic, or 11-14 membered tricyclic ring system) having 1-3 heteroatoms if monocyclic, 1-6 heteroatoms if bicyclic, or 1-9 heteroatoms if tricyclic or polycyclic, said heteroatoms selected from O, N, P, S, B, or Si (e.g., carbon atoms and 1-3, 1-6, or 1-9 heteroatoms of N, O, P, S, B, or Si if monocyclic, bicyclic, or tricyclic, respectively), wherein one or more ring atoms may 10 be substituted by 1-3 oxo (forming, e.g., a lactam or phosphinane oxide) and one or more N or S atoms may be substituted by 1-2 oxido (forming, e.g., an N-oxide, an S-oxide, or an S,S- dioxide),valence permitting; and wherein 0, 1, 2 or 3 atoms of each ring may be substituted by 1-2 substituents. Examples of heterocyclyl groups include piperazinyl, pyrrolidinyl, dioxanyl, morpholinyl, tetrahydrofuranyl, tetrahydropyridyl, dihydropyrazinyl, dihydropyridyl, 15 dihydropyrrolyl, dihydrofuranyl, dihydrothiophenyl, oxaphosphinanyl oxide, azaphosphinanyl oxide, and the like. Heterocyclyl may include multiple fused and bridged rings. Non-limiting examples of fused / bridged heteorocyclyl includes: 2-azabicyclo[1.1.0]butane, 2- azabicyclo[2.1.0]pentane, 2-azabicyclo[1.1.1]pentane, 3-azabicyclo[3.1.0]hexane, 5- azabicyclo[2.1.1]hexane, 3-azabicyclo[3.2.0]heptane, octahydrocyclopenta[c]pyrrole, 3-20 azabicyclo[4.1.0]heptane, 7-azabicyclo[2.2.1]heptane, 6-azabicyclo[3.1.1]heptane, 7- azabicyclo[4.2.0]octane, 2-azabicyclo[2.2.2]octane, 3-azabicyclo[3.2.1]octane, 2- oxabicyclo[1.1.0]butane, 2-oxabicyclo[2.1.0]pentane, 2-oxabicyclo[1.1.1]pentane, 3- oxabicyclo[3.1.0]hexane, 5-oxabicyclo[2.1.1]hexane, 3-oxabicyclo[3.2.0]heptane, 3- oxabicyclo[4.1.0]heptane, 7-oxabicyclo[2.2.1]heptane, 6-oxabicyclo[3.1.1]heptane, 7- 25 oxabicyclo[4.2.0]octane, 2-oxabicyclo[2.2.2]octane, 3-oxabicyclo[3.2.1]octane, and the like. Heterocyclyl also includes spirocyclic rings (e.g., spirocyclic bicycle wherein two rings are connected through just one atom). Non-limiting examples of spirocyclic heterocyclyls include 2-azaspiro[2.2]pentane, 4-azaspiro[2.5]octane, 1-azaspiro[3.5]nonane, 2-azaspiro[3.5]nonane, 7-azaspiro[3.5]nonane, 2-azaspiro[4.4]nonane, 6-azaspiro[2.6]nonane, 1,7-30 diazaspiro[4.5]decane, 7-azaspiro[4.5]decane 2,5-diazaspiro[3.6]decane, 3- 22 Attorney Docket No.57891-0006WO1 azaspiro[5.5]undecane, 2-oxaspiro[2.2]pentane, 4-oxaspiro[2.5]octane, 1- oxaspiro[3.5]nonane, 2-oxaspiro[3.5]nonane, 7-oxaspiro[3.5]nonane, 2-oxaspiro[4.4]nonane, 6-oxaspiro[2.6]nonane, 1,7-dioxaspiro[4.5]decane, 2,5-dioxaspiro[3.6]decane, 1- oxaspiro[5.5]undecane, 3-oxaspiro[5.5]undecane, 3-oxa-9-azaspiro[5.5]undecane and the 5 like. As used herein, examples of aromatic rings include: benzene, pyridine, pyrimidine, pyrazine, pyridazine, pyridone, pyrrole, pyrazole, oxazole, thioazole, isoxazole, isothiazole, and the like. The term “haloalkyl” refers to an alkyl, in which one or more hydrogen atoms is / are 10 replaced with an independently selected halogen. The term “halocycloalkyl” refers to a cycloalkyl, in which one or more hydrogen atoms is / are replaced with an independently selected halogen. The term “hydroxyalkyl” refers to an alkyl, in which one or more hydrogen atoms is / are replaced with hydroxyl. 15 The term “haloalkenyl” refers to an alkenyl, in which one or more hydrogen atoms is / are replaced with an independently selected halogen. The term “haloalkynyl” refers to an alkynyl, in which one or more hydrogen atoms is / are replaced with an independently selected halogen. The term “alkoxy” refers to an -O-alkyl radical (e.g., -OCH3). 20 The term “alkoxyalkyl” refers to an alkyl, in which one or two hydrogen atoms is / are replaced with an independently selected alkoxy (e.g., methoxyethyl). The term “hydroxyalkoxy” refers to an alkoxy group, in which one or two hydrogen atoms is / are replaced with hydroxy. The term “alkoxyalkoxy” refers to an alkoxy group, in which one or two hydrogen 25 atoms is / are replaced with an independently selected alkoxy. The term “alkoxyamino” refers to an –O-amino radical (e.g., -OCH2CH2N(CH3)2). The term “haloalkoxy” refers to an -O-haloalkyl radical (e.g., -OCF3). The term “alkenoxy” refers to an -O-alkenyl radical (e.g., -O-allyl). The term “haloalkenoxy” refers to an -O-haloalkenyl radical. 30 The term “alkynoxy” refers to an -O-alkynyl radical (e.g., -O-propargyl). The term “haloalkynoxy” refers to an -O-haloalkynyl radical. The term “cycloalkoxy” refers to an -O-cycloalkyl radical (e.g., -O-cyclopropyl). The term “aryloxy” refers to an -O-aryl radical (e.g., phenoxy). 23 Attorney Docket No.57891-0006WO1 The term “heteroaryloxy” refers to an -O-heteroaryl radical (e.g., pyridinoxy). The term “heterocyclyloxy” refers to an -O-heterocyclyl radical (e.g., -O-pyrrolidinyl or –O-oxetanyl). 5 The term “aralkyl” refer to an aryl group connected, as a substituent, via an alkyl group (e.g., benzyl). The term “cycloalkylalkyl” refers to a cycloalkyl group connected, as a substituent, via an alkyl group (e.g., ethylcyclobutyl). The term “heteroaralkyl” refers to a heteroaryl group connected, as a substituent, via an 10 alkyl group (e.g., methylpyrimidinyl). The term “heterocyclylalkyl” refers to a heterocyclyl group connected, as a substituent, via an alkyl group (e.g., methyloxetanyl). The term “aralkoxy” refers to an aryl group connected, as a substituent, via an alkoxy group (e.g., benzyloxy). 15 The term “cycloalkylalkoxy” refers to a cycloalkyl connected, as a substituent, via an alkoxy group (e.g., methoxycyclopropyl). The term “aminoalkyl” refers to an amino group connected, as a substituent, via an alkyl group (e.g., methyl(dimethylamino)). A “sulfenyl” group refers to an -SR group in which R can be hydrogen, alkyl, alkenyl, 20 alkynyl, cycloalkyl, cycloalkenyl, aryl, heteroaryl, heterocyclyl, aralkyl heteroaralkyl, heterocyclylalkyl, or cycloalkylalkyl. A “halosulfenyl” group refers to a sulfenyl, in which one or more hydrogen atoms is / are replaced with an independently selected halogen (e.g., -S(CF3) or –S(CHF2)). A “sulfinyl” group refers to an -S(=O)R group in which R can be the same as defined 25 with respect to sulfenyl. A “sulfonyl” group refers to an -SO2R group in which R can be the same as defined with respect to sulfenyl. A “sulfoximine” group refers to an –S(=O)(=NR)R’, where R is hydrogen, alkyl, haloalkyl, hydroxyalkyl, aminoalkyl, alkenyl, alkynyl, cycloalkyl, cycloalkenyl, aryl, 30 heteroaryl, heterocyclyl, aralkyl heteroaralkyl, heterocyclylalkyl, or cycloalkylalkyl; and where R’ alkyl, haloalkyl, hydroxyalkyl, aminoalkyl, alkenyl, alkynyl, cycloalkyl, cycloalkenyl, aryl, heteroaryl, heterocyclyl, aralkyl heteroaralkyl, heterocyclylalkyl, or cycloalkylalkyl. 24 Attorney Docket No.57891-0006WO1 A “sulfonimidamido” group refers to an –S(=O)(=NR)NR’R” where R, R’, and R” are independently hydrogen, alkyl, haloalkyl, hydroxyalkyl, aminoalkyl, alkenyl, alkynyl, cycloalkyl, cycloalkenyl, aryl, heteroaryl, heterocyclyl, aralkyl heteroaralkyl, heterocyclylalkyl, or cycloalkylalkyl; and where R’ alkyl, haloalkyl, hydroxyalkyl, aminoalkyl, 5 alkenyl, alkynyl, cycloalkyl, cycloalkenyl, aryl, heteroaryl, heterocyclyl, aralkyl heteroaralkyl, heterocyclylalkyl, or cycloalkylalkyl. An “O-carboxy” group refers to a RC(=O)O- group in which R can be hydrogen, alkyl, alkoxy, hydroxyalkyl, aminoalkyl, alkenyl, alkynyl, cycloalkyl, cycloalkenyl, aryl, heteroaryl, heterocyclyl, aralkyl heteroaralkyl, heterocyclylalkyl, or cycloalkylalkyl. 10 The terms “ester” and “C-carboxy” refer to a -C(=O)OR group in which R can be the same as defined with respect to O-carboxy. A “thiocarbonyl” group refers to a -C(=S)R group in which R can be the same as defined with respect to O-carboxy. A “trihalomethanesulfonyl” group refers to an X3CSO2- group wherein each X is a15halogen. A “trihalomethanesulfonamido” group refers to an X3CS(O)2N(R’)- group wherein each X is a halogen, and R’ is hydrogen, alkyl, alkenyl, alkynyl, cycloalkyl, cycloalkenyl, aryl, heteroaryl, heterocyclyl, aralkyl heteroaralkyl, heterocyclylalkyl, or cycloalkylalkyl. An “S-sulfonamido” group refers to a -SO2N(RR’) group in which R and R’ are 20 independently hydrogen, alkyl, alkoxy, hydroxyalkyl, aminoalkyl, alkenyl, alkynyl, cycloalkyl, cycloalkenyl, aryl, heteroaryl, heterocyclyl, aralkyl heteroaralkyl, heterocyclylalkyl, or cycloalkylalkyl. An “N-sulfonamido” group refers to a RSO2N(R’)- group in which R and R’ are independently hydrogen, alkyl, alkoxy, hydroxyalkyl, aminoalkyl, alkenyl, alkynyl, cycloalkyl,25cycloalkenyl, aryl, heteroaryl, heterocyclyl, aralkyl heteroaralkyl, heterocyclylalkyl, or cycloalkylalkyl. An “O-carbamyl” group refers to a -OC(=O)N(RR’) group in which R and R’ are independently hydrogen, alkyl, alkoxy, hydroxyalkyl, aminoalkyl, alkenyl, alkynyl, cycloalkyl, cycloalkenyl, aryl, heteroaryl, heterocyclyl, aralkyl heteroaralkyl, heterocyclylalkyl, or 30 cycloalkylalkyl. An “N-carbamyl” group refers to an ROC(=O)N(R’)- group in which R and R’ are independently hydrogen, alkyl, alkoxy, hydroxyalkyl, aminoalkyl, alkenyl, alkynyl, cycloalkyl, 25 Attorney Docket No.57891-0006WO1 cycloalkenyl, aryl, heteroaryl, heterocyclyl, aralkyl heteroaralkyl, heterocyclylalkyl, or cycloalkylalkyl. An “O-thiocarbamyl” group refers to a -OC(=S)N(RR’) group in which R and R’ are independently hydrogen, alkyl, alkoxy, hydroxyalkyl, aminoalkyl, alkenyl, alkynyl, cycloalkyl, 5 cycloalkenyl, aryl, heteroaryl, heterocyclyl, aralkyl heteroaralkyl, heterocyclylalkyl, or cycloalkylalkyl. An “N-thiocarbamyl” group refers to an ROC(=S)N(R’)— group in which R and R’ are independently hydrogen, alkyl, alkoxy, hydroxyalkyl, aminoalkyl, alkenyl, alkynyl, cycloalkyl, cycloalkenyl, aryl, heteroaryl, heterocyclyl, aralkyl heteroaralkyl, 10 heterocyclylalkyl, or cycloalkylalkyl. A “C-amido” group refers to a -C(=O)N(RR’) group in which R and R’ are independently hydrogen, alkyl, alkoxy, alkoxyalkyl, hydroxyalkyl, aminoalkyl, alkenyl, alkynyl, cycloalkyl, cycloalkenyl, aryl, heteroaryl, heterocyclyl, aralkyl heteroaralkyl, heterocyclylalkyl, or cycloalkylalkyl.15An “N-amido” group refers to a RC(=O)N(R’) group in which R and R’ are independently hydrogen, alkyl, alkoxy, hydroxyalkyl, aminoalkyl, alkenyl, alkynyl, cycloalkyl, cycloalkenyl, aryl, heteroaryl, heterocyclyl, aralkyl heteroaralkyl, heterocyclylalkyl, or cycloalkylalkyl. The terms “ureido” or “urea” refer to an –NR(C=O)NR’R’’ group, in which R, R’, and 20 R” are independently hydrogen, hydroxyl, alkyl, haloalkyl, hydroxyalkyl, aminoalkyl, alkenyl, alkynyl, cycloalkyl, cycloalkenyl, aryl, heteroaryl, heterocyclyl, aralkyl heteroaralkyl, heterocyclylalkyl, or cycloalkylalkyl. The term “carboxaldehyde” refers to a –C(=O)H radical. The term “imine” or “imino” refers to a –N=R radical, in which R is hydrogen,25hydroxyl, alkyl, haloalkyl, alkenyl, alkynyl, cycloalkyl, cycloalkenyl, aryl, heteroaryl, heterocyclyl, aralkyl heteroaralkyl, heterocyclylalkyl, or cycloalkylalkyl. The term “amino” refers to a –NRR’ radical, where R and R’ are independently hydrogen, alkyl, haloalkyl, hydroxyalkyl, alkenyl, alkynyl, cycloalkyl, cycloalkenyl, aryl, heteroaryl, heterocyclyl, aralkyl heteroaralkyl, heterocyclylalkyl, or cycloalkylalkyl. In some 30 instances, an amino group is –NH2, a mono-alkyl amine (R is hydrogen and R’ is alkyl) or a dialkylamine (R and R’ are independently selected alkyl). The term “phosphine oxide” refers to a –P(=O)RR’ radical, where R and R’ are independently alkyl, haloalkyl, hydroxyalkyl, aminoalkyl, alkenyl, alkynyl, cycloalkyl, 26 Attorney Docket No.57891-0006WO1 cycloalkenyl, aryl, heteroaryl, heterocyclyl, aralkyl heteroaralkyl, heterocyclylalkyl, or cycloalkylalkyl. As used herein, when a ring is described as being “partially unsaturated”, it means said ring has one or more additional degrees of unsaturation (in addition to the degree of unsaturation attributed to the ring itself; e.g., one or more double or triple bonds between 5 constituent ring atoms), provided that the ring is not aromatic. Examples of such rings include: cyclopentene, cyclohexene, cycloheptene, dihydropyridine, tetrahydropyridine, dihydropyrrole, dihydrofuran, dihydrothiophene, and the like. For the avoidance of doubt, and unless otherwise specified, for rings and cyclic groups (e.g., aryl, heteroaryl, heterocyclyl, cycloalkyl, and the like described herein) containing a 10 sufficient number of ring atoms to form bicyclic or higher order ring systems (e.g., tricyclic, polycyclic ring systems), it is understood that such rings and cyclic groups encompass those having fused rings, including those in which the points of fusion are located (i) on adjacent ring atoms (e.g., [x.x.0] ring systems, in which 0 represents a zero atom bridge (e.g., )); (ii) a single ring atom (spiro-fused ring systems) ( 15 ), or (iii) a contiguous array of ring atoms (bridged ring systems having all bridge lengths > 0) In addition, atoms making up the compounds of the present embodiments are intended to include all isotopic forms of such atoms. Isotopes, as used herein, include those atoms having the same atomic number but different mass numbers. By way of general example and without20limitation, isotopes of hydrogen include tritium and deuterium, and isotopes of carbon include 13C and14C. In addition, the compounds generically or specifically disclosed herein are intended to include all tautomeric forms. Thus, by way of example, a compound containing the moiety: encompasses the tautomeric form containing the moiety: . Similarly, 25 a pyridinyl or pyrimidinyl moiety that is described to be optionally substituted with hydroxyl encompasses pyridone or pyrimidone tautomeric forms. 27 Attorney Docket No.57891-0006WO1 The compounds provided herein may encompass various stereochemical forms. The compounds also encompass enantiomers (e.g., R and S isomers), diastereomers, as well as mixtures of enantiomers (e.g., R and S isomers) including racemic mixtures and mixtures of diastereomers, as well as individual enantiomers and diastereomers, which arise as a 5 consequence of structural asymmetry in certain compounds. Unless otherwise indicated, when a disclosed compound is named or depicted by a structure without specifying the stereochemistry (e.g., a “flat” structure) and has one or more chiral centers, it is understood to represent all possible stereoisomers of the compound. Likewise, unless otherwise indicated, when a disclosed compound is named or depicted by a structure that specifies the 10 stereochemistry (e.g., a structure with “wedge” and / or “dashed” bonds) and has one or more chiral centers, it is understood to represent the indicated stereoisomer of the compound. The details of one or more embodiments of this disclosure are set forth in the accompanying drawings and the description below. Other features and advantages of the present disclosure will be apparent from the description and drawings, and from the claims. 15 BRIEF DESCRIPTION OF THE DRAWINGS The following drawings illustrate certain embodiments of the features and advantages of this disclosure. These embodiments are not intended to limit the scope of the appended claims in any manner. Like reference symbols in the drawings indicate like elements. 20 Figure 1 shows a crosslinking and gel shift protocol. Figure 2 shows a gel shift assay after incubation between the antigen-binding domains shown and EGFR. Figure 3 is a gel shift assay showing crosslinking between the antigen-binding domains shown and EGFR after incubation. 25 Figure 4 is a gel shift assay showing crosslinking between the antigen-binding domains shown and EGFR with increased run time. Figure 5 is a Western blot showing crosslinking between the antigen-binding domains shown and EGFR. Figure 6 is a Western blot showing crosslinking between the antigen-binding domains 30 shown and EGFR. Figure 7 are graphs (left) showing crosslinking between the antigen-binding domains shown and EGFR over time and a Western blot showing crosslinking between the antigen- binding domain and EGFR. 28 Attorney Docket No.57891-0006WO1 Figure 8 shows a crosslinking and gel shift protocol (left) and a gel shift assay after incubation between the antigen-binding domains shown and EGFR. Figure 9 is a gel shift assay showing crosslinking between the antigen-binding domains shown and EGFR after incubation. 5 Figure 10 are Western blots showing crosslinking between the antigen-binding domains shown and EGFR. Figure 11 are Western blots showing crosslinking between the antigen-binding domains shown and EGFR. Figure 12 are Western blots showing crosslinking between the antigen-binding domains 10 and EGFR. Figure 13 is a crosslinking and gel shift protocol (left) and a gel shift assay (right) after incubation between S31C-MFS-5-1 and EGFR over time. Figure 14 is a gel shift assay (left) and graph (right) showing the percent covalency over time. 15 Figure 15 are mass spectrometry graphs showing a molecular weight difference between conjugated and non-conjugated antigen-binding domains. Figure 16 are Western blots showing covalent conjugation between the antigen-binding domains shown and EGFR in either EGFR+ or EGFR- cell lines. Figure 17 are Western blots showing covalent conjugation between the antigen-binding 20 domains shown and EGFR over time. Figure 18 shows a crosslinking and gel shift protocol (left) and a gel shift assay (right) after incubation between the antigen-binding domains shown and EGFR. Figure 19 shows a crosslinking and gel shift protocol (left) and a gel shift assay (right) after incubation between the antigen-binding domains shown and EGFR. 25 Figure 20 shows a crosslinking and gel shift protocol (left) and a gel shift assay (right) after incubation between the antigen-binding domains shown and EGFR. Figure 21 shows a crosslinking and gel shift protocol (left) and a gel shift assay (right) after incubation between the antigen-binding domains shown and EGFR. Figure 22 shows a crosslinking and gel shift protocol (left) and a gel shift assay (right) 30 after incubation between the antigen-binding domains shown and EGFR. Figure 23 shows a graph of the percent covalency of the antigen-binding domains shown and EGFR. 29 Attorney Docket No.57891-0006WO1 Figure 24 are Western blots showing crosslinking between the antigen-binding domains and EGFR. Lane values summarized in the table below. Figure 25 shows a crosslinking and gel shift protocol (left) and a gel shift assay (right) 5 after incubation between the antigen-binding domains shown and EGFR. Figure 26 shows a crosslinking and gel shift protocol (left) and a gel shift assay (right) after incubation between the antigen-binding domains shown and EGFR. For Figures 25 and 26, lane assignments for gel shift assays are provided in the Table below. 30 Attorney Docket No.57891-0006WO1 Figure 27 shows a graph of the percent covalency for the antigen-binding domains shown. Figure 28 is a Western blot showing covalency after 24 hours between the antigen- 5 binding domains shown and EGFR. Figure 29 shows SDS-PAGE analysis of preparative crosslinking reactions prior to digestion for LC-MS / MS. Figures 30 and 31 are mass spectrometry data showing conjugation between an antigen- binding domain and a linker. 10 Figure 32 is a Western blot showing crosslinking between the target antigen (EGFR) and the antigen-binding domains shown. Figure 33 and 34 are Western blots showing plasma stability of the complexes shown in Fig. 32 in human plasma. Figure 35 shows crosslink spectral matches from tandem mass spectrometry for15exemplary antigen-binding domains with linkers after reacting with antigen. DETAILED DESCRIPTION This disclosure provides biomolecules (e.g., a macromolecule, such as a polypeptide or a protein; or a smaller building block thereof (e.g., a peptide or an individual amino acid)), 20 having one or more reactive groups, e.g. having a covalent warhead, and compositions of same, as well as chemical entities that are useful for preparing the biomolecules described herein (any of the linkers described herein; e.g., compounds having formula (A) as described herein; e.g., 31 Attorney Docket No.57891-0006WO1 gold-containing organometallic agents), methods of making and using the proteins and compositions, kits comprising the protein or composition, and methods of screening. Gold Complex Embodiments 5 Variable R61In some embodiments, R61is divalent C6-10 aryl optionally substituted with 1-4 substituents independently selected from the group consisting of oxo, Ra, and Rb. In certain embodiments, R61is divalent phenyl optionally substituted with 1-4 substituents independently selected from the group consisting of Raand Rb. 10 In certain embodiments, R61is divalent phenyl optionally substituted with 1-4 independently selected Ra. In certain embodiments, R61is divalent phenyl optionally substituted with 1-2 independently selected Ra. In certain of the foregoing embodiments, each occurrence of Rais independently 15 selected from the group consisting of halo and C1-10 alkyl which is optionally substituted with 1-6 independently selected Rd. For example, wherein each occurrence of Racan be independently selected from the group consisting of fluoro and CH3. In some embodiments, R61is divalent heteroaryl of 5-10 ring atoms, wherein 1-4 ring 20 atoms are heteroatoms, each independently selected from the group consisting of N, N(H), N(Rc), O, and S(O)0-2, and wherein the heteroaryl is optionally substituted with 1-4 substituents independently selected from the group consisting of oxo, Ra, and Rb. Variable R6225 In some embodiments, R62is absent. In other embodiments, R62is C1-C16alkylene, C2-C16alkenylene, or C2-C16alkynylene, each of which is optionally substituted with 1-2 substituents independently selected from halogen and C3-C6 cycloalkyl; and wherein 1-8 alkylene units are optionally replaced with a 30 group independently selected from the group consisting of: (i) -O-; (ii) -NH-; (iii) -N(C1-C6 alkyl)-; 32 Attorney Docket No.57891-0006WO1 (iv) -C(O)-; (v) -S-; (vi) –S(O)–; (vii) –S(O)2–; 5 (viii) divalent C3-C10 cycloalkyl, which is optionally substituted with 1-4 Ra; (ix) divalent C6-C10 aryl, which is optionally substituted with 1-4 Ra; (x) divalent heteroaryl of 5-10 ring atoms, wherein 1-4 ring atoms are heteroatoms, each independently selected from the group consisting of N, N(H), N(Rc), O, and S(O)0-2; and which is optionally substituted with 1-4 Ra; and 10 (xi) divalent heterocyclyl of 3-10 ring atoms, wherein 1-3 ring atoms are heteroatoms, each independently selected from the group consisting of N, N(H), N(Rc), N(O-), O, and S(O)0-2, and which is optionally substituted with 1-4 Ra. In certain embodiments, R62is C1-C16alkylene, which is optionally substituted with 1- 15 2 substituents independently selected from halogen and C3-C6 cycloalkyl; and wherein 1-8 alkylene units are each optionally replaced with a group independently selected from the group consisting of: (i) -O-; (ii) -NH-; 20 (iii) -N(C1-C6alkyl)-; (iv) -C(O)-; (v) -S-; (vi) –S(O)–; (vii) –S(O)2–; 25 (viii) divalent C3-C10 cycloalkyl, which is optionally substituted with 1-4 Ra; (ix) divalent phenyl, which is optionally substituted with 1-4 Ra; (x) divalent heteroaryl of 5-10 ring atoms, wherein 1-4 ring atoms are heteroatoms, each independently selected from the group consisting of N, N(H), N(Rc), O, and S(O)0-2; and which is optionally substituted with 1-4 Ra; and 30 (xi) divalent heterocyclyl of 3-10 ring atoms, wherein 1-3 ring atoms are heteroatoms, each independently selected from the group consisting of N, N(H), N(Rc), N(O-), O, and S(O)0-2, and which is optionally substituted with 1-4 Ra. 33 Attorney Docket No.57891-0006WO1 In certain embodiments, R62is C1-C8alkylene, which is optionally substituted with 1- 2 substituents independently selected from halogen and C3-C6 cycloalkyl; and wherein 1-6 alkylene units are each optionally replaced with a group independently selected from the group consisting of: 5 (i) -O-; (ii) -NH-; (iii) -N(C1-C6alkyl)-; (iv) -C(O)-; (v) -S-; 10 (vi) –S(O)–; (vii) –S(O)2–; (viii) divalent C3-C10 cycloalkyl, which is optionally substituted with 1-4 Ra; (ix) divalent phenyl, which is optionally substituted with 1-4 Ra; (x) divalent heteroaryl of 5-10 ring atoms, wherein 1-4 ring atoms are heteroatoms, each 15 independently selected from the group consisting of N, N(H), N(Rc), O, and S(O)0-2; and which is optionally substituted with 1-4 Ra; and (xi) divalent heterocyclyl of 3-10 ring atoms, wherein 1-3 ring atoms are heteroatoms, each independently selected from the group consisting of N, N(H), N(Rc), N(O-), O, and S(O)0- 2, and which is optionally substituted with 1-4 Ra. 20 In certain embodiments, R62is C1-C8alkylene, which is optionally substituted with 1- 2 substituents independently selected from halogen and C3-C6 cycloalkyl; and wherein 1-6 alkylene units are each optionally replaced with a group independently selected from the group consisting of: 25 (i) -O-; (ii) -NH-; (iii) -N(C1-C6alkyl)-; (iv) -C(O)-; (viii) divalent C3-C10 cycloalkyl, which is optionally substituted with 1-4 Ra; 30 (ix) divalent phenyl, which is optionally substituted with 1-4 Ra; and (xi) divalent heterocyclyl, wherein 1-3 ring atoms are heteroatoms, each independently selected from the group consisting of N, N(H), N(Rc), N(O-), O, and S(O)0-2, and which is optionally substituted with 1-4 Ra. 34 Attorney Docket No.57891-0006WO1 In certain embodiments, R62has formula (II): **-(L11)n11-(L12)n12-(L13)n13-(L14)n14-(L15)n15-*** (II) 5 wherein ** indicates the point of attachment of formula (II) to R61, and *** indicates the point of attachment of formula (II) to the reactive group; wherein each of n11, n12, n13, n14, and n15 is independently 0 or 1, provided that at least one of n11, n12, n13, n14, and n15 is 1; and 10 each occurrence of L11, L12, L13, L14, and L15is independently selected from the group consisting of: (i) -O-; (ii) -NH-; (iii) -N(C1-C6alkyl)-; 15 (iv) -C(O)-; (v) -S-; (vi) –S(O)–; (vii) –S(O)2–; (viii) divalent C3-C10 cycloalkyl, which is optionally substituted with 1-4 Ra; 20 (ix) divalent phenyl, which is optionally substituted with 1-4 Ra; (x) divalent heteroaryl of 5-10 ring atoms, wherein 1-4 ring atoms are heteroatoms, each independently selected from the group consisting of N, N(H), N(Rc), O, and S(O)0-2; and which is optionally substituted with 1-4 Ra; (xi) divalent heterocyclyl of 3-10 ring atoms, wherein 1-3 ring atoms are heteroatoms,25 each independently selected from the group consisting of N, N(H), N(Rc), N(O-), O, and S(O)0- 2, and which is optionally substituted with 1-4 Ra; and (xi) C1-C2alkylene. In some formula (II) embodiments, each occurrence of L11, L12, L13, L14, and L15is 30 independently selected from the group consisting of: (i) -O-; (ii) -NH-; (iii) -N(C1-C6 alkyl)-; 35 Attorney Docket No.57891-0006WO1 (iv) -C(O)-; (viii) divalent C3-C10 cycloalkyl, which is optionally substituted with 1-4 Ra; (ix) divalent phenyl, which is optionally substituted with 1-4 Ra; (xi) divalent heterocyclyl of 3-10 ring atoms, wherein 1-3 ring atoms are heteroatoms, 5 each independently selected from the group consisting of N, N(H), N(Rc), N(O-), O, and S(O)0- 2, and which is optionally substituted with 1-4 Ra; and (xi) C1-C2alkylene. In certain formula (II) embodiments, n11 is 1. In certain of these formula (II) embodiments, L11is -NH-. 10 In other of these formula (II) embodiments, L11is -O-. In still other of these embodiments, L11is -CH2-. In still other of these embodiments, L11is -C(O)-. In certain formula (II) embodiments, n15 is 1. 15 In certain of these formula (II) embodiments, L15is divalent phenyl, which is optionally substituted with 1-4 Ra. For example, L15is unsubstituted divalent phenyl. In certain formula (II) embodiments, one of n12, n13, and n14 is 1, and the others are 0. 20 In certain formula (II) embodiments, two of n12, n13, and n14 are 1, and the other is 0. In certain formula (II) embodiments, each of n12, n13, and n14 is 1. In certain formula (II) embodiments, each of n12, n13, and n14 is 0. In certain of these formula (II) embodiments, each of L12, L13, and L14is independently 25 selected from the group consisting of: (iv) -C(O)-; (viii) divalent C3-C10cycloalkyl, which is optionally substituted with 1-4 Ra; (ix) divalent phenyl, which is optionally substituted with 1-4 Ra; (xi) divalent heterocyclyl of 3-10 ring atoms, wherein 1-3 ring atoms are heteroatoms,30 each independently selected from the group consisting of N, N(H), N(Rc), N(O-), O, and S(O)0-2, and which is optionally substituted with 1-4 Ra; and (xi) C1-C2 alkylene. 36 Attorney Docket No.57891-0006WO1 For example, each of L12, L13, and L14, when present, can each independently be selected from the group consisting of -C(O)-, divalent cyclohexyl, and divalent piperidinyl. In certain formula (II) embodiments, n11 is 1, and n15 is 1. 5 In certain of these formula (II) embodiments, L11is -NH-. In certain of these formula (II) embodiments, L11is -O-. In certain of these formula (II) embodiments, L11is -CH2-. In certain of these formula (II) embodiments, L11is -C(O)-. 10 In certain of the foregoing formula (II) embodiments, L15is divalent phenyl, which is optionally substituted with 1-4 Ra. For example, L15can be unsubstituted divalent phenyl. In certain of the foregoing formula (II) embodiments, one, two, or three of n12, n13, and 15 n14 are 1, and the others are 0. In certain of the foregoing formula (II) embodiments, each of n12, n13, and n14 is 0. In other formula (II) embodiments, each of L12, L13, and L14is independently selected from the group consisting of: 20 (iv) -C(O)-; (viii) divalent C3-C10cycloalkyl, which is optionally substituted with 1-4 Ra; (ix) divalent phenyl, which is optionally substituted with 1-4 Ra; (xi) divalent heterocyclyl of 3-10 ring atoms, wherein 1-3 ring atoms are heteroatoms, each independently selected from the group consisting of N, N(H), N(Rc), N(O-), O, and S(O)0-25 2, and which is optionally substituted with 1-4 Ra; and (xi) C1-C2 alkylene. For example, each of L12, L13, and L14is independently selected from the group consisting of -C(O)-, divalent cyclohexyl, and divalent piperidinyl. 30 In certain formula (II) embodiments: n11 is 1, and n15 is 1; L11is -NH-. -O-, -CH2-, or -C(O)-; optionally wherein L11is -NH- or -O-; 37 Attorney Docket No.57891-0006WO1 L15is divalent phenyl, which is optionally substituted with 1-4 Ra; optionally wherein, L15is unsubstituted divalent phenyl; and each of n12, n13, and n14 is 0. 5 In certain formula (II) embodiments: n11 is 1, and n15 is 1; L11is -NH-. -O-, -CH2-, or -C(O)-; optionally wherein L11is -NH- or -O-; L15is divalent phenyl, which is optionally substituted with 1-4 Ra; optionally wherein, L15is unsubstituted divalent phenyl; 10 one, two, or three of n12, n13, and n14 are 1, and the others are 0; and each of L12, L13, and L14is independently selected from the group consisting of: (iv) -C(O)-; (viii) divalent C3-C10 cycloalkyl, which is optionally substituted with 1-4 Ra; (ix) divalent phenyl, which is optionally substituted with 1-4 Ra; 15 (xi) divalent heterocyclyl of 3-10 ring atoms, wherein 1-3 ring atoms are heteroatoms, each independently selected from the group consisting of N, N(H), N(Rc), N(O-), O, and S(O)0- 2, and which is optionally substituted with 1-4 Ra; and (xi) C1-C2 alkylene. For example, each of L12, L13, and L14can be independently selected from the group 20 consisting of -C(O)-, divalent cyclohexyl, and divalent piperidinyl. Variable R63Variable R63is a reactive group. Non-limiting examples of reactive groups include: 25 1) α,β unsaturated systems (e.g., LW1-EWG, wherein LW1is alkenyl or alkynyl; and EWG is an electron withdrawing group; e.g., Michael acceptors, e.g., acrylamides, acrylates, vinylsulfones, α,β-unsaturated ketones, and the like) 2) Strained heterocycles (e.g., heterocycles including from 3-4 ring atoms wherein 1 ring atom is a heteroatom selected from oxygen, nitrogen, and sulfur; e.g., epoxide, aziridine, 30 beta-lactam, and other strained systems); 3) Strained carbocyclic systems (e.g., cyclopropyl substituted with one or more electron-withdrawing groups); 38 Attorney Docket No.57891-0006WO1 4) Electron-deficient arenes / heteroarenes (e.g., pyridine or fluorobenzene) which can undergo SNAr reaction (e.g., with cysteine or lysine); 5) Sulfur-containing heteroarenes (e.g., thiadiazole); 6) Styrenyl moieties (i.e., aryl / heteroaryl that is directly conjugated to an alkenyl or 5 alkynyl); 7) Activated ketone (e.g., halomethylketone); 8) Acylating agents (e.g., carbamates, aza-peptides, acyl hydroxamates); 9) phosphonylating agents (e.g., phosphonyl fluorides), 10) sulfonylation agents (e.g., sulfonyl fluoride, e.g., -OSO2-F or sulfonyl-HET, e.g., - 10 OSO2-HET, in which HET is an optionally substituted heteroaryl of 5-10 ring atoms, wherein from 1-4 ring atoms are heteroatoms, each independently selected from the group consisting of N and N(H); and wherein the heteroaryl is linked to the sulfur atom by a ring nitrogen atom); 11) Aldehydes; 12) Boronic acids or boronic esters; and 15 13) Organonitrile compounds (e.g., alkyl nitrile, cyanamide, or acyl cyanamide). Exemplary reactive groups include, but are not limited to: NRX; and RXis hydrogen, C1-C6 alkyl, or C3-C6 cycloalkyl. 20 In certain embodiments, R63is , wherein X is O. In certain embodiments, R63is sulfonyl-HET, e.g., -OSO2-HET, in which HET is an optionally substituted heteroaryl of 5-10 ring atoms, wherein from 1-4 ring atoms are heteroatoms, each independently selected from the group consisting of N and N(H); and 25 wherein the heteroaryl is linked to the sulfur atom by a ring nitrogen atom. In other embodiments, HET can further include O and / or S. In certain of the foregoing embodiments, HET is an optionally substituted heteroaryl of 5-6 ring atoms, wherein from 1-4 ring atoms are heteroatoms, each independently selected from 39 Attorney Docket No.57891-0006WO1 the group consisting of N and N(H); and wherein the heteroaryl is linked to the sulfur atom by a ring nitrogen atom. In certain of the foregoing embodiments, HET is an optionally substituted heteroaryl of 5 ring atoms, wherein from 1-4 ring atoms are heteroatoms, each independently selected from 5 the group consisting of N and N(H); and wherein the heteroaryl is linked to the sulfur atom by a ring nitrogen atom. For example, HET can be pyrrolyl, imidazolyl, triazolyl, pyrazolyl, or tetrazolyl. In certain of the foregoing embodiments, HET is an optionally substituted heteroaryl of 6 ring atoms, wherein from 1-2 ring atoms are heteroatoms, each independently selected from 10 the group consisting of N and N(H); and wherein the heteroaryl is linked to the sulfur atom by a ring nitrogen atom. For example, HET can be 6-member aromatic lactams, aromatic cyclic ureas, or vinylogous analogs thereof, in which each ring nitrogen adjacent to a carbonyl is tertiary (i.e., all three valences are occupied by non-hydrogen substituents), such as one or more 15 carbonyl is tertiary (i.e., the oxo group (i.e., “=O”) herein is a constituent part of the heteroaryl ring). Non-limiting examples of sulfonyl-HET are provided below (here, for illustrative20purposes only, as a substituent present on a gold complex): 40 Attorney Docket No.57891-0006WO1 , 5 Variables Ring A, R1and R2and R3and R4In some embodiments, Ring A is C6-14aryl optionally substituted with 1-4 substituents independently selected from the group consisting of oxo, Ra, and Rb. In certain embodiments, Ring A is phenyl optionally substituted with 1-4 substituents independently selected from the group consisting of oxo, Ra, and Rb. 10 41 Attorney Docket No.57891-0006WO1 In some embodiments, each of R1and R2is independently C3-12cycloalkyl optionally substituted with substituents independently selected from the group consisting of oxo, Ra, and Rb. 5 In certain embodiments,each of R1and R2is independently C5-7 cycloalkyl optionally substituted with substituents independently selected from the group consisting of oxo, Ra, and Rb. In certain embodiments,each of R1and R2is independently C6 cycloalkyl optionally substituted with substituents independently selected from the group consisting of oxo, Ra, and 10 Rb. In some embodiments, each of R3and R4is independently C1-10 alkyl optionally substituted with 1-4 independently selected Rd. In certain embodiments, each of R3and R4is CH3. 15 Variable R5In some embodiments, R5is monovalent (i.e., including one formal negative charge). An anionic counterion may also be multivalent (i.e., including more than one formal negative charge), such as divalent or trivalent. Exemplary monovalent anions include halide ions (e.g., 20 F–, Cl–, Br–, I–), NO3–, ClO4–, OH–, H2PO4–, HCO3−,HSO4–, sulfonate ions (e.g., methansulfonate, trifluoromethanesulfonate, p– toluenesulfonate, benzenesulfonate, 10– camphor sulfonate, naphthalene–2–sulfonate, naphthalene–1–sulfonic acid–5–sulfonate, ethan–1–sulfonic acid–2–sulfonate), carboxylate ions (e.g., acetate, propanoate, benzoate, glycerate, lactate, tartrate, glycolate, gluconate), BF4−, PF4–, PF6–, AsF6–, SbF6–, B[3,5- 25 (CF3)2C6H3]4]–, B(C6F5)4−, BPh4–, Al(OC(CF3)3)4–, and carborane anions (e.g., CB11H12–or (HCB11Me5Br6)–). Exemplary anions which may be multivalent include CO32−, HPO42−, PO433−, B4O72−, SO42−, S2O32−, carboxylate anions (e.g., tartrate, citrate, fumarate, maleate, malate, malonate, gluconate, succinate, glutarate, adipate, pimelate, suberate, azelate, sebacate, salicylate, phthalates, aspartate, glutamate, and the like), and carboranes. 30 In some embodiments, R5is chloro. Non-Limiting Combinations [A] 42 Attorney Docket No.57891-0006WO1 In some embodiments: R61is divalent C6-10 aryl optionally substituted with 1-4 substituents independently selected from the group consisting of oxo, Ra, and Rb; e.g., R61is divalent phenyl optionally substituted with 1-4 substituents independently selected from the group consisting of Raand 5 Rband R62is absent; In some embodiments of [A], R63is: 10 NRX; and RXis hydrogen, C1-C6 alkyl, or C3-C6 cycloalkyl. In certain embodiments of [A], R63is , wherein X is O. In certain embodiments of [A], R63is -OSO2-HET. In some embodiments of [A], R5is chloro. 15 In some embodiments of [A], each of R1and R2is independently C5-7cycloalkyl optionally substituted with substituents independently selected from the group consisting of oxo, Ra, and Rb; e.g., each of R1and R2is independently C6 cycloalkyl optionally substituted with substituents independently selected from the group consisting of oxo, Ra, and Rb. In some embodiments of [A], each of R3and R4is independently C1-10 alkyl optionally20substituted with 1-4 independently selected Rd; e.g., each of R3and R4is CH3. In some embodiments of [A], Ring A is phenyl optionally substituted with 1-4 substituents independently selected from the group consisting of oxo, Ra, and Rb. [B] 25 In some embodiments: R61is divalent C6-10 aryl optionally substituted with 1-4 substituents independently selected from the group consisting of oxo, Ra, and Rb; e.g., R61is divalent phenyl optionally 43 Attorney Docket No.57891-0006WO1 substituted with 1-4 substituents independently selected from the group consisting of Raand Rband R62is C1-C16 alkylene, C2-C16 alkenylene, or C2-C16 alkynylene, each of which is optionally substituted with 1-2 substituents independently selected from halogen and C3-C65 cycloalkyl; and wherein 1-8 alkylene units are optionally replaced with a group independently selected from the group consisting of: (i) -O-; (ii) -NH-; (iii) -N(C1-C6 alkyl)-; 10 (iv) -C(O)-; (v) -S-; (vi) –S(O)–; (vii) –S(O)2–; (viii) divalent C3-C10cycloalkyl, which is optionally substituted with 1-4 Ra; 15 (ix) divalent C6-C10 aryl, which is optionally substituted with 1-4 Ra; (x) divalent heteroaryl of 5-10 ring atoms, wherein 1-4 ring atoms are heteroatoms, each independently selected from the group consisting of N, N(H), N(Rc), O, and S(O)0-2; and which is optionally substituted with 1-4 Ra; and (xi) divalent heterocyclyl of 3-10 ring atoms, wherein 1-3 ring atoms are heteroatoms,20 each independently selected from the group consisting of N, N(H), N(Rc), N(O-), O, and S(O)0-2, and which is optionally substituted with 1-4 Ra. In some embodiments of [B], R62has formula (II): In some embodiments of [B], n11 is 1. In some embodiments of [B], L11is -NH-. 25 In some embodiments of [B], L11is -O-. In some embodiments of [B], L11is -CH2-. In some embodiments of [B], L11is -C(O)-. In some embodiments of [B], n15 is 1. In some embodiments of [B], L15is divalent phenyl, which is optionally substituted 30 with 1-4 Ra. For example, L15is unsubstituted divalent phenyl. In some embodiments of [B], one of n12, n13, and n14 is 1, and the others are 0. In some embodiments of [B], two of n12, n13, and n14 are 1, and the other is 0. In some embodiments of [B], each of n12, n13, and n14 is 1. 44 Attorney Docket No.57891-0006WO1 In some embodiments of [B], each of n12, n13, and n14 is 0. In some embodiments of [B], each of L12, L13, and L14is independently selected from the group consisting of: (iv) -C(O)-; 5 (viii) divalent C3-C10 cycloalkyl, which is optionally substituted with 1-4 Ra; (ix) divalent phenyl, which is optionally substituted with 1-4 Ra; (xi) divalent heterocyclyl of 3-10 ring atoms, wherein 1-3 ring atoms are heteroatoms, each independently selected from the group consisting of N, N(H), N(Rc), N(O-), O, and S(O)0- 2, and which is optionally substituted with 1-4 Ra; and 10 (xi) C1-C2alkylene. For example, each of L12, L13, and L14, when present, can each independently be selected from the group consisting of -C(O)-, divalent cyclohexyl, and divalent piperidinyl. In some embodiments of [B], R63is:15 NRX; and RXis hydrogen, C1-C6 alkyl, or C3-C6 cycloalkyl. In certain embodiments of [B], R63is , wherein X is O. In certain embodiments of [B], R63is -OSO2-HET.20In some embodiments of [B], R5is chloro. In some embodiments of [B], each of R1and R2is independently C5-7cycloalkyl optionally substituted with substituents independently selected from the group consisting of oxo, Ra, and Rb; e.g., each of R1and R2is independently C6 cycloalkyl optionally substituted with substituents independently selected from the group consisting of oxo, Ra, and Rb. 25 In some embodiments of [B], each of R3and R4is independently C1-10alkyl optionally substituted with 1-4 independently selected Rd; e.g., each of R3and R4is CH3. In some embodiments of [B], Ring A is phenyl optionally substituted with 1-4 substituents independently selected from the group consisting of oxo, Ra, and Rb. 45 Attorney Docket No.57891-0006WO1 In some embodiments, the compound of formula (I) is selected from a compound in Table L. In some embodiments, the protein is modified by a chemical linker selected from Table L. 5 Table L. Exemplary Linkers 46 Attorney Docket No.57891-0006WO1 47 Attorney Docket No.57891-0006WO1 48 Attorney Docket No.57891-0006WO1 49 Attorney Docket No.57891-0006WO1 50 Attorney Docket No.57891-0006WO1 51 Attorney Docket No.57891-0006WO1 52 Attorney Docket No.57891-0006WO1 53 Attorney Docket No.57891-0006WO1 54 Attorney Docket No.57891-0006WO1 55 Attorney Docket No.57891-0006WO1 56 Attorney Docket No.57891-0006WO1 57 Attorney Docket No.57891-0006WO1 58 Attorney Docket No.57891-0006WO1 59 Attorney Docket No.57891-0006WO1 60 Attorney Docket No.57891-0006WO1 61 Attorney Docket No.57891-0006WO1 62 Attorney Docket No.57891-0006WO1 63 Attorney Docket No.57891-0006WO1 64 Attorney Docket No.57891-0006WO1 Proteins 65 Attorney Docket No.57891-0006WO1 Some embodiments provide a protein comprising an antigen-binding domain, wherein the antigen-binding domain comprising an oxime, the oxime having the structure: , wherein: 5 * and ** represent the points of connection of the oxime to the antigen-binding domain; L1is a bond or a C1-C6 alkylene optionally substituted with 1-2 substituents independently selected from halogen and C3-C6 cycloalkyl, and wherein 1-2 alkylene units are optionally replaced by O, N, C3-C6 cycloalkyl, or phenyl; R1is azido, tetrazinyl, a C2-C3 alkyne, or an optionally substituted C8-C12 10 cycloalkyne. In some embodiments, the oxime is connected to the antigen-binding domain via an L amino acid. In some embodiments, the oxime is connected to the antigen-binding domain via a D amino acid. In some embodiments, L1is a C1-C6 alkylene optionally substituted with 1-215substituents independently selected from halogen and C3-C6 cycloalkyl, and wherein 1-2 alkylene units are optionally replaced by O, N, C3-C6 cycloalkyl, or phenyl. In some embodiments, L1is a C1-C6 alkylene substituted with 1-2 substituents independently selected from halogen and C3-C6 cycloalkyl. In some embodiments, L1is a C1-C6 alkylene wherein 1-2 alkylene units are replaced 20 by O, N, C3-C6 cycloalkyl, or phenyl. In some embodiments, L1is a C1-C6 alkylene. In some embodiments, L1is methylene or ethylene. In some embodiments, L1is n-propylene or isopropylene. In some embodiments, L1is a C4-C6 cycloalkyl (for example, by replacing a single methylene group with the C4-C6 cycloalkyl).25In some embodiments, L1is a PEG unit. In some embodiments, L1is , wherein “a” represents the point of connection of L1to the oxime and “b” represents the point of connection of L1to R1. In some embodiments, L1is a bond. 66 Attorney Docket No.57891-0006WO1 In some embodiments, R1is azido. In some embodiments, R1is tetrazinyl. In some embodiments, R1is a C2-C3 alkyne. In some embodiments, R1is an optionally substituted C8-C12 cycloalkyne. In some 5 embodiments, R1is a C8-C12 cycloalkyne. In some embodiments, . Some embodiments provide a protein comprising an antigen-binding domain, wherein the antigen-binding domain comprises a modified phenylalanine residue, the modified10phenylalanine residue having the structure: , wherein: * and ** represent the points of connection of the modified phenylalanine residue to the antigen-binding domain; 15 L2is a C2-C16 alkylene optionally substituted with 1-2 substituents independently selected from halogen and C3-C6 cycloalkyl, and wherein 1-6 alkylene units are optionally replaced by O, N, S, C3-C10 cycloalkyl, phenyl, 5-12 membered heteroaryl, and 4-14 membered heterocyclyl; 67 Attorney Docket No.57891-0006WO1 X is O or NRX; RXis hydrogen, C1-C6 alkyl, or C3-C6 cycloalkyl; 5 R3is halogen or C1-C6 alkyl; R4is hydrogen or C1-C6 alkyl; R4Ais C1-C6 alkyl or C3-C6 cycloalkyl; R5Aand R5Bare independently hydrogen, halogen, or C1-C6 alkyl; or R5Aand R5Btogether with the carbon atom to which they are attached form a 10 cyclopropyl; Ring A is a 4-10 membered heterocyclyl. In some embodiments, L2is a C2-C16 alkylene optionally substituted with 1-2 substituents independently selected from halogen and C3-C6 cycloalkyl, and wherein 1-6 alkylene units are optionally replaced by O, N, S, C3-C10 cycloalkyl, phenyl, 5-12 membered15heteroaryl, -C(O)-, and 4-14 membered heterocyclyl. In some embodiments, L2is a C1-C16 alkylene optionally substituted with 1-2 substituents independently selected from halogen and C3-C6 cycloalkyl, and wherein 1-6 alkylene units are optionally replaced by O, N, S, C3-C10 cycloalkyl, phenyl, 5-12 membered heteroaryl, -C(O)-, and 4-14 membered heterocyclyl. 20 Some embodiments provide a protein comprising an antigen-binding domain, wherein the antigen-binding domain comprises a modified cysteine residue, the modified cysteine residue having the structure: , 25 wherein: 68 Attorney Docket No.57891-0006WO1 * and ** represent the points of connection of the modified cysteine residue to the antigen-binding domain; wherein “a” represents the point of connection of L to the sulfur atom of the modified cysteine 5 residue and “b” represents the point of connection of L to L2; n is 1 or 2; RL1, RL2, and RL3, are each independently selected C1-C10 alkyl; L2is a C2-C16 alkylene optionally substituted with 1-2 substituents independently selected from halogen and C3-C6 cycloalkyl, and wherein 1-6 alkylene units are optionally 10 replaced by O, N, S, C3-C10 cycloalkyl, phenyl, 5-12 membered heteroaryl, and 4-14 membered heterocyclyl; , X is O or NRX; 15 RXis hydrogen, C1-C6 alkyl, or C3-C6 cycloalkyl; R3is halogen or C1-C6 alkyl; R4is hydrogen or C1-C6 alkyl; R4Ais C1-C6 alkyl or C3-C6 cycloalkyl; R5Aand R5Bare independently hydrogen, halogen, or C1-C6 alkyl; or20R5Aand R5Btogether with the carbon atom to which they are attached form a cyclopropyl; Ring A is a 4-10 membered heterocyclyl. In some embodiments, L2is a C2-C16 alkylene optionally substituted with 1-2 substituents independently selected from halogen and C3-C6 cycloalkyl, and wherein 1-6 25 alkylene units are optionally replaced by O, N, S, C3-C10 cycloalkyl, phenyl, 5-12 membered heteroaryl, -C(O)-, and 4-14 membered heterocyclyl. 69 Attorney Docket No.57891-0006WO1 In some embodiments, L2is a C1-C16 alkylene optionally substituted with 1-2 substituents independently selected from halogen and C3-C6 cycloalkyl, and wherein 1-6 alkylene units are optionally replaced by O, N, S, C3-C10 cycloalkyl, phenyl, 5-12 membered heteroaryl, -C(O)-, and 4-14 membered heterocyclyl. 5 In some embodiments, it is provided that the structure does not contain a GLP-1 peptide or variant thereof, optionally wherein the structure does not contain a modified GLP-1peptide, optionally wherein the structure does not contain a peptide as described in WO 2025 / 076010. In some embodiments, L is , wherein “a” represents the point of connection of L to the sulfur atom of the modified cysteine residue and “b” represents the point of10connection of L to L2. In some embodiments, n is 1. In some embodiments, n is 2. In some embodiments, L is , wherein “a” represents the point of connection of L to the sulfur atom of the modified cysteine residue and “b” represents the point of connection of L to L2. 15 In some embodiments, L is , wherein “a” represents the point of connection of L to the sulfur atom of the modified cysteine residue and “b” represents the point of connection of L to L2. In some embodiments, L is , wherein “a” represents the point of connection of L to the sulfur atom of the modified cysteine residue and “b” represents the point of20connection of L to L2. In some embodiments, RL1is a C1-C6 alkyl. In some embodiments, RL1is ethyl. 70 Attorney Docket No.57891-0006WO1 In some embodiments, , wherein “a” represents the point of connection of L to the sulfur atom of the modified cysteine residue and “b” represents the point of connection of L to L2. In some embodiments, RL2and RL3are independently selected C1-C6 alkyl. In some 5 embodiments, RL2and RL3are each methyl. In some embodiments, L is a bond. In some embodiments, L2is a C2-C16 alkylene optionally substituted with 1-2 substituents independently selected from halogen and C3-C6 cycloalkyl. In some embodiments, L2is a C2-C16 alkylene wherein 1-6 alkylene units are10 optionally replaced by O, N, S, C3-C10 cycloalkyl, phenyl, 5-12 membered heteroaryl, and 4- 14 membered heterocyclyl. In some embodiments, L2is a C2-C16 alkylene substituted with 1-2 substituents independently selected from halogen and C3-C6 cycloalkyl, and wherein 1-6 alkylene units are optionally replaced by O, N, S, C3-C10 cycloalkyl, phenyl, 5-12 membered heteroaryl, and 4-1514 membered heterocyclyl. In some embodiments, L2is a C2-C16 alkylene optionally substituted with 1-2 substituents independently selected from halogen and C3-C6 cycloalkyl, and wherein 1-6 alkylene units are replaced by O, N, S, C3-C10 cycloalkyl, phenyl, 5-12 membered heteroaryl, and 4-14 membered heterocyclyl. 20 In some embodiments, L2is a C2-C16 alkylene substituted with 1-2 substituents independently selected from halogen and C3-C6 cycloalkyl, and wherein 1-6 alkylene units are replaced by O, N, S, C3-C10 cycloalkyl, phenyl, 5-12 membered heteroaryl, and 4-14 membered heterocyclyl. In some embodiments, L2is a C2-C16 alkylene. In some embodiments, L2is a C2-C625alkylene. In some embodiments, L2comprises one triazole ring. In some embodiments, the triazole is a single 5-membered ring. In some embodiments, the triazole is part of a larger (e.g., fused) ring system. 71 Attorney Docket No.57891-0006WO1 In some embodiments, L2is selected from the group consisting of: , wherein “a” represents the point of connection of L2to L or to the modified 5 phenylalanine residue or to the modified cysteine residue and “b” represents the point of connection of L2to R2. In some embodiments, L2is selected from the group consisting of: wherein “a” represents the point of connection of L2to L or to the modified 10 phenylalanine residue or to the modified cysteine residue and “b” represents the point of connection of L2to R2. In some embodiments, L2is selected from the group consisting of: , 15wherein “a” represents the point of connection of L2to L or to the modified phenylalanine residue or to the modified cysteine residue and “b” represents the point of connection of L2to R2. 72 Attorney Docket No.57891-0006WO1 In some embodiments, wherein “a” represents the point of connection of L2to L or to the modified phenylalanine residue or to the modified cysteine residue and “b” represents the point of connection of L2to R2. 5 In some embodiments, R2is . In some embodiments, X is NRX. In some embodiments, RXis hydrogen. In some embodiments, RXis C1-C6 alkyl. In some embodiments, RXis methyl. In some embodiments, RXis C3-C6 cycloalkyl. In some embodiments, RXis 10 cyclopropyl. In some embodiments, X is O. In some embodiments, . In some embodiments, R4Ais C1-C6 alkyl. In some embodiments, R4Ais methyl. In some embodiments, R4Ais C3-C6 cycloalkyl. 15 In some embodiments, . In some embodiments, R4is C1-C6 alkyl. In some embodiments, R4is methyl. In some embodiments, R4is hydrogen. In some embodiments, . In some embodiments, R5Aand R5Bare independently hydrogen, halogen, or C1-C6 20 alkyl. In some embodiments, R5Aand R5Bare each hydrogen. In some embodiments, R5Aand R5Bare each independently C1-C6 alkyl. In some embodiments, one of R5Aand R5Bis hydrogen and the other of R5Aand R5Bis C1-C6 alkyl. In some embodiments, one of R5Aand R5Bis halogen and the other of R5Aand R5Bis hydrogen, halogen, or C1-C6 alkyl. 73 Attorney Docket No.57891-0006WO1 In some embodiments, R5Aand R5Btogether with the carbon atom to which they are attached form a cyclopropyl. In some embodiments, Ring A is a 4-10 membered heterocyclyl. In some embodiments, Ring A is a 5-6 membered heterocyclyl. In some embodiments, Ring A is 5 piperidine or piperazine. In some embodiments, . In some embodiments, . In some embodiments, . In some embodiments, . 10 In some embodiments, . In some embodiments, L2is selected from the group consisting of: wherein “a” represents the point of connection of L2to L or to the modified phenylalanine residue or to the modified cysteine residue and “b” represents the point of 15 connection of L2to R2. In some embodiments, . In some embodiments, R3is halogen. In some embodiments, R3is C1-C6 alkyl. 74 Attorney Docket No.57891-0006WO1 In some embodiments, , , , , wherein * represents the point of connection of L2to L. In some embodiments, the modified amino acid residue is an L modified amino acid 5 residue. In some embodiments, the modified amino acid residue is a D modified amino acid residue. In some embodiments, the modified amino acid residue is present in a CDR of the antigen-binding domain. In some embodiments, the CDR is a heavy chain CDR. In some embodiments, the CDR is a light chain CDR. 10 In some embodiments, the modified amino acid residue is present in a framework region of the antigen-binding domain. In some embodiments, the modified phenylalanine residue is an L modified phenylalanine residue. In some embodiments, the modified phenylalanine residue is a D modified phenylalanine residue. 15 In some embodiments, the modified phenylalanine residue is present in a CDR of the antigen-binding domain. In some embodiments, the CDR is a heavy chain CDR. In some embodiments, the CDR is a light chain CDR. In some embodiments, the modified phenylalanine residue is present in a framework region of the antigen-binding domain. 20 In some embodiments, the modified cysteine residue is an L modified cysteine residue. In some embodiments, the modified cysteine residue is a D modified cysteine residue. In some embodiments, the modified cysteine residue is present in a CDR of the antigen- binding domain. In some embodiments, the CDR is a heavy chain CDR. In some embodiments, the CDR is a light chain CDR. 25 In some embodiments, the modified cysteine residue is present in a framework region of the antigen-binding domain. In some embodiments, the protein is an antibody. In some embodiments, the antibody is a human antibody, a humanized antibody, or a veneered antibody. In some embodiments, the antibody is a human IgG1, human IgG2, human IgG3, or human IgG4 antibody. 75 Attorney Docket No.57891-0006WO1 In some embodiments, the protein is or comprises a single chain Fv (scFv), a VHH, a VNAR, a DARpin, a single domain antibody (sdAb), an Adnectin / Centyrin, an Affibody, a Knottin, a bicyclic peptide, or a cyclic peptide. In some embodiments, the protein further comprises a conjugated cytotoxic or 5 cytostatic agent. In some embodiments, the protein comprises a radioisotope. Examples of radioisotopes include, but are not limited to At211, 1131, 1125, Y90, Re186, Re188, Sm153, Bi212or213, P32and radioactive isotopes of Lu including Lu177. In some embodiments, the antigen-binding domain specifically binds to a target protein. 10 In some embodiments, the target protein comprises an extracellular domain, and the antigen-binding domain specifically binds to the extracellular domain. Any of the proteins comprising an antigen-binding domain described herein can be a single polypeptide, or can include two, three, four, five, six, seven, eight, nine, or ten (the same or different) polypeptides. In some embodiments where the protein is a single polypeptide, the 15 protein can include a single antigen-binding domain or two antigen-binding domains. In some embodiments where the protein is a single polypeptide and includes two antigen-binding domains, the first and second antigen-binding domains can be identical or different from each other (and can specifically bind to the same or different antigens or epitopes). In some embodiments where the protein is a single polypeptide, the antigen-binding domain can each be independently selected from the group of: a VH domain, a VHH domain, a VNAR domain, a scFv, a DARpin, a single domain antibody (sdAb), an Adnectin / Centyrin, an Affibody, a bicyclic peptide (see, e.g., Eder et al., Cancer Res.79(4):841-852, 2019; Gan et al., J. Med. Chem. 66(21):14623-14632, 2023), or a cyclic peptide (see, e.g., Costa et al., Pharmaceuticals 16(7):996, 2023). In some embodiments where the protein is a single polypeptide, the protein can comprise or be a BiTe, a (scFv)2, a nanobody, a nanobody-HSA, a DART, a TandAb, a scDiabody, a scDiabody-CH3, scFv-CH-CL-scFv, a HSAbody, scDiabody-HAS, a tandem-scFv, a scFv, a sdAb, an Affibody, a Knottin, an Adnectin / Centyrin, a DARPin, a fibronectin, a DEP conjugate, a bicyclic peptide, or a cyclic peptide. Additional examples of antigen-binding domains that can be used when the protein is a single polypeptide are known in the art. A VHH domain is a single monomeric variable antibody domain that can be found in20camelids. A VNAR domain is a single monomeric variable antibody domain that can be found in cartilaginous fish. Non-limiting aspects of VHH domains and VNAR domains are described 76 Attorney Docket No.57891-0006WO1 in, e.g., Cromie et al., Curr. Top. Med. Chem.15:2543-2557, 2016; De Genst et al., Dev. Comp. Immunol. 30:187-198, 2006; De Meyer et al., Trends Biotechnol. 32:263-270, 2014; Kijanka et al., Nanomedicine 10:161-174, 2015; Kovaleva et al., Expert. Opin. Biol. Ther. 14:1527- 1539, 2014; Krah et al., Immunopharmacol. Immunotoxicol. 38:21-28, 2016; Mujic-Delic et 5 al., Trends Pharmacol. Sci.35:247-255, 2014; Muyldermans, J. Biotechnol.74:277-302, 2001; Muyldermans et al., Trends Biochem. Sci. 26:230-235, 2001; Muyldermans, Ann. Rev. Biochem. 82:775-797, 2013; Rahbarizadeh et al., Immunol. Invest. 40:299-338, 2011; Van Audenhove et al., EBioMedicine 8:40-48, 2016; Van Bockstaele et al., Curr. Opin. Investig. Drugs 10:1212-1224, 2009; Vincke et al., Methods Mol. Biol. 911:15-26, 2012; and 10 Wesolowski et al., Med. Microbiol. Immunol. 198:157-174, 2009. In some embodiments where the protein is a single polypeptide and includes two antigen-binding domains, the first antigen-binding domain and the second antigen-binding domain can both be VHH domains, or at least one antigen-binding domain can be a VHH domain. In some embodiments where the protein is a single polypeptide and includes two 15 antigen-binding domains, the first antigen-binding domain and the second antigen-binding domain are both VNAR domains, or at least one antigen-binding domain is a VNAR domain. In some embodiments where the protein is a single polypeptide, the antigen-binding domain is a scFv domain. In some embodiments where the protein is a single polypeptide and includes two antigen-binding domains, the first antigen-binding domain and the second antigen-binding 20 domain can both be scFv domains, or at least one antigen-binding domain can be a scFv domain. In some embodiments, the protein can include two or more polypeptides (e.g., two, three, four, five, six, seven, eight, nine, or ten polypeptides). In some embodiments where the protein includes two or more polypeptides, two, three, four, five or six of the polypeptides of the two or more polypeptides can be identical. In some embodiments where the protein includes two or more polypeptides (e.g., two, three, four, five, six, seven, eight, nine, or ten polypeptides), two or more of the polypeptides of the protein can assemble (e.g., non-covalently assemble) to form one or more antigen- binding domains, e.g., an antigen-binding fragment of an antibody (e.g., any of the antigen- binding fragments of an antibody described herein), a VHH-scAb, a VHH-Fab, a Dual scFab, a F(ab’)2, a diabody, a crossMab, a DAF (two-in-one), a DAF (four-in-one), a DutaMab, a DT- IgG, a knobs-in-holes common light chain, a knobs-in-holes assembly, a charge pair, a Fab- arm exchange, a SEEDbody, a LUZ-Y, a Fcab, a κλ-body, an orthogonal Fab, a DVD-IgG, a 77 Attorney Docket No.57891-0006WO1 IgG(H)-scFv, a scFv-(H)IgG, IgG(L)-scFv, scFv-(L)IgG, IgG(L,H)-Fv, IgG(H)-V, V(H)-IgG, IgG(L)-V, V(L)-IgG, KIH IgG-scFab, 2scFv-IgG, IgG-2scFv, scFv4-Ig, Zybody, DVI-IgG, Diabody-CH3, a triple body, a miniantibody, a minibody, a TriBi minibody, scFv-CH3 KIH, Fab-scFv, a F(ab’)2-scFv2, a scFv-KIH, a Fab-scFv-Fc, a tetravalent HCAb, a scDiabody-Fc, a Diabody-Fc, a tandem scFv-Fc, a VHH-Fc, a tandem VHH-Fc, a VHH-Fc KiH, a Fab-VHH- Fc, an Intrabody, a dock and lock, an ImmTAC, an IgG-IgG conjugate, a Cov-X-Body, a scFv1-PEG-scFv2, an Adnectin, a DARPin, a fibronectin, and a DEP conjugate. See, e.g., Spiess et al., Mol. Immunol. 67:95-106, 2015, incorporated in its entirety herewith, for a description of these elements. Non-limiting examples of an antigen-binding fragment of an antibody include an Fv fragment, a Fab fragment, a F(ab')2fragment, and a Fab' fragment. Additional examples of an antigen-binding fragment of an antibody is an antigen-binding fragment of an IgG (e.g., an antigen-binding fragment of IgG1, IgG2, IgG3, or IgG4) (e.g., an antigen-binding fragment of a human or humanized IgG, e.g., human or humanized IgG1, IgG2, IgG3, or IgG4); an antigen-binding fragment of an IgA (e.g., an antigen-binding fragment of IgA1 or IgA2) (e.g., an antigen-binding fragment of a human or humanized IgA, e.g., a human or humanized IgA1 or IgA2); an antigen-binding fragment of an IgD (e.g., an antigen-binding fragment of a human or humanized IgD); an antigen-binding fragment of an IgE (e.g., an antigen-binding fragment of a human or humanized IgE); or an antigen-binding fragment of an IgM (e.g., an antigen-binding fragment of a human or humanized IgM). A “Fv” fragment includes a non-covalently-linked dimer of one heavy chain variable domain and one light chain variable domain. A “Fab” fragment includes, the constant domain of the light chain and the first constant domain (CH1) of the heavy chain, in addition to the heavy and light chain variable domains of 5 the Fv fragment. A “F(ab')2” fragment includes two Fab fragments joined, near the hinge region, by disulfide bonds. A “dual variable domain immunoglobulin” or “DVD-Ig” refers to multivalent and multispecific binding proteins as described, e.g., in DiGiammarino et al., Methods Mol. Biol.10899:145-156, 2012; Jakob et al., MABs 5:358-363, 2013; and U.S. Patent Nos. 7,612,181; 8,258,268; 8,586,714; 8,716,450; 8,722,855; 8,735,546; and 8,822,645, each of which is incorporated by reference in its entirety. DARTs are described in, e.g., Garber, Nature Reviews Drug Discovery 13:799-801, 2014. 78 Attorney Docket No.57891-0006WO1 Additional aspects of antigen-binding domains are known in the art. In some embodiments of any of the proteins described herein, the KD of the antigen- binding domain at a physiological pH (e.g., pH 7.4) is between about 1 pM to about 5 ^M (e.g., about 1 pM to about 2 ^M, about 1 pM to about 1 ^M, about 1 pM to about 500 nM, about 1 5 pM to about 250 nM, about 1 pM to about 200 nM, about 1 pM to about 100 nM, about 1 pM to about 50 nM, about 1 pM to about 10 nM, about 1 pM to about 1 nM, about 1 pM to about 800 pM, about 1 pM to about 600 pM, about 1 pM to about 400 pM, about 1 pM to about 200 pM, about 1 pM to about 100 pM, about 1 pM to about 50 pM, about 50 pM to about 5 ^M, about 50 pM to about 2 ^M, about 50 pM to about 1 ^M, about 50 pM to about 500 nM, about 10 50 pM to about 250 nM, about 50 pM to about 200 nM, about 50 pM to about 100 nM, about 50 pM to about 50 nM, about 50 pM to about 10 nM, about 50 pM to about 1 nM, about 50 pM to about 800 pM, about 50 pM to about 600 pM, about 50 pM to about 400 pM, about 50 pM to about 200 pM, about 50 pM to about 100 pM, about 100 pM to about 5 ^M, about 100 pM to about 2 ^M, about 100 pM to about 1 ^M, about 100 pM to about 500 nM, about 100 pM to15about 250 nM, about 100 pM to about 200 nM, about 100 pM to about 100 nM, about 100 pM to about 50 nM, about 100 pM to about 10 nM, about 100 pM to about 1 nM, about 100 pM to about 800 pM, about 100 pM to about 600 pM, about 100 pM to about 400 pM, about 100 pM to about 200 pM, about 200 pM to about 5 ^M, about 200 pM to about 2 ^M, about 200 pM to about 1 ^M, about 200 pM to about 500 nM, about 200 pM to about 250 nM, about 200 pM to 20 about 200 nM, about 200 pM to about 100 nM, about 200 pM to about 50 nM, about 200 pM to about 10 nM, about 200 pM to about 1 nM, about 200 pM to about 800 pM, about 200 pM to about 600 pM, about 200 pM to about 400 pM, about 400 pM to about 5 ^M, about 400 pM to about 2 ^M, about 400 pM to about 1 ^M, about 400 pM to about 500 nM, about 400 pM to about 250 nM, about 400 pM to about 200 nM, about 400 pM to about 100 nM, about 400 pM 25 to about 50 nM, about 400 pM to about 10 nM, about 400 pM to about 1 nM, about 400 pM to about 800 pM, about 400 pM to about 600 pM, about 600 pM to about 5 ^M, about 600 pM to about 2 ^M, about 600 pM to about 1 ^M, about 600 pM to about 500 nM, about 600 pM to about 250 nM, about 600 pM to about 200 nM, about 600 pM to about 100 nM, about 600 pM to about 50 nM, about 600 pM to about 10 nM, about 600 pM to about 1 nM, about 600 pM to30about 800 pM, about 800 pM to about 5 ^M, about 800 pM to about 2 ^M, about 800 pM to about 1 ^M, about 800 pM to about 500 nM, about 800 pM to about 250 nM, about 800 pM to about 200 nM, about 800 pM to about 100 nM, about 800 pM to about 50 nM, about 800 pM to about 10 nM, about 800 pM to about 1 nM, about 1 nM to about 5 ^M, about 1 nM to about 79 Attorney Docket No.57891-0006WO1 2 ^M, about 1 nM to about 1 ^M, about 1 nM to about 500 nM, about 1 nM to about 250 nM, about 1 nM to about 200 nM, about 1 nM to about 100 nM, about 1 nM to about 50 nM, about 1 nM to about 10 nM, about 10 nM to about 5 ^M, about 10 nM to about 2 ^M, about 10 nM to about 1 ^M, about 10 nM to about 500 nM, about 10 nM to about 250 nM, about 10 nM to 5 about 200 nM, about 10 nM to about 100 nM, about 10 nM to about 50 nM, about 50 nM to about 5 ^M, about 50 nM to about 2 ^M, about 50 nM to about 1 ^M, about 50 nM to about 500 nM, about 50 nM to about 250 nM, about 50 nM to about 200 nM, about 50 nM to about 100 nM, about 100 nM to about 5 ^M, about 100 nM to about 2 ^M, about 100 nM to about 1 ^M, about 100 nM to about 500 nM, about 100 nM to about 250 nM, about 100 nM to about 10 200 nM, about 200 nM to about 5 ^M, about 200 nM to about 2 ^M, about 200 nM to about 1 ^M, about 200 nM to about 500 nM, about 200 nM to about 250 nM, about 250 nM to about 5 ^M, about 250 nM to about 2 ^M, about 250 nM to about 1 ^M, about 250 nM to about 500 nM, about 500 nM to about 5 ^M, about 500 nM to about 2 ^M, about 500 nM to about 1 ^M, about 1 ^M to about 5 ^M, about 1 ^M to about 2 ^M, or about 2 ^M to about 5 ^M. 15 In some embodiments, the protein comprising an antigen-binding domain can further comprise a conjugated cytotoxic or cytostatic agent. Examples of cytotoxic or cytostatic agent include, but are not limited to auristatins (e.g., auristatin E, auristatin F, MMAE and MMAF), auromycins, maytansinoids, ricin, duocarmycins, dolastatins, doxorubicin, daunorubicin, taxols (e.g., paclitaxel), cisplatin, 20 camptothecin, CC-1065, amatoxins, ethidium bromide, mitomycin, etoposide, tenoposide, vincristine, vinblastine, colchicine, actinomycin, calicheamicin, Pseudomonas exotoxin (PE), diphtheria toxin (DT) Expression of a Protein Comprising an Antigen-Binding Domain in a Cell 25 Also provided herein are methods of generating a recombinant cell that expresses an protein (e.g., any of the proteins including an antigen-binding domain described herein) that include: introducing into a cell a nucleic acid encoding the protein to produce a recombinant cell; and culturing the recombinant cell under conditions sufficient for the expression of the protein. In some embodiments, the introducing step includes introducing into a cell an 30 expression vector including a nucleic acid encoding the protein to produce a recombinant cell. Any of the proteins described herein can be produced by any cell, e.g., a eukaryotic cell or a prokaryotic cell. As used herein, the term “eukaryotic cell” refers to a cell having a distinct, membrane-bound nucleus. Such cells may include, for example, mammalian (e.g., rodent, non- 80 Attorney Docket No.57891-0006WO1 human primate, or human), insect, fungal, or plant cells. In some embodiments, the eukaryotic cell is a yeast cell, such as Saccharomyces cerevisiae. In some embodiments, the eukaryotic cell is a higher eukaryote, such as mammalian, avian, plant, or insect cells. As used herein, the term “prokaryotic cell” refers to a cell that does not have a distinct, membrane-bound nucleus. 5 In some embodiments, the prokaryotic cell is a bacterial cell. Methods of culturing cells are well known in the art. Cells can be maintained in vitro under conditions that favor proliferation, differentiation, and growth. Briefly, cells can be cultured by contacting a cell (e.g., any cell) with a cell culture medium that includes the necessary growth factors and supplements to support cell viability and growth. 10 Methods of introducing nucleic acids and expression vectors into a cell (e.g., a eukaryotic cell) are known in the art. Non-limiting examples of methods that can be used to introduce a nucleic acid into a cell include lipofection, transfection, electroporation, microinjection, calcium phosphate transfection, dendrimer-based transfection, cationic polymer transfection, cell squeezing, sonoporation, optical transfection, impalection, 15 hydrodynamic delivery, magnetofection, viral transduction (e.g., adenoviral and lentiviral transduction), and nanoparticle transfection. Provided herein are methods that further include isolation of the protein from a cell (e.g., a eukaryotic cell) using techniques well-known in the art (e.g., ammonium sulfate precipitation, polyethylene glycol precipitation, ion-exchange chromatography (anion or 20 cation), chromatography based on hydrophobic interaction, metal-affinity chromatography, ligand-affinity chromatography, and size exclusion chromatography). Compositions Also provided herein are compositions (e.g., pharmaceutical compositions) that include at least one of any of the proteins described herein and at least one pharmaceutically acceptable 25 excipient. In some embodiments, the compositions (e.g., pharmaceutical compositions) can be disposed in a sterile vial or a pre-loaded syringe. In some embodiments, the compositions (e.g., pharmaceutical compositions) are formulated for different routes of administration (e.g., intravenous, subcutaneous, intramuscular, or intratumoral). In some embodiments, the compositions (e.g., pharmaceutical 30 compositions) can include a pharmaceutically acceptable carrier (e.g., phosphate buffered saline). Single or multiple administrations of any of the pharmaceutical compositions described herein can be given to a subject depending on, for example: the dosage and frequency as required and tolerated by the subject. A dosage of the pharmaceutical composition should 81 Attorney Docket No.57891-0006WO1 provide a sufficient quantity of the protein to effectively treat or ameliorate conditions, diseases, or symptoms. Also provided herein are methods of treating a subject having a cancer (e.g., any of the cancers described herein) that include administering a therapeutically effective amount of at 5 least one of any of the compositions or pharmaceutical compositions provided herein. Kits Also provided herein are kits that include any of the proteins described herein, any of the compositions described herein, or any of the pharmaceutical compositions described herein. 10 In some embodiments, the kits can include instructions for performing any of the methods described herein. In some embodiments, the kits can include at least one dose of any of the compositions (e.g., pharmaceutical compositions) described herein. In some embodiments, the kits can provide a syringe for administering any of the pharmaceutical compositions described herein. In some embodiments, the kits can include instructions for administration of the 15 pharmaceutical composition to a human subject. Methods of Treatment Provided herein are methods of treating a subject in need thereof that include: administering a therapeutically effective amount of any of the pharmaceutical compositions described herein or any of the proteins comprising an antigen-binding domain described herein to a subject identified as being in need thereof. In some embodiments, the subject is further administered one or more additional therapeutic agents. In some embodiments, the one or more additional therapeutic agents is 20 administered to the subject at approximately the same time as any of the proteins described herein are administered to the subject. In some embodiments, the one or more additional therapeutic agents are administered to the subject after the administration of any of the proteins described herein to the subject. In some embodiments, the one or more additional therapeutic agents are administered to the subject before the administration of any of the proteins described25herein to the subject. Also provided herein are methods of inducing or increasing (e.g., at least a 1% increase, at least a 5% increase, at least a 10% increase, at least a 15% increase, at least a 20% increase, at least a 30% increase, at least a 40% increase, or at least a 50% increase) internalization of a target protein (specifically bound by the antigen-binding domain of the protein) that includes 82 Attorney Docket No.57891-0006WO1 contacting the mammalian cell with the protein, e.g., as compared to the level of internalization of the target protein in the absence of the protein. In some embodiments, the mammalian cell is in vivo. In some embodiments, the mammalian cell is in vitro. Also provided are methods of inhibiting (e.g., at least a 1% decrease, at least a 5% 5 decrease, at least a 10% decrease, at least a 20% decrease, at least a 30% decrease, at least a 40% decrease, at least a 50% decrease, at least a 60% decrease, at least a 70% decrease, at least a 80% decrease, or at least a 90% decrease) an activity of a target protein (specifically bound by the antigen-binding domain of the protein) in a mammalian cell that includes contacting the target protein with the protein, e.g., as compared to the level of activity of the target protein in 10 the absence of the protein. In some embodiments, the mammalian cell is in vivo. In some embodiments, the mammalian cell is in vitro. Also provided are methods of reducing (e.g., at least a 1% decrease, at least a 5% decrease, at least a 10% decrease, at least a 20% decrease, at least a 30% decrease, at least a 40% decrease, at least a 50% decrease, at least a 60% decrease, at least a 70% decrease, at least 15 a 80% decrease, or at least a 90% decrease) the amount of the target protein (specifically bound by the antigen-binding domain of the protein) in a mammalian cell that includes contacting the target protein with the protein, e.g., as compared to the amount of the target protein in the absence of the protein. In some embodiments, the mammalian cell is in vivo. In some embodiments, the mammalian cell is in vitro. 20 Also provided are methods of inducing (e.g., at least a 1% increase, at least a 5% increase, at least a 10% increase, at least a 15% increase, at least a 20% increase, at least a 30% increase, at least a 40% increase, or at least a 50% increase) cell death in a mammalian cell comprising the target protein (specifically bound by the antigen-binding domain of the protein) that includes contacting the cell with the protein, e.g., as compared to the level of cell death in 25 a similar mammalian cell not contacted with the protein. In some embodiments, the mammalian cell is in vivo. In some embodiments, the mammalian cell is in vitro. Methods of Screening Also provided herein are methods for screening for a protein that forms a 30 covalent bond with a target protein in a mammalian cell that include contacting the target protein with any of the proteins that include an antigen-binding domain described herein and determining whether a covalent bond has been formed between the protein and the target protein. In some embodiments, the method further includes determining whether the 83 Attorney Docket No.57891-0006WO1 mammalian cell has internalized the protein. In some embodiments, the method further includes determining whether the contacting has inhibiting an activity of the target protein and / or determining whether the contacting has induced cell death of the mammalian cell. In some embodiments, the method further includes testing the protein in an animal model of a 5 disease. Protein-Protein Conjugates Some embodiments provide a protein-protein conjugate comprising a first protein A and a second protein B, wherein the protein-protein conjugate has the structure: 10 , wherein the first protein A comprises an antigen-binding domain, wherein the antigen- binding domain comprises a modified phenylalanine residue, wherein: * and ** represent the points of connection of the modified phenylalanine residue to the antigen-binding domain of the first protein A; 15 L2is a C2-C16 alkylene optionally substituted with 1-2 substituents independently selected from halogen and C3-C6 cycloalkyl, and wherein 1-6 alkylene units are optionally replaced by O, N, S, C3-C10 cycloalkyl, phenyl, 5-12 membered heteroaryl, and 4-14 membered heterocyclyl; , 20 , “a” represents the connection of R2Ato L2, “b” represents the connection of R2Ato protein B, N* is a nitrogen atom of a lysine residue of protein B, S* is a sulfur atom of a cysteine residue of protein B, O* is an oxygen atom from a serine residue or a threonine residue 84 Attorney Docket No.57891-0006WO1 of protein B, Nb is the nitrogen atom of a histidine residue of protein B and the connection of R2Ato protein B, and O** is an oxygen atom from a tyrosine residue of protein B; X is O or NRX; RXis hydrogen, C1-C6 alkyl, or C3-C6 cycloalkyl; 5 R3is halogen or C1-C6 alkyl; R4is hydrogen or C1-C6 alkyl; R4Ais C1-C6 alkyl or C3-C6 cycloalkyl; R5Aand R5Bare independently hydrogen, halogen, or C1-C6 alkyl; or R5Aand R5Btogether with the carbon atom to which they are attached form a 10 cyclopropyl; Ring A is a 4-10 membered heterocyclyl; wherein the antigen-binding domain of the first protein A specifically binds to the second protein B. In some embodiments, L2is a C2-C16 alkylene optionally substituted with 1-2 15 substituents independently selected from halogen and C3-C6 cycloalkyl, and wherein 1-6 alkylene units are optionally replaced by O, N, S, C3-C10 cycloalkyl, phenyl, 5-12 membered heteroaryl, -C(O)-, and 4-14 membered heterocyclyl. In some embodiments, L2is a C1-C16 alkylene optionally substituted with 1-2 substituents independently selected from halogen and C3-C6 cycloalkyl, and wherein 1-6 20 alkylene units are optionally replaced by O, N, S, C3-C10 cycloalkyl, phenyl, 5-12 membered heteroaryl, -C(O)-, and 4-14 membered heterocyclyl. In some embodiments, the modified phenylalanine residue is present in a CDR of the antigen-binding domain. In some embodiments, the CDR is a heavy chain CDR. In some 25 embodiments, the CDR is a light chain CDR. In some embodiments, the modified phenylalanine residue is present in a framework region of the antigen-binding domain. Some embodiments provide a protein-protein conjugate comprising a first protein A and a second protein B, wherein the protein-protein conjugate has the structure: 85 Attorney Docket No.57891-0006WO1 , wherein the first protein A comprises an antigen-binding domain, wherein the antigen- binding domain comprises a modified cysteine residue, wherein: * and ** represent the points of connection of the modified cysteine residue to the 5 antigen-binding domain; , wherein a represents the point of connection of L to the sulfur atom of the modified cysteine residue and b represents the point of connection of L to L2; n is 1 or 2;10RL1, RL2, and RL3, are each independently selected C1-C10 alkyl; L2is a C2-C16 alkylene optionally substituted with 1-2 substituents independently selected from halogen and C3-C6 cycloalkyl, and wherein 1-6 alkylene units are optionally replaced by O, N, S, C3-C10 cycloalkyl, phenyl, 5-12 membered heteroaryl, and 4-14 membered heterocyclyl; 15 , , “a” represents the connection of R2Ato L2, “b” represents the connection of R2Ato protein B, N* is a nitrogen atom of a lysine residue of protein B, S* is a sulfur atom of a 20 cysteine residue of protein B, O* is an oxygen atom from a serine residue or a threonine residue of protein B, Nb is the nitrogen atom of a histidine residue of protein B and the connection of R2Ato protein B, and O** is an oxygen atom from a tyrosine residue of protein B; 86 Attorney Docket No.57891-0006WO1 X is O or NRX; RXis hydrogen, C1-C6 alkyl, or C3-C6 cycloalkyl; R3is halogen or C1-C6 alkyl; R4is hydrogen or C1-C6 alkyl; 5 R4Ais C1-C6 alkyl or C3-C6 cycloalkyl; R5Aand R5Bare independently hydrogen, halogen, or C1-C6 alkyl; or R5Aand R5Btogether with the carbon atom to which they are attached form a cyclopropyl; Ring A is a 4-10 membered heterocyclyl, 10 wherein the antigen-binding domain of the first protein A specifically binds to the second protein B. In some embodiments, L2is a C2-C16 alkylene optionally substituted with 1-2 substituents independently selected from halogen and C3-C6 cycloalkyl, and wherein 1-6 alkylene units are optionally replaced by O, N, S, C3-C10 cycloalkyl, phenyl, 5-12 membered 15 heteroaryl, -C(O)-, and 4-14 membered heterocyclyl. In some embodiments, L2is a C1-C16 alkylene optionally substituted with 1-2 substituents independently selected from halogen and C3-C6 cycloalkyl, and wherein 1-6 alkylene units are optionally replaced by O, N, S, C3-C10 cycloalkyl, phenyl, 5-12 membered heteroaryl, -C(O)-, and 4-14 membered heterocyclyl. 20 In some embodiments, it is provided that the structure does not contain a GLP-1 peptide or variant thereof, optionally wherein the structure does not contain a modified GLP-1peptide, optionally wherein the structure does not contain a peptide as described in WO 2025 / 076010. In some embodiments, the modified cysteine residue is present in a CDR of the antigen- binding domain. In some embodiments, the CDR is a heavy chain CDR. In some 25 embodiments, the CDR is a light chain CDR. In some embodiments, the modified cysteine residue is present in a framework region of the antigen-binding domain. In some embodiments, the first protein A is an antibody. In some embodiments, the antibody is a human antibody, a humanized antibody, or a veneered antibody. In some 30 embodiments, the antibody is a human IgG1, human IgG2, human IgG3, or human IgG4 antibody. 87 Attorney Docket No.57891-0006WO1 In some embodiments, the first protein A is or comprises a single chain Fv (scFv), a VHH, a VNAR, a DARpin, a single domain antibody (sdAb), an Adnectin / Centyrin, an Affibody, a Knottin, a bicyclic peptide, or a cyclic peptide. In some embodiments, the first protein A further comprises a conjugated cytotoxic or 5 cytostatic agent. In some embodiments, the first protein A comprises a radioisotope. In some embodiments, the second protein B comprises an extracellular domain, and the antigen-binding domain specifically binds to the extracellular domain. 10 Methods of Making a Protein Some embodiments provide a method of making a protein, wherein the antigen-binding domain comprises a modified phenylalanine residue, the modified phenylalanine residue having the structure: ,15the method comprising contacting a compound having the structure Z-R2with a protein comprising an antigen-binding domain, wherein the antigen-binding domain comprising an oxime, the oxime having the structure: , 20 wherein: Z reacts with -L1- to form -L2-, wherein when R1is azido or tetrazinyl, then Z is a C2- C3 alkyne or an optionally substituted C8-C12 cycloalkyne, and when R1is a C2-C3 alkyne or an optionally substituted C8-C12 cycloalkyne, then Z is azido or tetrazinyl; * and ** represent the points of connection of the oxime to the antigen-binding domain; 88 Attorney Docket No.57891-0006WO1 L2is a C2-C16 alkylene optionally substituted with 1-2 substituents independently selected from halogen and C3-C6 cycloalkyl, and wherein 1-6 alkylene units are optionally replaced by O, N, S, C3-C10 cycloalkyl, phenyl, 5-12 membered heteroaryl, and 4-14 membered heterocyclyl; 5, X is O or NRX; RXis hydrogen, C1-C6 alkyl, or C3-C6 cycloalkyl; R3is halogen or C1-C6 alkyl; 10 R4is hydrogen or C1-C6 alkyl; R4Ais C1-C6 alkyl or C3-C6 cycloalkyl; R5Aand R5Bare independently hydrogen, halogen, or C1-C6 alkyl; or R5Aand R5Btogether with the carbon atom to which they are attached form a cyclopropyl;15Ring A is a 4-10 membered heterocyclyl; L1is a bond or a C1-C6 alkylene optionally substituted with 1-2 substituents independently selected from halogen and C3-C6 cycloalkyl, and wherein 1-2 alkylene units are optionally replaced by O, N, C3-C6 cycloalkyl, or phenyl; and R1is azido, tetrazinyl, a C2-C3 alkyne, or an optionally substituted C8-C12 20 cycloalkyne. In some embodiments, L2is a C2-C16 alkylene optionally substituted with 1-2 substituents independently selected from halogen and C3-C6 cycloalkyl, and wherein 1-6 alkylene units are optionally replaced by O, N, S, C3-C10 cycloalkyl, phenyl, 5-12 membered heteroaryl, -C(O)-, and 4-14 membered heterocyclyl.25In some embodiments, L2is a C1-C16 alkylene optionally substituted with 1-2 substituents independently selected from halogen and C3-C6 cycloalkyl, and wherein 1-6 alkylene units are optionally replaced by O, N, S, C3-C10 cycloalkyl, phenyl, 5-12 membered heteroaryl, -C(O)-, and 4-14 membered heterocyclyl. 89 Attorney Docket No.57891-0006WO1 In some embodiments, the modified phenylalanine residue is present in a CDR of the antigen-binding domain. In some embodiments, the CDR is a heavy chain CDR. In some embodiments, the CDR is a light chain CDR. In some embodiments, the modified phenylalanine residue is present in a framework 5 region of the antigen-binding domain. In some embodiments, the protein is an antibody. In some embodiments, the antibody is a human antibody, a humanized antibody, or a veneered antibody. In some embodiments, the antibody is a human IgG1, human IgG2, human IgG3, or human IgG4 antibody. In some embodiments, the protein is or comprises a single chain Fv (scFv), a VHH, a 10 VNAR, a DARpin, a single domain antibody (sdAb), an Adnectin / Centyrin, an Affibody, a Knottin, a bicyclic peptide, or a cyclic peptide. In some embodiments, the protein further comprises a conjugated cytotoxic or cytostatic agent. In some embodiments, the protein comprises a radioisotope. Examples of radioisotopes 15 include, but are not limited to At211, 1131, 1125, Y90, Re186, Re188, Sm153, Bi212or213, P32and radioactive isotopes of Lu including Lu177. In some embodiments, the antigen-binding domain specifically binds to a target protein. In some embodiments, the target protein comprises an extracellular domain, and the antigen-binding domain specifically binds to the extracellular domain. 20 EXAMPLES Compound Preparation The compounds disclosed herein can be prepared in a variety of ways using commercially available starting materials, compounds known in the literature, or from readily 25 prepared intermediates, by employing standard synthetic methods and procedures either known to those skilled in the art, or in light of the teachings herein. The synthesis of the compounds disclosed herein can be achieved by generally following the schemes provided herein, with modification for specific desired substituents. Standard synthetic methods and procedures for the preparation of organic molecules30and functional group transformations and manipulations can be obtained from the relevant scientific literature or from standard textbooks in the field. Although not limited to any one or several sources, classic texts such as R. Larock, Comprehensive Organic Transformations, VCH Publishers (1989); L. Fieser and M. Fieser, Fieser and Fieser's Reagents for Organic Synthesis, John Wiley and Sons (1994); Smith, M. B., March, J., March' s Advanced Organic 90 Attorney Docket No.57891-0006WO1 Chemistry: Reactions, Mechanisms, and Structure, 5th edition, John Wiley & Sons: New York, 2001; and Greene, T.W., Wuts, P.G. M., Protective Groups in Organic Synthesis, 3rd edition, John Wiley & Sons: New York, 1999, are useful and recognized reference textbooks of organic synthesis known to those in the art. The following descriptions of synthetic methods are 5 designed to illustrate, but not to limit, general procedures for the preparation of compounds of the present disclosure. The synthetic processes disclosed herein can tolerate a wide variety of functional groups; therefore, various substituted starting materials can be used. The starting materials that can be used for the synthesis can be synthesized according to known literature procedures or 10 obtained from commercial sources, such as, but not limited to, Sigma-Aldrich, Fluka, Acros Organics, Alfa Aesar, VWR Scientific, and the like. The following general reaction schemes are provided for illustrative purposes only to exemplify chemical transformations useful for preparing various embodiments of the chemical entities described herein (e.g., linkers) as well as intermediates used in preparing the same. 15 1. General synthesis of alkoxylamine fluorosulfates 2. Conjugation of VHH from engineered pAF to fluorosulfate 203. Conjugation of VHH with alkynyl linker from pAF, followed by Cu mediated AAC to introduce fluorosulfate 4. Preparation of maleimide fluorosulfate 91 Attorney Docket No.57891-0006WO1 5. Conjugation of maleimide fluorosulfate with unpaired Cys 6. Synthesis of alkynyl cyclopropenone 5 7. Conjugation of unpaired Cys with alkynyl cyclopropenone and Cu AAc click reaction 8. Conjugation of unpaired Cys with 10Synthesis of Linkers Example 1. Synthesis of Au-1-3-Me Step 1: To a stirred solution of 2-iodo-3-methylphenol (250 mg, 1.068 mmol, 1 15 equiv) and 3-(fluorosulfonyl)-1,2-dimethylimidazol-1-ium triflate (525.96 mg, 1.602 mmol, 1.5 equiv) in MeCN (3 mL) was added TEA (216.19 mg, 2.136 mmol, 2.00 equiv) dropwise at 92 Attorney Docket No.57891-0006WO1 0 °C under nitrogen atmosphere. The resulting mixture was concentrated under reduced pressure. The residue was purified by reversed-phase flash chromatography with the following conditions: column, C18 silica gel; mobile phase, MeCN in Water (0.1% FA), 10% to 95% gradient in 10 min; detector, UV 254 nm. This resulted in 2-iodo-3-methylphenyl 5 sulfurofluoridate (120 mg, 35.54% yield) as a light yellow oil. Step 2: To a stirred solution of Silver Hexafluoroantimonate(V) (130.46 mg, 0.380 mmol, 1 equiv) in DCM (3 mL) at 0°C under nitrogen atmosphere. To the above mixture was added 2-iodo-3-methylphenyl sulfurofluoridate (120 mg, 0.380 mmol, 1 equiv) and 2- [(chloroaurio)dicyclohexyl-lambda5-phosphanyl]-N,N-dimethylaniline (208.76 mg, 0.380 10 mmol, 1 equiv) in portions at 0°C. The resulting mixture was stirred at room temperature for additional 3 h. The resulting mixture was filtered, the filter cake was washed with DCM (1 mL x 3). The filtrate was concentrated under reduced pressure, and added DCM (0.6 mL) to the concentrated filtrate. The system was purified by trituration with MTBE (1.8 mL). This resulted in 2-chloro-3,3-dicyclohexyl-2-{2-[(fluorosulfonyl)oxy]-6-methylphenyl}-1,1-15 dimethyl-2H,3H-3lambda5-benzo[d]1-aza-3lambda5-phospha-2-auracyclopentan-1-ium-3- ylium-2,2-diuide (70 mg, 24.95% yield, 97.9% purity) as a light brown solid. LCMS:(ES, m / z): [M]+= 738.0. 1H NMR- (300 MHz, DMSO-d6, ppm) δ 8.41 (dd, J = 8.6, 4.4 Hz, 1H), 8.13 – 7.97 (m, 2H), 7.82 (td, J = 7.6, 2.5 Hz, 1H), 7.57 – 7.27 (m, 3H), 3.89 – 3.36 (m, 6H), 3.27 (s, 1H), 2.83 20 (d, J = 12.6 Hz, 1H), 2.64 (s, 3H), 1.98 (d, J = 14.8 Hz, 2H), 1.841 – 1.58 (m, 6H), 1.55 – 1.14 (m, 8H), 1.00 (t, J = 12.1 Hz, 2H), 0.74 (s, 1H), 0.26 (s, 1H). Example 2. Synthesis of Au-1-4-F Step 1: To a stirred solution / mixture of 3-fluoro-2-iodophenol (100 mg, 0.420 mmol, 1 25 equiv) and 3-(fluorosulfonyl)-1,2-dimethylimidazol-1-ium triflate (165.50 mg, 0.504 mmol, 1.2 equiv) in DCM (4 mL) was added TEA (85.04 mg, 0.840 mmol, 2 equiv) dropwise at 0 °C. The resulting mixture was stirred at room temperature for additional 1 h. The reaction was monitored by TLC. The residue was purified by silica gel column chromatography, eluted with 93 Attorney Docket No.57891-0006WO1 PE / EA (5:1) to afford 3-fluoro-2-iodophenyl sulfurofluoridate (40 mg, 29.75% yield) as a colorless oil. Step 1: To a stirred mixture of AgSbF6 (42.95 mg, 0.125 mmol, 1 equiv) in DCM (3 mL) were added 3-fluoro-2-iodophenyl sulfurofluoridate (40 mg, 0.125 mmol, 1 equiv) and 3- 5 fluoro-2-iodophenyl sulfurofluoridate (40 mg, 0.125 mmol, 1 equiv) in portions at 0 °C. The resulting mixture was stirred at 25 °C for additional 2 h. The resulting mixture was filtered, and the filter cake was washed with DCM. The filtrate was concentrated under reduced pressure, and added DCM (0.6 mL) to the concentrated filtrate. The system was purified by trituration with MTBE (1.8 mL). This resulted in 2-chloro-3,3-dicyclohexyl-2-{2-fluoro-6-10 [(fluorosulfonyl) oxy] phenyl}-1,1-dimethyl-2H,3H-3lambda5-benzo[d]1-aza-3lambda5- phospha-2-auracyclopentan-1-ium-3-ylium-2,2-diuide (40 mg, 43.07% yield, 90.2% purity) as an off-white solid. LCMS: (ES, m / z): [M]+= 742.0. 1H NMR (300 MHz, DMSO-d6, ppm) δ 8.44 (dd, J = 8.6, 4.4 Hz, 1H), 8.18 – 8.06 (m, 2H), 7.86 (dt, J = 8.0, 4.0 Hz, 1H), 7.80 – 7.60 (m, 2H), 7.60 – 7.49 (m, 1H), 3.60 (d, J = 15.1 15 Hz, 6H), 3.22 (d, J = 11.2 Hz, 1H), 3.03 (s, 1H), 1.86 (s, 3H), 1.67 (s, 7H), 1.35 (dd, J = 29.5, 17.1 Hz, 6H), 1.02 (d, J = 11.5 Hz, 2H), 0.67 (s, 1H), 0.43 (s, 1H). Example 3. Synthesis of Au-2-2-CN Step 1: To a stirred solution of 2-hydroxy-4-iodobenzonitrile (250 mg, 1.020 mmol, 120equiv) and 3-(fluorosulfonyl)-1,2-dimethylimidazol-1-ium triflate (502.38 mg, 1.530 mmol, 1.5 equiv) in MeCN (3 mL) was added TEA (206.50 mg, 2.040 mmol, 2 equiv) dropwise at 0 °C under nitrogen atmosphere. The resulting mixture was stirred at room temperature for additional 30 min. The resulting mixture was concentrated under reduced pressure. The residue was purified by reversed-phase flash chromatography with the following conditions: column, 25 C18 silica gel; mobile phase, MeCN in Water (0.1% FA), 10% to 90% gradient in 10 min; detector, UV 254 nm. This resulted in 2-cyano-5-iodophenyl sulfurofluoridate (130 mg, 38.95% yield) as a light yellow solid. 94 Attorney Docket No.57891-0006WO1 Step 2: To a stirred solution of Silver Hexafluoroantimonate(V) (136.58 mg, 0.397 mmol, 1 equiv) in DCM (3 mL) at 0 °C under nitrogen atmosphere. To the above mixture was added 2-cyano-5-iodophenyl sulfurofluoridate (130 mg, 0.397 mmol, 1 equiv) and 2- [(chloroaurio)dicyclohexyl-lambda5-phosphanyl]-N,N-dimethylaniline (218.56 mg, 0.397 5 mmol, 1 equiv) in portions at 0 °C. The resulting mixture was stirred at room temperature for additional overnight. The resulting mixture was filtered, the filter cake was washed with DCM (1 mL x 3). The filtrate was concentrated under reduced pressure, and added DCM (0.6 mL) to the concentrated filtrate. The system was purified by trituration with MTBE (1.8 mL). This resulted in 2-chloro-2-{4-cyano-3-[(fluorosulfonyl)oxy] phenyl}-3,3-dicyclohexyl-10 1,1-dimethyl-2H,3H-3lambda5-benzo[d]1-aza-3lambda5-phospha-2-auracyclopentan-1-ium- 3-ylium-2,2-diuide (120 mg, 40.25% yield, 98.7% purity) as a grey solid. LCMS:(ES, m / z): [M]+= 749.0. 1H NMR (300 MHz, DMSO-d6, ppm) δ 8.39 (dd, J = 8.6, 4.4 Hz, 1H), 8.33 (s, 1H), 8.20 (d, J = 8.2 Hz, 1H), 8.11 – 8.01 (m, 2H), 7.87 (dd, J = 8.2, 1.3 Hz, 1H), 7.81 (td, J = 7.5, 15 2.5 Hz, 1H), 3.51 (s, 6H), 2.94 (s, 2H), 1.94 (s, 2H), 1.82 – 1.52(m, 10H), 1.29 (d, J = 25.8 Hz, 4H), 1.07 (d, J = 13.2 Hz, 2H), 0.60(s, 2H) Example 4. Synthesis of Au-3-1-OMe Step 1: To a stirred solution of 4-iodo-2-methoxyphenol (500 mg, 2.000 mmol, 120equiv) and 3-(fluorosulfonyl)-1,2-dimethylimidazol-1-ium triflate (984.61 mg, 3.000 mmol, 1.5 equiv) in MeCN (5 mL) was added TEA (404.72 mg, 4.000 mmol, 2 equiv) dropwise at 0 °C under nitrogen atmosphere. The resulting mixture was concentrated under reduced pressure. The residue was purified by reversed-phase flash chromatography with the following conditions: column, C18 silica gel; mobile phase, MeCN in Water (0.1% FA), 10% to 95% 25 gradient in 10 min; detector, UV 254 nm. This resulted in 4-iodo-2-methoxyphenyl sulfurofluoridate (300 mg, 45.18%yield) as a light yellow solid. Step 2: To a stirred solution of Silver Hexafluoroantimonate(V) (103.47 mg, 0.301 mmol, 1 equiv) in DCM (3 mL) at 0 °C under nitrogen atmosphere. To the above mixture was added 4-iodo-2-methoxyphenyl sulfurofluoridate (100 mg, 0.301 mmol, 1 equiv) and 2- 95 Attorney Docket No.57891-0006WO1 [(chloroaurio)dicyclohexyl-lambda5-phosphanyl]-N,N-dimethylaniline (165.58 mg, 0.301 mmol, 1 equiv) in portions at 0 °C. The resulting mixture was stirred at room temperature for additional 3 h. The resulting mixture was filtered, the filter cake was washed with DCM (1 mL x 3). The filtrate was concentrated under reduced pressure, and added DCM (0.6 mL) to the 5 concentrated filtrate. The system was purified by trituration with MTBE (1.8 mL). This resulted in 2-chloro-3,3-dicyclohexyl-2-{4-[(fluorosulfonyl)oxy]-3-methoxyphenyl}-1,1- dimethyl-2H,3H-3lambda5-benzo[d]1-aza-3lambda5-phospha-2-auracyclopentan-1-ium-3- ylium-2,2-diuide (60 mg, 26.39% yield, 98.5 % purity) as a grey solid. LCMS:(ES, m / z): [M]+= 754.1. 101H NMR (300 MHz, DMSO-d6, ppm) δ 8.37 (dd, J = 8.5, 4.3 Hz, 1H), 8.06 (q, J = 7.9, 7.2 Hz, 2H), 7.79 (td, J = 7.5, 2.3 Hz, 1H), 7.66 (d, J = 8.5 Hz, 1H), 7.57 (s, 1H), 7.17 (dd, J = 8.6, 1.7 Hz, 1H), 3.99 (s, 3H), 3.47 (s, 6H), 2.99 (s, 2H), 1.93 (s, 2H), 1.79 – 1.50 (m, 10H), 1.45 – 1.21 (m, 4H), 1.01 (s, 2H), 0.52 (s, 2H). Example 5. Synthesis of Au-3-2-CN 15 Step 1: To a stirred solution of 2-hydroxy-5-iodobenzonitrile (500 mg, 2.041 mmol, 1 equiv) and 3-(fluorosulfonyl)-1,2-dimethylimidazol-1-ium triflate (1004.77 mg, 3.061 mmol, 1.5 equiv) in MeCN (5 mL) was added TEA (413.00 mg, 4.082 mmol, 2 equiv) dropwise at 0 °C under nitrogen atmosphere. The resulting mixture was stirred at room temperature for 20 additional 30 min. The resulting mixture was concentrated under reduced pressure. The residue was purified by reversed-phase flash chromatography with the following conditions: column, C18 silica gel; mobile phase, MeCN in Water (0.1% FA), 10% to 95% gradient in 10 min; detector, UV 254 nm. This resulted in 2-cyano-4-iodophenyl sulfurofluoridate (300 mg, 44.95% yield) as a light yellow oil.25Step 2: To a stirred solution of Silver Hexafluoroantimonate(V) (105.06 mg, 0.306 mmol, 1 equiv) in DCM (3 mL) at 0 °C under nitrogen atmosphere. To the above mixture was added 2-cyano-4-iodophenyl sulfurofluoridate (100 mg, 0.306 mmol, 1 equiv) and 2- [(chloroaurio)dicyclohexyl-lambda5-phosphanyl]-N,N-dimethylaniline (168.12 mg, 0.306 mmol, 1 equiv) dropwise at 0 °C. The resulting mixture was stirred at 40 °C for additional 96 Attorney Docket No.57891-0006WO1 overnight. The mixture was allowed to cool down to room temperature. The resulting mixture was filtered, the filter cake was washed with DCM (1 mL x 3). The filtrate was concentrated under reduced pressure, and added DCM (0.6 mL) to the concentrated filtrate. The system was purified by trituration with MTBE (1.8 mL). This resulted in 2-chloro-2-{3-cyano-4- 5 [(fluorosulfonyl)oxy] phenyl}-3,3-dicyclohexyl-1,1-dimethyl-2H,3H-3lambda5-benzo[d]1- aza-3lambda5-phospha-2-auracyclopentan-1-ium-3-ylium-2,2-diuide (60 mg, 26.16% yield, 91.5% purity) as a grey solid. LCMS:(ES, m / z): [M]+= 749.1. 1H NMR (300 MHz, DMSO-d6, ppm) δ 8.44 (d, J = 1.9 Hz, 1H), 8.39 (dd, J = 8.5, 4.4 Hz, 1H), 8.15 – 7.99 (m, 4H), 7.80 (td, J = 7.5, 2.5 Hz, 1H), 3.50 (s, 6H), 2.98 (s, 2H), 1.96 (s, 10 2H), 1.77 - 1.53 (m, 10H), 1.34 (s, 4H), 1.04 (t, J = 12.8 Hz, 2H), 0.49 (s, 2H). Example 6. Synthesis of Au-MP-7 Step 1: To a stirred solution of 3-iodophenol (3 g, 13.636 mmol, 1 equiv) and 2-[4- 15 (benzyloxy)phenyl]-4,4,5,5-tetramethyl-1,3,2-dioxaborolane (5.08 g, 16.363 mmol, 1.2 equiv) in 1,4-dioxane (5 mL) were added Cu(NO3)2 (3.84 g, 20.454 mmol, 1.5 equiv) and TMEDA (4.75 g, 40.908 mmol, 3 equiv) in portions at room temperature. The reaction was monitored by LCMS. The resulting mixture was filtered, the filter cake was washed with MeOH (3x1 mL). The filtrate was concentrated under reduced pressure. The residue product was purified20by reverse phase flash to afford 1-[4-(benzyloxy)phenoxy]-3-iodobenzene (240 mg, 4.38% yield) as a white solid. Step 2: To a stirred solution of 1-[4-(benzyloxy)phenoxy]-3-iodobenzene (240 mg, 0.597 mmol, 1 equiv) in DCM (3 mL) was added BBr3 (3 mL, 0.448 mmol, 1.00 equiv) dropwise at 0 °C. The reaction was monitored by LCMS. The reaction was quenched with ice 25 water at 0 °C. The resulting mixture was extracted with CH2Cl2(3x1 mL). The combined organic layers were washed with water (3x1 mL), dried over anhydrous Na2SO4. After filtration, the filtrate was concentrated under reduced pressure. The residue was purified by silica gel column chromatography, eluted with PE / EA (5:1) to afford 4-(3- iodophenoxy)phenol (140 mg, 75.18% yield) as a yellow oil. 97 Attorney Docket No.57891-0006WO1 Step 3: To a stirred solution of 4-(3-iodophenoxy) phenol (140 mg, 0.449 mmol, 1 equiv) in ACN (3 mL) was added TEA (90.78 mg, 0.898 mmol, 2 equiv) dropwise at 0 °C. The reaction was monitored by LCMS. The resulting mixture was concentrated under reduced pressure. The residue product was purified by reverse phase flash to afford 4-(3-iodophenoxy) 5 phenyl sulfurofluoridate (80 mg, 45.25% yield) as a yellow solid. Step 4: Into a 40 mL sealed tube were added Silver Hexafluoroantimonate(V) (69.74 mg, 0.203 mmol, 1 equiv) and DCM (10 mL) at 0 °C. To the above mixture was added 2- [(chloroaurio)dicyclohexyl-lambda5-phosphanyl]-N,N-dimethylaniline (111.61 mg, 0.203 mmol, 1 equiv) and 4-(3-iodophenoxy)phenyl sulfurofluoridate (80 mg, 0.203 mmol, 1.00 10 equiv) dropwise over 3 min at 0 °C. The resulting mixture was stirred at room temperature for additional overnight. The resulting mixture was filtered, the filter cake was washed with MeCN (3x3 mL). The filtrate was concentrated under reduced pressure, and added DCM (0.6 mL) to the concentrated filtrate. The system was purified by trituration with MTBE (1.8 mL). This resulted in 4-(3-{2- chloro-3,3-dicyclohexyl-1,1-dimethylbenzo[d]1-aza-3-phospha-2- 15 auracyclopentan-2-yl} phenoxy) phenyl sulfurofluoridate (100 mg, 60.30% yield, 96.3% purity) as a white solid. LCMS:(ES, m / z): [M]+ = 816.1. 1H NMR (300 MHz, DMSO-d6, ppm) δ 8.34 (dd, J = 8.6, 4.3 Hz, 1H), 8.11 – 7.98 (m, 2H), 7.78 (td, J = 7.5, 2.4 Hz, 1H), 7.74 – 7.66 (m, 2H), 7.49 (t, J = 7.9 Hz, 1H), 7.32 (d, J = 8.0 Hz, 1H), 7.26 – 7.12 (m, 4H), 3.43 (s, 6H), 2.86 (s, 2H), 1.89 (s, 2H), 1.77 - 1.49 (m, 10H), 20 1.21 (d, J = 17.6 Hz, 4H), 0.99 (s, 2H), 0.64 (s, 2H). Example 7. Synthesis of Au-PM-2 Step 1: To a stirred solution of benzenamine, 4-iodo- (500 mg, 2.283 mmol, 1 equiv), tert-butyl 4-oxopiperidine-1-carboxylate (454.86 mg, 2.283 mmol, 1 equiv) and AcOH (137.09 25 mg, 2.283 mmol, 1 equiv) in DCM (15 mL) at room temperature under nitrogen atmosphere. The mixture was stirred for 15 min. STAB (967.65 mg, 4.566 mmol, 2 equiv) was added and stirred for 2 h. The resulting mixture was diluted with water (10 mL) and extracted with DCM (15 mL x 2). The mixture was acidified to pH 7 with saturated NaHCO3(aq.). The aqueous phase was extracted with EtOAc (10 mL x 2). The combined organic layers were washed with 98 Attorney Docket No.57891-0006WO1 brine (15 mL), dried over anhydrous Na2SO4. After filtration, the filtrate was concentrated under reduced pressure. The residue was purified by silica gel column chromatography, eluted with PE / THF (3: 1) to afford tert-butyl 4-[(4-iodophenyl) amino] piperidine-1-carboxylate (750 mg, 81.67% yield) as a yellow solid. 5 Step 2: To a stirred solution of tert-butyl 4-[(4-iodophenyl) amino] piperidine-1- carboxylate (500 mg, 1.243 mmol, 1 equiv) in DCM (3 mL) and HCl in 1,4-dioxane (3 mL) at room temperature under nitrogen atmosphere. The resulting mixture was stirred at room temperature for additional 1h. The resulting mixture was filtered , the filter cake was washed with DCM (3 x 3 mL). The filtrate was concentrated under reduced pressure. This resulted in 10 N-(4-iodophenyl) piperidin-4-amine hydrochloride (350 mg, 83.16% yield) as a light yellow solid. The crude product mixture was used in the next step directly without further purification. Step 3: To a stirred solution of N-(4-iodophenyl) piperidin-4-amine (300 mg, 0.993 mmol, 1 equiv), HATU (566.28 mg, 1.490 mmol, 1.5 equiv) and DIEA (192.49 mg, 1.490 mmol, 1.5 equiv) in DCM (5 mL) at room temperature under nitrogen atmosphere. The 15 resulting mixture was stirred for 15 min. 3-[(fluorosulfonyl)oxy] benzoic acid (262.32 mg, 1.192 mmol, 1.2 equiv) was added and stirred for 30 min. The resulting mixture was diluted with H2O (5 mL) and extracted with DCM (3 x 5 mL). The combined organic layers were washed with brine (5 mL), dried over anhydrous Na2SO4. The resulting mixture was concentrated under reduced pressure. The residue was purified by reversed-phase flash 20 chromatography with the following conditions: column, C18 silica gel; mobile phase, MeCN in Water (0.1% FA), 10% to 50% gradient in 10 min; detector, UV 254 nm. This resulted in 3- {4-[(4-iodophenyl) amino] piperidine-1-carbonyl} phenyl sulfurofluoridate (250 mg, 49.93% yield) as a white solid. Step 4: To a stirred solution of 3-{4-[(4-iodophenyl) amino] piperidine-1-carbonyl}25 phenyl sulfurofluoridate (100 mg, 0.198 mmol, 1 equiv) and 2-[(chloroaurio)dicyclohexyl- lambda5-phosphanyl]-N, N-dimethylaniline (109.03 mg, 0.198 mmol, 1 equiv) in DCM (5 mL) was added Silver Hexafluoroantimonate(V) (68.14 mg, 0.198 mmol, 1 equiv) dropwise at -20 °C. The resulting mixture was stirred at -10 °C for 2 h. The reaction was monitored by LCMS. The resulting mixture was filtered , the filter cake was washed with DCM (5 mL) (3 x 1 mL). 30 The filtrate was concentrated under reduced pressure, and added DCM (0.6 mL) to the concentrated filtrate. The system was purified by trituration with MTBE (1.8 mL). This resulted in 2-chloro-3,3-dicyclohexyl-2-{4-[(1-{3-[(fluorosulfonyl)oxy] benzoyl} piperidin-4- yl) amino] phenyl}-1,1-dimethyl-2H,3H-3lambda5-benzo[d]1-aza-3lambda5-phospha-2- 99 Attorney Docket No.57891-0006WO1 auracyclopentan-1-ium-3-ylium-2,2-diuide (41 mg, 22.30% yield, 98.36% purity) as a brown solid. LCMS:(ES, m / z): [M]+= 926.2. 1H NMR (300 MHz, DMSO-d6, ppm) δ 8.32 (dd, J = 8.5, 4.4 Hz, 1H), 8.11 – 7.96 (m, 2H), 7.77 (t, J = 7.8 Hz, 1H), 7.73 – 7.64 (m, 3H), 7.56 (dt, J = 6.1, 2.2 Hz, 1H), 7.01 (d, J = 5 8.4 Hz, 2H), 6.68 (d, J = 8.5 Hz, 2H), 5.70 (s, 1H), 4.36 (s, 1H), 3.53 (s, 7H), 3.16 (d, J = 36.4 Hz, 2H), 2.90 (d, J = 11.5 Hz, 2H), 1.93 (d, J = 57.6 Hz, 4H), 1.66 (d, J = 25.4 Hz, 10H), 1.35 (s, 7H), 1.03 (d, J = 13.6 Hz, 2H), 0.66 (s, 2H). Example 8. Synthesis of Au-PP-10 10 Step 1: To a stirred mixture of P-anisidine (2 g, 16.240 mmol, 1 equiv) and 1,4- diiodobenzene (8.04 g, 24.360 mmol, 1.5 equiv) in toluene (40 mL) were added t-BuONa (4.68 g, 48.720 mmol, 3 equiv) and Pd(dppf)Cl2(2.38 g, 3.248 mmol, 0.2 equiv) in portions at room temperature under nitrogen atmosphere. The resulting mixture was stirred at 70 °C for 2 h under nitrogen atmosphere. The resulting mixture was extracted with EtOAc (3 x 40 mL). The 15 combined organic layers were washed with water (3 x 40 mL), dried over anhydrous Na2SO4.After filtration, the filtrate was concentrated under reduced pressure. The residue was purified by reversed-phase flash chromatography with the following conditions: column, C18 silica gel; mobile phase, MeCN in Water (0.1% FA), 10% to 95% gradient in 10 min; detector, UV 254 nm. This resulted in N-(4-iodophenyl)-4-methoxyaniline (2 g, 37.88% yield) as a brown oil. 20 Step 2: A mixture of N-(4-iodophenyl)-4-methoxyaniline (1.5 g, 4.613 mmol, 1 equiv) and methyl 4-chloro-4-oxobutanoate (0.83 g, 5.536 mmol, 1.2 equiv) in toluene (20 mL) was stirred at 90 °C for 2 h. The resulting mixture was extracted with EtOAc (3 x 20 mL). The combined organic layers were washed with water (3 x 10 mL), dried over anhydrous Na2SO4. After filtration, the filtrate was concentrated under reduced pressure. The residue was purified 25 by reversed-phase flash chromatography with the following conditions: column, C18 silica gel; mobile phase, MeCN in Water (0.1% NH3.H2O), 10% to 95% gradient in 10 min; detector, UV 254 nm. This resulted in methyl 3-[(4-iodophenyl)(4- methoxyphenyl)carbamoyl]propanoate (1 g, 49.35% yield) as a brown oil. 100 Attorney Docket No.57891-0006WO1 Step 3: A solution of methyl 3-[(4-iodophenyl) (4-methoxyphenyl) carbamoyl] propanoate (1 g, 2.277 mmol, 1 equiv) in Borane-tetrahydrofuran complex (1.0M in THF) (15 mL) was stirred at 0 °C for 12 h. The reaction was quenched by the addition of MeOH (3 mL) at 0 °C. The resulting mixture was concentrated under reduced pressure. The residue was 5 purified by reversed-phase flash chromatography with the following conditions: column, C18 silica gel; mobile phase, MeCN in Water (0.1% NH3.H2O), 10% to 95% gradient in 15 min; detector, UV 254 nm. This resulted in methyl 4-[(4-hydroxyphenyl) (4-iodophenyl) amino] butanoate (500 mg, 53.41% yield) as a yellow oil. Step 4: A solution of methyl 4-[(4-iodophenyl) (4-methoxyphenyl) amino] butanoate 10 (500 mg, 1.176 mmol, 1 equiv) in DCM (2 mL) and BBr3(4 mL) was stirred at 0 °C for 2 h. The reaction was quenched by the addition of ice water (20 mL) at 0 °C.The resulting mixture was extracted with CH2Cl2 (3 x 20 mL). The combined organic layers were washed with water (3 x 20 mL), dried over anhydrous Na2SO4. After filtration, the filtrate was concentrated under reduced pressure. The resulting mixture was concentrated under reduced pressure. The residue 15 was purified by reversed-phase flash chromatography with the following conditions: column, C18 silica gel; mobile phase, MeCN in Water (0.1% NH3.H2O), 10% to 95% gradient in 10 min; detector, UV 254 nm. This resulted in methyl 4-[(4-hydroxyphenyl)(4- iodophenyl)amino]butanoate (300 mg, 62.05%yield) as a yellow oil. Step 5: A solution of methyl 4-[(4-hydroxyphenyl)(4-iodophenyl)amino]butanoate 20 (300 mg, 0.730 mmol, 1 equiv) in NH3.H2O (5 mL) was stirred at room temperature for 12 h. The residue was purified by reversed-phase flash chromatography with the following conditions: column, C18 silica gel; mobile phase, MeCN in Water (0.1% NH3.H2O), 10% to 95% gradient in 10 min; detector, UV 254 nm. This resulted in 4-[(4-hydroxyphenyl) (4- iodophenyl) amino] butanamide (60 mg, 20.76% yield) as a yellow oil. 25 Step 6: To a stirred mixture of 4-[(4-hydroxyphenyl) (4-iodophenyl) amino] butanamide (50 mg, 0.126 mmol, 1 equiv) and 3-(fluorosulfonyl)-1,2-dimethylimidazol-1-ium triflate (49.71 mg, 0.151 mmol, 1.2 equiv) in ACN (3 mL) was added TEA (19.15 mg, 0.189 mmol, 1.5 equiv) in portions at 0 °C. The resulting mixture was stirred at 0 °C for 30 min. The resulting mixture was concentrated under reduced pressure. The residue was purified by 30 reversed-phase flash chromatography with the following conditions: column, C18 silica gel; mobile phase, MeCN in Water (0.1% NH3.H2O), 10% to 50% gradient in 10 min; detector, UV 254 nm. This resulted in 4-[(3-carbamoylpropyl) (4-iodophenyl) amino] phenyl sulfurofluoridate (40 mg, 66.28% yield) as a colorless oil. 101 Attorney Docket No.57891-0006WO1 Step 7: To a stirred solution of 4-[(3-carbamoylpropyl) (4-iodophenyl) amino] phenyl sulfurofluoridate (30 mg, 0.063 mmol, 1 equiv) and 2-[(chloroaurio)dicyclohexyl-lambda5- phosphanyl]-N,N-dimethylaniline (34.49 mg, 0.063 mmol, 1 equiv) in DCM (3 mL) were added Silver Hexafluoroantimonate(V) (21.55 mg, 0.063 mmol, 1 equiv) in portions at 0 °C 5 under nitrogen atmosphere. The resulting mixture was stirred at room temperature for additional 2 h. The resulting mixture was filtered, the filter cake was washed with DCM (3 x 3 mL). The filtrate was concentrated under reduced pressure, and added DCM (0.6 mL) to the concentrated filtrate. The system was purified by trituration with MTBE (1.8 mL). The precipitated solids were collected by filtration and washed with MTBE (1 mL) to afford in 2-10 {4-[(3-carbamoylpropyl) ({4-[(fluorosulfonyl)oxy] phenyl}) amino] phenyl}-2-chloro-3,3- dicyclohexyl-1,1-dimethyl-2H,3H-3lambda5-benzo[d]1-aza-3lambda5-phospha-2- auracyclopentan-1-ium-3-ylium-2,2-diuide (29 mg, 51.30% yield, 96.3% purity) as a light green solid. LCMS:(ES, m / z): [M]+= 900.2 1H NMR (300 MHz, DMSO-d6, ppm) δ 8.36 (dd, J = 8.4, 4.3 Hz, 1H), 8.13 – 7.98 (m, 15 2H), 7.79 (t, J = 7.7 Hz, 1H), 7.41 (dd, J = 8.8, 7.0 Hz, 4H), 7.31 (s, 1H), 7.23 (d, J = 8.5 Hz, 2H), 6.99 (d, J = 9.3 Hz, 2H), 6.79 (s, 1H), 3.74 (t, J = 7.8 Hz, 2H), 3.44 (s, 6H), 3.00 (d, J = 11.2 Hz, 2H), 2.15 (t, J = 7.2 Hz, 2H), 1.89 (s, 2H), 1.81 – 1.44 (m, 12H), 1.36 (q, J = 13.3 Hz, 4H), 1.01 (d, J = 13.6 Hz, 2H), 0.54 (s, 2H). Example 9. Synthesis of SFY-Au-7-1 20 Step 1: To a stirred solution of 2-methoxy-5-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan- 2-yl) benzenesulfonyl fluoride (500 mg, 1.582 mmol, 1 equiv) and 3-iodophenol (347.95 mg, 1.582 mmol, 1 equiv) in dioxane (5 mL) were added Cu(NO3)2 (444.93 mg, 2.373 mmol, 1.5 equiv) and TMEDA (551.36 mg, 4.746 mmol, 3 equiv) dropwise at room temperature. The 25 resulting mixture was stirred at 80 °C for 2 h. The reaction was monitored by LCMS. The resulting mixture was concentrated under reduced pressure. The residue product was purified by reverse phase flash to afford 5-(3-iodophenoxy)-2-methoxybenzenesulfonyl fluoride (100 mg, 15.49% yield) as a white solid. 102 Attorney Docket No.57891-0006WO1 Step 2: To a stirred solution of 5-(3-iodophenoxy)-2-methoxybenzenesulfonyl fluoride (100 mg, 0.245 mmol, 1 equiv) and 2-[(chloroaurio)dicyclohexyl-lambda5-phosphanyl]-N, N- dimethylaniline (134.71 mg, 0.245 mmol, 1 equiv) in DCM (5 mL) was added AgSbF6 (84.18 mg, 0.245 mmol, 1 equiv) dropwise at -20 °C. The resulting mixture was stirred at -10 °C for 5 2 h under nitrogen atmosphere. The reaction was monitored by LCMS. The resulting mixture was filtered, the filter cake was washed with DCM (3 mL) (3 x 1 mL). The filtrate was concentrated under reduced pressure, and added DCM (0.6 mL) to the concentrated filtrate. The system was purified by trituration with MTBE (1.8 mL). This resulted in 2-chloro-3,3- dicyclohexyl-2-{3-[3-(fluorosulfonyl)-4-methoxyphenoxy] phenyl}-1,1-dimethyl-2H,3H- 10 3lambda5-benzo[d]1-aza-3lambda5-phospha-2-auracyclopentan-1-ium-3-ylium-2,2-diuide (129.3 mg, 63.50% yield, 98.6% purity) as a white solid. LCMS:(ES, m / z): [M]+= 830.1. 1H NMR (300 MHz, DMSO-d6, ppm) δ 8.28 (dd, J = 8.5, 4.4 Hz, 1H), 8.00 (d, J = 8.8 Hz, 2H), 7.76 (dd, J = 10.7, 4.2 Hz, 1H), 7.69 (dd, J = 9.2, 2.9 Hz, 1H), 7.61 – 7.52 (m, 2H), 7.47 (t, J = 8.0 Hz, 1H), 7.30 (d, J = 8.0 Hz, 1H), 7.15 (d, J = 8.0 Hz, 1H), 7.04 (s, 1H), 3.99 15 (s, 3H), 3.34 (d, J = 45.4 Hz, 6H), 1.97 – 1.37 (s, 12H), 1.34 – 0.83 (m, 6H), 0.57 (s, 2H). Example 10. Synthesis of SFY-Au-8-1 Step 1: To a stirred solution of 5-bromo-2-methoxybenzenesulfonyl fluoride (2.5 g, 9.291 mmol, 1 equiv) and bis(pinacolato)diboron (3.54 g, 13.937 mmol, 1.5 equiv) in DMSO20(20 mL) were added Pd(dppf)Cl2 (0.68 g, 0.929 mmol, 0.1 equiv) and K2CO3 (3.85 g, 27.873 mmol, 3 equiv) dropwise at room temperature. The resulting mixture was stirred at 90 °C for 3 h under nitrogen atmosphere. The resulting mixture was extracted with EtOAc (3 x 3 mL). The combined organic layers were washed with water (3 x 3 mL), dried over anhydrous Na2SO4. After filtration, the filtrate was concentrated under reduced pressure. The residue was25 purified by silica gel column chromatography, eluted with PE / EA (5 : 1) to afford 2-methoxy- 5-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)benzenesulfonyl fluoride (2 g, 68.09% yield) as a yellow oil. Step 2: To a stirred solution of 2-methoxy-5-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan- 2-yl) benzenesulfonyl fluoride (500 mg, 1.582 mmol, 1 equiv) and 4-iodophenol (347.95 mg, 103 Attorney Docket No.57891-0006WO1 1.582 mmol, 1 equiv) in dioxane (5 mL) were added Cu(NO3)2(444.93 mg, 2.373 mmol, 1.5 equiv) and TMEDA (551.36 mg, 4.746 mmol, 3 equiv) dropwise at room temperature. The resulting mixture was stirred at 80 °C for 2 h. The reaction was monitored by LCMS. The resulting mixture was concentrated under reduced pressure. The residue product was purified 5 by reverse phase flash to afford 5-(4-iodophenoxy)-2-methoxybenzenesulfonyl fluoride (50 mg, 7.75% yield) as a white solid. Step 3: To a stirred solution of 5-(4-iodophenoxy)-2-methoxybenzenesulfonyl fluoride (50 mg, 0.122 mmol, 1 equiv) and 2-[(chloroaurio)dicyclohexyl-lambda5-phosphanyl]-N, N- dimethylaniline (67.36 mg, 0.122 mmol, 1 equiv) in DCM (3 mL) was added Silver 10 Hexafluoroantimonate(V) (42.09 mg, 0.122 mmol, 1 equiv) dropwise at -20 °C. The resulting mixture was stirred at -10 °C for 2 h. The reaction was monitored by LCMS. The resulting mixture was filtered, the filter cake was washed with DCM (3 mL) (3 x 1 mL). The filtrate was concentrated under reduced pressure, and added DCM (0.6 mL) to the concentrated filtrate. The system was purified by trituration with MTBE (1.8 mL). This resulted in [(2-{[chloro({4- 15 [3-(fluorosulfonyl)-4-methoxyphenoxy] phenyl}) aurio] dicyclohexyl-lambda5-phosphanyl} phenyl) dimethylammonio] methanidylidene (35.1 mg, 46.44% yield, 97.7% purity) as a white solid. LCMS:(ES, m / z): [M]+=830.1. 1H NMR (300 MHz, DMSO-d6, ppm) δ 8.35 (dd, J = 8.7, 4.3 Hz, 1H), 8.05 (q, J = 9.2 Hz, 2H), 7.79 (t, J = 6.8 Hz, 1H), 7.67 (dd, J = 9.1, 3.0 Hz, 1H), 7.55 (d, J = 9.2 Hz, 1H), 7.51 20 – 7.25 (m, 3H), 7.17 (dd, J = 8.5, 4.2 Hz, 2H), 4.02 (s, 3H), 3.44 (s, 6H), 2.94 (d, J = 11.2 Hz, 2H), 1.88 (s, 2H), 1.79 – 1.47 (m, 10H), 1.41 – 1.24 (m, 4H), 1.02 (d, J = 13.1 Hz, 2H), 0.59 (s, 2H). Example 11. Synthesis of Au-8-2 25 Step 1: To a stirred solution of 2-methoxy-5-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan- 2-yl) benzenesulfonyl fluoride (500 mg, 1.582 mmol, 1 equiv) and 5-iodo-2,3-dihydro-1H- indole (387.57 mg, 1.582 mmol, 1 equiv) in dioxane (10 mL) were added Cu(NO3)2(444.93 mg, 2.373 mmol, 1.5 equiv) and TMEDA (551.36 mg, 4.746 mmol, 3 equiv) dropwise at room temperature. The resulting mixture was stirred at 80 °C for 2 h. The reaction was monitored by 104 Attorney Docket No.57891-0006WO1 LCMS. The resulting mixture was concentrated under reduced pressure. The residue product was purified by reverse phase flash to afford 5-(6-iodo-2,3-dihydroindol-1-yl)-2- methoxybenzenesulfonyl fluoride (50 mg, 7.30% yield) as a white solid. Step 2: To a stirred solution of 5-(6-iodo-2,3-dihydroindol-1-yl)-2- 5 methoxybenzenesulfonyl fluoride (50 mg, 0.115 mmol, 1 equiv) and (chloroaurio)dicyclohexyl[2-(dimethylamino) phenyl]-lambda5-phosphanyl (63.46 mg, 0.115 mmol, 1 equiv) in DCM (3 mL) was added Silver Hexafluoroantimonate(V) (39.66 mg, 0.115 mmol, 1 equiv) dropwise at -20 °C. The resulting mixture was stirred at -10°C for 2 h under nitrogen atmosphere. The reaction was monitored by LCMS. The resulting mixture was 10 filtered, the filter cake was washed with DCM (3 mL) (3 x 1 mL). The filtrate was concentrated under reduced pressure, and added DCM (0.6 mL) to the concentrated filtrate. The system was purified by trituration with MTBE (1.8 mL). This resulted in [chloro({1-[3-(fluorosulfonyl)-4- methoxyphenyl]-2,3-dihydroindol-6-yl}) aurio] dicyclohexyl[2-(dimethylamino) phenyl]- lambda5-phosphanyl (25.7 mg, 26.01% yield, 87.8% purity) as a white solid. LCMS:(ES, m / z): 15 [M]+= 855.1. 1H NMR (300 MHz, DMSO-d6, ppm) δ 8.34 (dd, J = 8.5, 4.3 Hz, 1H), 8.04 (q, J = 9.2 Hz, 2H), 7.86 – 7.73 (m, 2H), 7.68 (d, J = 2.8 Hz, 1H), 7.50 (d, J = 9.2 Hz, 1H), 7.25 (s, 1H), 7.04 (s, 2H), 4.01 (d, J = 7.8 Hz, 5H), 3.41 (s, 6H), 3.19 (t, J = 8.3 Hz, 2H), 2.91 (d, J = 11.3 Hz, 2H), 1.87 (s, 2H), 1.80 – 1.48 (m, 10H), 1.41 – 1.25 (m, 4H), 1.06 (d, J = 12.6 Hz, 2H), 20 0.70 (s, 2H). Example 12. Synthesis of Au-1-1-OMe Step 1: To a stirred mixture of 2-iodo-6-methoxyphenol (250 mg, 1.000 mmol, 1.00 equiv) and 3-(fluorosulfonyl)-1,2-dimethylimidazol-1-ium triflate (393.84 mg, 1.200 mmol, 25 1.20 equiv) in ACN (6 mL) was added TEA (202.36 mg, 2.000 mmol, 2 equiv) dropwise at 0 °C. The resulting mixture was stirred at room temperature for additional 30 min. The reaction was monitored by LCMS. The residue was purified by reversed-phase flash chromatography with the following conditions: column, C18 silica gel; mobile phase, MeCN in Water (0.1% 105 Attorney Docket No.57891-0006WO1 FA), 10% to 60% gradient in 10 min; detector, UV 254 nm. This resulted in 2-iodo-6- methoxyphenyl sulfurofluoridate (130 mg, 39.15% yield) as a white solid. Step 2: To a stirred mixture of AgSbF6 (124.17 mg, 0.361 mmol, 1 equiv) in DCM (6 mL) were added 2-iodo-6- methoxyphenyl sulfurofluoridate (120 mg, 0.361 mmol, 1 equiv) 5 and (chloroaurio)dicyclohexyl[2-(dimethylamino) phenyl]-lambda5-phosphanyl (198.70 mg, 0.361 mmol, 1 equiv) dropwise at 0 °C. The resulting mixture was stirred at 25 °C for additional 2 h. The resulting mixture was filtered, and the filter cake was washed with DCM. The filtrate was concentrated under reduced pressure, and added DCM (1 mL) to the concentrated filtrate. The system was purified by trituration with MTBE (3 mL). This resulted in 2-{2-chloro-3,3-10 dicyclohexyl-1,1-dimethylbenzo[d]1-aza-3-phospha-2-auracyclopentan-2-yl}-6- methoxyphenyl sulfurofluoridate (120 mg, 43.98% yield, 97.51% purity) as a light grey solid. LCMS: (ES, m / z): [M]+= 754.0. 1H NMR (300 MHz, DMSO-d6, ppm) δ 8.40 (dd, J = 8.6, 4.4 Hz, 1H), 8.17 – 7.96 (m, 2H), 7.82 (td, J = 7.4, 2.5 Hz, 1H), 7.50 (t, J = 8.1 Hz, 1H), 7.32 (ddd, J = 22.9, 8.2, 1.3 Hz, 15 2H), 3.97 (s, 3H), 3.58 (s, 6H), 2.95 (dd, J = 67.6, 10.5 Hz, 2H), 1.90 (s, 2H), 1.82-1.53 (m, 8H), 1.51-1.16 (m, 6H), 1.06 (dd, J = 23.5, 10.3 Hz, 2H), 0.70-0.49 (m, 2H). Example 13. Synthesis of Au-2-1-OMe Step 1: To a stirred solution of 5-iodo-2-methoxyphenol (250 mg, 1.000 mmol, 1 20 equiv) and 3-(fluorosulfonyl)-1,2-dimethylimidazol-1-ium triflate (492.31 mg, 1.500 mmol, 1.5 equiv) in MeCN (3 mL) was added TEA (202.36 mg, 2.000 mmol, 2 equiv) dropwise at 0 °C under nitrogen atmosphere. The resulting mixture was stirred at room temperature for additional 30 min. The resulting mixture was concentrated under reduced pressure. The residue was purified by reversed-phase flash chromatography with the following conditions: column,25C18 silica gel; mobile phase, MeCN in Water (0.1% FA), 10% to 95% gradient in 10 min; detector, UV 254 nm. This resulted in 5-iodo-2-methoxyphenyl sulfurofluoridate (120 mg, 36.14% yield) as a yellow oil. Step 2: To a stirred solution of Silver Hexafluoroantimonate(V) (124.17 mg, 0.361 mmol, 1 equiv) in DCM (3 mL) at 0°C under nitrogen atmosphere. To the above mixture was 106 Attorney Docket No.57891-0006WO1 added 5-iodo-2-methoxyphenyl sulfurofluoridate (120 mg, 0.361 mmol, 1 equiv) and 2- [(chloroaurio)dicyclohexyl-lambda5-phosphanyl]-N,N-dimethylaniline (198.70 mg, 0.361 mmol, 1 equiv) in portions at 0 °C. The resulting mixture was stirred at room temperature for additional 3 h. The resulting mixture was filtered, the filter cake was washed with DCM (1 mL 5 x 3). The filtrate was concentrated under reduced pressure, and added DCM (0.6 mL) to the concentrated filtrate. The system was purified by trituration with MTBE (1.8 mL). This resulted in 2-chloro-3,3-dicyclohexyl-2-{3-[(fluorosulfonyl)oxy]-4-methoxyphenyl}-1,1- dimethyl-2H,3H-3lambda5-benzo[d]1-aza-3lambda5-phospha-2-auracyclopentan-1-ium-3- ylium-2,2-diuide (60 mg, 21.99% yield, 96% purity) as a grey solid. LCMS:(ES, m / z): [M]+= 10 754.1. 1H NMR (300 MHz, DMSO-d6, ppm) δ 8.39 (dd, J = 8.5, 4.5 Hz, 1H), 8.09 (d, J = 7.6 Hz, 3H), 7.83 (dt, J = 8.4, 4.2 Hz, 1H), 7.68 (dd, J = 8.6, 1.8 Hz, 1H), 7.59 (d, J = 8.9 Hz, 1H), 3.99 (s, 3H), 3.33 (s, 6H), 3.12 – 2.80 (m, 2H), 2.15 (s, 1H), 1.92 – 1.59 (m, 11H), 1.33 (s, 4H), 1.09 (d, J = 10.7 Hz, 2H), 0.66 (s, 2H). 15 Example 14. Synthesis of Au-5-1-Me Step 1: To a stirred solution of 2-fluoro-4-iodo-5-methylphenol (200 mg, 0.794 mmol, 1 equiv) and 3-(fluorosulfonyl)-1,2-dimethylimidazol-1-ium triflate (312.59 mg, 0.953 mmol, 1.2 equiv) in ACN (8 mL) was added TEA (120.45 mg, 1.191 mmol, 1.5 equiv) dropwise at 020°C. The resulting mixture was stirred at room temperature for 20 min. The resulting mixture was concentrated under reduced pressure. The residue was purified by reversed-phase flash chromatography with the following conditions: column, C18 silica gel; mobile phase, MeCN in Water (0.1% FA), 10% to 50% gradient in 10 min; detector, UV 254 nm. This resulted in 2- fluoro-4-iodo-5-methylphenyl sulfurofluoridate (72 mg, 27.16% yield) as a yellow oil. 25 Step 2: To a stirred solution of 2-fluoro-4-iodo-5-methylphenyl sulfurofluoridate (50 mg, 0.150 mmol, 1 equiv) and 2-[(chloroaurio)dicyclohexyl-lambda5-phosphanyl]-N, N- dimethylaniline (82.30 mg, 0.150 mmol, 1 equiv) in DCM (2 mL) was added AgSbF6(51.43 mg, 0.150 mmol, 1 equiv) dropwise at 0 °C. The resulting mixture was stirred at room temperature for overnight. The resulting mixture was filtered,the filter cake was washed with30DCM (2 mL). The filtrate was concentrated under reduced pressure, and added DCM (1 mL) 107 Attorney Docket No.57891-0006WO1 to the concentrated filtrate. The system was purified by trituration with MTBE (4 mL). This resulted in 4-{2-chloro-3,3-dicyclohexyl-1,1-dimethylbenzo[d]1-aza-3-phospha-2- auracyclopentan-2-yl}-2-fluoro-5-methylphenyl sulfurofluoridate (80 mg, 70.61% yield, 100.0% purity) as a grey solid. LCMS:(ES, m / z): [M]+= 756.1. 51H NMR (300 MHz, DMSO-d6, ppm) δ 8.38 (dd, J = 8.6, 4.4 Hz, 1H), 8.05 (td, J = 7.7, 2.1 Hz, 2H), 7.81 (dd, J = 7.7, 4.0 Hz, 2H), 7.70 (d, J = 10.0 Hz, 1H), 3.49 (d, J = 9.0 Hz, 6H), 3.12 (d, J = 10.7 Hz, 1H), 2.95 (d, J = 11.1 Hz, 1H), 2.58 (s, 3H), 2.17 (s, 1H), 1.90 – 1.49 (m, 10H), 1.48 – 1.14 (m, 5H), 1.04 (d, J = 13.3 Hz, 2H), 0.71 (s, 1H), 0.41 (d, J = 8.5 Hz, 1H). Example 15. Synthesis of Au-610 Step 1: To a stirred mixture of 6-bromo-2-naphthol (1 g, 4.483 mmol, 1 equiv) and KI (3.72 g, 22.415 mmol, 5 equiv) in DMF (15 mL) were added NiBr2 (0.29 g, 1.345 mmol, 0.3 equiv) and Tributylphosphane (0.27 g, 1.345 mmol, 0.3 equiv) in portions at room temperature under nitrogen atmosphere. The resulting mixture was stirred at 120 °C for 12 h under nitrogen15atmosphere. The resulting mixture was filtered, the filter cake was washed with MeOH (3 x 3 mL). The filtrate was concentrated under reduced pressure. The residue was purified by reversed-phase flash chromatography with the following conditions: column, C18 silica gel; mobile phase, MeCN in Water (0.1% FA), 10% to 95% gradient in 10 min; detector, UV 254 nm. This resulted in 6-iodonaphthalen-2-ol (600 mg, 49.56% yield) as a yellow solid. 20 Step 2: To a stirred mixture of 6-iodonaphthalen-2-ol (500 mg, 1.851 mmol, 1 equiv) and 3-(fluorosulfonyl)-1,2-dimethylimidazol-1-ium triflate (729.26 mg, 2.221 mmol, 1.2 equiv) in ACN (5 mL) were added TEA (281.02 mg, 2.776 mmol, 1.5 equiv) in portions at 0 °C. The resulting mixture was stirred at 0 °C for 30 min. The resulting mixture was concentrated under reduced pressure. The residue was purified by reversed-phase flash25chromatography with the following conditions: column, C18 silica gel; mobile phase, MeCN in Water (0.1% FA), 10% to 95% gradient in 10 min; detector, UV 254 nm. This resulted in 6- iodonaphthalen-2-yl sulfurofluoridate (300 mg, 46.02% yield) as a yellow solid. Step 3: To a stirred solution of 6-bromonaphthalen-2-yl sulfurofluoridate (100 mg, 0.328 mmol, 1 equiv) and (chloroaurio)dicyclohexyl[2-(dimethylamino) phenyl]-lambda5- 108 Attorney Docket No.57891-0006WO1 phosphanyl (180.21 mg, 0.328 mmol, 1 equiv) in DCM (3 mL) were added Silver Hexafluoroantimonate(V) (112.62 mg, 0.328 mmol, 1 equiv) in portions at 0 °C under nitrogen atmosphere. The resulting mixture was stirred at room temperature for additional 2 h. The reaction was monitored by LCMS. The resulting mixture was filtered, the filter cake was 5 washed with DCM (3 x 3 mL). The filtrate was concentrated under reduced pressure, and added DCM (1 mL) to the concentrated filtrate. The system was purified by trituration with MTBE (3 mL). This resulted in [chloro({6-[(fluorosulfonyl) oxy] naphthalen-2-yl}) aurio] dicyclohexyl[2-(dimethylamino) phenyl]-lambda5-phosphanyl (62 mg, 24.41% yield, 95.6% purity) as a yellow solid. LCMS:(ES, m / z): [M]+= 774.1. 101H NMR (300 MHz, DMSO-d6, ppm) δ 8.38 (dd, J = 8.7, 4.3 Hz, 1H), 8.32 (d, J = 2.6 Hz, 1H), 8.20 (d, J = 9.1 Hz, 1H), 8.16 – 7.98 (m, 4H), 7.85 – 7.72 (m, 3H), 3.36 (s, 6H), 3.03 – 2.84 (m, 2H), 1.92 (s, 2H), 1.82-1.44 (m, 10H), 1.44-1.18 (m, 4H), 1.06 (t, J = 13.0 Hz, 2H), 0.62 (s, 2H). Example 16. Synthesis of Au-715 Step 1: To a stirred mixture of 2,6-difluoro-4-iodophenol (800 mg, 3.12 mmol, 1 equiv) and 3-(fluorosulfonyl)-1,2-dimethylimidazol-1-ium triflate (1538.73 mg, 4.68 mmol, 1.5 equiv) in ACN (3 mL) was added TEA (632.48 mg, 6.25 mmol, 2 equiv) dropwise at 0 °C. The reaction was monitored by LCMS. The resulting mixture was concentrated under reduced20 pressure. The crude product was purified by reverse phase flash to afford 2,6-difluoro-4- iodophenyl sulfurofluoridate (120 mg, 11.36% yield) as a off-white oil. Step 2: A solution of Silver Hexafluoroantimonate(V) (116.90 mg, 0.34 mmol, 1 equiv) in DCM (3 mL) was treated with 2,6-difluoro-4-iodophenyl sulfurofluoridate (115 mg, 0.34 mmol, 1 equiv) at 0 °C for 3 min under nitrogen atmosphere followed by the addition of 2-25[(chloroaurio)dicyclohexyl-lambda5-phosphanyl]-N,N-dimethylaniline (187.41 mg, 0.34 mmol, 1 equiv) in portions at 0 °C. The resulting mixture was filtered, the filter cake was washed with DCM (3 mL) (3 x 2 mL). The filtrate was concentrated under reduced pressure, and added DCM (1 mL) to the concentrated filtrate. The system was purified by trituration with MTBE (4 mL). This resulted in 4-{2-chloro-3,3-dicyclohexyl-1,1-dimethylbenzo[d]1-aza-3- 109 Attorney Docket No.57891-0006WO1 phospha-2-auracyclopentan-2-yl}-2,6-difluorophenyl sulfurofluoridate (100 mg, 38.63% yield) as a grey solid. LCMS:(ES, m / z): [M]+= 760.1. 1H NMR (300 MHz, DMSO-d6, ppm) δ 8.38 (dd, J = 8.5, 4.3 Hz, 1H), 8.05 (t, J = 9.3 Hz, 2H), 7.82 (d, J = 8.9 Hz, 3H), 3.49 (s, 6H), 3.02 (d, J = 11.2 Hz, 2H), 1.99 (s, 2H), 1.87- 5 1.48 (m, 10H), 1.34 (d, J = 12.9 Hz, 4H), 1.00 (d, J = 12.9 Hz, 2H), 0.66-0.44 (s, 2H). Example 17. Synthesis of Au-8 Step 1: To a stirred mixture of 2,3-difluoro-4-iodophenol (500 mg, 1.95 mmol, 1 equiv) and 3-(fluorosulfonyl)-1,2-dimethylimidazol-1-ium triflate (961.71 mg, 2.92 mmol, 1.5 equiv)10in ACN (3 mL) was added TEA (395.30 mg, 3.90 mmol, 2 equiv) dropwise at 0 °C. The reaction was monitored by LCMS. The resulting mixture was concentrated under reduced pressure. The crude product was purified by reverse phase flash to afford 2,3-difluoro-4- iodophenyl sulfurofluoridate (60 mg, 9.09% yield) as a yellow oil. Step 2: To a stirred mixture of Silver Hexafluoroantimonate(V) (60.99 mg, 0.17 mmol, 15 1 equiv) in DCM (3 mL) were added 2,3-difluoro-4-iodophenyl sulfurofluoridate (60 mg, 0.17 mmol, 1 equiv) and 2-[(chloroaurio)dicyclohexyl-lambda5-phosphanyl]-N,N-dimethylaniline (97.78 mg, 0.17 mmol, 1 equiv) in portions at 0 °C under nitrogen atmosphere. The reaction was monitored by LCMS. The resulting mixture was filtered, the filter cake was washed with DCM (3 mL) (3 x 1 mL). The filtrate was concentrated under reduced pressure, and added20DCM (1 mL) to the concentrated filtrate. The system was purified by trituration with MTBE (3 mL). This resulted in 4-{2-chloro-3,3-dicyclohexyl-1,1-dimethylbenzo[d]1-aza-3-phospha- 2-auracyclopentan-2-yl}-2,3-difluorophenyl sulfurofluoridate (60 mg, 44.42% yield) as a grey solid. LCMS:(ES, m / z): [M]+= 760.1. 1H NMR (300 MHz, DMSO-d6, ppm) δ 8.41 (dd, J = 8.5, 4.3 Hz, 1H), 8.08 (t, J = 9.1 25 Hz, 2H), 7.91 – 7.78 (m, 2H), 7.69 (d, J = 9.2 Hz, 1H), 3.56 (d, J = 13.3 Hz, 6H), 3.08 (s, 2H), 1.98 (d, J = 37.0 Hz, 2H), 1.65 (s, 9H), 1.46 – 1.24 (m, 5H), 1.14 – 0.86 (m, 2H), 0.55 (s, 2H). Example 18. Synthesis of Au-MM-1 110 Attorney Docket No.57891-0006WO1 Step 1: To a stirred solution of 3-[(fluorosulfonyl)oxy]benzoic acid (331.73 mg, 1.507 mmol, 1.10 equiv), DIEA (531.09 mg, 4.110 mmol, 3 equiv) and HATU (781.22 mg, 2.055 mmol, 1.5 equiv) in DCM (8 mL) were added 3-iodo-benzenamine (300 mg, 1.370 mmol, 1.00 5 equiv) dropwise at 0 °C. The resulting mixture was stirred at 25 °C for additional 1 h. The reaction was monitored by LCMS. The resulting mixture was extracted with DCM (3 x 5 mL). The combined organic layers were dried over anhydrous Na2SO4. After filtration, the filtrate was concentrated under reduced pressure. The residue was purified by reversed-phase flash chromatography with the following conditions: column, C18 silica gel; mobile phase, MeCN10in Water (0.1% FA), 10% to 70% gradient in 12 min; detector, UV 254 nm. This resulted in 3- [(3-iodophenyl)carbamoyl]phenyl sulfurofluoridate (150 mg, 26.00% yield) as a white solid. Step 2: To a stirred mixture of AgSbF6 (118.30 mg, 0.344 mmol, 1 equiv) in DCM (6 mL) were added 3-[(3- iodophenyl)carbamoyl]phenyl sulfurofluoridate (145 mg, 0.344 mmol, 15 1 equiv) and 2-[(chloroaurio)dicyclohexyl-lambda5-phosphanyl]-N,N-dimethylaniline (189.30 mg, 0.344 mmol, 1 equiv) in portions at 0 °C. The resulting mixture was stirred at 25 °C for additional 2 h. The resulting mixture was filtered, and the filter cake was washed with DCM. The filtrate was concentrated under reduced pressure, and added DCM (1 mL) to the concentrated filtrate. The system was purified by trituration with MTBE (4 mL). This resulted20in product (55 mg, 18.93% yield, 99.54% purity) as a light grey solid. LCMS:(ES, m / z): [M]+= 843.1. 1H NMR (300 MHz, DMSO-d6, ppm) δ 10.61 (s, 1H), 8.36 (dd, J = 8.4, 4.4 Hz, 1H), 8.22 – 7.99 (m, 5H), 7.87 – 7.75 (m, 3H), 7.44 – 7.34 (m, 2H), 7.31-7.23 (m, 1H), 3.45 (s, 6H), 3.62-3.02 (m, 2H), 1.90-1.46 (m, 12H), 1.30 (d, J = 31.8 Hz, 4H), 1.05 (s, 2H), 0.71-0.48 (s, 25 2H). Example 19. Synthesis of Au-MP-4 Attorney Docket No.57891-0006WO1 Step 1: To a stirred solution of 2(1H)-pyridinone, 5-iodo- (500 mg, 2.262 mmol, 1 equiv) and K2CO3 (469.03 mg, 3.393 mmol, 1.5 equiv) in DMF (5 mL) were added 4- methoxybenzyl chloride (425.19 mg, 2.714 mmol, 1.2 equiv) dropwise at 0 °C under nitrogen atmosphere. The resulting mixture was stirred at room temperature for 5 additional 3 h. The resulting mixture was diluted with 5 mL H2O and extracted with EtOAc (5 mL x 3). The combined organic layers were washed with brine (5 mL), dried over anhydrous Na2SO4. After filtration, the filtrate was concentrated under reduced pressure. The residue was purified by silica gel column chromatography, eluted with PE / EA (3:1) to afford 5-iodo-1-[(4-methoxyphenyl) methyl] pyridin-2-one (500 mg, 64.78% yield) as a light 10 yellow oil. Step 2: To a stirred solution of 5-iodo-1-[(4-methoxyphenyl) methyl] pyridin-2-one (500 mg, 1.466 mmol, 1 equiv) in DCM (3 mL) were added Boron tribromide 1M solution in methylene chloride (6 mL) dropwise at 0 °C under nitrogen atmosphere. The resulting mixture was stirred at 0 °C for additional 1 h. The reaction was quenched with ice water at 0 °C. The 15 resulting mixture was stirred at room temperature for additional 3 h. The resulting mixture was diluted with 10 mL H2O and extracted with DCM (10 mL x 3). The combined organic layers were washed with brine (10 mL), dried over anhydrous Na2SO4. After filtration, the filtrate was concentrated under reduced pressure. This resulted in 1-[(4-hydroxyphenyl) methyl]-5- iodopyridin-2-one (300 mg, 62.57% yield) as a light brown solid. The crude product was used 20 in the next step directly without further purification. Step 3: To a stirred solution of 1-[(4-hydroxyphenyl)methyl]-5-iodopyridin-2-one (300 mg, 0.917 mmol, 1 equiv) and 3-(fluorosulfonyl)-1,2-dimethylimidazol-1-ium triflate (451.55 mg, 1.376 mmol, 1.5 equiv) in MeCN (5 mL) were added TEA (185.61 mg, 1.834 mmol, 2 equiv) dropwise at 0°C under nitrogen atmosphere. The resulting mixture was stirred at room 25 temperature for additional 30 min. The resulting mixture was concentrated under reduced pressure. The residue was purified by reversed-phase flash chromatography with the following conditions: column, C18 silica gel; mobile phase, MeCN in Water (0.1% FA), 10% to 90% gradient in 10 min; detector, UV 254 nm. This resulted in 4-[(5-iodo-2-oxopyridin-1-yl) methyl] phenyl sulfurofluoridate (150 mg, 39.97% yield) as a light yellow solid. 30 Step 4: To a stirred solution of Silver Hexafluoroantimonate(V) (117.57 mg, 0.342 mmol, 1 equiv) in DCM (3 mL) at 0 °C under nitrogen atmosphere. To the above mixture was added 4-[(5-iodo-2-oxopyridin-1-yl)methyl]phenyl sulfurofluoridate (140 mg, 0.342 mmol, 1 equiv) and 2-[(chloroaurio)dicyclohexyl-lambda5-phosphanyl]-N,N-dimethylaniline (188.14 112 Attorney Docket No.57891-0006WO1 mg, 0.342 mmol, 1 equiv) in portions at 0 °C. The resulting mixture was stirred at room temperature for additional overnight. The resulting mixture was filtered, the filter cake was washed with DCM (1 mL x 3). The filtrate was concentrated under reduced pressure, and added DCM (1 mL) to the concentrated filtrate. The system was purified by trituration with MTBE 5 (4 mL). This resulted in 2-chloro-3,3-dicyclohexyl-2-[1-({4-[(fluorosulfonyl)oxy] phenyl} methyl)-6-oxopyridin-3-yl]-1,1-dimethyl-2H,3H-3lambda5-benzo[d]1-aza-3lambda5- phospha-2-auracyclopentan-1-ium-3-ylium-2,2-diuide (40 mg, 14.05% yield, 95% purity) as a light brown solid. LCMS:(ES, m / z): [M]+= 831.1. 1H NMR (300 MHz, DMSO-d6, ppm) δ 8.43 – 8.30 (m, 1H), 8.13 – 7.99 (m, 2H), 7.86 10 – 7.72 (m, 1H), 7.66 (td, J = 8.3, 2.4 Hz, 3H), 7.61 – 7.38 (m, 3H), 6.69 (dd, J = 31.1, 9.6 Hz, 1H), 5.56 – 4.98 (m, 2H), 3.58 – 3.11 (m, 6H), 2.91 (s, 2H), 2.03 (s, 1H), 1.88 – 1.33 (m, 12H), 1.26 – 1.05 (d, J = 38.8 Hz, 4H), 0.94 – 0.64 (d, J = 46.3 Hz, 3H). Example 20. Synthesis of Au-MP-5 15Step 1: To a stirred solution of P-hydroxybenzaldehyde (1 g, 8.188 mmol, 1 equiv) and 3-(fluorosulfonyl)-1,2-dimethylimidazol-1-ium triflate (4.03 g, 12.282 mmol, 1.5 equiv) in MeCN (10 mL) was added TEA (1.66 g, 16.376 mmol, 2 equiv) dropwise at 0 °C under nitrogen atmosphere. The resulting mixture was stirred at room temperature for additional 30 min. The resulting mixture was concentrated under reduced pressure. The residue 20 was purified by reversed-phase flash chromatography with the following conditions: column, C18 silica gel; mobile phase, MeCN in Water (0.1% FA), 10% to 90% gradient in 10 min; detector, UV 254 nm. This resulted in 4-formylphenyl sulfurofluoridate (600 mg, 35.89% yield) as a light yellow oil. Step 2: To a stirred solution of 4-formylphenyl sulfurofluoridate (200 mg, 0.980 mmol,251 equiv),benzenamine, 3-iodo- (257.46 mg, 1.176 mmol, 1.2 equiv) and HOAc (58.83 mg, 0.980 mmol, 1 equiv) in DCM (4 mL) at room temperature under nitrogen atmosphere. The mixture was stirred for 15 min. STAB (415.22 mg, 1.960 mmol, 2 equiv) was added and stirred for 2 h. The resulting mixture was diluted with 5 mL H2O and extracted with EtOAc (5 mLx3). The combined organic layers were washed with brine (5 mL), dried over 113 Attorney Docket No.57891-0006WO1 anhydrous Na2SO4. After filtration, the filtrate was concentrated under reduced pressure. The residue was purified by reversed-phase flash chromatography with the following conditions: column, C18 silica gel; mobile phase, MeCN in Water (0.1% FA), 10% to 90% gradient in 10 min; detector, UV 254 nm. This resulted in 4-{[(3-iodophenyl) amino] methyl} phenyl 5 sulfurofluoridate (100 mg, 25.07% yield) as a light yellow oil. Step 3: To a stirred solution of Silver Hexafluoroantimonate(V) (84.39 mg, 0.246 mmol, 1 equiv) in DCM (3 mL) at 0 °C under nitrogen atmosphere. To the above mixture was added 4-{[(3-iodophenyl) amino] methyl} phenyl sulfurofluoridate (100 mg, 0.246 mmol, 1 equiv) and 2-[(chloroaurio)dicyclohexyl-lambda5-phosphanyl]-N,N-dimethylaniline (135.04 10 mg, 0.246 mmol, 1 equiv) in portions at 0 °C. The resulting mixture was stirred at room temperature for additional overnight. The resulting mixture was filtered, the filter cake was washed with DCM (1 mL x 3). The filtrate was concentrated under reduced pressure, and added DCM (1 mL) to the concentrated filtrate. The system was purified by trituration with MTBE (4 mL). This resulted in [(2-{[chloro({3-[({4-[(fluorosulfonyl) oxy] phenyl} methyl) 15 amino] phenyl}) aurio] dicyclohexyl-lambda5-phosphanyl} phenyl) dimethylammonio] methanidylidene (64 mg, 30.94% yield, 92.7% purity) as a light brown solid. LCMS:(ES, m / z): [M]+= 829.1. 1H NMR (300 MHz, DMSO-d6, ppm) δ 8.31 (dd, J = 8.6, 4.4 Hz, 1H), 8.09 – 7.94 (m, 2H), 7.75 (td, J = 7.5, 2.3 Hz, 1H), 7.54 (s, 4H), 7.02 (dd, J = 15.0, 7.1 Hz, 1H), 6.90 – 6.60 20 (m, 2H), 6.59 – 6.29 (m, 2H), 4.38 (s, 2H), 3.30 (d, J = 43.2 Hz, 6H), 2.88 (d, J = 11.6 Hz, 2H), 1.86 – 1.36 (m, 12H), 1.32 – 1.12 (m, 4H), 1.01 (t, J = 12.3 Hz, 2H), 0.61 (s, 2H). Example 21. Synthesis of Au-MP-6 Step 1: To a stirred solution of 3-iodobenzoyl chloride (2 g, 7.506 mmol, 1 25 equiv) and AlCl3(2.20 g, 16.513 mmol, 2.2 equiv) in DCM (20 mL) was added anisole (0.89 g, 8.257 mmol, 1.1 equiv) dropwise at 0 °C under nitrogen atmosphere. The resulting mixture was stirred at room temperature for additional 2 h. The reaction was quenched by the addition of ice water (20 mL) at 0 °C. The resulting mixture was extracted with DCM (20 mL x 3). The combined organic layers were washed with brine (20 mL), dried over anhydrous Na2SO4. After30filtration, the filtrate was concentrated under reduced pressure. The residue was purified by 114 Attorney Docket No.57891-0006WO1 silica gel column chromatography, eluted with PE / EA (4:1) to afford (3-iodophenyl) (4- methoxyphenyl) methanone (1.5 g, 59.10% yield) as a light yellow oil. Step 2: To a stirred solution of (3-iodophenyl)(4-methoxyphenyl)methanone (1.5 g, 4.436 mmol, 1 equiv) in MeCN (20 mL) at 0 °C under nitrogen atmosphere. To the above 5 mixture was added Et3SiH (1.16 g, 9.981 mmol, 2.25 equiv) and Boron trifluoride in diethyl ether solution (3.35 g, 11.090 mmol, 2.5 equiv, 47%) dropwise at 0 °C. The resulting mixture was stirred at room temperature for additional overnight. The mixture was basified to pH 7 with saturated NaHCO3 (aq.). The resulting mixture was diluted with 20 mL H2O and extracted with EtOAc (20 mL x 3). The combined organic layers were washed with brine (20 10 mL), dried over anhydrous Na2SO4. After filtration, the filtrate was concentrated under reduced pressure. The residue was purified by silica gel column chromatography, eluted with PE / EA (5:1) to afford 1-iodo-3-[(4- methoxyphenyl) methyl] benzene (1.1 g, 76.50% yield) as a light yellow solid. Step 3: To a stirred solution of 1-iodo-3-[(4-methoxyphenyl) methyl] benzene (1.1 g, 15 3.393 mmol, 1 equiv) in DCM (3 mL) was added Boron tribromide 1M solution in methylene chloride (9 mL) dropwise at 0 °C under nitrogen atmosphere. The resulting mixture was stirred at 0 °C for additional 1h. The reaction was quenched by the addition of ice water (10 mL) at 0 °C. The resulting mixture was extracted with DCM (20 mL x 3). The combined organic layers were washed with brine (20 mL), dried over anhydrous Na2SO4. After filtration, the filtrate was 20 concentrated under reduced pressure. This resulted in 4-[(3-iodophenyl) methyl] phenol (700 mg, 66.51% yield) as a light brown solid. The crude product was used in the next step directly without further purification. Step 4: To a stirred solution of 4-[(3-iodophenyl) methyl] phenol (700 mg, 2.257 mmol, 1 equiv) and 3-(fluorosulfonyl)-1,2-dimethylimidazol-1-ium triflate (1111.33 mg, 3.386 mmol, 25 1.5 equiv) in MeCN (10 mL) was added TEA (456.80 mg, 4.514 mmol, 2 equiv) dropwise at 0 °C under nitrogen atmosphere. The resulting mixture was stirred at room temperature for additional 30 min. The residue was purified by reversed-phase flash chromatography with the following conditions: column, C18 silica gel; mobile phase, MeCN in Water (0.1% FA), 10% to 90% gradient in 10 min; detector, UV 254 nm. This resulted in 4-[(3-iodophenyl) methyl] 30 phenyl sulfurofluoridate (400 mg, 45.19% yield) as a light yellow oil. Step 5: To a stirred solution of Silver Hexafluoroantimonate(V) (87.62 mg, 0.255 mmol, 1 equiv) in DCM (3 mL) at 0 °C under nitrogen atmosphere. To the above mixture was added 4-[(3-iodophenyl) methyl] phenyl sulfurofluoridate (100 mg, 0.255 mmol, 1 115 Attorney Docket No.57891-0006WO1 equiv) and 2-[(chloroaurio)dicyclohexyl-lambda5-phosphanyl]-N,N-dimethylaniline (140.21 mg, 0.255 mmol, 1 equiv) in portions at 0 °C. The resulting mixture was stirred at room temperature for additional overnight. The resulting mixture was filtered, the filter cake was washed with DCM (1 mL x 3). The filtrate was concentrated under reduced pressure, and 5 added DCM (2 mL) to the concentrated filtrate. The system was purified by trituration with MTBE (4 mL). This resulted in 2-chloro-3,3-dicyclohexyl-2-[3-({4-[(fluorosulfonyl) oxy] phenyl} methyl) phenyl]-1,1-dimethyl-2H,3H-3lambda5-benzo[d]1-aza-3lambda5-phospha- 2-auracyclopentan-1-ium-3-ylium-2,2-diuide (100 mg, 48.11% yield, 93.9 % purity) as a grey solid. LCMS:(ES, m / z): [M]+= 814.1. 101H NMR (300 MHz, DMSO-d6, ppm) δ 8.34 (dd, J = 8.6, 4.4 Hz, 1H), 8.03 (q, J = 7.7 Hz, 2H), 7.76 (td, J = 7.4, 2.4 Hz, 1H), 7.57 (d, J = 8.5 Hz, 2H), 7.51 – 7.42 (m, 2H), 7.40 – 7.12 (m, 4H), 4.08 (s, 2H), 3.08 – 2.55 (m, 2H), 1.59 (d, J = 34.0 Hz, 12H), 1.21 (d, J = 19.7 Hz, 4H), 0.91 (s, 2H), 0.47 (s, 2H). Example 22. Synthesis of Au-MP-8 15 Step 1: Into a 100 mL 2-necked round-bottom flask were added 1,3-diiodobenzene (1.5 g, 4.547 mmol, 1 equiv), P-anisidine (0.56 g, 4.547 mmol, 1 equiv), Pd(dppf)Cl2 (0.33 g, 0.455 mmol, 0.1 equiv), t-BuONa (1.31 g, 13.641 mmol, 3 equiv) in toluene (50 mL) at room temperature. The resulting mixture was stirred at 90 °C for additional 36 h. The reaction was20monitored by LCMS. The resulting mixture was extracted with EtOAc (3 x 20 mL). The combined organic layers were washed with water (3 x 20 mL), dried over anhydrous Na2SO4. After filtration, the filtrate was concentrated under reduced pressure. The residue was purified by reversed-phase flash chromatography with the following conditions: column, C18 silica gel; mobile phase, MeCN in Water (0.1% FA), 10% to 60% gradient in 12 min; detector, UV 254 25 nm. This resulted in 3-iodo-N-(4-methoxyphenyl)aniline (640 mg, 43.29% yield) as a black oil. Step 2: To a stirred mixture of 3-iodo-N-(4-methoxyphenyl)aniline (650 mg, 1.999 mmol, 1 equiv) in DCM was added BBr3(10 mL) dropwise at 0 °C. The resulting mixture was stirred at room temperature for additional 20 min. The reaction was quenched with ice water at300 °C. The resulting mixture was extracted with DCM (3 x 10 mL). The combined organic layers 116 Attorney Docket No.57891-0006WO1 were washed with water (1 x 5 mL), dried over anhydrous Na2SO4. After filtration, the filtrate was concentrated under reduced pressure. The crude product mixture was used in the next step directly without further purification. Step 3: To a stirred mixture of 4-[(3-iodophenyl)amino]phenol (460 mg, 1.479 mmol, 5 1 equiv) and 3-(fluorosulfonyl)-1,2-dimethylimidazol-1-ium triflate (582.39 mg, 1.775 mmol, 1.2 equiv) in ACN (10 mL) were added TEA (299.23 mg, 2.958 mmol, 2 equiv) dropwise at 0 °C. The resulting mixture was stirred at room temperature for additional 30 min. The reaction was monitored by LCMS. The residue was purified by reversed-phase flash chromatography with the following conditions: column, C18 silica gel; mobile phase, MeCN in Water (0.1%10 FA), 10% to 70% gradient in 12 min; detector, UV 254 nm. This resulted in 4-[(3- iodophenyl)amino]phenyl sulfurofluoridate (280 mg, 48.17% yield) as a colorless oil. Step 4: To a stirred mixture of AgSbF6 (61.18 mg, 0.178 mmol, 1.00 equiv) in DCM (4 mL) were added 4-[(3-iodophenyl) amino] phenyl sulfurofluoridate (70 mg, 0.178 mmol, 1.00 equiv) and (chloroaurio)dicyclohexyl[2-(dimethylamino) phenyl]-lambda5-phosphanyl (97.90 15 mg, 0.178 mmol, 1.00 equiv) dropwise at 0 °C. The resulting mixture was stirred at 25 °C for additional 2 h. The resulting mixture was filtered, and the filter cake was washed with DCM. The filtrate was concentrated under reduced pressure, and added DCM (1 mL) to the concentrated filtrate. The system was purified by trituration with MTBE (4 mL). This resulted in {chloro[3-({4-[(fluorosulfonyl) oxy] phenyl} amino) phenyl] aurio} dicyclohexyl[2- 20 (dimethylamino) phenyl] -lambda5-phosphanyl (50 mg, 34.41% yield, 99.57% purity) as a light yellow solid. LCMS: (ES, m / z): [M]+= 815.0. 1H NMR (300 MHz, DMSO-d6, ppm) δ 8.66 (s, 1H), 8.34 (dd, J = 8.5, 4.4 Hz, 1H), 8.12 – 7.97 (m, 2H), 7.83 – 7.73 (m, 1H), 7.47 (d, J = 8.9 Hz, 2H), 7.28 (t, J = 7.9 Hz, 1H), 7.24 – 7.14 (m, 3H), 7.09 – 7.00 (m, 1H), 6.93 (d, J = 7.8 Hz, 1H), 3.42 (s, 6H), 2.94 (d, J = 25 11.4 Hz, 2H), 1.96-1.41 (m, 12H), 1.25 (s, 4H), 1.01 (s, 2H), 0.65 (s, 2H). Example 23. Synthesis of Au-PM-3A and Au-PM-3B Step 1: To a stirred solution of tert-butyl N-(4-oxocyclohexyl)carbamate (2 g, 9.377 mmol, 1 equiv),benzenamine, 4-iodo- (2.46 g, 11.252 mmol, 1.2 equiv) and HOAc (0.56 g, 117 Attorney Docket No.57891-0006WO1 9.377 mmol, 1 equiv) in DCM (20 mL) at room temperature under nitrogen atmosphere. To the above mixture was added STAB (3.97 g, 18.754 mmol, 2 equiv) in portions at room temperature. The resulting mixture was stirred at room temperature for additional 2 h. The resulting mixture was diluted with 20 mL H2O and extracted with DCM (20 mL x 3). The 5 combined organic layers were washed with brine (20 mL), dried over anhydrous Na2SO4. After filtration, the filtrate was concentrated under reduced pressure. This resulted in tert-butyl N- {4-[(4-iodophenyl) amino] cyclohexyl} carbamate (3.5 g, 89.65% yield) as a light yellow solid. The crude product was used in the next step directly without further purification. Step 2: To a stirred solution of tert-butyl N-{4-[(4-iodophenyl) amino]10 cyclohexyl}carbamate (4 g, 9.608 mmol, 1 equiv) in DCM (20 mL) were added tert-butyl N- {4-[(4-iodophenyl)amino]cyclohexyl}carbamate (4 g, 9.608 mmol, 1 equiv) dropwise at room temperature under nitrogen atmosphere. The resulting mixture was stirred at room temperature for additional 2 h. The precipitated solids were collected by filtration and washed with DCM (5 mL x 3). This resulted in N1-(4-iodophenyl) cyclohexane-1,4-diamine 15 hydrochloride (3 g, 88.54% yield) as a light yellow solid. The crude product was used in the next step directly without further purification. Step 3: To a stirred solution 3-[(fluorosulfonyl)oxy]benzoic acid (522.25 mg, 2.372 mmol, 1.5 equiv),HATU (901.93 mg, 2.372 mmol, 1.5 equiv) and DIEA (408.77 mg, 3.162 mmol, 2 equiv) in DCM (5 mL) at room temperature under nitrogen atmosphere. The mixture 20 was stirred for 15 min. N1-(4-iodophenyl) cyclohexane-1,4-diamine (500 mg, 1.581 mmol, 1 equiv) was added and stirred for 30 min. The resulting mixture was diluted with 5 mL H2O and extracted with DCM (5 mL x 3). The combined organic layers were washed with brine (5 mL), dried over anhydrous Na2SO4. After filtration, the filtrate was concentrated under reduced pressure. The residue was purified by reversed-phase flash chromatography with the following 25 conditions: column, C18 silica gel; mobile phase, MeCN in Water (0.1% FA), 10% to 50% gradient in 10 min; detector, UV 254 nm. This resulted in 3-{[(1s,4s)-4-[(4-iodophenyl) amino] cyclohexyl] carbamoyl} phenyl sulfurofluoridate (100 mg, 12.20% yield) and 3-{[(1r,4r)-4- [(4-iodophenyl)amino]cyclohexyl]carbamoyl}phenyl sulfurofluoridate (140 mg, 17.08% yield) as a light yellow oil. 30 Step 4A: To a stirred solution of Silver Hexafluoroantimonate(V) (66.29 mg, 0.193 mmol, 1 equiv) in DCM (3 mL) at 0 °C under nitrogen atmosphere. To the above mixture was added 3-{[(1s,4s)-4-[(4-iodophenyl)amino]cyclohexyl]carbamoyl}phenyl sulfurofluoridate (100 mg, 0.193 mmol, 1 equiv) and (chloroaurio)dicyclohexyl[2-(dimethylamino)phenyl]- 118 Attorney Docket No.57891-0006WO1 lambda5-phosphanyl (106.08 mg, 0.193 mmol, 1 equiv) in portions at 0 °C. The resulting mixture was stirred at room temperature for additional overnight. The resulting mixture was stirred at room temperature for additional overnight. The resulting mixture was filtered, the filter cake was washed with DCM (1 mL x 3). The filtrate was concentrated under reduced 5 pressure, and added DCM (1 mL) to the concentrated filtrate. The system was purified by trituration with MTBE (4 mL). This resulted in 2-chloro-3,3-dicyclohexyl-1,1-dimethyl-2-(4- {[(1s,4s)-4-{3-[(fluorosulfonyl)oxy] benzamido} cyclohexyl] amino} phenyl)-2H,3H- 3lambda5-benzo[d]1-aza-3lambda5-phospha-2-auracyclopentan-1-ium-3-ylium-2,2-diuide (80 mg, 44.05% yield, 97.2% purity) as a light yellow solid. LCMS Au-PM-3-0A:(ES, m / z): 10 [M]+= 940.1 1H NMR Au-PM-3A (300 MHz, DMSO-d6, ppm) δ 8.52 (d, J = 7.7 Hz, 1H), 8.33 (dd, J = 8.5, 4.4 Hz, 1H), 8.12 – 7.96 (m, 4H), 7.88 – 7.47 (m, 4H), 7.04 (s, 2H), 6.76 (d, J = 29.5 Hz, 2H), 3.74 (d, J = 27.1 Hz, 6H), 3.26 (s, 2H), 2.92 (d, J = 11.6 Hz, 2H), 2.05 (d, J = 12.1 Hz, 2H), 1.94 (d, J = 11.9 Hz, 2H), 1.83 (s, 2H), 1.78 – 1.57 (m, 8H), 1.47 (t, J = 12.0 Hz, 4H), 15 1.29 (dd, J = 22.9, 11.1 Hz, 6H), 1.05 (t, J = 12.1 Hz, 2H), 0.64 (s, 2H). Step 4B: To a stirred solution of Silver Hexafluoroantimonate(V) (92.81 mg, 0.270 mmol, 1 equiv) in DCM (3 mL) at 0°C under nitrogen atmosphere. To the above mixture was added 3-{[(1r,4r)-4-[(4-iodophenyl)amino]cyclohexyl]carbamoyl}phenyl sulfurofluoridate (140 mg, 0.270 mmol, 1 equiv) and(chloroaurio)dicyclohexyl[2-(dimethylamino)phenyl]- 20 lambda5-phosphanyl (148.52 mg, 0.270 mmol, 1 equiv) in portions at 0°C. The resulting mixture was filtered, the filter cake was washed with DCM (1 mL x 3). The filtrate was concentrated under reduced pressure, and added DCM (1 mL) to the concentrated filtrate. The system was purified by trituration with MTBE (4 mL). This resulted in 2-chloro-3,3- dicyclohexyl-1,1-dimethyl-2-(4-{[(1r,4r)-4-{3-[(fluorosulfonyl) oxy] benzamido} cyclohexyl]25 amino} phenyl)-2H,3H-3lambda5-benzo[d]1-aza-3lambda5-phospha-2-auracyclopentan-1- ium-3-ylium-2,2-diuide (80 mg, 31.47% yield, 97.4% purity) as a light yellow solid. LCMS Au-PM-3-0B:(ES, m / z): [M]+= 940.2 1H NMR Au-PM-3B (300 MHz, DMSO-d6, ppm) δ 8.42 (d, J = 6.6 Hz, 1H), 8.33 (dd, J = 8.6, 4.3 Hz, 1H), 8.16 – 7.97 (m, 4H), 7.87 – 7.58 (m, 4H), 7.06 (s, 2H), 6.87 – 6.64 (m, 30 2H), 4.13(s, 6H), 3.91 (s, 2H), 3.46 (s, 1H), 2.90 (d, J = 11.0 Hz, 1H), 2.00 – 1.41 (m, 20H), 1.32 (dd, J = 24.0, 11.9 Hz, 4H), 1.05 (t, J = 12.2 Hz, 2H), 0.63 (s, 2H). Example 24. Synthesis of Au-PM-5 119 Attorney Docket No.57891-0006WO1 Step 1: A mixture of 4-iodo-1H-pyridin-2-one (1 g, 4.525 mmol, 1 equiv) and 1- (bromomethyl)-3-methoxybenzene (1.09 g, 5.430 mmol, 1.2 equiv) in DMF (20 mL) was stirred at room temperature for 1 h. The resulting mixture was filtered, the filter cake was 5 washed with MeOH (3 x 3 mL). The filtrate was concentrated under reduced pressure. The residue was purified by reversed-phase flash chromatography with the following conditions: column, C18 silica gel; mobile phase, MeCN in Water (0.1% FA), 10% to 95% gradient in 10 min; detector, UV 254 nm. This resulted in 4-iodo-1-[(3-methoxyphenyl) methyl] pyridin-2- one (800 mg, 51.82% yield) as a white solid.10Step 2: To a stirred mixture of 4-iodo-1-[(3-methoxyphenyl) methyl] pyridin-2-one (500 mg, 1.466 mmol, 1 equiv) in DCM (2 mL) was added BBr3 (4 mL) dropwise at 0 °C. The resulting mixture was stirred at 0 °C for 1 h. The reaction mixture was quenched by ice water and extracted with DCM (3 x 20 mL), dried over anhydrous Na2SO4. After filtration, the filtrate was concentrated under reduced pressure to afford 1-[(3-hydroxyphenyl) methyl] -4- 15 iodopyridin-2-one (400 mg, 83.43% yield) as a white solid. The crude resulting mixture was used in the next step directly without further purification. Step 3: To a stirred mixture of 1-[(3-hydroxyphenyl) methyl] -4-iodopyridin-2-one (300 mg, 0.917 mmol, 1 equiv) and 3-(fluorosulfonyl)-1,2-dimethylimidazol-1-ium triflate (361.24 mg, 1.100 mmol, 1.2 equiv) in MeCN (5 mL) was added TEA (139.20 mg, 1.376 mmol, 1.520equiv) dropwise at 0 °C. The resulting mixture was stirred at 0 °C for 30 min. The resulting mixture was concentrated under reduced pressure. The residue was purified by reversed-phase flash chromatography with the following conditions: column, C18 silica gel; mobile phase, MeCN in Water (0.1% FA), 10% to 95% gradient in 10 min; detector, UV 254 nm. This resulted in 3-[(4-iodo-2-oxopyridin-1-yl) methyl] phenyl sulfurofluoridate (200 mg, 53.30% 25 yield) as a white solid. Step 4: To a stirred solution of 3-[(4-iodo-2-oxopyridin-1-yl) methyl] phenyl sulfurofluoridate (100 mg, 0.244 mmol, 1 equiv) and (chloroaurio)dicyclohexyl[2- (dimethylamino) phenyl]-lambda5-phosphanyl (134.39 mg, 0.244 mmol, 1 equiv) in DCM (5 mL) were added Silver Hexafluoroantimonate(V) (83.98 mg, 0.244 mmol, 1 equiv) in portions 120 Attorney Docket No.57891-0006WO1 at 0 °C under nitrogen atmosphere. The resulting mixture was stirred at room temperature for additional 2 h. The reaction was monitored by LCMS. The resulting mixture was filtered, the filter cake was washed with DCM (3 x 3 mL). The filtrate was concentrated under reduced pressure, and added DCM (1 mL) to the concentrated filtrate. The system was purified by 5 trituration with MTBE (4 mL). This resulted in {chloro[1-({3-[(fluorosulfonyl) oxy] phenyl} methyl)-2-oxopyridin-4-yl] aurio} dicyclohexyl[2-(dimethylamino) phenyl]-lambda5- phosphanyl (50 mg, 24.59% yield, 93.3% purity) as a grey solid. LCMS:(ES, m / z): [M]+= 831.1. 1H NMR (300 MHz, DMSO-d6, ppm) δ 8.36 (dd, J = 8.6, 4.4 Hz, 1H), 8.03 (d, J = 8.6 10 Hz, 2H), 7.79 (t, J = 7.2 Hz, 1H), 7.69 – 7.53 (m, 4H), 7.50 (s, 1H), 7.44 (d, J = 7.3 Hz, 1H), 6.64 (d, J = 9.6 Hz, 1H), 5.28 (s, 2H), 2.67 (s, 2H), 1.83 (s, 2H), 1.70 – 1.48 (m, 10H), 1.27 – 1.14 (m, 4H), 0.98 (s, 2H), 0.83 (s, 2H). Example 25. Synthesis of Au-PM-7 15 Step 1: Into a 100 mL 2-necked round-bottom flask were added 1,4-diiodobenzene (1.5 g, 4.547 mmol, 1 equiv), M-anisidine (0.56 g, 4.547 mmol, 1 equiv), Pd(dppf)Cl2 (332.69 mg, 0.455 mmol, 0.1 equiv), t-OBuNa (1.31 g, 13.641 mmol, 3 equiv) in toluene (50 mL) at room temperature. The resulting mixture was stirred at 90 °C for additional 36 h. The reaction was monitored by LCMS. The resulting mixture was extracted with EtOAc (3 x 20 mL). The20combined organic layers were washed with water (3 x 20 mL), dried over anhydrous Na2SO4. After filtration, the filtrate was concentrated under reduced pressure. The residue was purified by reversed-phase flash chromatography with the following conditions: column, C18 silica gel; mobile phase, MeCN in Water (0.1% FA), 10% to 60% gradient in 12 min; detector, UV 254 nm. This resulted in 4-iodo-N-(3-methoxyphenyl)aniline (500 mg, 33.82% yield) as a black 25 oil. Step 2: To a stirred mixture of 4-iodo-N-(3-methoxyphenyl)aniline (500 mg, 1.538 mmol, 1 equiv) in DCM was added BBr3(8 mL) dropwise at 0°C. The resulting mixture was stirred at room temperature for additional 20 min. The reaction was quenched with ice water at 0 °C. The resulting mixture was extracted with DCM (3 x 10 mL). The combined organic layers30were washed with water (1 x 5 mL), dried over anhydrous Na2SO4. After filtration, the filtrate 121 Attorney Docket No.57891-0006WO1 was concentrated under reduced pressure. The crude product mixture was used in the next step directly without further purification. Step 3: To a stirred mixture of 3-[(4-iodophenyl)amino]phenol (370 mg, 1.189 mmol, 1 equiv) and 3-(fluorosulfonyl)-1,2-dimethylimidazol-1-ium triflate (468.44 mg, 1.427 mmol, 5 1.2 equiv) in ACN (8 mL) were added TEA (240.69 mg, 2.379 mmol, 2 equiv) dropwise at 0 °C. The resulting mixture was stirred at room temperature for additional 30 min. The reaction was monitored by LCMS. The residue was purified by reversed-phase flash chromatography with the following conditions: column, C18 silica gel; mobile phase, MeCN in Water (0.1% FA), 10% to 70% gradient in 12 min; detector, UV 254 nm. This resulted in 3-[(4-iodophenyl) 10 amino] phenyl sulfurofluoridate (160 mg, 34.22% yield) as a colorless oil. Step 4: To a stirred mixture of AgSbF6(61.18 mg, 0.178 mmol, 1 equiv) in DCM (3 mL) were added 3-[(4-iodophenyl)amino]phenyl sulfurofluoridate (70 mg, 0.178 mmol, 1 equiv) and (chloroaurio)dicyclohexyl[2--(dimethylamino)phenyl]-lambda5-phosphanyl (97.90 mg, 0.178 mmol, 1 equiv) dropwise at 0 °C. The resulting mixture was stirred at 25 °C for 15 additional 2 h. The resulting mixture was filtered, and the filter cake was washed with DCM, and added DCM (0.5 mL) to the concentrated filtrate. The system was purified by trituration with MTBE (2 mL). The residue was purified by trituration with MTBE (2 mL). This resulted in product (20 mg, 13.76% yield, 94.28% purity) as a yellow solid. LCMS: (ES, m / z): [M]+= 815.1. 201H NMR (400 MHz, DMSO-d6, ppm) δ 8.77 (s, 1H), 8.35 (dd, J = 8.6, 4.3 Hz, 1H), 8.05 (dt, J = 15.7, 8.3 Hz, 2H), 7.79 (t, J = 7.5 Hz, 1H), 7.44 (t, J = 8.3 Hz, 1H), 7.32 (d, J = 8.4 Hz, 2H), 7.20 (d, J = 8.4 Hz, 2H), 7.17 – 7.11 (m, 1H), 7.07 (t, J = 2.3 Hz, 1H), 7.01 – 6.94 (m, 1H), 3.44 (s, 6H), 2.96 (d, J = 11.1 Hz, 2H), 1.88 (s, 2H), 1.81-1.48 (m, 10H), 1.47 – 1.28 (m, 4H), 1.16-1.00 (m, 2H), 0.74-0.52 (m, 2H). 25 Example 26. Synthesis of Au-PP-3A and Au-PP-3B Step 1: To a stirred solution of 4-[(fluorosulfonyl)oxy]benzoic acid (468.26 mg, 2.127 mmol, 1.5 equiv),HATU (808.69 mg, 2.127 mmol, 1.5 equiv) and DIEA (366.51 mg, 2.836 122 Attorney Docket No.57891-0006WO1 mmol, 2 equiv) in DCM (5 mL) at room temperature under nitrogen atmosphere. The mixture was stirred for 15 min. N1-(4-iodophenyl) cyclohexane-1,4-diamine hydrochloride (500 mg, 1.418 mmol, 1 equiv) was added stirred for 30 min. The resulting mixture was diluted with 5 mL H2O and extracted with DCM (5 mL x 3). The combined organic layers were washed 5 with brine (5 mL), dried over anhydrous Na2SO4. After filtration, the filtrate was concentrated under reduced pressure. The residue was purified by reversed-phase flash chromatography with the following conditions: column, C18 silica gel; mobile phase, MeCN in Water (0.1% FA), 10% to 50% gradient in 10 min; detector, UV 254 nm. This resulted in 4-{[(1s,4s)-4-[(4- iodophenyl) amino] cyclohexyl] carbamoyl} phenyl sulfurofluoridate (110 mg, 14.97% 10 yield) and 4-{[(1r,4r)-4-[(4-iodophenyl)amino]cyclohexyl]carbamoyl}phenyl sulfurofluoridate (120 mg, 16.33% yield) as a light yellow solid. Step 2A: To a stirred solution Silver Hexafluoroantimonate(V) (72.92 mg, 0.212 mmol, 1 equiv) in DCM (3 mL) at 0 °C under nitrogen atmosphere. To the above mixture was added (chloroaurio)dicyclohexyl[2-(dimethylamino)phenyl]-lambda5-phosphanyl (116.69 15 mg, 0.212 mmol, 1 equiv) and dropwise at 0 °C. The resulting mixture was stirred at room temperature for additional 2 h. The resulting mixture was filtered, the filter cake was washed with DCM (1 mL x 3). The filtrate was concentrated under reduced pressure, and added DCM (1 mL) to the concentrated filtrate. The system was purified by trituration with MTBE (4 mL). This resulted in 2-chloro-3,3-dicyclohexyl-1,1-dimethyl-2-(4-{[(1s,4s)-4-{4-20 [(fluorosulfonyl)oxy] benzamido}cyclohexyl]amino}phenyl)-2H,3H-3lambda5-benzo[d]1- aza-3lambda5-phospha-2-auracyclopentan-1-ium-3-ylium-2,2-diuide (Au-PP-3A; 90 mg, 45.05% yield, 95.0% purity) as a light brown solid. LCMS:(ES, m / z): [M]+= 940.2. 1H NMR (300 MHz, DMSO-d6, ppm) δ 8.48 (d, J = 7.6 Hz, 1H), 8.33 (dd, J = 8.5, 4.3 Hz, 1H), 8.13 – 7.96 (m, 4H), 7.83 – 7.32 (m, 4H), 7.05 (s, 2H), 6.73 (s, 2H), 4.08 (s, 2H), 3.40 25 (s, 6H), 2.92 (d, J = 10.6 Hz, 2H), 2.05 (d, J = 12.3 Hz, 2H), 1.93 (d, J = 12.2 Hz, 2H), 1.83 (s, 2H), 1.67 (d, J = 22.4 Hz, 8H), 1.48 (d, J = 12.1 Hz, 4H), 1.41 – 1.24 (m, 6H), 1.03 (d, J = 13.2 Hz, 2H), 0.64 (s, 2H). Step 2B: To a stirred solution of Silver Hexafluoroantimonate(V) (79.55 mg, 0.232 mmol, 1 equiv) in DCM (3 mL) at 0°C under nitrogen atmosphere. To the above mixture was 30 added 4-{[(1r,4r)-4-[(4-iodophenyl) amino]cyclohexyl]carbamoyl}phenyl sulfurofluoridate (120 mg, 0.232 mmol, 1 equiv) and (chloroaurio)dicyclohexyl[2-(dimethylamino)phenyl]- lambda5-phosphanyl (127.30 mg, 0.232 mmol, 1 equiv) in portions at 0°C. The resulting mixture was stirred at room temperature for additional 2h. The resulting mixture was filtered, 123 Attorney Docket No.57891-0006WO1 the filter cake was washed with DCM (1 mL x 3). The filtrate was concentrated under reduced pressure, and added DCM (1 mL) to the concentrated filtrate. The system was purified by trituration with MTBE (4 mL). This resulted in 2-chloro-3,3-dicyclohexyl-1,1-dimethyl-2-(4- {[(1r,4r)-4-{4-[(fluorosulfonyl)oxy] benzamido} cyclohexyl] amino} phenyl)-2H,3H- 5 3lambda5-benzo[d]1-aza-3lambda5-phospha-2-auracyclopentan-1-ium-3-ylium-2,2-diuide (Au-PP-3B; 90 mg, 41.30% yield, 95.0% purity) as a light brown solid. LCMS:(ES, m / z): [M]+= 940.1. 1H NMR (300 MHz, DMSO-d6, ppm) δ 8.39 (d, J = 6.6 Hz, 1H), 8.33 (dd, J = 8.6, 4.3 Hz, 1H), 8.15 – 7.96 (m, 4H), 7.86 – 7.17 (m, 4H), 7.04 (d, J = 8.2 Hz, 2H), 6.71 (d, J = 8.4 10 Hz, 2H), 4.23 (s, 1H), 3.90 (s, 1H), 3.39 (s, 6H), 2.91 (d, J = 11.2 Hz, 2H), 1.92 – 1.48 (d, J = 29.1 Hz, 20H), 1.30 (dt, J = 18.3, 9.3 Hz, 4H), 1.03 (d, J = 13.0 Hz, 2H), 0.63 (s, 2H). Example 27. Synthesis of Au-PP-9 Step 1: To a stirred solution of 4-formylphenyl sulfurofluoridate (200 mg, 0.980 mmol, 15 1 equiv), benzenamine, 4-iodo- (257.46 mg, 1.176 mmol, 1.2 equiv) and HOAc (58.83 mg, 0.980 mmol, 1 equiv) in DCM (5 mL) at room temperature under nitrogen atmosphere. The mixture was stirred for 15 min. STAB (415.22 mg, 1.960 mmol, 2 equiv) was added and stirred for 2 h. The resulting mixture was diluted with 5 mL H2O and extracted with EtOAc (5 mL x 3). The combined organic layers were washed with brine (5 mL), dried over20anhydrous Na2SO4. After filtration, the filtrate was concentrated under reduced pressure. The residue was purified by reversed-phase flash chromatography with the following conditions: column, C18 silica gel; mobile phase, MeCN in Water (0.1% FA), 10% to 95% gradient in 10 min; detector, UV 254 nm. This resulted in 4-{[(4-iodophenyl) amino]methyl}phenyl sulfurofluoridate (100 mg, 25.07% yield) as a light brown oil. 25 Step 2: To a stirred solution of Silver Hexafluoroantimonate(V) (84.39 mg, 0.246 mmol, 1 equiv) in DCM (3 mL) at 0 °C under nitrogen atmosphere. To the above mixture was added 4-{[(4-iodophenyl) amino] methyl} phenyl sulfurofluoridate (100 mg, 0.246 mmol, 1 equiv) and 2-[(chloroaurio)dicyclohexyl-lambda5-phosphanyl]-N,N-dimethylaniline (135.04 mg, 0.246 mmol, 1 equiv) in portions at 0 °C. The resulting mixture was stirred at room 124 Attorney Docket No.57891-0006WO1 temperature for additional overnight. The resulting mixture was filtered, the filter cake was washed with DCM (1 mL x 3). The filtrate was concentrated under reduced pressure, and added DCM (1 mL) to the concentrated filtrate. The system was purified by trituration with MTBE (4 mL). This resulted in 2-chloro-3,3-dicyclohexyl-2-{4-[({4-[(fluorosulfonyl) oxy] 5 phenyl} methyl) amino] phenyl}-1,1-dimethyl-2H,3H-3lambda5-benzo[d]1-aza-3lambda5- phospha-2-auracyclopentan-1-ium-3-ylium-2,2-diuide (60 mg, 29.43% yield, 94.4% purity) as a light brown solid. LCMS:(ES, m / z): [M]+= 829.1. 1H NMR (300 MHz, DMSO-d6, ppm) δ 8.31 (dd, J = 8.3, 4.4 Hz, 1H), 8.12 – 7.93 (m, 2H), 7.82 – 7.69 (m, 1H), 7.55 (d, J = 3.6 Hz, 4H), 7.17 (d, J = 8.4 Hz, 1H), 6.99 (d, J = 8.3 10 Hz, 2H), 6.62 (d, J = 8.5 Hz, 2H), 4.38 (s, 2H), 3.39 (d, J = 8.8 Hz, 6H), 2.87 (d, J = 11.2 Hz, 2H), 2.34 – 1.35 (m, 12H), 1.25 (td, J = 25.3, 23.8, 9.2 Hz, 4H), 0.97 (t, J = 13.2 Hz, 2H), 0.56 (s, 2H). Example 28. Synthesis of SFY-Au-2-1 15 Step 1: To a stirred mixture of 2-iodo-6-methoxyaniline (1 g, 4.01 mmol, 1 equiv) and NaNO2 (0.28 g, 4.015 mmol, 1 equiv) in EtOH (3 mL) were added Tetrafluoroboric acid (40% in H2O) (1.94 g, 22.08 mmol, 5.5 equiv) and H2O (1:1) dropwise at 0 °C. The reaction was monitored by LCMS. The precipitated solids were collected by filtration and washed with EtOH (2 mL) (1x2 mL) to afford 2-iodo-6-methoxybenzenediazonium (800 mg, 76.33% yield)20as a yellow solid. Step 2: To a stirred solution / mixture of 2-iodo-6-methoxybenzenediazonium (800 mg, 3.06 mmol, 1 equiv) and N-(benzenesulfonyl)-S-phenylfluoranesulfonamido (966.37 mg, 3.065 mmol, 1 equiv) in ACN (4.5 mL) was added potassium metabisulfite (1362.60 mg, 6.130 mmol, 2 equiv) in portions at room temperature under nitrogen atmosphere. To the above 25 mixture was added AcOH (0.3 mL) and H2O (75 uL) in portions over 5 min at room temperature. The resulting mixture was stirred at room temperature for additional 6 h. The reaction was monitored by LCMS. The resulting mixture was extracted with CH2Cl2 (3x1 mL). The combined organic layers were washed with water (3x1 mL), dried over anhydrous Na2SO4. After filtration, the filtrate was concentrated under reduced pressure. The residue was purified 125 Attorney Docket No.57891-0006WO1 by silica gel column chromatography, eluted with PE / EA (5:1) to afford 2-iodo-6- methoxybenzenesulfonic acid (400 mg, 41.56% yield) as a white solid. Step 3: A solution of 2-iodo-6-methoxybenzenesulfonic acid (400 mg, 1.274 mmol, 1 equiv) in DCM (4 mL) was treated with DAST (41.06 mg, 0.255 mmol, 0.2 equiv) at room 5 temperature for 1 h under nitrogen atmosphere. The reaction was monitored by LCMS. The reaction was quenched by the addition of ice water (4 mL) at room temperature. The combined organic layers were washed with water (2 x 1 mL), dried over anhydrous Na2SO4. After filtration, the filtrate was concentrated under reduced pressure. The residue was purified by silica gel column chromatography, eluted with PE / EA (5:1) to afford 2-iodo-6- 10 methoxybenzenesulfonyl fluoride (170 mg, 42.23% yield) as a yellow solid. Step 4: Into a 40 mL sealed tube were added Silver Hexafluoroantimonate(V) (184.81 mg, 0.538 mmol, 1 equiv) and DCM (5 mL) at 0 °C. To the above mixture was added 2- [(chloroaurio)dicyclohexyl-lambda5-phosphanyl]-N,N-dimethylaniline (296.28 mg, 0.538 mmol, 1 equiv) and 2-iodo-6-methoxybenzenesulfonyl fluoride (170 mg, 0.538 mmol, 1 equiv) 15 dropwise over 3 min at 0 °C. The resulting mixture was stirred at room temperature for additional overnight. The resulting mixture was filtered, the filter cake was washed with MeCN (3 x 3 mL). The filtrate was concentrated under reduced pressure, and added DCM (1 mL) to the concentrated filtrate. The system was purified by trituration with MTBE (3 mL). This resulted in 2-{2-chloro-3,3-dicyclohexyl-1,1-dimethylbenzo[d]1-aza-3-phospha-2-20 auracyclopentan-2-yl}-6-methoxybenzenesulfonyl fluoride and 2-{3,3-dicyclohexyl-2-iodo- 1,1-dimethylbenzo[d]1-aza-3-phospha-2-auracyclopentan-2-yl}-6-methoxybenzenesulfonyl fluoride (130 mg, 32.71% yield, 98.1% purity) as a yellow solid. LCMS:(ES, m / z): [M]+= 738.1. 1H NMR (300 MHz, DMSO-d6, ppm) δ 8.40 (dd, J = 8.5, 4.3 Hz, 1H), 8.05 (t, J = 9.0 25 Hz, 2H), 7.94 – 7.71 (m, 2H), 7.41 (dd, J = 29.2, 8.5 Hz, 1H), 7.09 – 6.97 (m, 1H), 4.05 (d, J = 2.2 Hz, 3H), 3.95 – 3.45 (m, 6H), 3.28 – 3.05 (m, 1H), 2.78 (s, 1H), 2.73 (s, 1H), 2.34 – 2.11 (m, 1H), 2.10 – 1.92 (m, 1H), 1.78 (s, 2H), 1.70 – 1.39 (m, 9H), 1.25 (s, 3H), 1.01 (dd, J = 34.3, 18.5 Hz, 3H), 0.38 (s, 1H). Example 29. Synthesis of SFY-Au-3-1 30 126 Attorney Docket No.57891-0006WO1 Step 1: To a stirred mixture of 5-iodo-2-methoxyaniline (1 g, 4.015 mmol, 1 equiv) and NaNO2 (0.28 g, 4.015 mmol, 1 equiv) in EtOH (2 mL) were added Tetrafluoroboric acid (40% in H2O) (1.76 g, 20.075 mmol, 5 equiv) and H2O (1:1) dropwise at 0 °C.The reaction was monitored by LCMS. The precipitated solids were collected by filtration and washed with 5 EtOH (2 mL) (2 x 1 mL). This resulted in 5-iodo-2-methoxybenzenediazonium (800 mg, 76.33% yield) as a white solid. Step 2: To a stirred mixture of 5-iodo-2-methoxybenzenediazonium (800 mg, 3.065 mmol, 1 equiv) and N-(benzenesulfonyl)-S-phenylfluoranesulfonamido (966.37 mg, 3.065 mmol, 1 equiv) in ACN (4.5 mL) was added potassium metabisulfite (1362.60 mg, 6.130 10 mmol, 2 equiv) in portions at room temperature under nitrogen atmosphere. To the above mixture was added AcOH (0.3 mL) and H2O (75 uL) in portions over 5 min at room temperature. The resulting mixture was stirred at room temperature for additional 6 h. The reaction was monitored by LCMS. The resulting mixture was extracted with CH2Cl2 (3 x 1 mL). The combined organic layers were washed with water (3 x 1 mL), dried over anhydrous 15 Na2SO4. After filtration, the filtrate was concentrated under reduced pressure. This resulted in 5-iodo-2-methoxybenzenesulfonic acid (900 mg, 93.50% yield) as a white solid. Step 3: A solution of 5-iodo-2-methoxybenzenesulfonic acid (900 mg, 2.865 mmol, 1 equiv) in DCM (4 mL) was treated with DAST (92.38 mg, 0.573 mmol, 0.2 equiv) at room temperature for 1h under nitrogen atmosphere. The reaction was monitored by LCMS. The 20 reaction was quenched with ice water at room temperature. The combined organic layers were washed with water (3 x 1 mL), dried over anhydrous Na2SO4. After filtration, the filtrate was concentrated under reduced pressure. The residue was purified by Prep-TLC (PE / EA 5:1) to afford 5-iodo-2-methoxybenzenesulfonyl fluoride (45 mg, 4.97% yield) as a yellow solid. Step 4: Into a 40 mL sealed tube were added Silver Hexafluoroantimonate(V) (54.3625 mg, 0.158 mmol, 1 equiv) and DCM (10 mL) at 0 °C. To the above mixture was added 2- [(chloroaurio)dicyclohexyl-lambda5-phosphanyl]-N,N-dimethylaniline (87.14 mg, 0.158 mmol, 1 equiv) and 5-iodo-2-methoxybenzenesulfonyl fluoride (50 mg, 0.158 mmol, 1.00 equiv) dropwise over 3 min at 0 °C. The resulting mixture was stirred at room temperature for additional overnight. The resulting mixture was filtered, the filter cake was washed with MeCN 30 (3 x 3 mL). The filtrate was concentrated under reduced pressure, and added DCM (0.6 mL) to the concentrated filtrate. The system was purified by trituration with MTBE (1.8 mL). This resulted in 5-{2-chloro-3,3-dicyclohexyl-1,1-dimethylbenzo[d]1-aza-3-phospha-2- 127 Attorney Docket No.57891-0006WO1 auracyclopentan-2-yl}-2-methoxybenzenesulfonyl fluoride (35 mg, 29.94% yield, 75.7% purity) as a grey solid. LCMS:(ES, m / z): [M]+= 738.1. 1H NMR (300 MHz, DMSO-d6, ppm) δ 8.46 – 8.29 (m, 1H), 8.22 – 7.85 (m, 3H), 7.84 – 7.58 (m, 2H), 7.39 (d, J = 8.4 Hz, 1H), 4.18 – 3.82 (m, 3H), 3.52 (d, J = 90.9 Hz, 6H), 3.03 5 (s, 2H), 2.04 (s, 2H), 1.66 (s, 10H), 1.36 (s, 4H), 1.04 (s, 2H), 0.62 (s, 2H). Example 30. Synthesis of AU-PM-8 Step 1: To a stirred mixture of benzenamine, 4-iodo- (500 mg, 2.283 mmol, 1 equiv) and 3-formylphenyl sulfurofluoridate (699.13 mg, 3.425 mmol, 1.5 equiv) in DCM (10 mL)10was added AcOH (137.09 mg, 2.283 mmol, 1 equiv) and STAB (967.65 mg, 4.566 mmol, 2 equiv) in portions at 0 °C. The resulting mixture was stirred at room temperature for 1 h. The resulting mixture was extracted with CH2Cl2 (3 x 10 mL). The combined organic layers were washed with water (3 x 10 mL), dried over anhydrous Na2SO4. After filtration, the filtrate was concentrated under reduced pressure. The residue was purified by reversed-phase flash 15 chromatography with the following conditions: column, C18 silica gel; mobile phase, MeCN in Water (0.1% FA), 10% to 95% gradient in 10 min; detector, UV 254 nm. This resulted in 3- {[(4-iodophenyl) amino] methyl} phenyl sulfurofluoridate (300 mg, 32.27% yield) as a white solid. Step 2: To a stirred solution of 3-{[(4-iodophenyl) amino] methyl} phenyl20sulfurofluoridate (100 mg, 0.246 mmol, 1 equiv) and (chloroaurio)dicyclohexyl[2- (dimethylamino) phenyl]-lambda5-phosphanyl (135.04 mg, 0.246 mmol, 1 equiv) in DCM (3 mL) were added Silver Hexafluoroantimonate(V) (84.39 mg, 0.246 mmol, 1 equiv) in portions at 0 °C under nitrogen atmosphere. The resulting mixture was stirred at room temperature for additional 2 h. The reaction was monitored by LCMS. The resulting mixture was filtered, the 25 filter cake was washed with DCM (3 x 3 mL). The filtrate was concentrated under reduced pressure, and added DCM (1 mL) to the concentrated filtrate. The system was purified by trituration with MTBE (4 mL). This resulted in [chloro({4-[({3-[(fluorosulfonyl) oxy] phenyl} methyl) amino] phenyl}) aurio] dicyclohexyl[2-(dimethylamino) phenyl]-lambda5- 128 Attorney Docket No.57891-0006WO1 phosphanyl (70.2 mg, 34.43% yield, 90.8% purity) as a dark green solid. LCMS:(ES, m / z): [M]+= 829.2. 1H NMR (300 MHz, DMSO-d6, ppm) δ 8.31 (dd, J = 8.4, 4.4 Hz, 1H), 8.10 – 7.96(m, 2H), 7.81 – 7.71 (m, 1H), 7.64 – 7.42 (m, 4H), 7.00 (d, J = 8.4 Hz, 2H), 6.63 (d, J = 8.5 Hz, 5 2H), 4.41 (s, 2H), 2.87 (d, J = 11.4 Hz, 2H), 1.84 – 1.46 (m, 12H), 1.28 (dd, J = 20.8, 11.1 Hz, 4H), 0.97 (t, J = 12.8 Hz, 2H), 0.58 (s, 2H). Example 31. Synthesis of Au-PP-8 Step 1: To a stirred solution of 4-iodo-1H-pyridin-2-one (500 mg, 2.262 mmol, 110equiv) and K2CO3 (469.03 mg, 3.393 mmol, 1.5 equiv) in DMF (5 mL) were added 4- methoxybenzyl chloride (425.19 mg, 2.714 mmol, 1.2 equiv) dropwise at 0 °C under nitrogen atmosphere. The resulting mixture was stirred at room temperature for additional 3 h. The resulting mixture was diluted with 5 mL H2O and extracted with EtOAc (5 mL x 3). The combined organic layers were washed with brine (5 mL), dried over 15 anhydrous Na2SO4. After filtration, the filtrate was concentrated under reduced pressure. The residue was purified by silica gel column chromatography, eluted with PE / EA (3:1) to afford 4-iodo-1-[(4-methoxyphenyl) methyl] pyridin-2-one (500 mg, 64.78% yield) as a light yellow oil. Step 2: To a stirred solution of 4-iodo-1-[(4-methoxyphenyl) methyl] pyridin-2-one20(500 mg, 1.466 mmol, 1 equiv) in DCM (3 mL) were added Boron tribromide 1M solution in methylene chloride (6 mL) dropwise at 0 °C under nitrogen atmosphere. The resulting mixture was stirred at 0 °C for additional 1h. The reaction was quenched with ice water at 0 °C. The resulting mixture was stirred at room temperature for additional 3h. The resulting mixture was diluted with 10 mL H2O and extracted with DCM (10 mL x 3). The combined organic layers 25 were washed with brine (10 mL), dried over anhydrous Na2SO4. After filtration, the filtrate was concentrated under reduced pressure. This resulted in 1-[(4-hydroxyphenyl) methyl]-4- iodopyridin-2-one (300 mg, 62.57% yield), as a light brown solid. The crude product was used in the next step directly without further purification. Step 3: To a stirred solution of 1-[(4-hydroxyphenyl) methyl]-4-iodopyridin-2-one (30030mg, 0.917 mmol, 1 equiv) and 3-(fluorosulfonyl)-1,2-dimethylimidazol-1-ium triflate (451.55 129 Attorney Docket No.57891-0006WO1 mg, 1.376 mmol, 1.5 equiv) in MeCN (5 mL) was added TEA (185.61 mg, 1.834 mmol, 2 equiv) dropwise at 0 °C under nitrogen atmosphere. The resulting mixture was stirred at room temperature for additional 30 min. The resulting mixture was concentrated under reduced pressure. The residue was purified by reversed-phase flash chromatography with the following 5 conditions: column, C18 silica gel; mobile phase, MeCN in Water (0.1% FA), 10% to 90% gradient in 10 min; detector, UV 254 nm. This resulted in 4-[(4-iodo-2-oxopyridin-1-yl) methyl] phenyl sulfurofluoridate (170 mg, 45.30% yield) as a light brown solid. Step 4: To a stirred solution of Silver Hexafluoroantimonate(V) (142.77 mg, 0.415 mmol, 1 equiv) in DCM (3 mL) at 0 °C under nitrogen atmosphere. To the above mixture was 10 added 4-[(4-iodo-2-oxopyridin-1-yl)methyl]phenyl sulfurofluoridate (170 mg, 0.415 mmol, 1 equiv) and in portions at 0 °C. The resulting mixture was stirred at room temperature for additional overnight. The resulting mixture was filtered, the filter cake was washed with DCM (1 mL x 3). The filtrate was concentrated under reduced pressure, and added DCM (1 mL) to the concentrated filtrate. The system was purified by trituration with MTBE (4 mL). This15 resulted in 2-chloro-3,3-dicyclohexyl-2-[1-({4-[(fluorosulfonyl)oxy] phenyl} methyl) -2- oxopyridin-4-yl]-1,1-dimethyl-2H,3H-3lambda5-benzo[d]1-aza-3lambda5-phospha-2- auracyclopentan-1-ium-3-ylium-2,2-diuide (55 mg, 15.91% yield, 99.9 % purity) as a light brown solid. LCMS:(ES, m / z): [M]+= 831.1. 1H NMR (300 MHz, DMSO-d6, ppm) δ 8.35 (dd, J = 8.4, 4.3 Hz, 1H), 8.05 (q, J = 8.9, 20 8.2 Hz, 2H), 7.81 (t, J = 5.9 Hz, 2H), 7.63 (d, J = 8.4 Hz, 2H), 7.49 (d, J = 8.7 Hz, 2H), 6.60 (d, J = 7.9 Hz, 2H), 5.16 (d, J = 26.4 Hz, 2H), 3.43 (s, 6H), 3.02 (s, 2H), 1.98 (s, 2H), 1.83 – 1.47 (m, 10H), 1.33 (d, J = 12.3 Hz, 4H), 1.03 (t, J = 12.5 Hz, 2H), 0.88 (d, J = 14.8 Hz, 2H). Example 32. Synthesis of AU-PP-1 25 Step 1: To a stirred solution of 4-[(fluorosulfonyl)oxy]benzoic acid (552.88 mg, 2.511 mmol, 1.1 equiv), DIEA (885.15 mg, 6.849 mmol, 3 equiv) and HATU (1302.03 mg, 3.425 mmol, 1.5 equiv) in DCM (12 mL) were added 4-iodo-benzenamine (500 mg, 2.283 mmol, 1.00 equiv) dropwise at 0 °C. The resulting mixture was stirred at 25 °C for additional 1 h. The reaction was monitored by LCMS. The resulting mixture was extracted with DCM (3 x 5 mL).30The combined organic layers were dried over anhydrous Na2SO4. After filtration, the filtrate 130 Attorney Docket No.57891-0006WO1 was concentrated under reduced pressure. The residue was purified by reversed-phase flash chromatography with the following conditions: column, C18 silica gel; mobile phase, MeCN in Water (0.1% FA), 10% to 60% gradient in 12 min; detector, UV 254 nm. This resulted in 4-[(4-iodophenyl)carbamoyl]phenyl sulfurofluoridate (300 mg, 31.20% yield) as a 5 white solid. Step 2: To a stirred mixture of AgSbF6 (163.17 mg, 0.475 mmol, 1 equiv) in DCM (8 mL) were added 4-[(4-iodophenyl)carbamoyl]phenyl sulfurofluoridate (200 mg, 0.475 mmol, 1 equiv) and (chloroaurio)dicyclohexyl[2-(dimethylamino)phenyl]-lambda5-phosphanyl (261.11 mg, 0.475 mmol, 1 equiv) in portions at -20 °C .The resulting mixture was stirred at 10 25 °C for additional 2 h. The resulting mixture was filtered, the filter cake was washed with MeCN. The filtrate was concentrated under reduced pressure. The residue was purified by trituration with Et2O (2 mL). This resulted in product (100 mg, 24.95% yield) as a light grey solid. LCMS: ((ES, m / z): [M]+= 843.0. 151H NMR (300 MHz, DMSO-d6, ppm) δ 10.54 (s, 1H), 8.35 (dd, J = 8.4, 4.4 Hz, 1H), 8.20 – 8.12 (m, 2H), 8.12 – 7.97 (m, 2H), 7.81 (dd, J = 9.3, 2.8 Hz, 5H), 7.42 (d, J = 8.5 Hz, 2H), 3.44 (s, 6H), 2.95 (q, J = 11.2 Hz, 2H), 1.89 (s, 2H), 1.81 – 1.47 (m, 10H), 1.47-1.19 (m, 4H), 1.07 (dd, J = 9.8, 6.0 Hz, 2H), 0.76 – 0.52 (m, 2H). Example 33. Synthesis 20 Step 1: A solution of 6-iodopyridin-3-ol (500 mg, 2.26 mmol, 1 equiv) in ACN (3 mL) was treated with 3-(fluorosulfonyl)-1,2-dimethylimidazol-1-ium triflate (1113.99 mg, 3.39 mmol, 1.5 equiv) at room temperature for 3min followed by the addition of TEA (457.89 mg, 4.524 mmol, 2 equiv) dropwise at 0 °C. The reaction was monitored by LCMS. The resulting 25 mixture was concentrated under reduced pressure. The crude product was purified by reverse phase flash to afford 6-iodopyridin-3-yl sulfurofluoridate (200 mg, 29.17% yield) as a yellow oil. Step 2: To a stirred mixture of 2-[(chloroaurio)dicyclohexyl-lambda5-phosphanyl]- N,N-dimethylaniline (127.25 mg, 0.23 mmol, 1 equiv) in DCM were added 6-iodopyridin-3- 131 Attorney Docket No.57891-0006WO1 yl sulfurofluoridate (70 mg, 0.23 mmol, 1 equiv) and Silver Hexafluoroantimonate(V) (79.37 mg, 0.23 mmol, 1 equiv) in portions at 0 °C under nitrogen atmosphere. The reaction was monitored by LCMS. The resulting mixture was filtered, the filter cake was washed with DCM (3 x 1 mL). The filtrate was concentrated under reduced pressure. The residue was purified by 5 trituration with Et2O (3 mL). The precipitated solids were collected by filtration and washed with Et2O (3 x 1 mL). This resulted in 6-{2-chloro-3,3-dicyclohexyl-1,1-dimethylbenzo[d]1- aza-3-phospha-2-auracyclopentan-2-yl} pyridin-3-yl sulfurofluoridate (65 mg, 38.76% yield, 97.5% purity) as a grey solid. LCMS:(ES, m / z): [M]+= 725.1. 1H NMR (300 MHz, DMSO-d6, ppm) δ 9.00 (d, J = 3.0 Hz, 1H), 8.34 (dd, J = 8.6, 4.4 10 Hz, 1H), 8.18 (dd, J = 8.8, 3.0 Hz, 1H), 8.11 – 7.96 (m, 3H), 7.77 (tt, J = 7.9, 4.0 Hz, 1H), 3.62 (s, 6H), 3.04 (q, J = 11.3 Hz, 2H), 1.83 (s, 2H), 1.75-1.45 (m, 10H), 1.31 (t, J = 13.2 Hz, 4H), 0.98 (q, J = 12.8 Hz, 2H), 0.42-0.25 (m, 2H). Example 34. Synthesis of Au-01 15Step 1: Into a 40 mL sealed tube were added dicyclohexylphosphane (1.5 g, 7.56 mmol, 1.00 equiv), 2-iodo-N,N-dimethylaniline (1.96 g, 7.94 mmol, 1.05 equiv), t-BuONa (1.09 g, 11.34 mmol, 1.5 equiv), 1,1'-bis(diisopropylphosphino)ferrocene (0.10 g, 0.22 mmol, 0.03 equiv), Pd(OAc)2 (0.04 g, 0.18 mmol, 0.025 equiv) and toluene (20 mL) at room temperature. The resulting mixture was stirred at 100°C for overnight under nitrogen atmosphere. The 20 mixture was allowed to cool down to room temperature. The resulting mixture was filtered, the filter cake was washed with MeCN (3x5 mL). The filtrate was concentrated under reduced pressure. The residue was purified by silica gel column chromatography, eluted with PE / EA (5:1) to afford 2-(dicyclohexylphosphanyl)-N,N-dimethylaniline (860 mg, 35.81%yield, 95%purity) as a yellow solid.25Step 2: Into a 40 mL sealed tube were added 2-(dicyclohexylphosphanyl)-N,N- dimethylaniline (905.33 mg, 2.85 mmol, 1 equiv) and DCM (10 mL) at room temperature. To the above mixture was added (chloroaurio)dimethyl-lambda3-sulfane (840 mg, 2.85 mmol, 1 equiv) dropwise over 3 min at -20°C. The resulting mixture was stirred at room temperature for additional overnight. The resulting mixture was filtered, the filter cake was washed with 132 Attorney Docket No.57891-0006WO1 DCM (3x3 mL). The filtrate was concentrated under reduced pressure. The residue was purified by trituration with Et2O (10 mL). This resulted in 2-[(chloroaurio)dicyclohexyl-lambda5- phosphanyl]-N,N-dimethylaniline (1 g, 63.65%yield, 95%purity) as a grey solid. Step 3: Into a 40 mL sealed tube were added 2-iodophenol (500 mg, 2.27 mmol, 1.00 5 equiv), MeCN (5 mL) and 3-(fluorosulfonyl)-1,2-dimethylimidazol-1-ium triflate (969.79 mg, 2.95 mmol, 1.3 equiv) at room temperature. To the above mixture was added Et3N (689.92 mg, 6.82 mmol, 3 equiv) dropwise over 3 min at 0°C. The resulting mixture was stirred at 0°C for additional 1 h. The residue was purified by silica gel column chromatography, eluted with PE / EA (1:1) to afford 2-iodophenyl sulfurofluoridate (600 mg, 87.40%yield, 95%purity) as a 10 yellow oil. Step 4: Into a 40 mL sealed tube were added Silver Hexafluoroantimonate(V) (155.94 mg, 0.45 mmol, 1 equiv) and DCM (10 mL) at -10°C.To the above mixture was added 2- [(chloroaurio)dicyclohexyl-lambda5-phosphanyl]-N,N-dimethylaniline (250 mg, 0.45 mmol, 1 equiv) and 2-iodophenyl sulfurofluoridate (150.79 mg, 0.50 mmol, 1.1 equiv) dropwise over 15 2 min at 0°C. The resulting mixture was stirred at room temperature for additional overnight. The resulting mixture was filtered, the filter cake was washed with MeCN (3x5 mL). The filtrate was concentrated under reduced pressure. The residue was purified by trituration with 1,4-dioxane (10 mL). The precipitated solids were collected by filtration and washed with 1,4- dioxane (3x5 mL).This resulted in 2-{2-chloro-3,3-dicyclohexyl-1,1-dimethylbenzo[d]1-aza- 20 3-phospha-2-auracyclopentan-2-yl}phenyl sulfurofluoridate (95.5 mg, 29.02%yield, 96.2%purity) as a grey solid. LCMS:(ES, m / z): [M]+= 724.1. 1H NMR (300 MHz, DMSO-d6) δ 8.40 (dd, J = 8.6, 4.3 Hz, 1H), 8.14 – 8.01 (m, 2H), 7.81 (ddd, J = 14.1, 7.2, 2.3 Hz, 2H), 7.69 – 7.66 (m, 1H), 7.63 – 7.53 (m, 2H), 3.59 (s, 3H), 3.48 (s, 3H), 3.12 – 2.84 (m, 2H), 1.64-1.89 (m, 11H), 1.28-1.41 (m, 5H), 1.07 (m, 2H), 0.53 25 (m, 2H). Example 35. Synthesis of Au-02 Step 1: Into a 40 mL sealed tube were added 3-iodophenol (300 mg, 1.36 mmol, 1.00 equiv), MeCN (10 mL) and 1-(fluorosulfonyl)-2,3-dimethyl-1H-imidazol-3-ium30trifluoromethanesulfonate (581.87 mg, 1.77 mmol, 1.30 equiv) at room temperature. To the 133 Attorney Docket No.57891-0006WO1 above mixture was added Et3N (413.95 mg, 4.09 mmol, 3.00 equiv) dropwise over 3 min at - 10°C. The resulting mixture was stirred at -10°C for additional 1 h. The residue was purified by silica gel column chromatography, eluted with PE / EA (8:1) to afford 3-iodophenyl sulfurofluoridate (200 mg, 48.56%yield, 95%purity) as a yellow oil. 5 Step 2: Into a 40 mL sealed tube were added Silver Hexafluoroantimonate(V) (124.75 mg, 0.36 mmol, 1.00 equiv) and DCM (10 mL) at -10°C. To the above mixture was added 2- [(chloroaurio)dicyclohexyl-lambda5-phosphanyl]-N,N-dimethylaniline (200 mg, 0.36 mmol, 1.00 equiv) and 3-iodophenyl sulfurofluoridate (120.63 mg, 0.40 mmol, 1.10 equiv) dropwise over 2 min at -10°C. The resulting mixture was stirred at room temperature for additional 10 overnight. The resulting mixture was filtered, the filter cake was washed with MeCN (3x3 mL). The filtrate was concentrated under reduced pressure. The residue was purified by trituration with DCM (10 mL).The precipitated solids were collected by filtration and washed with DCM (10 mL) (3x3 mL). This resulted in 3-{2-chloro-3,3-dicyclohexyl-1,1-dimethyl-3H- 1lambda4,3lambda5-benzo[d]1l ambda4-aza-3lambda5-phospha-2-auracyclopentan-2- 15 yl}phenyl sulfurofluoridate (80.3 mg, 30.46%yield, 93.2%purity) as a grey solid. LCMS:(ES, m / z): [M]+= 724.0. 1H NMR (300 MHz, DMSO-d6,ppm) δ 8.36 (dd, J = 8.5, 4.4 Hz, 1H), 8.12 – 7.97 (m, 2H), 7.86 – 7.72 (m, 2H), 7.61 (d, J = 3.2 Hz, 3H), 3.46 (s, 6H), 2.92 (d, J = 11.1 Hz, 2H), 2.72 (s, 2H), 1.87 (s, 2H), 1.63 (s, 10H), 1.43 – 1.20 (m, 4H), 1.07 (d, J = 12.6 Hz, 2H), 0.56 (s, 20 2H). Example 36. Synthesis of Au-03 Step 1: Into a 40 mL sealed tube were added 4-iodophenol (300 mg, 1.36 mmol, 1 equiv), MeCN (10 mL) and 1-(fluorosulfonyl)-2,3-dimethyl-1H-imidazol-3-ium 25 trifluoromethane sulfonate (581.87 mg, 1.77 mmol, 1.3 equiv) at room temperature. To the above mixture was added Et3N (413.95 mg, 4.092 mmol, 3 equiv) dropwise over 3 min at - 10°C. The resulting mixture was stirred at -10°C for additional 1 h. The residue was purified by silica gel column chromatography, eluted with PE / EA (8:1) to afford 4-iodophenyl sulfurofluoridate (200 mg, 48.56%yield, 95%purity) as a yellow oil. 134 Attorney Docket No.57891-0006WO1 Step 2: Into a 40 mL sealed tube were added Silver Hexafluoroantimonate(V) (124.75 mg, 0.36 mmol, 1 equiv) and DCM (10 mL) at -10°C.To the above mixture was added 2- [(chloroaurio)dicyclohexyl-lambda5-phosphanyl]-N,N-dimethylaniline (200 mg, 0.36 mmol, 1 equiv) and 4-iodophenyl sulfurofluoridate (120.63 mg, 0.399 mmol, 1.1 equiv) dropwise 5 over 3 min at -10°C. The resulting mixture was stirred at room temperature for additional overnight. The resulting mixture was filtered, the filter cake was washed with MeCN (3x3 mL). The filtrate was concentrated under reduced pressure. The residue was purified by trituration with MTBE (20 mL).The precipitated solids were collected by filtration and washed with MTBE (3x3 mL).This resulted in 4-{2-chloro-3,3-dicyclohexyl-1,1-dimethylbenzo[d]1-aza-3- 10 phospha-2-auracyclopentan-2-yl}phenyl sulfurofluoridate (93.2 mg, 35.41%yield, 97.0%purity) as a white solid. LCMS:(ES, m / z): [M]+= 724.1. 1H NMR (300 MHz, DMSO-d6) δ 8.36 (dd, J = 8.5, 4.4 Hz, 1H), 8.05 (q, J = 7.8, 7.3 Hz, 2H), 7.78 (td, J = 7.4, 2.4 Hz, 1H), 7.76 – 7.63 (m, 4H), 3.46 (s, 6H), 2.95 (q, J = 11.7 Hz, 2H), 1.87 (m, 2H), 1.60 (m, 10H), 1.31 (dt, J = 23.9, 12.0 Hz, 4H), 1.14 – 0.95 (m, 2H), 0.46 15 (m, 2H). Example 37. Synthesis of Au-04 Step 1: Into a mL sealed tube were added 2-fluoro-5-iodophenol (800 mg, 3.36 mmol, 1 equiv), MeCN (10 mL) and 1-(fluorosulfonyl)-2,3-dimethyl-1H-imidazol-3-ium20trifluoromethanesulfonate (1434.37 mg, 4.36 mmol, 1.3 equiv) at room temperature. To the above mixture was added Et3N (1020.43 mg, 10.08 mmol, 3 equiv) dropwise over 3 min at - 10°C. The resulting mixture was stirred at -10°C for additional 1 h. The residue was purified by silica gel column chromatography, eluted with PE / EA (8:1) to afford 2-fluoro-5- iodophenyl sulfurofluoridate (460 mg, 42.76%yield, 99%purity) as a yellow oil. 25 Step 2: Into a 40 mL sealed tube were added silver(I) hexafluorophosphate(V) (79.00 mg, 0.31 mmol, 1 equiv) and DCM (10 mL) at room temperature. To the above mixture was added 2-[(chloroaurio)dicyclohexyl-lambda5-phosphanyl]-N,N-dimethylaniline (172.12 mg, 0.31 mmol, 1 equiv) and 2-fluoro-5-iodophenyl sulfurofluoridate (110 mg, 0.34 mmol, 1.1 equiv) dropwise over 3 min at -10°C. The resulting mixture was stirred at room temperature30for additional overnight. The resulting mixture was filtered, the filter cake was washed with 135 Attorney Docket No.57891-0006WO1 MeCN (3x3 mL). The filtrate was concentrated under reduced pressure. The residue was purified by trituration with MTBE (10 mL). The precipitated solids were collected by filtration and washed with MTBE (3x3 mL). This resulted in 5-{2-chloro-3,3-dicyclohexyl-1,1- dimethylbenzo[d]1-aza-3-phospha-2-auracyclopentan-2-yl}-2-fluorophenyl sulfurofluoridate 5 (141.4 mg, 60.91%yield, 96.5%purity) as a grey solid. LCMS:(ES, m / z): [M]+= 742.0. 1H NMR (300 MHz, DMSO-d6) δ 8.37 (dd, J = 8.5, 4.3 Hz, 1H), 8.14 – 7.98 (m, 3H), 7.85 – 7.70 (m, 2H), 7.64 (ddd, J = 8.8, 4.8, 1.9 Hz, 1H), 3.48 (s, 6H), 2.93 (m, 2H), 1.91 (m, 2H), 1.64 (m, 10H), 1.32 (m, 4H), 1.07 (m, 2H), 0.61 (m, 2H). Example 38. Synthesis of Au-05 10 Step 1: Into a mL sealed tube were added O-fluorophenol (300 mg, 2.67 mmol, 1 equiv), MeCN (5 mL) and 1-(fluorosulfonyl)-2,3-dimethyl-1H-imidazol-3-ium trifluoromethanesulfonate (1141.96 mg, 3.47 mmol, 1.3 equiv) at room temperature. To the above mixture was added Et3N (812.41 mg, 8.02 mmol, 3 equiv) dropwise over 3 min at - 15 10°C. The resulting mixture was stirred at -10°C for additional 1 h. The residue was purified by silica gel column chromatography, eluted with PE / EA (8:1) to afford 2-fluoro-4- iodophenyl sulfurofluoridate (110 mg, 12.84%yield, 99%purity) as a yellow oil. Step 2: Into a 40 mL sealed tube were added Silver Hexafluoroantimonate(V) (214.73 mg, 0.62 mmol, 1 equiv) and DCM (10 mL) at -10°C.To the above mixture was added 2-fluoro-204-iodophenyl sulfurofluoridate (200 mg, 0.62 mmol, 1 equiv) and 2- [(chloroaurio)dicyclohexyl-lambda5-phosphanyl]-N,N-dimethylaniline (378.67 mg, 0.68 mmol, 1.1 equiv) dropwise over 3 min at -10°C. The resulting mixture was stirred at room temperature for additional overnight. The resulting mixture was filtered, the filter cake was washed with MeCN (3x3 mL). The filtrate was concentrated under reduced pressure. The 25 residue was purified by trituration with MTBE (10 mL).The precipitated solids were collected by filtration and washed with DCM (10 mL) (3x3 mL).This resulted in 4-{2-chloro-3,3- dicyclohexyl-1,1-dimethylbenzo[d]1-aza-3-phospha-2-auracyclopentan-2-yl}-2-fluorophenyl sulfurofluoridate (57.8 mg, 12.45%yield, 92.4%purity) as a grey solid. LCMS:(ES, m / z): [M]+= 742.0. 136 Attorney Docket No.57891-0006WO1 1H NMR (300 MHz, DMSO-d6) δ 8.36 (dd, J = 8.6, 4.4 Hz, 1H), 8.11 – 7.98 (m, 2H), 7.97 – 7.84 (m, 2H), 7.78 (td, J = 7.5, 2.5 Hz, 1H), 7.51 (d, J = 8.8 Hz, 1H), 3.46 (s, 6H), 2.95 (m, 2H), 1.91 (s, 2H), 1.63 (m, 10H), 1.39 – 1.25 (m, 4H), 1.12 – 0.93 (m, 2H), 0.48 (m, 2H). Example 39. Synthesis of Au-8 5 Step 1: Into a 40 mL sealed tube were added 2,3-difluoro-4-iodophenol (500 mg, 1.95 mmol, 1.00 equiv), MeCN (5 mL) and 3-(fluorosulfonyl)-1,2-dimethylimidazol-1-ium triflate (833.48 mg, 2.54 mmol, 1.3 equiv) at room temperature. To the above mixture was added Et3N (592.95 mg, 5.86 mmol, 3 equiv) dropwise over 3 min at 0°C. The resulting mixture was stirred 10 at °C for additional 1 h. The residue was purified by reversed-phase flash chromatography with the following conditions: column, C18 silica gel; mobile phase, MeCN in Water (0.1% FA), 10% to 50% gradient in 10 min; detector, UV 254 nm. This resulted in 2,3-difluoro-4- iodophenyl sulfurofluoridate (60 mg, 9.09%yield, 95%purity) as a yellow oil. Step 2: Into a 8 mL sealed tube were added Silver Hexafluoroantimonate(V) (60.99 mg,150.18 mmol, 1 equiv) and DCM (3 mL) at room temperature. To the above mixture was added 2-[(chloroaurio)dicyclohexyl-lambda5-phosphanyl]-N,N-dimethylaniline (97.78 mg, 0.18 mmol, 1 equiv) and 2,3-difluoro-4-iodophenyl sulfurofluoridate (60 mg, 0.18 mmol, 1.00 equiv) dropwise over 3 min at 0°C. The resulting mixture was stirred at 0°C for additional 4 h. The resulting mixture was filtered, the filter cake was washed with MeOH (3x3 mL). The 20 filtrate was concentrated under reduced pressure. The residue was purified by trituration with MTBE(3 mL). This resulted in 4-{2-chloro-3,3-dicyclohexyl-1,1-dimethylbenzo[d]1-aza-3- phospha-2-auracyclopentan-2-yl}-2,3-difluorophenyl sulfurofluoridate (63 mg, 46.64%yield, 96.5%purity) as a grey solid. LCMS:(ES, m / z): [M]+= 760.1. 1H NMR (300 MHz, DMSO-d6) δ 8.41 (dd, J = 8.5, 4.3 Hz, 1H), 8.08 (m, 2H), 7.92 –257.76 (m, 2H), 7.69 (m, 1H), 3.56 (d, J = 13.3 Hz, 6H), 3.08 (m, 2H), 2.04 (m, 1H), 1.92 (m, 1H), 1.65 (m, 9H), 1.40 – 1.27 (m, 5H), 0.98 (m, 2H), 0.55 (m, 2H). Example 40. Synthesis of Au-4-1-Me 137 Attorney Docket No.57891-0006WO1 Step 1: To a stirred mixture of 2-fluoro-5-iodo-4-methylphenol (250 mg, 0.992 mmol, 1 equiv) and 3-(fluorosulfonyl)-1,2-dimethylimidazol-1-ium triflate (390.73 mg, 1.190 mmol, 1.2 equiv) in MeCN (5 mL) was added TEA (150.57 mg, 1.488 mmol, 1.5 equiv) dropwise at 5 0 °C. The resulting mixture was concentrated under reduced pressure. The residue was purified by reversed-phase flash chromatography with the following conditions: column, C18 silica gel; mobile phase, MeCN in Water (0.1% FA), 10% to 95% gradient in 10 min; detector, UV 254 nm. This resulted in 2-fluoro-5-iodo-4-methylphenyl sulfurofluoridate (100 mg, 30.18% yield) as a yellow oil.10Step 2: To a stirred solution of 2-fluoro-5-iodo-4-methylphenyl sulfurofluoridate (100 mg, 0.299 mmol, 1 equiv) and 2-[(chloroaurio)dicyclohexyl-lambda5-phosphanyl]-N,N- dimethylaniline (164.59 mg, 0.299 mmol, 1 equiv) in DCM (3 mL) were added Silver Hexafluoroantimonate(V) (102.86 mg, 0.299 mmol, 1 equiv) in portions at room temperature under nitrogen atmosphere. The resulting mixture was stirred at room temperature for 15 additional 2 h. The reaction was monitored by LCMS. The resulting mixture was filtered, the filter cake was washed with DCM (3 x 3 mL). The filtrate was concentrated under reduced pressure. The residue was purified by trituration with Methyl tert-butyl ether (3 mL). This resulted in 2-chloro-3,3-dicyclohexyl-2-{4-fluoro-5-[(fluorosulfonyl)oxy]-2-methylphenyl}- 1,1-dimethyl-2H,3H-3lambda5-benzo[d]1-aza-3lambda5-phospha-2-auracyclopentan-1-ium-203-ylium-2,2-diuide (100 mg, 44.13% yield, 93.6% purity) as a grey solid. LCMS:(ES, m / z): [M]+= 756.0. 1H NMR (300 MHz, DMSO-d6, ppm) δ 8.39 (dd, J = 8.6, 4.4 Hz, 1H), 8.13 – 8.00 (m, 2H), 7.81 (td, J = 7.4, 2.5 Hz, 1H), 7.70 (dd, J = 19.4, 9.7 Hz, 2H), 3.50 (d, J = 4.6 Hz, 6H), 3.25 (d, J = 10.3 Hz, 1H), 2.74 (d, J = 10.4 Hz, 1H), 2.63 (s, 3H), 2.37-2.23 (m, 1H), 2.01-1.87 25 (m, 1H), 1.82 – 1.24 (m, 14H), 1.17 – 0.95 (m, 2H), 0.81 (d, J = 13.3 Hz, 1H), 0.40 – 0.21 (m, 1H). Example 41. Synthesis of Au-2-6-F 138 Attorney Docket No.57891-0006WO1 Step 1: To a stirred mixture of 2-fluoro-3-iodophenol (250 mg, 1.050 mmol, 1 equiv) and 3-(fluorosulfonyl)-1,2-dimethylimidazol-1-ium triflate (413.76 mg, 1.260 mmol, 1.2 equiv) in MeCN (5 mL) was added TEA (159.44 mg, 1.575 mmol, 1.5 equiv) in portions at 0 5 °C. The resulting mixture was stirred at 0 °C for 30 min. The resulting mixture was concentrated under reduced pressure. The residue was purified by reversed-phase flash chromatography with the following conditions: column, C18 silica gel; mobile phase, MeCN in Water (0.1% FA), 10% to 95% gradient in 10 min; detector, UV 254 nm. This resulted in 2- fluoro-3-iodophenyl sulfurofluoridate (100 mg, 29.75% yield) as a white solid. 10 Step 2: To a stirred solution of 2-fluoro-3-iodophenyl sulfurofluoridate (50 mg, 0.156 mmol, 1 equiv) and (chloroaurio)dicyclohexyl[2-(dimethylamino)phenyl]-lambda5- phosphanyl (85.90 mg, 0.156 mmol, 1 equiv) in DCM (3 mL) were added Silver Hexafluoroantimonate(V) (53.68 mg, 0.156 mmol, 1 equiv) in portions at room temperature under nitrogen atmosphere. The resulting mixture was stirred at room temperature for15additional 2 h. The reaction was monitored by LCMS. The resulting mixture was filtered, the filter cake was washed with DCM (3 x 3 mL). The filtrate was concentrated under reduced pressure. The residue was purified by trituration with Methyl tert-butyl ether (3 mL). This resulted in 3-[chloro({dicyclohexyl[2-(dimethylamino)phenyl]-lambda5- phosphanylidene})aurio]-2-fluorophenyl sulfurofluoridate (63 mg, 54.27% yield, 95.1% 20 purity) as a grey solid. LCMS:(ES, m / z): [M]+= 742.0. 1H NMR (300 MHz, DMSO-d6, ppm) δ 8.41 (dd, J = 8.6, 4.3 Hz, 1H), 8.09 (dt, J = 9.7, 7.1 Hz, 2H), 7.94 – 7.78 (m, 2H), 7.74 (ddd, J = 8.2, 3.6, 1.4 Hz, 1H), 7.55 (dd, J = 8.7, 7.5 Hz, 1H), 3.56 (d, J = 16.3 Hz, 6H), 2.98 (s, 2H), 2.12 – 1.84 (m, 2H), 1.80 – 1.54 (m, 10H), 1.35 (dd, J = 26.6, 13.7 Hz, 4H), 1.08 (s, 2H), 0.61 (s, 2H).25Example 42. Synthesis of Au-MP-1 139 Attorney Docket No.57891-0006WO1 Step 1: To a stirred solution of 4-[(fluorosulfonyl)oxy]benzoic acid (552.88 mg, 2.511 mmol, 1.1 equiv), DIEA (885.15 mg, 6.849 mmol, 3 equiv) and HATU (1302.03 mg, 3.425 mmol, 1.5 equiv) in DCM (12 mL) were added 3-iodo-benzenamine (500 mg, 2.283 mmol, 5 1.00 equiv) dropwise at 0 °C. The resulting mixture was stirred at 25 °C for additional 1 h. The reaction was monitored by LCMS. The resulting mixture was extracted with DCM (3 x 5 mL). The combined organic layers were dried over anhydrous Na2SO4. After filtration, the filtrate was concentrated under reduced pressure. The residue was purified by reversed-phase flash chromatography with the following conditions: column, C18 silica gel; mobile 10 phase, MeCN in Water (0.1% FA), 10% to 60% gradient in 12 min; detector, UV 254 nm. This resulted in 4-[(3-iodophenyl)carbamoyl]phenyl sulfurofluoridate (300 mg, 31.20% yield) as a brown solid. Step 2: To a stirred mixture of AgSbF6(163.17 mg, 0.475 mmol, 1 equiv) in DCM (8 mL) were added 4-[(3-iodophenyl)carbamoyl]phenyl sulfurofluoridate (200 mg, 0.475 mmol,151 equiv) and (chloroaurio)dicyclohexyl[2-(dimethylamino)phenyl]-lambda5-phosphanyl (261.11 mg, 0.475 mmol, 1 equiv) in portions at -20 °C. The resulting mixture was stirred at 25 °C for additional 2 h. The resulting mixture was filtered, the filter cake was washed with MeCN. The filtrate was concentrated under reduced pressure. The residue was purified by trituration with Et2O (2 mL). This resulted in product (80 mg, 19.96% yield) as a light grey 20 solid. LCMS: (ES, m / z): [M]+= 843.0. 1H NMR (300 MHz, DMSO-d6, ppm) δ 10.61 (s, 1H), 8.36 (dd, J = 8.5, 4.3 Hz, 1H), 8.19 – 7.98 (m, 5H), 7.88 – 7.73 (m, 3H), 7.43 – 7.32 (m, 2H), 7.31-7.21 (m, 1H), 3.44 (s, 6H), 3.21-3.02 (m, 2H), 1.95-1.81 (m, 2H), 1.80-1.50 (m, 10H), 1.47-1.15 (m, 4H), 1.15-0.92 (m, 2H), 0.59 (s, 2H).25Example 43. Synthesis of Au-MP-3 140 Attorney Docket No.57891-0006WO1 Step 1: A solution of tert-butyl N-(4-hydroxyphenyl) carbamate (500 mg, 2.39 mmol, 1 equiv) in MeCN (3 mL) was treated with 3-(fluorosulfonyl)-1,2-dimethylimidazol-1-ium triflate (1176.55 mg, 3.58 mmol, 1.5 equiv) at room temperature for 5 min under nitrogen atmosphere followed by the addition of TEA (483.61 mg, 4.78 mmol, 2 equiv) dropwise at 0 5 °C. The reaction was monitored by LCMS. The resulting mixture was concentrated under reduced pressure. The residue product was purified by reverse phase flash to afford tert-butyl N-{4-[(fluorosulfonyl) oxy] phenyl} carbamate (700 mg, 64.57% yield) as a yellow solid. Step 2: To the above mixture was added HCl in 1,4-dioxane (4.0 M) (4 mL, 1 equiv) dropwise over 1min at room temperature. The resulting mixture was stirred at room 10 temperature for additional 1 h. The reaction was monitored by LCMS. The resulting mixture was concentrated under reduced pressure. This resulted in 4-aminophenyl sulfurofluoridate hydrochloride (350 mg, 63.98% yield) as a white solid. The crude product was used in the next step directly without further purification. Step 3 To a stirred mixture of 4-aminophenyl sulfurofluoridate hydrochloride (350 mg, 15 1.53 mmol, 1 equiv) and 3-iodobenzoic acid (381.35 mg, 1.53 mmol, 1 equiv) in DMF (3 mL) were added HATU (876.96 mg, 2.30 mmol, 1.5 equiv) and DIEA (596.18 mg, 4.61 mmol, 3 equiv) dropwise at room temperature. The reaction was monitored by LCMS. The resulting mixture was extracted with EtOAc (3 x 2 mL). The combined organic layers were washed with water (3 x 2 mL), dried over anhydrous Na2SO4. After filtration, the filtrate was concentrated 20 under reduced pressure. The residue was purified by silica gel column chromatography, eluted with PE / EA (5:1) to afford 4-(3-iodobenzamido) phenyl sulfurofluoridate (150 mg, 23.16% yield) as a white solid. Step 4: To a stirred solution of 2-[(chloroaurio)dicyclohexyl-lambda5-phosphanyl]- N,N-dimethylaniline (91.56 mg, 0.16 mmol, 1 equiv) and 4-(3-iodobenzamido)phenyl 25 sulfurofluoridate (70 mg, 0.16 mmol, 1.00 equiv) in DCM (5 mL) were added Silver Hexafluoroantimonate(V) (57.11 mg, 0.16 mmol, 1 equiv) in portions at 0 °C under nitrogen atmosphere. The resulting mixture was stirred at room temperature for additional 2 h. The resulting mixture was filtered, the filter cake was washed with DCM (5.00 mL) (3 x 2 mL). The filtrate was concentrated under reduced pressure. The residue was purified by trituration30 with ethyl ether (5 mL). This resulted in 4-(3-{2-chloro-3,3-dicyclohexyl-1,1- dimethylbenzo[d]1-aza-3-phospha-2-auracyclopentan-2-yl} benzamido) phenyl sulfurofluoridate (65 mg, 46.33% yield, 95.1% purity) as a grey solid. LCMS:(ES, m / z): [M]+=843.1. 141 Attorney Docket No.57891-0006WO1 1H NMR (300 MHz, DMSO-d6, ppm) δ 10.63 (s, 1H), 8.37 (dd, J = 8.6, 4.3 Hz, 1H), 8.15 – 7.91 (m, 6H), 7.79 (d, J = 6.7 Hz, 1H), 7.73 (d, J = 8.0 Hz, 1H), 7.67 – 7.53 (m, 3H), 3.47 (s, 6H), 2.92 (d, J = 11.0 Hz, 2H), 1.91 (s, 2H), 1.67 (d, J = 24.9 Hz, 10H), 1.32 (dd, J = 30.0, 13.6 Hz, 4H), 1.08 (t, J = 12.6 Hz, 2H), 0.62 (s, 2H). 5 Example 44. Synthesis of Au-MM-2 Step 1: A solution of benzenamine, 3-iodo- (1 g, 4.56 mmol, 1.00 equiv), tert-butyl 4- oxopiperidine-1-carboxylate (1.36 g, 6.84 mmol, 1.5 equiv) and HOAc (0.03 g, 0.45 mmol, 0.1 equiv) in DCM (10 mL) was stirred at room temperature for 3 min under nitrogen atmosphere.10To the above mixture was added STAB (4.84 g, 22.83 mmol, 5 equiv) in portions over 3 min at 0 °C. The resulting mixture was stirred at 0 °C for additional 1 h. The reaction was quenched by the addition of water (20 mL) at 0 °C.The resulting mixture was extracted with CH2Cl2 (3 x 20 mL). The combined organic layers were washed with brine (1 x 20 mL), dried over anhydrous Na2SO4. After filtration, the filtrate was concentrated under reduced pressure. This 15 resulted in crude tert-butyl 4-[(3-iodophenyl) amino] piperidine-1-carboxylate (2 g) as a yellow oil. Step 2: A solution of tert-butyl 4-[(3-iodophenyl) amino] piperidine-1-carboxylate (2 g, 4.97 mmol, 1 equiv) in HCl in 1,4-dioxane (4.0 M) (20 mL) was stirred at room temperature for 2 h under nitrogen atmosphere. The resulting mixture was concentrated under reduced20pressure. This resulted in N-(3-iodophenyl) piperidin -4-amine hydrochloride (1.5 g, Crude Product) as a white solid. Step 3: A solution of N-(3-iodophenyl) piperidin-4-amine hydrochloride (1.5 g, 4.43 mmol, 1 equiv), 3-[(fluorosulfonyl) oxy] benzoic acid (0.98 g, 4.43 mmol, 1 equiv), HATU (3.37 g, 8.86 mmol, 2 equiv) and DIEA (1.72 g, 13.29 mmol, 3 equiv) in DCM (20 mL) was 25 stirred at room temperature for 2 h under nitrogen atmosphere. The resulting mixture was concentrated under reduced pressure. The residue was purified by reversed-phase flash chromatography with the following conditions: column, C18 silica gel; mobile phase, MeCN in Water (0.1% FA), 10% to 50% gradient in 10 min; detector, UV 254 nm. This resulted in 3- {4-[(3-iodophenyl) amino] piperidine-1-carbonyl} phenyl sulfurofluoridate (150 mg, 6.71%30yield, 95% purity) as a yellow oil. 142 Attorney Docket No.57891-0006WO1 Step 4: A solution of 2-[(chloroaurio)dicyclohexyl-lambda5-phosphanyl]-N, N- dimethylaniline (150 mg, 0.27 mmol, 1 equiv) and 3-{4-[(3-iodophenyl) amino] piperidine-1- carbonyl} phenyl sulfurofluoridate (151.05 mg, 0.29 mmol, 1.1 equiv) in DCM (10 mL) was stirred at room temperature for 3 min under nitrogen atmosphere. To the above mixture was 5 added Silver Hexafluoroantimonate(V) (93.56 mg, 0.27 mmol, 1 equiv) dropwise over 3 min at 0 °C. The resulting mixture was stirred at room temperature for additional overnight. The resulting mixture was filtered, the filter cake was washed with DCM (10 mL) (3 x 5 mL). The filtrate was concentrated under reduced pressure. The residue was purified by trituration with Et2O (5 mL). The precipitated solids were collected by filtration and washed with Et2O (3 x 510 mL). This resulted in 2-chloro-3,3-dicyclohexyl-2-{3-[(1-{3- [(fluorosulfonyl)oxy]benzoyl}piperidin-4-yl)amino] phenyl}-1,1-dimethyl-2H,3H-3lambda5- benzo[d]1-aza-3lambda5-phospha-2-auracyclopentan-1-ium-3-ylium-2,2-diuide (95 mg, 34.44% yield, 91.2% purity) as a reddish brown solid. LCMS:(ES, m / z): [M]+= 926.1. 1H NMR (300 MHz, DMSO-d6, ppm) δ 8.33 (dd, J = 8.6, 4.4 Hz, 1H), 8.04 (dt, J = 15 14.1, 8.3 Hz, 2H), 7.82 – 7.63 (m, 4H), 7.56 (dt, J = 6.2, 2.1 Hz, 1H), 7.04 (t, J = 7.9 Hz, 1H), 6.68 – 6.63 (m, 1H), 6.56 (d, J = 8.2 Hz, 1H), 6.47 (d, J = 7.8 Hz, 1H), 5.83 (d, J = 8.0 Hz, 1H), 5.76 (s, 0H), 4.33 (s, 1H), 3.57 (s, 2H), 3.39 (s, 4H), 3.29 – 3.06 (m, 3H), 2.93 (s, 2H), 2.15 – 1.82 (m, 3H), 1.66 (d, J = 28.4 Hz, 11H), 1.28 (dd, J = 35.5, 10.0 Hz, 7H), 1.04 (d, J = 12.7 Hz, 2H), 0.68 (s, 2H). 20 Example 45. Synthesis of Au-MM-5 Step 1: To a stirred mixture of tert-butyl N-(3-hydroxyphenyl)carbamate (1.70 g, 7.31 mmol, 1.00 equiv) and 3-(fluorosulfonyl)-1,2-dimethylimidazol-1-ium triflate (3.60 g, 10.96 mmol, 1.5 equiv) in MeCN (5 mL) was added TEA (1.48 g, 14.624 mmol, 2 equiv) dropwise 25 at 0 °C. The resulting mixture was stirred at room temperature for additional 30 min. The reaction was monitored by LCMS. The resulting mixture was concentrated under reduced pressure. The residue was purified by silica gel column chromatography, eluted with PE / EA (5:1) to afford tert-butyl N-{3-[(fluorosulfonyl)oxy]phenyl}carbamate (1.2 g, 56.34% yield) as a white solid. 143 Attorney Docket No.57891-0006WO1 Step 2. To the above mixture was added HCl in dioxane (3 mL, 1 equiv) dropwise over 1 min at 25 °C. The resulting mixture was stirred at room temperature for additional 1 h. The resulting mixture was concentrated under reduced pressure. This resulted in 3-aminophenyl sulfurofluoridate (0.8 g, 67.67% yield) as a red crude solid. The crude product was used in the 5 next step directly without further purification. Step 2: To a stirred mixture of 3-aminophenyl sulfurofluoridate (200 mg, 0.837 mmol, 1.00 equiv, 80%) and 3-iodobenzoic acid (207.57 mg, 0.83 mmol, 1.0 equiv) in DMF (3 mL) were added DIEA (162.25 mg, 1.256 mmol, 1.5 equiv) and HATU (954.66 mg, 2.51 mmol, 3 equiv) in portions at room temperature. The resulting mixture was stirred at room temperature 10 for 2 h. The reaction was monitored by LCMS. The resulting mixture was extracted with EtOAc (3 x 2 mL). The combined organic layers were washed with water (3 x 2 mL), dried over anhydrous Na2SO4. After filtration, the filtrate was concentrated under reduced pressure. The residue was purified by silica gel column chromatography, eluted with PE / EA (5:1) to afford 3-(3-iodobenzamido)phenyl sulfurofluoridate (100 mg, 28.37% yield) as a white solid. 15 Step 3: To a stirred mixture of 3-(3-iodobenzamido)phenyl sulfurofluoridate (80 mg, 0.19 mmol, 1 equiv) and 2-[(-[(chloroaurio)dicyclohexyl-lambda5-phosphanyl]-N,N- dimethylaniline (104.64 mg, 0.19 mmol, 1 equiv) in DCM (3 mL) was added Silver Hexafluoroantimonate(V) (65.27 mg, 0.19 mmol, 1 equiv) dropwise at -20 °C . The resulting mixture was stirred at room temperature for 2 h. The reaction was monitored by LCMS. The 20 resulting mixture was filtered, the filter cake was washed with DCM (3 mL) (3 x 1 mL). The filtrate was concentrated under reduced pressure. The residue was purified by trituration with MTBE (2 mL). This resulted in [3-({3-[(fluorosulfonyl)oxy]phenyl}carbamoyl)phenyl]gold (100 mg, 24.95% yield, 94% purity) as a grey solid. LCMS:(ES, m / z): [M]+= 843.1. 1H NMR (300 MHz, DMSO-d6,ppm) δ 10.71 (s, 1H), 8.37 (dd, J = 8.5, 4.3 Hz, 1H), 25 8.12 – 7.86 (m, 6H), 7.85 – 7.67 (m, 2H), 7.60 (dt, J = 10.6, 8.1 Hz, 2H), 7.36 (dd, J = 8.3, 2.6 Hz, 1H), 3.91 (s, 6H), 2.93 (d, J = 11.3 Hz, 2H), 1.91 (s, 2H), 1.80-1.52 (m, 10H), 1.40 – 1.22 (m, 4H), 1.07 (t, J = 12.8 Hz, 2H), 0.61 (s, 2H). Example 46. Synthesis of Au-MM-6 144 Attorney Docket No.57891-0006WO1 Step 1: To a stirred mixture of 3-hydroxybenzaldehyde (2 g, 16.377 mmol, 1 equiv) and 3-(fluorosulfonyl)-1,2-dimethylimidazol-1-ium triflate (6.45 g, 19.652 mmol, 1.2 equiv) in MeCN (20 mL) was added TEA (2.49 g, 24.566 mmol, 1.5 equiv) in portions at 0 °C. The resulting mixture was stirred at 0°C for 30 min. The resulting mixture was concentrated under 5 reduced pressure. The residue was purified by reversed-phase flash chromatography with the following conditions: column, C18 silica gel; mobile phase, MeCN in Water (0.1% FA), 10% to 95% gradient in 10 min; detector, UV 254 nm. This resulted in 3-formylphenyl sulfurofluoridate (1.8 g, 53.83% yield) as a white solid. Step 2: To a stirred mixture of 3-formylphenyl sulfurofluoridate (500 mg, 2.449 mmol, 10 1 equiv) and benzenamine, 3-iodo- (804.57 mg, 3.673 mmol, 1.5 equiv) in DCM (10 mL) were added AcOH (147.06 mg, 2.449 mmol, 1 equiv) and STAB (1038.06 mg, 4.898 mmol, 2 equiv) in portions at 0 °C. The resulting mixture was stirred at room temperature for 1h. The resulting mixture was extracted with CH2Cl2 (3 x 10 mL). The combined organic layers were washed with water (3 x 10 mL), dried over anhydrous Na2SO4. After filtration, the filtrate was 15 concentrated under reduced pressure. The residue was purified by reversed-phase flash chromatography with the following conditions: column, C18 silica gel; mobile phase, MeCN in Water (0.1% FA), 10% to 95% gradient in 10 min; detector, UV 254 nm. This resulted in 3- {[(3-iodophenyl) amino] methyl} phenyl sulfurofluoridate (300 mg, 30.08% yield) as a white solid. 20 Step 3: To a stirred solution of 3-{[(3-iodophenyl) amino] methyl} phenyl sulfurofluoridate (100 mg, 0.246 mmol, 1 equiv) and (chloroaurio)dicyclohexyl[2- (dimethylamino) phenyl]-lambda5-phosphanyl (135.04 mg, 0.246 mmol, 1 equiv) in DCM (3 mL) were added Silver Hexafluoroantimonate(V) (84.39 mg, 0.246 mmol, 1 equiv) in portions at 0 °C under nitrogen atmosphere. The resulting mixture was stirred at room temperature for 25 additional 2 h. The reaction was monitored by LCMS. The resulting mixture was filtered, the filter cake was washed with DCM (3 x 3 mL). The filtrate was concentrated under reduced pressure. The residue was purified by trituration with Methyl tert-butyl ether (3 mL). This resulted in [chloro({3-[({3-[(fluorosulfonyl) oxy] phenyl} methyl) amino] phenyl}) aurio]dicyclohexyl[2-(dimethylamino)phenyl]-lambda5-phosphanyl (103.7 mg, 50.87% yield, 30 94.8% purity) as a yellow solid. LCMS:(ES, m / z): [M]+= 829.2. 1H NMR (300 MHz, DMSO-d6,ppm) δ 8.33 (dd, J = 8.4, 4.5 Hz, 1H), 8.12-7.94 (m, 2H), 7.77 (dt, J = 8.5, 4.2 Hz, 1H), 7.66 – 7.39 (m, 4H), 7.02 (t, J = 7.9 Hz, 1H), 6.66 (s, 1H), 145 Attorney Docket No.57891-0006WO1 6.59 – 6.40 (m, 2H), 4.45 (s, 2H), 3.51 – 3.26 (m, 6H), 2.91 (s, 2H), 1.89 – 1.42 (m, 12H), 1.29 (dt, J = 29.9, 13.5 Hz, 4H), 1.04 (t, J = 12.7 Hz, 2H), 0.63 (s, 2H). Example 47. Synthesis of Au-PM-1 5 Step 1: To a stirred solution of 3-[(fluorosulfonyl)oxy]benzoic acid (552.88 mg, 2.511 mmol, 1.1 equiv), DIEA (885.15 mg, 6.849 mmol, 3 equiv) and HATU (1302.03 mg, 3.425 mmol, 1.5 equiv) in DCM (12 mL) were added 4-iodo-benzenamine (500 mg, 2.283 mmol, 1.00 equiv) dropwise at 0 °C. The resulting mixture was stirred at 25 °C for additional 1 h. The reaction was monitored by LCMS. The resulting mixture was extracted with DCM (3 x 5 mL). 10 The combined organic layers were dried over anhydrous Na2SO4. After filtration, the filtrate was concentrated under reduced pressure. The residue was purified by reversed-phase flash chromatography with the following conditions: column, C18 silica gel; mobile phase, MeCN in Water (0.1% FA), 10% to 60% gradient in 12 min; detector, UV 254 nm. This resulted in 3-[(4-iodophenyl)carbamoyl]phenyl sulfurofluoridate (300 mg, 31.20% yield) as a15yellow oil. Step 2: To a stirred mixture of AgSbF6(163.17 mg, 0.475 mmol, 1 equiv) in DCM (8 mL) were added 3-[(4-iodophenyl)carbamoyl]phenyl sulfurofluoridate (200 mg, 0.475 mmol, 1 equiv) and (chloroaurio)dicyclohexyl[2-(dimethylamino)phenyl]-lambda5-phosphanyl (261.11 mg, 0.475 mmol, 1.00 equiv) in portions at -20 °C .The resulting mixture was stirred 20 at 25 °C for additional 2 h. The resulting mixture was filtered, the filter cake was washed with MeCN. The filtrate was concentrated under reduced pressure. The residue was purified by trituration with Et2O (2 mL). This resulted in product (80 mg, 19.96% yield) as a light grey solid. LCMS: (ES, m / z): [M]+= 843.0. 1H NMR (300 MHz, DMSO-d6, ppm) δ 10.54 (s, 1H), 8.35 (dd, J = 8.6, 4.3 Hz, 1H),258.21 – 7.96 (m, 4H), 7.96 – 7.71 (m, 5H), 7.43 (d, J = 8.5 Hz, 2H), 3.44 (s, 6H), 2.97-2.93 (m, 2H), 1.89 (m, 2H), 1.72-1.63 (m, 10H), 1.47 – 1.20 (m, 4H), 1.16 – 0.97 (m, 2H), 0.67 (m, 2H). Example 48. Synthesis of Au-PM-4 146 Attorney Docket No.57891-0006WO1 Step 1: To a stirred mixture of tert-butyl N-(3-hydroxyphenyl)carbamate (1.7 g, 7.31 mmol, 1.00 equiv) and 3-(fluorosulfonyl)-1,2-dimethylimidazol-1-ium triflate (3.60 g, 10.968 mmol, 1.5 equiv) in MeCN (5 mL) was added TEA (1.48 g, 14.624 mmol, 2 equiv) dropwise 5 at 0 °C. The resulting mixture was stirred at room temperature for additional 30 min.The reaction was monitored by LCMS. The resulting mixture was concentrated under reduced pressure. The residue was purified by silica gel column chromatography, eluted with PE / EA (5:1) to afford tert-butyl N-{3-[(fluorosulfonyl)oxy]phenyl}carbamate (1.2 g, 56.34% yield) as a white solid.10Step 2: To the above mixture was added HCl in dioxane (3 mL, 1 equiv) dropwise over 1min at 25 °C. The resulting mixture was stirred at room temperature for additional 1 h. The resulting mixture was concentrated under reduced pressure. This resulted in 3-aminophenyl sulfurofluoridate (0.8 g, 67.67% yield) as a red crude solid. The crude product was used in the next step directly without further purification. 15 Step 3: To a stirred mixture of 3-aminophenyl sulfurofluoridate (200 mg, 0.83 mmol, 1.00 equiv, 80%) and 4-iodobenzoic acid (207.57 mg, 0.837 mmol, 1.0 equiv) in DMF were added DIEA (162.25 mg, 1.256 mmol, 1.5 equiv) and HATU (954.66 mg, 2.511 mmol, 3 equiv) in portions at room temperature. The resulting mixture was stirred at room temperature for 2 h. The reaction was monitored by LCMS. The resulting mixture was extracted with EtOAc (320x 2 mL). The combined organic layers were washed with water (3 x 2 mL), dried over anhydrous Na2SO4. After filtration, the filtrate was concentrated under reduced pressure. The residue was purified by silica gel column chromatography, eluted with PE / EA (5:1) to afford 3-(4-iodobenzamido)phenyl sulfurofluoridate (150 mg, 28.37% yield, 90% purity) as a white solid. 25 Step 4: To a stirred solution of 3-(4-iodobenzamido)phenyl sulfurofluoridate (100 mg, 0.19 mmol, 1 equiv) and 2-[(chloroaurio)dicyclohexyl-lambda5-phosphanyl]-N,N- dimethylaniline (104.64 mg, 0.19 mmol, 1 equiv) in DCM (3 mL) was added Silver Hexafluoroantimonate(V) (65.27 mg, 0.190 mmol, 1 equiv) dropwise at -20 °C. The resulting mixture was stirred at room temperature for 2 h. The reaction was monitored by LCMS. The30resulting mixture was filtered, the filter cake was washed with DCM (3 mL) (3 x 1 mL). The 147 Attorney Docket No.57891-0006WO1 filtrate was concentrated under reduced pressure. The residue was purified by trituration with MTBE (2 mL). This resulted in [3-({4-[(fluorosulfonyl)oxy]phenyl}carbamoyl)phenyl]gold (150 mg, 36.25% yield, 97.6% purity) as a grey solid. LCMS:(ES, m / z): [M]+= 843.1. 1H NMR (300 MHz, DMSO-d6,ppm) δ 10.70 (s, 1H), 8.37 (dd, J = 8.5, 4.3 Hz, 1H), 5 8.17 – 7.93 (m, 5H), 7.89 (dd, J = 8.5, 1.9 Hz, 1H), 7.80 (td, J = 7.5, 2.4 Hz, 1H), 7.71 – 7.56 (m, 3H), 7.36 (dd, J = 8.2, 2.5 Hz, 1H), 3.46 (s, 6H), 2.96 (d, J = 11.0 Hz, 2H), 1.91 (s, 2H), 1.81 – 1.49 (m, 10H), 1.32 (dt, J = 25.2, 13.1 Hz, 4H), 1.08 (t, J = 13.1 Hz, 2H), 0.64 (s, 2H). Example 49. Synthesis of Au-PM-6 10Step 1: A solution of 3-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl) phenol (2 g, 9.08 mmol, 1 equiv) in MeCN (3 mL) was treated with 3-(fluorosulfonyl)-1,2-dimethylimidazol-1- ium triflate (4.47 g, 13.63 mmol, 1.5 equiv) at room temperature for 3min followed by the addition of TEA (1.84 g, 18.17 mmol, 2 equiv) dropwise at 0 °C. The reaction was monitored by LCMS. The crude product was purified by reverse phase flash to afford 3-(4,4,5,5- 15 tetramethyl-1,3,2-dioxaborolan-2-yl) phenyl sulfurofluoridate (1 g, 36.42% yield) as a red solid. Step 2: To a stirred mixture of 3-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl) phenyl sulfurofluoridate (1 g, 3.31 mmol, 1 equiv) and 4-iodophenol (0.73 g, 3.31 mmol, 1 equiv) in 1,4-dioxane were added Cu(NO3)2 (0.93 g, 4.96 mmol, 1.5 equiv) and TMEDA (1.15 g, 9.9320mmol, 3 equiv) in portions at room temperature. The resulting mixture was stirred at 60 °C for additional 2 h. The reaction was monitored by LCMS. The resulting mixture was concentrated under reduced pressure. The residue / crude product was purified by reverse phase flash to afford 3-(4-iodophenoxy) phenyl sulfurofluoridate as a white solid. Step 3: To a stirred mixture of 3-(4-iodophenoxy) phenyl sulfurofluoridate (51 mg, 0.12 25 mmol, 1 equiv) and 2-[(chloroaurio)dicyclohexyl-lambda5-phosphanyl]-N,N-dimethylaniline (71.28 mg, 0.12 mmol, 1 equiv) in DCM (3 mL) were added Silver Hexafluoroantimonate(V) (44.46 mg, 0.12 mmol, 1 equiv) dropwise at 0 °C . The resulting mixture was stirred at 0 °C for 2 h under nitrogen atmosphere. The reaction was monitored by LCMS. The resulting mixture was filtered, the filter cake was washed with DCM (3 mL) (3 x 1 mL). The filtrate was30concentrated under reduced pressure. The residue was purified by trituration with Et2O (3 mL). 148 Attorney Docket No.57891-0006WO1 This resulted in 3-(4-{2-chloro-3,3-dicyclohexyl-1,1-dimethylbenzo[d]1-aza-3-phospha-2- auracyclopentan-2-yl} phenoxy) phenyl sulfurofluoridate (73 mg, 69.04% yield, 92.5% purity) as a white solid. LCMS:(ES, m / z): [M]+= 816.1. 1H NMR (300 MHz, DMSO-d6,ppm) δ 8.36 (dd, J = 8.4, 4.4 Hz, 1H), 8.12 – 7.98 (m, 5 2H), 7.80 (td, J = 7.5, 2.3 Hz, 1H), 7.65 (t, J = 8.4 Hz, 1H), 7.52 (d, J = 8.7 Hz, 2H), 7.41 (dd, J = 8.4, 2.4 Hz, 1H), 7.28 – 7.19 (m, 3H), 7.15 (dd, J = 8.2, 2.3 Hz, 1H), 3.45 (s, 6H), 2.98 (d, J = 11.1 Hz, 2H), 1.91 (s, 2H), 1.82 – 1.47 (m, 10H), 1.44 – 1.26 (m, 4H), 1.06 (t, J = 12.6 Hz, 2H), 0.59 (s, 2H). Example 50. Synthesis of Au-PP-410 Step 1: To a stirred solution of 4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl) phenol (1 g, 4.544 mmol, 1 equiv) and 3-(fluorosulfonyl)-1,2-dimethylimidazol-1-ium triflate (2.24 g, 6.816 mmol, 1.5 equiv) in MeCN (10 mL) were added TEA (0.92 g, 9.088 mmol, 2 equiv) dropwise at 0 °C under nitrogen atmosphere. The resulting mixture was stirred at room 15 temperature for additional 30 min. The residue was purified by silica gel column chromatography, eluted with PE / THF (5:1) to afford 4-(4,4,5,5-tetramethyl-1,3,2- dioxaborolan-2-yl)phenyl sulfurofluoridate (500 mg, 36.42% yield) as a light yellow oil. Step 2: To a stirred solution of 4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl) phenylsulfurofluoridate (500 mg, 1.655 mmol, 1 equiv),4-iodophenol (291.29 mg, 1.324 mmol, 20 0.8 equiv), TMEDA (288.48 mg, 2.482 mmol, 1.5 equiv) and Cu(NO3)2 (620.79 mg, 3.310 mmol, 2 equiv) in dioxane (10 mL) at room temperature under Oxygen atmosphere. The resulting mixture was stirred at 60 °C for additional overnight under Oxygen atmosphere. The resulting mixture was diluted with 10 mL H2O and extracted with EtOAc (10 mL x 3). The combined organic layers were washed with brine (10 mL), dried over anhydrous Na2SO4. After 25 filtration, the filtrate was concentrated under reduced pressure. The residue was purified by reversed-phase flash chromatography with the following conditions: column, C18 silica gel; mobile phase, MeCN in Water (0.1% TFA), 10% to 50% gradient in 10 min; detector, UV 254 nm. This resulted in 4-(4-iodophenoxy) phenyl sulfurofluoridate (80 mg, 12.26% yield) as a light yellow oil. 149 Attorney Docket No.57891-0006WO1 Step 3: To a stirred solution of Silver Hexafluoroantimonate(V) (69.74 mg, 0.203 mmol, 1 equiv) in DCM (3 mL) at -10 °C under nitrogen atmosphere. To the above mixture was added 4-(4-iodophenoxy)phenyl sulfurofluoridate (80 mg, 0.203 mmol, 1 equiv)and (chloroaurio)dicyclohexyl[2-(dimethylamino)phenyl]-lambda5-phosphanyl 5 (111.61 mg, 0.203 mmol, 1 equiv) in portions over 2 min at -10 °C. The resulting mixture was stirred at room temperature for additional overnight. The resulting mixture was filtered, the filter cake was washed with DCM (1 mL x 3). The residue was purified by trituration with Methyl tert-butyl ether (3 mL). This resulted in 2-chloro-3,3-dicyclohexyl-2-(4-{4- [(fluorosulfonyl)oxy] phenoxy} phenyl)-1,1-dimethyl-2H,3H-3lambda5-benzo[d]1-aza- 10 3lambda5-phospha-2-auracyclopentan-1-ium-3-ylium-2,2-diuide (47.9 mg, 28.88% yield, 88% purity) as a yellow oil. LCMS-:(ES, m / z): [M]+= 816.2. 1H NMR (300 MHz, DMSO-d6, ppm) δ 8.35 (dd, J = 8.4, 4.4 Hz, 1H), 8.14 – 7.98 (m, 2H), 7.79 (td, J = 7.4, 2.4 Hz, 1H), 7.72 – 7.63 (m, 2H), 7.49 (d, J = 8.5 Hz, 2H), 7.24 – 7.13 (m, 4H), 3.44 (s, 6H), 2.97 (q, J = 11.2 Hz, 2H), 1.90 (s, 2H), 1.80 – 1.46 (m, 10H), 1.33 (dt, J 15 = 26.9, 13.5 Hz, 4H), 1.02 (q, J = 9.8, 7.2 Hz, 2H), 0.65-0.45 (m, 2H). Example 51. Synthesis of Au-PP-5 Step 1: To a stirred solution of P-anisidine (2 g, 16.240 mmol, 1 equiv),1,4- diiodobenzene (8.04 g, 24.360 mmol, 1.5 equiv), Pd(dppf)Cl2 (5.94 g, 8.120 mmol, 0.5 equiv)20and t-BuONa (3.12 g, 32.480 mmol, 2 equiv) in toluene (20 mL) at room temperature under nitrogen atmosphere. The resulting mixture was stirred at 70 °C for additional 2 h. The mixture was allowed to cool down to room temperature. The resulting mixture was diluted with 20 mL H2O and extracted with EtOAc (20 mL x 3). The combined organic layers were washed with brine (20 mL), dried over anhydrous Na2SO4. After filtration, 25 the filtrate was concentrated under reduced pressure. The residue was purified by silica gel column chromatography, eluted with PE / THF (4:1) to afford 4-iodo-N-(4- methoxyphenyl)aniline (1.8 g, 34.09% yield) as a light yellow solid. Step 2: To a stirred solution of 4-iodo-N-(4-methoxyphenyl) aniline (900 mg, 2.768 mmol, 1 equiv) in DCM (3 mL) was added Boron tribromide 1M solution in methylene30chloride (5.54 mL, 5.540 mmol, 2.00 equiv) dropwise at 0 °C under nitrogen atmosphere. The 150 Attorney Docket No.57891-0006WO1 resulting mixture was stirred at room temperature for additional 1 h. The reaction was quenched by the addition of ice water (5 mL) at 0 °C. The resulting mixture was diluted with 5 mL H2O and extracted with DCM (10 mL x 3). The combined organic layers were washed with brine (10 mL), dried over anhydrous Na2SO4. After filtration, the filtrate was concentrated 5 under reduced pressure. This resulted in 4-[(4-iodophenyl) amino] phenol (600 mg, 69.67% yield) as a light brown solid. The crude product was used in the next step directly without further purification. Step 3: To a stirred solution of 4-[(4-iodophenyl) amino] phenol (300 mg, 0.964 mmol, 1 equiv) and 3-(fluorosulfonyl)-1,2-dimethylimidazol-1-ium triflate (474.77 mg, 1.446 mmol, 10 1.5 equiv) in MeCN (5 mL) were added TEA (195.15 mg, 1.928 mmol, 2 equiv) dropwise at 0 °C under nitrogen atmosphere. The resulting mixture was stirred at room temperature for additional 30 min.The resulting mixture was concentrated under reduced pressure. The residue was purified by reversed-phase flash chromatography with the following conditions: column, C18 silica gel; mobile phase, MeCN in Water (0.1% FA), 10% to 90% gradient in 10 min; 15 detector, UV 254 nm. This resulted in 4-[(4-iodophenyl) amino] phenyl sulfurofluoridate (150 mg, 39.57% yield) as a light yellow oil. Step 4: To a stirred solutione of Silver Hexafluoroantimonate(V) (131.10 mg, 0.382 mmol, 1 equiv) in DCM (2 mL) at -10 °C under nitrogen atmosphere. To the above mixture was added 4-[(4-iodophenyl) amino] phenyl sulfurofluoridate (150 mg, 0.382 mmol, 1 20 equiv) and (chloroaurio)dicyclohexyl[2-(dimethylamino) phenyl]-lambda5-phosphanyl (209.78 mg, 0.382 mmol, 1 equiv) in portions over 2 min at -10 °C. The resulting mixture was stirred at room temperature for additional overnight. The resulting mixture was filtered, the filter cake was washed with DCM (1 mL x 3). The filtrate was concentrated under reduced pressure. The residue was purified by trituration with Methyl tert-butyl ether (3 mL). This 25 resulted in {[2-({chloro[4-({4-[(fluorosulfonyl) oxy] phenyl} amino) phenyl] aurio} dicyclohexyl-lambda5-phosphanyl) phenyl] dimethylammonio} methanidylidene (100 mg, 31.65% yield, 91.6% purity) as a yellow solid. LCMS:(ES, m / z): [M]+= 815.2. 1H NMR (300 MHz, DMSO-d6, ppm) δ 8.64 (s, 1H), 8.34 (dd, J = 8.5, 4.4 Hz, 1H), 8.15 – 7.97 (m, 2H), 7.78 (t, J = 6.9 Hz, 1H), 7.45 (d, J = 8.9 Hz, 2H), 7.28 (d, J = 8.5 Hz, 2H), 7.17 30 (dd, J = 8.7, 5.7 Hz, 4H), 2.95 (d, J = 11.7 Hz, 2H), 1.87 (s, 2H), 1.80-1.45 (m, 10H), 1.47 – 1.24 (m, 4H), 1.11 – 1.01 (m, 2H), 0.70-0.55 (m, 2H). Example 52. Synthesis of 2-((2,5-dioxo-2,5-dihydro-1H-pyrrol-1-yl)methyl)-6- fluorophenyl sulfurofluoridate (MFS-3-3) 151 Attorney Docket No.57891-0006WO1 Step 1: To a stirred mixture of 3-fluoro-2-hydroxybenzonitrile (1 g, 7.293 mmol, 1 equiv) in Et2O (20 mL) was added LiAlH4 (7.29 mL, 14.586 mmol, 2 equiv) dropwise at 0 °C. The resulting mixture was stirred at room temperature for 4 h. To the above mixture was added 5 disodium decahydrate sulfate in portions at 0 °C. The resulting mixture was stirred at 0 °C for additional 10 min. The resulting mixture was filtered, the filter cake was washed with Et2O (3x10 mL). The filtrate was concentrated under reduced pressure. The residue was purified by reversed-phase flash chromatography with the following conditions: column, C18 silica gel; mobile phase, MeCN in Water (0.1% FA), 10% to 85% gradient in 10 min; detector, UV 25410nm. This resulted in 2-(aminomethyl)-6-fluorophenol (800 mg, 77.71% yield) as a white solid. Step 2: A mixture of 2-(aminomethyl)-6-fluorophenol (500 mg, 3.542 mmol, 1 equiv), maleic anhydride (416.84 mg, 4.250 mmol, 1.2 equiv) and 4A Molecular Sievesin in AcOH (10 mL) was stirred at 120 °C for 12 h. The resulting mixture was concentrated under reduced pressure. The residue was purified by reversed-phase flash chromatography with the following 15 conditions: column, C18 silica gel; mobile phase, MeCN in Water (0.1% FA), 10% to 95% gradient in 10 min; detector, UV 254 nm. This resulted in 1-[(3-fluoro-2-hydroxyphenyl) methyl] pyrrole-2,5-dione (300 mg, 38.29% yield) as a brown oil. Step 3: To a stirred mixture of 1-[(3-fluoro-2-hydroxyphenyl) methyl] pyrrole-2,5- dione (200 mg, 0.904 mmol, 1 equiv) and 3-(fluorosulfonyl)-1,2-dimethylimidazol-1-ium20triflate (356.17 mg, 1.085 mmol, 1.2 equiv) in DCM (3 mL) was added TEA (137.25 mg, 1.356 mmol, 1.5 equiv) dropwise at 0 °C. The resulting mixture was stirred at 0 °C for 30 min. The residue was purified by silica gel column chromatography, eluted with PE / EA (5:1) to afford 2-[(2,5-dioxopyrrol-1-yl) methyl]-6-fluorophenyl sulfurofluoridate (110 mg, 40.12% yield, 99.4% purity) as a white solid. GCMS:(ES, m / z): [M]+=303.0. 251H NMR (300 MHz, DMSO-d6, ppm) δ 7.64 – 7.48 (m, 2H), 7.34 – 7.25 (m, 1H), 7.13 (s, 2H), 4.74 (s, 2H). Example 53. Synthesis of 2-(2-(2,5-dioxo-2,5-dihydro-1H-pyrrol-1-yl)ethyl)phenyl sulfurofluoridate (MFS-4-2) 152 Attorney Docket No.57891-0006WO1 Step 1: A solution of 2-hydroxyphenethylamine (500 mg, 3.64 mmol, 1 equiv) and 2,5- dihydrofuran-2,5-dione (1072.19 mg, 10.93 mmol, 3 equiv) in acetic acid (10 mL) was stirred at 100 °C for overnight under nitrogen atmosphere. The mixture was allowed to cool down to 5 room temperature. The resulting mixture was concentrated under reduced pressure. The residue was purified by silica gel column chromatography, eluted with PE / EA (5:1) to afford 1-[2-(2- hydroxyphenyl) ethyl] pyrrole-2,5-dione (450 mg, 56.84% yield, 95% purity) as a yellow oil. Step 2: A solution of 1-[2-(2-hydroxyphenyl) ethyl] pyrrole-2,5-dione (450 mg, 2.07 mmol, 1 equiv) in MeCN (10 mL) was treated with 3-(fluorosulfonyl)-1,2-dimethylimidazol-101-ium triflate (1360.00 mg, 4.14 mmol, 2 equiv) at 0 °C for 3 min under nitrogen atmosphere followed by the addition of Et3N (838.52 mg, 8.28 mmol, 4 equiv) dropwise at 0 °C. The resulting mixture was stirred at 0 °C for additional 1 h. The resulting mixture was concentrated under reduced pressure. The residue was purified by reversed-phase flash chromatography with the following conditions: column, C18 silica gel; mobile phase, MeCN in Water (0.1% 15 NH3.H2O+10 mmol / L NH4HCO3), 10% to 50% gradient in 10 min; detector, UV 254 nm. This resulted in 2-[2-(2,5-dioxopyrrol-1-yl) ethyl] phenyl sulfurofluoridate (151.7 mg, 24.47% yield, 100% purity) as a yellow solid. GCMS:(GS, m / z): [M]+= 299.0. 1H NMR (300 MHz, DMSO-d6, ppm) δ 7.76 – 7.32 (m, 4H), 6.99 (s, 2H), 3.68 (t, J = 6.8 Hz, 2H), 2.95 (t, J = 6.8 Hz, 2H).20Example 54. Synthesis of 5-((2,5-dioxo-2,5-dihydro-1H-pyrrol-1-yl)methyl)-2- fluorophenyl sulfurofluoridate (MFS-4-4) Step 1: A solution of 4-fluoro-3-hydroxybenzonitrile (1.5 g, 10.94 mmol, 1 equiv) in 25 Diethyl ether (20 mL) at 0°C for 3 min under nitrogen atmosphere followed by the addition of Lithium aluminum hydriden(1.0 M in THF) (0.62 g, 16.41 mmol, 1.5 equiv) dropwise at 0 °C. The resulting mixture was stirred at 0 °C for 2 h under nitrogen atmosphere. The reaction was quenched by the addition of water (20 mL) at 0 °C. The mixture was acidified to pH 3 with conc. HCl. The resulting mixture was extracted with EtOAc (2 x 30 mL). The combined organic 153 Attorney Docket No.57891-0006WO1 layers were washed with brine (1 x 30 mL), dried over anhydrous Na2SO4. After filtration, the filtrate was concentrated under reduced pressure. The residue was purified by silica gel column chromatography, eluted with PE / EA (5:1) to afford 5-(aminomethyl)-2-fluorophenol (1 g, 64.76% yield, 95% purity) as a yellow oil. 5 Step 2: A solution of 5-(aminomethyl)-2-fluorophenol (1 g, 7.08 mmol, 1 equiv) and maleic anhydride (2.08 g, 21.25 mmol, 3 equiv) in HOAc (10 mL) was stirred at 120 °C for overnight under nitrogen atmosphere. The mixture was allowed to cool down to room temperature. The resulting mixture was concentrated under reduced pressure. The residue was purified by reversed-phase flash chromatography with the following conditions: column, C18 10 silica gel; mobile phase, MeCN in Water (0.1% FA), 10% to 50% gradient in 10 min; detector, UV 254 nm. This resulted in 1-[(4-fluoro-3-hydroxyphenyl) methyl] pyrrole-2,5-dione (190 mg, 12.12% yield, 95% purity) as a yellow oil. Step 3: A solution of 1-[(4-fluoro-3-hydroxyphenyl) methyl] pyrrole-2,5-dione (98.48 mg, 0.44 mmol, 1 equiv) in MeCN (10 mL) was treated with 3-(fluorosulfonyl)-1,2- 15 dimethylimidazol-1-ium triflate (190 mg, 0.57 mmol, 1.3 equiv) at 0 °C for 3 min under nitrogen atmosphere followed by the addition of Et3N (135.17 mg, 1.336 mmol, 3 equiv) dropwise at 0 °C. The resulting mixture was stirred at 0 °C for additional 1 h. The resulting mixture was concentrated under reduced pressure. The residue was purified by reversed-phase flash chromatography with the following conditions: column, C18 silica gel; mobile phase, 20 MeCN in Water (0.1% FA), 10% to 50% gradient in 10 min; detector, UV 254 nm. This resulted in 5-[(2,5-dioxopyrrol-1-yl) methyl]-2-fluorophenyl sulfurofluoridate (102.9 mg, 76.21% yield, 96.7% purity) as a yellow solid. GCMS:(ES, m / z): [M]+= 303.1. 1H NMR (300 MHz, DMSO-d6, ppm) δ 7.77 – 7.68 (m, 1H), 7.59 (dd, J = 10.2, 8.6 Hz, 1H), 7.44 (ddd, J = 8.6, 4.6, 2.2 Hz, 1H), 7.10 (s, 2H), 4.66 (s, 2H). 25 Example 55. Synthesis of (R)-3-(3-(2,5-dioxo-2,5-dihydro-1H-pyrrol-1-yl)pyrrolidin- 1-yl)phenyl sulfurofluoridate (MFS-6-2) Step 1: A solution of tert-butyl N-[(3R)-pyrrolidin-3-yl] carbamate (3 g, 16.10 mmol, 1 equiv), 1-(benzyloxy)-3-bromobenzene (5.09 g, 19.32 mmol, 1.2 equiv), XPhos (1.54 g, 3.22 30 mmol, 0.2 equiv), t-BuONa (4.64 g, 48.32 mmol, 3 equiv) and Pd2(dba)3(1.47 g, 1.61 mmol, 0.1 equiv) in toluene (30 mL) was stirred at 100 °C for overnight under nitrogen atmosphere. 154 Attorney Docket No.57891-0006WO1 The mixture was allowed to cool down to room temperature. The resulting mixture was filtered, the filter cake was washed with toluene (3 x 10 mL). The filtrate was concentrated under reduced pressure. The residue was purified by reversed-phase flash chromatography with the following conditions: column, C18 silica gel; mobile phase, MeCN in Water (0.1% FA), 10% 5 to 50% gradient in 10 min; detector, UV 254 nm. This resulted in tert-butyl N-[(3R)-1-[3- (benzyloxy) phenyl] pyrrolidin-3-yl] carbamate (2.5 g, 42.12% yield, 95% purity) as a yellow oil. Step 2: A solution of tert-butyl N-[(3R)-1-[3-(benzyloxy) phenyl] pyrrolidin-3-yl] carbamate (2.5 g, 6.78 mmol, 1 equiv) and Pd / C (0.36 g, 3.39 mmol, 0.5 equiv) in MeOH (25 10 mL) was stirred at room temperature for overnight under nitrogen atmosphere. The resulting mixture was filtered, the filter cake was washed with MeOH (3 x 10 mL). The filtrate was concentrated under reduced pressure. This resulted in tert-butyl N-[(3R)-1-(3-hydroxyphenyl) Step 3: A solution of tert-butyl N-[(3R)-1-(3-hydroxyphenyl) pyrrolidin-3-yl] carbamate (1.7 g, 6.10 mmol, 1 equiv) in MeCN (20 mL) was treated with 1-(fluorosulfonyl)- 15 2,3-dimethyl-1H-imidazol-3-ium trifluoromethanesulfonate (2.61 g, 7.93 mmol, 1.3 equiv) at 0 °C for 2 min under nitrogen atmosphere followed by the addition of TEA (1.85 g, 18.32 mmol, 3 equiv) dropwise at 0 °C. The resulting mixture was stirred at 0 °C for 1 h under nitrogen atmosphere. The resulting mixture was concentrated under reduced pressure. The residue was purified by reversed-phase flash chromatography with the following conditions: 20 column, C18 silica gel; mobile phase, MeCN in Water (0.1% FA), 10% to 50% gradient in 10 min; detector, UV 254 nm. This resulted in tert-butyl N-[(3R)-1-{3-[(fluorosulfonyl) oxy] phenyl} pyrrolidin-3-yl] carbamate (1.1 g, 49.98% yield, 95% purity) as a yellow oil. Step 4: A solution of tert-butyl N-[(3R)-1-{3-[(fluorosulfonyl)oxy] phenyl} pyrrolidin- 3-yl] carbamate (1.1 g, 3.05 mmol, 1 equiv) and HCl in 1,4-dioxane (4.0 M) (5 mL) in DCM 25 (5 mL) was stirred at room temperature for 2 h under nitrogen atmosphere. The resulting mixture was concentrated under reduced pressure. This resulted in 3-[(3R)-3-aminopyrrolidin- 1-yl] phenyl sulfurofluoridate (1.1 g, Crude Product) as a white solid. Step 5: A solution of 3-[(3R)-3-aminopyrrolidin-1-yl] phenyl sulfurofluoridate (1.1 g, 4.22 mmol, 1 equiv), 2,5-dihydrofuran-2,5-dione (0.83 g, 8.45 mmol, 2 equiv) and TEA (1.28 30 g, 12.67 mmol, 3 equiv) in MeCN (15 mL) was stirred at 80 °C for overnight under nitrogen atmosphere. The mixture was allowed to cool down to room temperature. The resulting mixture was concentrated under reduced pressure. The residue was purified by reversed-phase flash chromatography with the following conditions: column, C18 silica gel; mobile phase, MeCN 155 Attorney Docket No.57891-0006WO1 in Water (0.1% FA), 10% to 50% gradient in 10 min; detector, UV 254 nm. This resulted in (2Z)-3-{[(3R)-1-{3-[(fluorosulfonyl)oxy] phenyl} pyrrolidin-3-yl] carbamoyl} prop-2-enoic acid (600 mg, 39.62% yield, 95% purity) as a yellow oil. Step 6: A solution of (2Z)-3-{[(3R)-1-{3-[(fluorosulfonyl) oxy] phenyl} pyrrolidin-3- 5 yl] carbamoyl} prop-2-enoic acid (350 mg, 0.97 mmol, 1 equiv) and maleic anhydride (287.32 mg, 2.93 mmol, 3 equiv) in HOAc (5 mL) was stirred at 100 °C for overnight under nitrogen atmosphere. The mixture was allowed to cool down to room temperature. The residue was purified by reversed-phase flash chromatography with the following conditions: column, C18 silica gel; mobile phase, MeCN in Water (0.1% FA), 10% to 50% gradient in 10 min; detector, 10 UV 254 nm. This resulted in 3-[(3R)-3-(2,5-dioxopyrrol-1-yl) pyrrolidin-1-yl] phenyl sulfurofluoridate (74.3 mg, 22.35% yield, 95.5% purity) as a red oil. LCMS:(ES, m / z): [M+H]+= 341.1. 1H NMR (400 MHz, DMSO-d6, ppm) δ 7.34 (t, J = 8.3 Hz, 1H), 7.03 (s, 2H), 6.75 – 6.70 (m, 1H), 6.65 – 6.58 (m, 2H), 4.77 (d, J = 7.8 Hz, 1H), 3.58 – 3.44 (m, 3H), 3.36 (d, J = 15 7.9 Hz, 1H), 2.47 – 2.36 (m, 1H), 2.29 – 2.21 (m, 1H). Example 56. Synthesis of (S)-3-(3-(2,5-dioxo-2,5-dihydro-1H-pyrrol-1-yl)pyrrolidin- 1-yl)phenyl sulfurofluoridate (MFS-6-3) Step 1: A solution of tert-butyl N-[(3S)-pyrrolidin-3-yl] carbamate (3 g, 16.10 mmol, 1 20 equiv), 1-(benzyloxy)-3-bromobenzene (5.09 g, 19.32 mmol, 1.2 equiv), Pd2(dba)3(1.47 g, 1.61 mmol, 0.1 equiv), XPhos (1.54 g, 3.22 mmol, 0.2 equiv) and t-BuONa (4.64 g, 48.32 mmol, 3 equiv) in toluene (30 mL) was stirred at 100 °C for overnight under nitrogen atmosphere. The mixture was allowed to cool down to room temperature. The resulting mixture was filtered, the filter cake was washed with MeCN (3 x 10 mL). The filtrate was concentrated25under reduced pressure. The residue was purified by reversed-phase flash chromatography with the following conditions: column, C18 silica gel; mobile phase, MeCN in Water (0.1% FA), 10% to 50% gradient in 10 min; detector, UV 254 nm. This resulted in tert-butyl N-[(3S)-1-[3- (benzyloxy)phenyl]pyrrolidin-3-yl]carbamate (3.3 g, 55.60% yield, 95% purity) as a yellow oil. 30 Step 2: A solution of tert-butyl N-[(3S)-1-[3-(benzyloxy) phenyl] pyrrolidin-3-yl] carbamate (3.3 g, 8.956= mmol, 1 equiv) and Pd / C (0.48 g, 4.478= mmol, 0.5 equiv) in MeOH 156 Attorney Docket No.57891-0006WO1 (35 mL) was stirred at room temperature for overnight under nitrogen atmosphere. The resulting mixture was filtered, the filter cake was washed with MeOH (3 x 5 mL). The filtrate was concentrated under reduced pressure. This resulted in tert-butyl N-[(3S)-1-(3- hydroxyphenyl) 5 Step 3: A solution of tert-butyl N-[(3S)-1-(3-hydroxyphenyl) pyrrolidin-3-yl] carbamate (2.4 g, 8.62 mmol, 1 equiv) in MeCN (25 mL) was treated with 3-(fluorosulfonyl)- 1,2-dimethylimidazol-1-ium triflate (3.68 g, 11.20 mmol, 1.3 equiv) at 0 °C for 3 min under nitrogen atmosphere followed by the addition of TEA (2.62 g, 25.86 mmol, 3 equiv) dropwise at 0 °C. The resulting mixture was stirred at 0 °C for 1 h under nitrogen atmosphere. The 10 resulting mixture was concentrated under reduced pressure. The residue was purified by reversed-phase flash chromatography with the following conditions: column, C18 silica gel; mobile phase, MeCN in Water (0.1% FA), 10% to 50% gradient in 10 min; detector, UV 254 nm. This resulted in tert-butyl N-[(3S)-1-{3-[(fluorosulfonyl) oxy] phenyl} pyrrolidin-3-yl] carbamate (1.4 g, 45.05% yield, 95% purity) as a yellow oil. 15 Step 4: A solution of tert-butyl N-[(3S)-1-{3-[(fluorosulfonyl) oxy] phenyl} pyrrolidin- 3-yl] carbamate (1.4 g, 3.88 mmol, 1 equiv) and HCl in 1,4-dioxane (4.0 M) (10 mL) in DCM (10 mL) was stirred at room temperature for 2 h under nitrogen atmosphere. The resulting mixture was concentrated under reduced pressure. This resulted in 3-[(3S)-3-aminopyrrolidin- 1-yl] phenyl sulfurofluoridate (1.4 g, Crude Product) as a white solid. 20 Step 5: A solution of (2Z)-3-{[(3S)-1-{3-[(fluorosulfonyl) oxy] phenyl} pyrrolidin-3- yl] carbamoyl} prop-2-enoic acid (1 g, 2.79 mmol, 1 equiv) and maleic anhydride (0.82 g, 8.37 mmol, 3 equiv) in HOAc (10 mL) was stirred at 120 °C for overnight under nitrogen atmosphere. The mixture was allowed to cool down to room temperature. The resulting mixture was concentrated under reduced pressure. The residue was purified by reversed-phase flash 25 chromatography with the following conditions: column, C18 silica gel; mobile phase, MeCN in Water (0.1% TFA), 10% to 50% gradient in 10 min; detector, UV 254 nm. This resulted in 3-[(3S)-3-(2,5-dioxopyrrol-1-yl) pyrrolidin-1-yl] phenyl sulfurofluoridate (116.8 mg, 12.30% yield, 99.5% purity) as a light yellow oil. LCMS:(ES, m / z): [M+H]+= 341.1. 1H NMR (300 MHz, DMSO-d6, ppm) δ 7.40 – 7.28 (m, 1H), 7.04 (s, 2H), 6.73 (d, J = 30 8.1 Hz, 1H), 6.68 – 6.59 (m, 2H), 4.79 (p, J = 7.9 Hz, 1H), 3.66 – 3.42 (m, 3H), 3.37 (d, J = 7.6 Hz, 1H), 2.50 – 2.35 (m, 1H), 2.33 – 2.16 (m, 1H). Example 57. Synthesis of 4-(3-(2,5-dioxo-2,5-dihydro-1H-pyrrol-1-yl)azetidin-1- yl)phenyl sulfurofluoridate (MFS-7-1) 157 Attorney Docket No.57891-0006WO1 Step 1: To a stirred solution of tert-butyl N-(azetidin-3-yl)carbamate (900 mg, 5.226 mmol, 1 equiv),1-(benzyloxy)-4-bromobenzene (2062.56 mg, 7.839 mmol, 1.5 equiv), Pd2(dba)3(478.53 mg, 0.523 mmol, 0.1 equiv), XPhos (498.24 mg, 1.045 mmol, 0.2 equiv) 5 and t-BuONa (1506.63 mg, 15.678 mmol, 3 equiv) in toluene (15 mL) at room temperature under nitrogen atmosphere. The resulting mixture was stirred at 100 °C for additional overnight. The mixture was allowed to cool down to room temperature. The resulting mixture was diluted with 15 mL H2O and extracted with EtOAc (15 mL x 3). The combined organic layers were washed with brine (15 mL), dried over anhydrous Na2SO4. After 10 filtration, the filtrate was concentrated under reduced pressure. The residue was purified by silica gel column chromatography, eluted with PE / THF (3:1) to afford tert-butyl N-{1-[4- (benzyloxy)phenyl]azetidin-3-yl}carbamate (800 mg, 43.19% yield) as a yellow solid. Step 2: To a stirred solution of tert-butyl N-{1-[4-(benzyloxy) phenyl] azetidin-3-yl} carbamate (800 mg, 2.257 mmol, 1 equiv) and palladium (100 mg, 0.940 mmol, 0.4215equiv) in MeOH (10 mL) at room temperature under nitrogen atmosphere. The resulting mixture was stirred at room temperature for additional 2h under hydrogen atmosphere. The resulting mixture was filtered,the filter cake was washed with MeOH (5 mL x 3). This resulted in tert-butyl N-[1-(4-hydroxyphenyl) azetidin-3-yl] carbamate (500 mg, 83.81% yield) as a light yellow oil. The crude product was used in the next step directly without further 20 purification. Step 3: To a stirred solution of tert-butyl N-[1-(4-hydroxyphenyl) azetidin-3-yl] carbamate (500 mg, 1.892 mmol, 1 equiv) in DCM (3 mL) was added TFA (3 mL) dropwise at room temperature under nitrogen atmosphere. The resulting mixture was stirred at room temperature for additional 2 h. The precipitated solids were collected by filtration and washed25with diethyl ether (2 mL x 3). This resulted in 4-(3-aminoazetidin-1-yl) phenol (300 mg, 96.58% yield) as a light yellow solid. The crude product was used in the next step directly without further purification. Step 4: To a stirred solution of 4-(3-aminoazetidin-1-yl) phenol (300 mg, 1.827 mmol, 1 equiv) and maleic anhydride (268.72 mg, 2.740 mmol, 1.5 equiv) in MeCN (5 mL) was 30 added TEA (369.75 mg, 3.654 mmol, 2 equiv) dropwise at 0 °C under nitrogen atmosphere. The resulting mixture was stirred at room temperature for additional 1 h. The residue was 158 Attorney Docket No.57891-0006WO1 purified by reversed-phase flash chromatography with the following conditions: column, C18 silica gel; mobile phase, MeCN in Water (0.1% FA), 10% to 50% gradient in 10 min; detector, UV 254 nm. This resulted in (2Z)-3-{[1-(4-hydroxyphenyl) azetidin-3-yl] carbamoyl} prop-2- enoic acid (300 mg, 62.61% yield) as a light yellow oil. 5 Step 5: To a stirred solution of (2Z)-3-{[1-(4-hydroxyphenyl)azetidin-3- yl]carbamoyl}prop-2-enoic acid (200 mg, 0.763 mmol, 1 equiv), HOSu (351.06 mg, 3.052 mmol, 4 equiv) in DMF (5 mL) was added TFAA (640.67 mg, 3.052 mmol, 4 equiv) dropwise at 0 °C under nitrogen atmosphere. The mixture was stirred for 15 min. 2,4,6-trimethylpyridine (184.83 mg, 1.526 mmol, 2 equiv) was added and the mixture was allowed to warm to RT and 10 stirred for overnight. The reaction was quenched by the addition of ice water (3 mL) at 0 °C. The resulting mixture was diluted with 3 mL H2O and extracted with EtOAc (5 mL x 3). The combined organic layers were washed with brine (5 mL), dried over anhydrous Na2SO4. After filtration, the filtrate was concentrated under reduced pressure. The residue was purified by reversed-phase flash chromatography with the following conditions: column, C18 silica gel; 15 mobile phase, MeCN in Water (0.1% TFA), 10% to 50% gradient in 10 min; detector, UV 254 nm. This resulted in 1-[1-(4-hydroxyphenyl) azetidin-3-yl] pyrrole-2,5-dione (150 mg, 80.53% yield) as a light yellow oil. Step 6: To a stirred solution of 1-[1-(4-hydroxyphenyl) azetidin-3-yl] pyrrole-2,5-dione (150 mg, 0.614 mmol, 1 equiv) and 3-(fluorosulfonyl)-1,2-dimethylimidazol-1-ium triflate 20 (403.17 mg, 1.228 mmol, 1.5 equiv) in MeCN (3 mL) was added TEA (165.72 mg, 1.638 mmol, 2 equiv) dropwise at 0 °C under nitrogen atmosphere. The resulting mixture was stirred at room temperature for additional 30 min. The resulting mixture was concentrated under reduced pressure. The residue was purified by reversed-phase flash chromatography with the following conditions: column, C18 silica gel; mobile phase, MeCN in Water (0.1% FA), 10% 25 to 90% gradient in 10 min; detector, UV 254 nm. This resulted in 4-[3-(2,5-dioxopyrrol-1-yl) azetidin-1-yl] phenyl sulfurofluoridate (70 mg, 34.93% yield, 99.0% purity) as a light yellow oil. LCMS:(ES, m / z): [M+H]+= 327.1. 1H NMR (300 MHz, DMSO-d6, ppm) δ 7.37 (d, J = 8.5 Hz, 2H), 7.03 (d, J = 1.5 Hz, 2H), 6.58 – 6.51 (m, 2H), 4.94 (p, J = 7.4 Hz, 1H), 4.20 (dd, J = 7.4, 1.5 Hz, 4H). 30 Example 58. Synthesis of (R)-4-(3-(2,5-dioxo-2,5-dihydro-1H-pyrrol-1-yl)pyrrolidin- 1-yl)phenyl sulfurofluoridate (MFS-7-2) 159 Attorney Docket No.57891-0006WO1 Step 1: To a stirred mixture of tert-butyl N-[(3R)-pyrrolidin-3-yl]carbamate (2 g, 10.738 mmol, 1 equiv),t-BuONa (3.10 g, 32.214 mmol, 3 equiv) and 1-(benzyloxy)-4- bromobenzene (3.39 g, 12.886 mmol, 1.2 equiv) in toluene (40 mL) were added Pd2(dba)3(1.97 5 g, 2.148 mmol, 0.2 equiv) and XPhos (1.02 g, 2.148 mmol, 0.2 equiv) in portions at room temperature under nitrogen atmosphere. The resulting mixture was stirred at 120 °C for 4 h under nitrogen atmosphere. The resulting mixture was extracted with EtOAc (3 x 40 mL). The combined organic layers were washed with saline water (3 x 20 mL), dried over anhydrous Na2SO4. After filtration, the filtrate was concentrated under reduced pressure. The residue was 10 purified by reversed-phase flash chromatography with the following conditions: column, C18 silica gel; mobile phase, MeCN in Water (0.1% FA), 10% to 95% gradient in 10 min; detector, UV 254 nm. This resulted in tert-butyl N-[(3R)-1-[4-(benzyloxy)phenyl]pyrrolidin-3- yl]carbamate (2.2 g, 55.60% yield) as a brown solid. Step 2: To a solution of tert-butyl N-[(3R)-1-[4-(benzyloxy)phenyl]pyrrolidin-3-15yl]carbamate (2.2 g, 5.971 mmol, 1 equiv) in 20 mL MeOH was added Pd / C (10%, 0.22 g) under nitrogen atmosphere in a 100 mL round-bottom flask. The mixture was hydrogenated at room temperature for 2 h under hydrogen atmosphere using a hydrogen balloon, filtered through a Celite pad and concentrated under reduced pressure to afford tert-butyl N-[(3R)-1- (4-hydroxyphenyl)pyrrolidin-3-yl]carbamate (1.5 g, 90.26% yield) as a light brown solid. The 20 crude resulting mixture was used in the next step directly without further purification. Step 3: A solution of tert-butyl N-[(3R)-1-(4-hydroxyphenyl)pyrrolidin-3-yl]carbamate (1.5 g, 5.389 mmol, 1 equiv) in DCM (12 mL) and HCl in 1,4-dioxane (4.0 M) (4 mL) was stirred at room temperature for 2 h. The resulting mixture was concentrated under reduced pressure to afford 4-[(3R)-3-aminopyrrolidin-1-yl]phenol (900 mg, 93.70% yield) as a white25solid. The crude resulting mixture was used in the next step directly without further purification. Step 4: To a stirred mixture of 4-[(3R)-3-aminopyrrolidin-1-yl]phenol (850 mg, 4.769 mmol, 1 equiv) and maleic anhydride (561.16 mg, 5.723 mmol, 1.2 equiv) in ACN (10 mL) was added TEA (965.18 mg, 9.538 mmol, 2 equiv) dropwise at 0 °C. The resulting mixture 30 was stirred at room temperature for 12 h. The resulting mixture was concentrated under reduced pressure. The residue was purified by reversed-phase flash chromatography with the following 160 Attorney Docket No.57891-0006WO1 conditions: column, C18 silica gel; mobile phase, MeCN in Water (0.1% FA), 10% to 50% gradient in 10 min; detector, UV 254 nm. This resulted in (2Z)-3-{[(3R)-1-(4- hydroxyphenyl)pyrrolidin-3-yl]carbamoyl}prop-2-enoic acid (700 mg, 53.13% yield) as a light yellow solid. 5 Step 5: A mixture of (2Z)-3-{[(3R)-1-(4-hydroxyphenyl)pyrrolidin-3- yl]carbamoyl}prop-2-enoic acid (600 mg, 2.172 mmol, 1 equiv) in AcOH (10 mL) was stirred at 70 °C for 12 h. The resulting mixture was concentrated under reduced pressure. The residue was purified by reversed-phase flash chromatography with the following conditions: column, C18 silica gel; mobile phase, MeCN in Water (0.1% FA), 10% to 60% gradient in 10 min;10 detector, UV 254 nm. This resulted in 1-[(3R)-1-(4-hydroxyphenyl)pyrrolidin-3-yl]pyrrole- 2,5-dione (300 mg, 53.49% yield) as a light yellow solid. Step 6: To a stirred mixture of 1-[(3R)-1-(4-hydroxyphenyl) pyrrolidin-3-yl]pyrrole- 2,5-dione (300 mg, 1.162 mmol, 1 equiv) and 3-(fluorosulfonyl)-1,2-dimethylimidazol-1-ium triflate (457.53 mg, 1.394 mmol, 1.2 equiv) in DCM (3 mL) was added TEA (176.31 mg, 1.743 15 mmol, 1.5 equiv) in portions at 0 °C. The resulting mixture was stirred at 0 °C for 30 min. The resulting mixture was concentrated under reduced pressure. The residue was purified by reversed-phase flash chromatography with the following conditions: column, C18 silica gel; mobile phase, MeCN in Water (0.1% FA), 10% to 95% gradient in 10 min; detector, UV 254 nm. This resulted in 4-[(3R)-3-(2,5-dioxopyrrol-1-yl)pyrrolidin-1-yl]phenyl sulfurofluoridate 20 (100 mg, 25.30% yield, 99.7% purity) as a white solid. LCMS:(ES, m / z): [M+H]+= 341.2 1H NMR (300 MHz, DMSO-d6, ppm) δ 7.36 (...

Claims

Attorney Docket No.57891-0006WO1 WHAT IS CLAIMED IS:

1. A compound having formula (I):Ring A is: ^ C6-14 aryl optionally substituted with 1-4 substituents independently selected from the group consisting of oxo, Ra, and Rb; or ^ heteroaryl of 5-12 ring atoms, wherein 1-4 ring atoms are heteroatoms, each independently selected from the group consisting of N, N(H), N(Rc), O, and S(O)0-2, and wherein the heteroaryl is optionally substituted with 1-4 substituents independently selected from the group consisting of oxo, Ra, and Rb; each of R1and R2is independently selected from the group consisting of: ^ C6-14 aryl optionally substituted with 1-4 substituents independently selected from the group consisting of oxo, Ra, and Rb; and ^ C3-12cycloalkyl optionally substituted with substituents independently selected from the group consisting of oxo, Ra, and Rb; each of R3and R4is independently selected from the group consisting of: ^ C1-10 alkyl optionally substituted with 1-4 independently selected Rd; and ^ C3-12cycloalkyl optionally substituted with substituents independently selected from the group consisting of oxo, Ra, and Rb; R5is a coordinating anion; 318Attorney Docket No.57891-0006WO1 R6is -*R61-R62-R63; wherein, the * indicates the point of attachment of R61-R62-R63to Au: R61is: ^ divalent C6-10 aryl optionally substituted with 1-4 substituents independently selected from the group consisting of oxo, Ra, and Rb; or ^ divalent heteroaryl of 5-10 ring atoms, wherein 1-4 ring atoms are heteroatoms, each independently selected from the group consisting of N, N(H), N(Rc), O, and S(O)0-2, and wherein the heteroaryl is optionally substituted with 1-4 substituents independently selected from the group consisting of oxo, Ra, and Rb; R62is absent or is C1-C16 alkylene, C2-C16 alkenylene, or C2-C16 alkynylene, each of which is optionally substituted with 1-2 substituents independently selected from halogen and C3-C6 cycloalkyl; and wherein 1-8 alkylene units are optionally replaced with a group independently selected from the group consisting of: (i) -O-; (ii) -NH-; (iii) -N(C1-C6 alkyl)-; (iv) -C(O)-; (v) -S-; (vi) –S(O)–; (vii) –S(O)2–; (viii) divalent C3-C10cycloalkyl, which is optionally substituted with 1-4 Ra; (ix) divalent C6-C10 aryl, which is optionally substituted with 1-4 Ra; (x) divalent heteroaryl of 5-10 ring atoms, wherein 1-4 ring atoms are heteroatoms, each independently selected from the group consisting of N, N(H), N(Rc), O, and S(O)0-2; and which is optionally substituted with 1-4 Ra; and 319Attorney Docket No.57891-0006WO1 (xi) divalent heterocyclyl of 3-10 ring atoms, wherein 1-3 ring atoms are heteroatoms, each independently selected from the group consisting of N, N(H), N(Rc), N(O-), O, and S(O)0- 2, and which is optionally substituted with 1-4 Ra; R63is a reactive group; each occurrence of Rais independently selected from the group consisting of: halo; cyano; C1-10 alkyl which is optionally substituted with 1-6 independently selected Rd; C2-6 alkenyl; C2-6 alkynyl; C1-4 alkoxy; C1-4 haloalkoxy; -S(O)1-2(C1-4 alkyl); -S(O)(=NH)(C1-4 alkyl); -NReRf; –OH; -S(O)1-2NR’R’’; -C1-4thioalkoxy; -NO2; -C(=O)(C1-10alkyl); - C(=O)O(C1-4alkyl); -OC(=O)(C1-4alkyl); -C(=O)OH; -C(=O)NR’R’’; -NR’C(=O)(C1-4alkyl) and –SF5; each occurrence of Rbis independently selected from the group consisting of: ^ L1-C3-12 cycloalkyl or C3-12 cycloalkenyl, each of which is optionally substituted with 1-4 substituents independently selected from the group consisting of oxo and Rd; ^ L1-heterocyclyl or L1-heterocycloalkenyl of 3-12 ring atoms, wherein 1-3 ring atoms are heteroatoms, each independently selected from the group consisting of N, N(H), N(Rc), O, and S(O)0-2, and wherein the heterocyclyl or heterocycloalkenyl is optionally substituted with 1-4 substituents independently selected from the group consisting of oxo and Rd; ^ L1-heteroaryl of 5-12 ring atoms, wherein 1-4 ring atoms are heteroatoms, each independently selected from the group consisting of N, N(H), N(Rc), O, and S(O)0-2, and wherein the heteroaryl is optionally substituted with 1-4 substituents independently selected from the group consisting of oxo and Rd; and ^ L1-C6-10aryl optionally substituted with 1-4 substituents independently selected from the group consisting of oxo and Rd; L1 is a bond or C1-4alkylene; 320Attorney Docket No.57891-0006WO1 each occurrence of Rcis independently selected from the group consisting of: C1-6alkyl optionally substituted with 1-3 independently selected Ra; -C(O)(C1-4 alkyl); -C(O)O(C1-4 alkyl); -CONR’R’’; -S(O)1-2NR’R’’; - S(O)1-2(C1-4 alkyl); -OH; and C1-4 alkoxy; each occurrence of Rdis independently selected from the group consisting of: –OH; - halo; –NReRf; C1-4 alkoxy; C1-4 haloalkoxy; -C(=O)O(C1-4 alkyl); -C(=O)(C1-4 alkyl); - OC(=O)(C1-4alkyl); -C(=O)OH; -CONR’R’’; -S(O)1-2NR’R’’; -S(O)1-2(C1-4alkyl); and cyano; each occurrence of Reand Rfis independently selected from the group consisting of: H; C1-6alkyl optionally substituted with 1-3 substituents each independently selected from the group consisting of NR’R’’, -OH, halo, C1-4alkoxy, and C1-4haloalkoxy; -C(O)(C1-4alkyl); - C(O)O(C1-4 alkyl); -CONR’R’’; -S(O)1-2NR’R’’; -S(O)1-2(C1-4 alkyl); -OH; and C1-4 alkoxy; and each occurrence of R’ and R’’ is independently selected from the group consisting of: H; -OH; and C1-4 alkyl.

2. The compound of claim 1, wherein R61is divalent C6-10aryl optionally substituted with 1-4 substituents independently selected from the group consisting of oxo, Ra, and Rb.

3. The compound of claim 1 or 2, wherein R61is divalent phenyl optionally substituted with 1-4 substituents independently selected from the group consisting of Raand Rb.

4. The compound of any one of claims 1-3, wherein R61is divalent phenyl optionally substituted with 1-4 independently selected Ra.

5. The compound of any one of claims 1-4, wherein R61is divalent phenyl optionally substituted with 1-2 independently selected Ra.

6. The compound of any one of claims 2-5, wherein each occurrence of Rais independently selected from the group consisting of halo and C1-10 alkyl which is optionally substituted with 1-6 independently selected Rd, optionally wherein each occurrence of Rais independently selected from the group consisting of fluoro and CH3. 321Attorney Docket No.57891-0006WO1 7. The compound of claim 1, wherein R61is divalent heteroaryl of 5-10 ring atoms, wherein 1-4 ring atoms are heteroatoms, each independently selected from the group consisting of N, N(H), N(Rc), O, and S(O)0-2, and wherein the heteroaryl is optionally substituted with 1- 4 substituents independently selected from the group consisting of oxo, Ra, and Rb.

8. The compound of any one of claims 1-7, wherein R62is absent.

9. The compound of any one of claims 1-7, wherein R62is C1-C16 alkylene, C2-C16 alkenylene, or C2-C16alkynylene, each of which is optionally substituted with 1-2 substituents independently selected from halogen and C3-C6 cycloalkyl; and wherein 1-8 alkylene units are optionally replaced with a group independently selected from the group consisting of: (i) -O-; (ii) -NH-; (iii) -N(C1-C6 alkyl)-; (iv) -C(O)-; (v) -S-; (vi) –S(O)–; (vii) –S(O)2–; (viii) divalent C3-C10cycloalkyl, which is optionally substituted with 1-4 Ra; (ix) divalent C6-C10 aryl, which is optionally substituted with 1-4 Ra; (x) divalent heteroaryl of 5-10 ring atoms, wherein 1-4 ring atoms are heteroatoms, each independently selected from the group consisting of N, N(H), N(Rc), O, and S(O)0-2; and which is optionally substituted with 1-4 Ra; and (xi) divalent heterocyclyl of 3-10 ring atoms, wherein 1-3 ring atoms are heteroatoms, each independently selected from the group consisting of N, N(H), N(Rc), N(O-), O, and S(O)0-2, and which is optionally substituted with 1-4 Ra.

10. The compound of any one of claims 1-7 and 9, wherein R62is C1-C16 alkylene, which is optionally substituted with 1-2 substituents independently selected from halogen and C3-C6cycloalkyl; and wherein 1-8 alkylene units are each optionally replaced with a group independently selected from the group consisting of: (i) -O-; (ii) -NH-; 322Attorney Docket No.57891-0006WO1 (iii) -N(C1-C6alkyl)-; (iv) -C(O)-; (v) -S-; (vi) –S(O)–; (vii) –S(O)2–; (viii) divalent C3-C10 cycloalkyl, which is optionally substituted with 1-4 Ra; (ix) divalent phenyl, which is optionally substituted with 1-4 Ra; (x) divalent heteroaryl of 5-10 ring atoms, wherein 1-4 ring atoms are heteroatoms, each independently selected from the group consisting of N, N(H), N(Rc), O, and S(O)0-2; and which is optionally substituted with 1-4 Ra; and (xi) divalent heterocyclyl of 3-10 ring atoms, wherein 1-3 ring atoms are heteroatoms, each independently selected from the group consisting of N, N(H), N(Rc), N(O-), O, and S(O)0- 2, and which is optionally substituted with 1-4 Ra.

11. The compound of any one of claims 1-7, 9, and 10, wherein R62is C1-C8alkylene, which is optionally substituted with 1-2 substituents independently selected from halogen and C3-C6 cycloalkyl; and wherein 1-6 alkylene units are each optionally replaced with a group independently selected from the group consisting of: (i) -O-; (ii) -NH-; (iii) -N(C1-C6alkyl)-; (iv) -C(O)-; (v) -S-; (vi) –S(O)–; (vii) –S(O)2–; (viii) divalent C3-C10 cycloalkyl, which is optionally substituted with 1-4 Ra; (ix) divalent phenyl, which is optionally substituted with 1-4 Ra; 323Attorney Docket No.57891-0006WO1 (x) divalent heteroaryl of 5-10 ring atoms, wherein 1-4 ring atoms are heteroatoms, each independently selected from the group consisting of N, N(H), N(Rc), O, and S(O)0-2; and which is optionally substituted with 1-4 Ra; and (xi) divalent heterocyclyl of 3-10 ring atoms, wherein 1-3 ring atoms are heteroatoms, each independently selected from the group consisting of N, N(H), N(Rc), N(O-), O, and S(O)0- 2, and which is optionally substituted with 1-4 Ra.

12. The compound of any one of claims 1-7 and 9-11, wherein R62is C1-C8alkylene, which is optionally substituted with 1-2 substituents independently selected from halogen and C3-C6 cycloalkyl; and wherein 1-6 alkylene units are each optionally replaced with a group independently selected from the group consisting of: (i) -O-; (ii) -NH-; (iii) -N(C1-C6 alkyl)-; (iv) -C(O)-; (viii) divalent C3-C10 cycloalkyl, which is optionally substituted with 1-4 Ra; (ix) divalent phenyl, which is optionally substituted with 1-4 Ra; and (xi) divalent heterocyclyl, wherein 1-3 ring atoms are heteroatoms, each independently selected from the group consisting of N, N(H), N(Rc), N(O-), O, and S(O)0-2, and which is optionally substituted with 1-4 Ra.

13. The compound of any one of claims 1-7 and 9-12, wherein R62has formula (II): **-(L11)n11-(L12)n12-(L13)n13-(L14)n14-(L15)n15-*** (II) wherein ** indicates the point of attachment of formula (II) to R61, and *** indicates the point of attachment of formula (II) to the reactive group; wherein each of n11, n12, n13, n14, and n15 is independently 0 or 1, provided that at least one of n11, n12, n13, n14, and n15 is 1; and each occurrence of L11, L12, L13, L14, and L15is independently selected from the group consisting of: (i) -O-; 324Attorney Docket No.57891-0006WO1 (ii) -NH-; (iii) -N(C1-C6 alkyl)-; (iv) -C(O)-; (v) -S-; (vi) –S(O)–; (vii) –S(O)2–; (viii) divalent C3-C10cycloalkyl, which is optionally substituted with 1-4 Ra; (ix) divalent phenyl, which is optionally substituted with 1-4 Ra; (x) divalent heteroaryl of 5-10 ring atoms, wherein 1-4 ring atoms are heteroatoms, each independently selected from the group consisting of N, N(H), N(Rc), O, and S(O)0-2; and which is optionally substituted with 1-4 Ra; (xi) divalent heterocyclyl of 3-10 ring atoms, wherein 1-3 ring atoms are heteroatoms, each independently selected from the group consisting of N, N(H), N(Rc), N(O-), O, and S(O)0-2, and which is optionally substituted with 1-4 Ra; and (xi) C1-C2 alkylene.

14. The compound of claim 13, wherein each occurrence of L11, L12, L13, L14, and L15is independently selected from the group consisting of: (i) -O-; (ii) -NH-; (iii) -N(C1-C6alkyl)-; (iv) -C(O)-; (viii) divalent C3-C10 cycloalkyl, which is optionally substituted with 1-4 Ra; (ix) divalent phenyl, which is optionally substituted with 1-4 Ra; (xi) divalent heterocyclyl of 3-10 ring atoms, wherein 1-3 ring atoms are heteroatoms, each independently selected from the group consisting of N, N(H), N(Rc), N(O-), O, and S(O)0- 2, and which is optionally substituted with 1-4 Ra; and (xi) C1-C2alkylene.

15. The compound of claim 13 or 14, wherein n11 is 1.

16. The compound of any one of claims 13-15, wherein L11is -NH-. 325Attorney Docket No.57891-0006WO1 17. The compound of any one of claims 13-15, wherein L11is -O-.

18. The compound of any one of claims 13-15, wherein L11is -CH2-.

19. The compound of any one of claims 13-15, wherein L11is -C(O)-.

20. The compound of any one of claims 13-19, wherein n15 is 1.

21. The compound of any one of claims 13-20, wherein L15is divalent phenyl, which is optionally substituted with 1-4 Ra.

22. The compound of any one of claims 13-21, wherein L15is unsubstituted divalent phenyl.

23. The compound of any one of claims 13-22, wherein one of n12, n13, and n14 is 1, and the others are 0.

24. The compound of any one of claims 13-22, wherein two of n12, n13, and n14 are 1, and the other is 0.

25. The compound of any one of claims 13-22, wherein each of n12, n13, and n14 is 1.

26. The compound of any one of claims 13-22, wherein each of n12, n13, and n14 is 0.

27. The compound of any one of claims 13-25, wherein each of L12, L13, and L14is independently selected from the group consisting of: (iv) -C(O)-; (viii) divalent C3-C10cycloalkyl, which is optionally substituted with 1-4 Ra; (ix) divalent phenyl, which is optionally substituted with 1-4 Ra; (xi) divalent heterocyclyl of 3-10 ring atoms, wherein 1-3 ring atoms are heteroatoms, each independently selected from the group consisting of N, N(H), N(Rc), N(O-), O, and S(O)0-2, and which is optionally substituted with 1-4 Ra; and (xi) C1-C2 alkylene.

28. The compound of any one of claims 13-25 and 27, wherein each of L12, L13, and L14, when present, is independently selected from the group consisting of -C(O)-, divalent cyclohexyl, and divalent piperidinyl.

29. The compound of claim 13 or 14, wherein n11 is 1, and n15 is 1.

30. The compound of claim 29, wherein L11is -NH-.

31. The compound of claim 29, wherein L11is -O-.

32. The compound of claim 29, wherein L11is -CH2-. 326Attorney Docket No.57891-0006WO1 33. The compound of claim 29, wherein L11is -C(O)-.

34. The compound of any one of claims 29-33, wherein L15is divalent phenyl, which is optionally substituted with 1-4 Ra.

35. The compound of any one of claims 29-34, wherein L15is unsubstituted divalent phenyl.

36. The compound of any one of claims 29-35, wherein one, two, or three of n12, n13, and n14 are 1, and the others are 0.

37. The compound of any one of claims 29-34, wherein each of n12, n13, and n14 is 0.

38. The compound of any one of claims 29-36, wherein each of L12, L13, and L14is independently selected from the group consisting of: (iv) -C(O)-; (viii) divalent C3-C10 cycloalkyl, which is optionally substituted with 1-4 Ra; (ix) divalent phenyl, which is optionally substituted with 1-4 Ra; (xi) divalent heterocyclyl of 3-10 ring atoms, wherein 1-3 ring atoms are heteroatoms, each independently selected from the group consisting of N, N(H), N(Rc), N(O-), O, and S(O)0-2, and which is optionally substituted with 1-4 Ra; and (xi) C1-C2 alkylene.

39. The compound of any one of claims 29-36 and 38, wherein each of L12, L13, and L14is independently selected from the group consisting of -C(O)-, divalent cyclohexyl, and divalent piperidinyl.

40. The compound of any one of claims 1-39, wherein R63is , ,C3-C6 cycloalkyl. 327Attorney Docket No.57891-0006WO1 41. The compound of any one of claims 1-39, wherein R63is , wherein X is O.

42. The compound of any one of claims 1-41, wherein Ring A is C6-14aryl optionally substituted with 1-4 substituents independently selected from the group consisting of oxo, Ra, and Rb.

43. The compound of any one of claims 1-42, wherein Ring A is phenyl optionally substituted with 1-4 substituents independently selected from the group consisting of oxo, Ra, and Rb.

44. The compound of any one of claims 1-43, wherein each of R1and R2is independently C3-12cycloalkyl optionally substituted with substituents independently selected from the group consisting of oxo, Ra, and Rb, optionally wherein each of R1and R2is independently C5-7cycloalkyl optionally substituted with substituents independently selected from the group consisting of oxo, Ra, and Rb.

45. The compound of any one of claims 1-44, wherein each of R1and R2is independently C6cycloalkyl optionally substituted with substituents independently selected from the group consisting of oxo, Ra, and Rb, optionally wherein each of R3and R4is independently C1-10 alkyl optionally substituted with 1-4 independently selected Rd.

46. The compound of any one of claims 1-45, wherein each of R3and R4is CH3.

47. The compound of any one of claims 1-46, wherein each of R5is chloro.

48. A composition comprising a thiol-containing biomolecule and a compound of Formula (I).

49. A composition comprising a biomolecule comprising at least one cysteine residue and a compound of Formula (I).

50. A method of preparing a thiol-aryl conjugated biomolecule, the method comprising contacting a compound of Formula (I) with a biomolecule comprising at least one thiol under conditions sufficient to prepare the thiol-aryl conjugated biomolecule.

51. A method of preparing a cysteine-aryl conjugated biomolecule, the method comprising contacting a compound of Formula (I) with a biomolecule comprising at least one cysteine under conditions sufficient to prepare the cysteine-aryl conjugated biomolecule. 328Attorney Docket No.57891-0006WO1 52. A method of preparing a gold(III) aryl complex comprising contacting a compound of Formula (I) and an aryl halide under conditions sufficient to prepare the gold(III) aryl complex.

53. The method of claim 51, wherein the aryl halide is an aryl iodide.

54. The compound of claim 1, wherein the the compound is selected from the group of compounds recited in Tables disclosed herein.

55. A protein comprising an antigen-binding domain, wherein the antigen-binding domain comprising an oxime, the oxime having the structure:, wherein: * and ** represent the points of connection of the oxime to the antigen-binding domain; L1is a bond or a C1-C6 alkylene optionally substituted with 1-2 substituents independently selected from halogen and C3-C6 cycloalkyl, and wherein 1-2 alkylene units are optionally replaced by O, N, C3-C6 cycloalkyl, or phenyl; R1is azido, tetrazinyl, a C2-C3 alkyne, or an optionally substituted C8-C12 cycloalkyne.

56. The protein of Claim 55, wherein the oxime is connected to the antigen-binding domain via an L amino acid.

57. The protein of Claim 55, wherein the oxime is connected to the antigen-binding domain via a D amino acid.

58. The protein of any one of Claims 55-57, wherein L1is a C1-C6 alkylene optionally substituted with 1-2 substituents independently selected from halogen and C3-C6 cycloalkyl, and wherein 1-2 alkylene units are optionally replaced by O, N, C3-C6 cycloalkyl, or phenyl.

59. The protein of any one of Claims 55-58, wherein L1is a C1-C6 alkylene substituted with 1-2 substituents independently selected from halogen and C3-C6 cycloalkyl.

60. The protein of any one of Claims 55-58, wherein L1is a C1-C6 alkylene wherein 1-2 alkylene units are replaced by O, N, C3-C6 cycloalkyl, or phenyl.

61. The protein of any one of Claims 55-58, wherein L1is a C1-C6 alkylene. 329Attorney Docket No.57891-0006WO1 62. The protein of any one of Claims 55-58 or 61, wherein L1is methylene or ethylene.

63. The protein of any one of Claims 55-58 or 61, wherein L1is n-propylene or isopropylene.

64. The protein of any one of Claims 55-58 or 60, wherein L1is a C4-C6 cycloalkyl.

65. The protein of any one of Claims 55-58, 60, or 64 wherein L1is.

66. The protein of any one of Claims 55-58 or 60, wherein L1is a PEG unit.

67. The protein of any one of Claims 55-58, wherein L1is , wherein “a” represents the point of connection of L1to the oxime and “b” represents the point of connection of L1to R1.

68. The protein of any one of Claims 55-57, wherein L1is a bond.

69. The protein of any one of Claims 55-68, wherein R1is azido.

70. The protein of any one of Claims 55-68, wherein R1is tetrazinyl.

71. The protein of any one of Claims 55-68, wherein R1is a C2-C3 alkyne.

72. The protein of any one of Claims 55-68, wherein R1is an optionally substituted C8-C12 cycloalkyne.

73. The protein of any one of Claims 55-68 or 72, wherein R1is a C8-C12 cycloalkyne.

74. The protein of any one of Claims 55-68 or 72-73, wherein.

75. A protein comprising an antigen-binding domain, wherein the antigen-binding domain comprises a modified phenylalanine residue, the modified phenylalanine residue having the structure:, 330Attorney Docket No.57891-0006WO1 wherein: * and ** represent the points of connection of the modified phenylalanine residue to the antigen-binding domain; L2is a C2-C16 alkylene optionally substituted with 1-2 substituents independently selected from halogen and C3-C6 cycloalkyl, and wherein 1-6 alkylene units are optionally replaced by O, N, S, C3-C10 cycloalkyl, phenyl, 5-12 membered heteroaryl, and 4-14 membered heterocyclyl; ,X is O or NRX; RXis hydrogen, C1-C6 alkyl, or C3-C6 cycloalkyl; R3is halogen or C1-C6 alkyl; R4is hydrogen or C1-C6 alkyl; R4Ais C1-C6 alkyl or C3-C6 cycloalkyl; R5Aand R5Bare independently hydrogen, halogen, or C1-C6 alkyl; or R5Aand R5Btogether with the carbon atom to which they are attached form a cyclopropyl; Ring A is a 4-10 membered heterocyclyl.

76. The protein of Claim 75, wherein the modified phenylalanine residue is an L modified phenylalanine residue.

77. The protein of Claim 75, wherein the modified phenylalanine residue is a D modified phenylalanine residue.

78. The protein of any one of claims 75-77, wherein the modified phenylalanine residue is present in a CDR of the antigen-binding domain.

79. The protein of claim 78, wherein the CDR is a heavy chain CDR.

80. The protein of claim 78, wherein the CDR is a light chain CDR.

81. The protein of any one of claims 75-77, wherein the modified phenylalanine residue is present in a framework region of the antigen-binding domain. 331Attorney Docket No.57891-0006WO1 82. A protein comprising an antigen-binding domain, wherein the antigen-binding domain comprises a modified cysteine residue, the modified cysteine residue having the structure:, wherein: * and ** represent the points of connection of the modified cysteine residue to the antigen-binding domain;wherein a represents the point of connection of L to the sulfur atom of the modified cysteine residue and “b” represents the point of connection of L to L2; n is 1 or 2; RL1, RL2, and RL3, are each independently selected C1-C10 alkyl; L2is a C2-C16 alkylene optionally substituted with 1-2 substituents independently selected from halogen and C3-C6 cycloalkyl, and wherein 1-6 alkylene units are optionally replaced by O, N, S, C3-C10 cycloalkyl, phenyl, 5-12 membered heteroaryl, and 4-14 membered heterocyclyl;X is O or NRX; RXis hydrogen, C1-C6 alkyl, or C3-C6 cycloalkyl; R3is halogen or C1-C6 alkyl; R4is hydrogen or C1-C6 alkyl; R4Ais C1-C6 alkyl or C3-C6 cycloalkyl; 332Attorney Docket No.57891-0006WO1 R5Aand R5Bare independently hydrogen, halogen, or C1-C6 alkyl; or R5Aand R5Btogether with the carbon atom to which they are attached form a cyclopropyl; Ring A is a 4-10 membered heterocyclyl.

83. The protein of Claim 82, wherein the modified cysteine residue is an L modified cysteine residue.

84. The protein of Claim 82, wherein the modified cysteine residue is a D modified cysteine residue.

85. The protein of any one of Claims 82-84, wherein the modified cystine residue is present in a CDR of the antigen-binding domain.

86. The protein of Claim 85, wherein the CDR is a heavy chain CDR.

87. The protein of Claim 85, wherein the CDR is a light chain CDR.

88. The protein of any one of Claims 82-84, wherein the modified cystine residue is present in a framework region of the antigen-binding domain.

89. The protein of any one of Claims 82-88, wherein L is , wherein “a” represents the point of connection of L to the sulfur atom of the modified cysteine residue and “b” represents the point of connection of L to L2.

90. The protein of any one of Claims 82-89, wherein n is 1.

91. The protein of any one of Claims 82-89, wherein n is 2.

92. The protein of any one of Claims 82-88, wherein L is , wherein “a” represents the point of connection of L to the sulfur atom of the modified cysteine residue and “b” represents the point of connection of L to L2.

93. The protein of any one of Claims 82-88, wherein, wherein “a” represents the point of connection of L to the sulfur atom of the modified cysteine residue and “b” represents the point of connection of L to L2. 333Attorney Docket No.57891-0006WO194. The protein of any one of Claims 82-88, wherein L is , wherein “a” represents the point of connection of L to the sulfur atom of the modified cysteine residue and “b” represents the point of connection of L to L2.

95. The protein of any one of Claims 82-88 or 93, wherein RL1is a C1-C6 alkyl.

96. The protein of any one of Claims 82-88 or 93-94, wherein RL1is ethyl.

97. The protein of any one of Claims 82-88, wherein, wherein “a” represents the point of connection of L to the sulfur atom of the modified cysteine residue and “b” represents the point of connection of L to L2.

98. The protein of any one of Claims 82-88 or 97, wherein RL2and RL3are independently selected C1-C6 alkyl.

99. The protein of any one of Claims 82-88 or 96-97, wherein RL2and RL3are each methyl.

100. The protein of any one of Claims 82-88, wherein L is a bond.

101. The protein of any one of Claims 75-93, wherein L2is a C2-C16 alkylene optionally substituted with 1-2 substituents independently selected from halogen and C3-C6 cycloalkyl.

102. The protein of any one of Claims 75-93, wherein L2is a C2-C16 alkylene wherein 1-6 alkylene units are optionally replaced by O, N, S, C3-C10 cycloalkyl, phenyl, 5- 12 membered heteroaryl, and 4-14 membered heterocyclyl.

103. The protein of any one of Claims 75-93, wherein L2is a C2-C16 alkylene substituted with 1-2 substituents independently selected from halogen and C3-C6 cycloalkyl, and wherein 1-6 alkylene units are optionally replaced by O, N, S, C3-C10 cycloalkyl, phenyl, 5-12 membered heteroaryl, and 4-14 membered heterocyclyl.

104. The protein of any one of Claims 75-93, wherein L2is a C2-C16 alkylene optionally substituted with 1-2 substituents independently selected from halogen and C3-C6 cycloalkyl, and wherein 1-6 alkylene units are replaced by O, N, S, C3-C10 cycloalkyl, phenyl, 5-12 membered heteroaryl, and 4-14 membered heterocyclyl.

105. The protein of any one of Claims 75-93, wherein L2is a C2-C16 alkylene substituted with 1-2 substituents independently selected from halogen and C3-C6 cycloalkyl, 334Attorney Docket No.57891-0006WO1 and wherein 1-6 alkylene units are replaced by O, N, S, C3-C10 cycloalkyl, phenyl, 5-12 membered heteroaryl, and 4-14 membered heterocyclyl.

106. The protein of any one of Claims 75-100 or 102-105, wherein one alkylene unit of L2is replaced by a 5-12 membered heteroaryl.

107. The protein of Claim 106, wherein the 5-12 membered heteroaryl is a 5-6 membered heteroaryl.

108. The protein of Claim 106 or 107, wherein the 5-12 membered heteroaryl is a 6 membered heteroaryl.

109. The protein of any one of Claims 106-108 wherein the 5-12 membered heteroaryl is pyridinyl, pyrimidinyl, or pyrazinyl.

110. The protein of any one of Claims 75-95, wherein L2is a C2-C16 alkylene.

111. The protein of any one of Claims 75-95 or 99, wherein L2is a C2-C6 alkylene.

112. The protein of any one of Claims 75-93 or 95-98, wherein L2comprises one triazole ring.

113. The protein of any one of Claims 75-93, wherein L2is selected from the groupwherein “a” represents the point of connection of L2to L or to the modified phenylalanine residue or to the modified cysteine residue and “b” represents the point of connection of L2to R2. 335Attorney Docket No.57891-0006WO1 114. The protein of any one of Claims 75-93, wherein L2is selected from the groupwherein “a” represents the point of connection of L2to L or to the modified phenylalanine residue or to the modified cysteine residue and “b” represents the point of connection of L2to R2.

115. The protein of any one of Claims 75-93, wherein L2is selected from the groupwherein “a” represents the point of connection of L2to L or to the modified phenylalanine residue or to the modified cysteine residue and “b” represents the point of connection of L2to R2.

116. The protein of any one of Claims 75-93, wherein L2is336Attorney Docket No.57891-0006WO1 wherein “a” represents the point of connection of L2to L or to the modified phenylalanine residue or to the modified cysteine residue and “b” represents the point of connection of L2to R2.

117. The protein of any one of Claims 75-116, wherein R2is or -O-SO2- HET, optionally R2is ; optionally R2is -O-SO2-HET.

118. The protein of Claims 75-117, wherein X is NRX.

119. The protein of any one of Claims 75-118, wherein RXis hydrogen.

120. The protein of any one of Claims 75-118, wherein RXis C1-C6 alkyl.

121. The protein of any one of Claims 75-118 or 120, wherein RXis methyl.

122. The protein of any one of Claims 75-118, wherein RXis C3-C6 cycloalkyl.

123. The protein of any one of Claims 75-118 or 122, wherein RXis cyclopropyl.

124. The protein of Claims 75-117, wherein X is O.

125. The protein of any one of Claims 75-116, wherein.

126. The protein of any one of Claims 75-116 or 125, wherein R4Ais C1-C6 alkyl.

127. The protein of any one of Claims 75-116 or 125-126, wherein R4Ais methyl.

128. The protein of any one of Claims 75-116 or 125, wherein R4Ais C3-C6 cycloalkyl.

129. The protein of any one of Claims 75-116, wherein R2is.

130. The protein of any one of Claims 75-116 or 125-129, wherein R4is C1-C6 alkyl.

131. The protein of any one of Claims 75-116 or 125-130, wherein R4is methyl.

132. The protein of any one of Claims 75-116 or 125-129, wherein R4is hydrogen.

133. The protein of any one of Claims 75-116, wherein. 337Attorney Docket No.57891-0006WO1 134. The protein of any one of Claims 75-116 or 129-133, wherein R5Aand R5Bare independently hydrogen, halogen, or C1-C6 alkyl.

135. The protein of any one of Claims 75-116 or 129-134, wherein R5Aand R5Bare each hydrogen.

136. The protein of any one of Claims 75-116 or 129-134, wherein R5Aand R5Bare each independently C1-C6 alkyl.

137. The protein of any one of Claims 75-116 or 129-134, wherein one of R5Aand R5Bis hydrogen and the other of R5Aand R5Bis C1-C6 alkyl.

138. The protein of any one of Claims 75-116 or 129-134, wherein one of R5Aand R5Bis halogen and the other of R5Aand R5Bis hydrogen, halogen, or C1-C6 alkyl.

139. The protein of any one of Claims 75-116 or 129-133, wherein R5Aand R5Btogether with the carbon atom to which they are attached form a cyclopropyl.

140. The protein of any one of Claims 75-105 or 133-139, wherein Ring A is a 4-10 membered heterocyclyl.

141. The protein of any one of Claims 75-105 or 139-140, wherein Ring A is a 5-6 membered heterocyclyl.

142. The protein of any one of Claims 75-105 or 139-141, wherein Ring A is piperidine or piperazine.

143. The protein of any one of Claims 75-116, wherein R2is.

144. The protein of any one of Claims 75-116, wherein R2is.

145. The protein of any one of Claims 75-116, wherein R2is.

146. The protein of any one of Claims 75-116, wherein R2is.

147. The protein of any one of Claims 75-116, wherein R2is.

148. The protein of any one of Claims 75-93, wherein L2is selected from the group; 338Attorney Docket No.57891-0006WO1 wherein “a” represents the point of connection of L2to L or to the modified phenylalanine residue or to the modified cysteine residue and “b” represents the point of connection of L2to R2.

149. The protein of any one of Claims 75-116 or 148, wherein.

150. The protein of any one of Claims 75-116 or 148-149, wherein R3is halogen.

151. The protein of Claims 75-116 or 148-149, wherein R3is C1-C6 alkyl.

152. The protein of any one of Claims 75-100, wherein -L2-R2is,, wherein * represents the point of connection of L2to L.

153. The protein of any one of Claims 55-152, wherein the protein is an antibody.

154. The protein of Claim 153, wherein the antibody is a human antibody, a humanized antibody, or a veneered antibody.

155. The protein of Claim 153, wherein the antibody is a human IgG1, human IgG2, human IgG3, or human IgG4 antibody.

156. The protein of any one of Claims 55-152, wherein the protein is or comprises a single chain Fv (scFv), a VHH, a VNAR, a DARpin, a single domain antibody (sdAb), an Adnectin / Centyrin, an Affibody, a Knottin, a bicyclic peptide, or a cyclic peptide.

157. The protein of any one of Claims 55-156, wherein the protein further comprises a conjugated cytotoxic or cytostatic agent.

158. The protein of any one of Claims 55-156, wherein the protein comprises a radioisotope.

159. The protein of any one of Claims 55-158, wherein the antigen-binding domain specifically binds to a target protein.

160. The protein of Claim 159, wherein the target protein comprises an extracellular domain, and the antigen-binding domain specifically binds to the extracellular domain.

161. A pharmaceutical composition comprising the protein of any one of Claims 75- 160 and at least one pharmaceutically acceptable excipient. 339Attorney Docket No.57891-0006WO1 162. A kit comprising (a) the protein of any one of Claims 75-160 and (b) a pharmaceutically acceptable excipient.

163. A kit comprising the pharmaceutical composition of Claim 161 and instructions for administration of the pharmaceutical composition to a human subject.

164. A method of treating in a subject in need thereof, comprising administering to the subject a therapeutically effective amount of the protein of any one of Claims 75-160, or the pharmaceutical composition of Claim 161.

165. A method of inducing or increasing internalization of the protein into a mammalian cell that expresses the target protein comprising contacting the mammalian cell with the protein of Claim 159 or 160.

166. The method of Claim 165, wherein the mammalian cell is in vivo.

167. The method of Claim 165, wherein the mammalian cell is in vitro.

168. A method of inhibiting the activity of the target protein in a mammalian cell, comprising contacting the target protein with the protein of Claim 159 or 160.

169. A method of reducing the amount of the target protein in a mammalian cell comprising the target protein, the method comprising contacting the target protein with the protein of Claim 159 or 160.

170. A method of inducing cell death in a mammalian cell comprising the target protein, the method comprising contacting the cell with the protein of Claim 159 or 160.

171. The method of any one of Claims 168-170, wherein the mammalian cell is in vivo.

172. The method of any one of Claims 168-170, wherein the mammalian cell is in vitro.

173. A method of screening for a protein that forms a covalent bond with a target protein in a mammalian cell, the method comprising: contacting the target protein with a protein of any one of Claims 75-160; and determining whether a covalent bond has been formed between the protein and the target protein.

174. The method of Claim 173, wherein the method further comprises: determining whether the mammalian cell has internalized the protein.

175. The method of Claim 173, wherein the method further comprises: determining whether the contacting has inhibited an activity of the target protein; and / or determining whether the contacting has induced cell death of the mammalian cell. 340Attorney Docket No.57891-0006WO1 176. A protein-protein conjugate comprising a first protein A and a second protein B, wherein the protein-protein conjugate has the structure:, wherein the first protein A comprises an antigen-binding domain, wherein the antigen- binding domain comprises a modified phenylalanine residue, wherein: * and ** represent the points of connection of the modified phenylalanine residue to the antigen-binding domain of the first protein A; L2is a C2-C16 alkylene optionally substituted with 1-2 substituents independently selected from halogen and C3-C6 cycloalkyl, and wherein 1-6 alkylene units are optionally replaced by O, N, S, C3-C10 cycloalkyl, phenyl, 5-12 membered heteroaryl, and 4-14 membered heterocyclyl; , ,“a” represents the connection of R2Ato L2, “b” represents the connection of R2Ato protein B, N* is a nitrogen atom of a lysine residue of protein B, S* is a sulfur atom of a cysteine residue of protein B, O* is an oxygen atom from a serine residue or a threonine residue of protein B, Nb is the nitrogen atom of a histidine residue of protein B and the connection of R2Ato protein B, and O** is an oxygen atom from a tyrosine residue of protein B; X is O or NRX; RXis hydrogen, C1-C6 alkyl, or C3-C6 cycloalkyl; R3is halogen or C1-C6 alkyl; R4is hydrogen or C1-C6 alkyl; R4Ais C1-C6 alkyl or C3-C6 cycloalkyl; 341Attorney Docket No.57891-0006WO1 R5Aand R5Bare independently hydrogen, halogen, or C1-C6 alkyl; or R5Aand R5Btogether with the carbon atom to which they are attached form a cyclopropyl; Ring A is a 4-10 membered heterocyclyl; wherein the antigen-binding domain of the first protein A specifically binds to the second protein B.

177. The protein-protein conjugate of Claim 176, wherein the modified phenylalanine residue is present in a CDR of the antigen-binding domain.

178. The protein-protein conjugate of Claim 177, wherein the CDR is a heavy chain CDR.

179. The protein-protein conjugate of Claim 177, wherein the CDR is a light chain CDR.

180. The protein-protein conjugate of Claim 176, wherein the modified phenylalanine residue is present in a framework region of the antigen-binding domain.

181. A protein-protein conjugate comprising a first protein A and a second protein B, wherein the protein-protein conjugate has the structure:, wherein the first protein A comprises an antigen-binding domain, wherein the antigen- binding domain comprises a modified cysteine residue, wherein: * and ** represent the points of connection of the modified cysteine residue to the antigen-binding domain;, wherein “a” represents the point of connection of L to the sulfur atom of the modified cysteine residue and “b” represents the point of connection of L to L2; n is 1 or 2; RL1, RL2, and RL3, are each independently selected C1-C10 alkyl; 342Attorney Docket No.57891-0006WO1 L2is a C2-C16 alkylene optionally substituted with 1-2 substituents independently selected from halogen and C3-C6 cycloalkyl, and wherein 1-6 alkylene units are optionally replaced by O, N, S, C3-C10 cycloalkyl, phenyl, 5-12 membered heteroaryl, and 4-14 membered heterocyclyl; , ,“a” represents the connection of R2Ato L2, “b” represents the connection of R2Ato protein B, N* is a nitrogen atom of a lysine residue of protein B, S* is a sulfur atom of a cysteine residue of protein B, O* is an oxygen atom from a serine residue or a threonine residue of protein B, Nb is the nitrogen atom of a histidine residue of protein B and the connection of R2Ato protein B, and O** is an oxygen atom from a tyrosine residue of protein B; X is O or NRX; RXis hydrogen, C1-C6 alkyl, or C3-C6 cycloalkyl; R3is halogen or C1-C6 alkyl; R4is hydrogen or C1-C6 alkyl; R4Ais C1-C6 alkyl or C3-C6 cycloalkyl; R5Aand R5Bare independently hydrogen, halogen, or C1-C6 alkyl; or R5Aand R5Btogether with the carbon atom to which they are attached form a cyclopropyl; Ring A is a 4-10 membered heterocyclyl, wherein the antigen-binding domain of the first protein A specifically binds to the second protein B.

182. The protein-protein conjugate of Claim 181, wherein the modified cysteine residue is present in a CDR of the antigen-binding domain. 343Attorney Docket No.57891-0006WO1 183. The protein-protein conjugate of Claim 181, wherein the CDR is a heavy chain CDR.

184. The protein-protein conjugate of Claim 181, wherein the CDR is a light chain CDR.

185. The protein-protein conjugate of Claim 181, wherein the modified cysteine residue is present in a framework region of the antigen-binding domain.

186. The protein-protein conjugate of any one of Claims 181-185, wherein the first protein A is an antibody.

187. The protein-protein conjugate of Claim 186, wherein the antibody is a human antibody, a humanized antibody, or a veneered antibody.

188. The protein-protein conjugate of Claim 186, wherein the antibody is a human IgG1, human IgG2, human IgG3, or human IgG4 antibody.

189. The protein-protein conjugate of any one of Claims 181-188, wherein the first protein A is or comprises a single chain Fv (scFv), a VHH, a VNAR, a DARpin, a single domain antibody (sdAb), an Adnectin / Centyrin, an Affibody, a Knottin, a bicyclic peptide, or a cyclic peptide.

190. The protein-protein conjugate of any one of Claims 181-189, wherein the first protein A further comprises a conjugated cytotoxic or cytostatic agent.

191. The protein-protein conjugate of any one of Claims 181-189 wherein the first protein A comprises a radioisotope.

192. The protein-protein conjugate of Claims 181-191, wherein the second protein B comprises an extracellular domain, and the antigen-binding domain specifically binds to the extracellular domain.

193. A method of making a protein comprising an antigen-binding domain, wherein the antigen-binding domain comprises a modified phenylalanine residue, the modified phenylalanine residue having the structure:, the method comprising contacting (a) a compound having the structure Z-R2with 344Attorney Docket No.57891-0006WO1 (b) a protein comprising an antigen-binding domain, wherein the antigen-binding domain comprising an oxime, the oxime having the structure:, wherein: Z reacts with -L1- to form -L2-, wherein when R1is azido or tetrazinyl, then Z is a C2- C3 alkyne or an optionally substituted C8-C12 cycloalkyne, and when R1is a C2-C3 alkyne or an optionally substituted C8-C12 cycloalkyne, then Z is azido or tetrazinyl; * and ** represent the points of connection of the oxime to the antigen-binding domain; L2is a C2-C16 alkylene optionally substituted with 1-2 substituents independently selected from halogen and C3-C6 cycloalkyl, and wherein 1-6 alkylene units are optionally replaced by O, N, S, C3-C10 cycloalkyl, phenyl, 5-12 membered heteroaryl, and 4-14 membered heterocyclyl; ,X is O or NRX; RXis hydrogen, C1-C6 alkyl, or C3-C6 cycloalkyl; R3is halogen or C1-C6 alkyl; R4is hydrogen or C1-C6 alkyl; R4Ais C1-C6 alkyl or C3-C6 cycloalkyl; R5Aand R5Bare independently hydrogen, halogen, or C1-C6 alkyl; or R5Aand R5Btogether with the carbon atom to which they are attached form a cyclopropyl; Ring A is a 4-10 membered heterocyclyl; 345Attorney Docket No.57891-0006WO1 L1is a bond or a C1-C6 alkylene optionally substituted with 1-2 substituents independently selected from halogen and C3-C6 cycloalkyl, and wherein 1-2 alkylene units are optionally replaced by O, N, C3-C6 cycloalkyl, or phenyl; and R1is azido, tetrazinyl, a C2-C3 alkyne, or an optionally substituted C8-C12 cycloalkyne.

194. The method of Claim 193, wherein the modified phenylalanine residue is present in a CDR of the antigen-binding domain.

195. The method of Claim 194, wherein the CDR is a heavy chain CDR.

196. The method of Claim 194, wherein the CDR is a light chain CDR.

197. The method of Claim 139, wherein the modified phenylalanine residue is present in a framework region of the antigen-binding domain.

198. The method of any one of Claims 193-197, wherein the protein is an antibody.

199. The method of Claim 198, wherein the antibody is a human antibody, a humanized antibody, or a veneered antibody.

200. The method of Claim 198, wherein the antibody is a human IgG1, human IgG2, human IgG3, or human IgG4 antibody.

201. The method of any one of Claims 193-200, wherein the protein is or comprises a single chain Fv (scFv), a VHH, a VNAR, a DARpin, a single domain antibody (sdAb), an Adnectin / Centyrin, an Affibody, a Knottin, a bicyclic peptide, or a cyclic peptide.

202. The method of any one of Claims 193-201, wherein the protein further comprises a conjugated cytotoxic or cytostatic agent.

203. The method of any one of Claims 193-201, wherein the protein comprises a radioisotope.

204. The method of any one of Claims 193-203, wherein the antigen-binding domain specifically binds to a target protein.

205. The protein of Claim 204 wherein the target protein comprises an extracellular domain, and the antigen-binding domain specifically binds to the extracellular domain. 346

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