Oligonucleotide compositions and methods thereof

Abstract

Among other things, the present disclosure provides oligonucleotide compositions and methods thereof. In some embodiments, oligonucleotides comprise various chemical modifications. In some embodiments, the present disclosure provides technologies useful for manufacturing oligonucleotides.

Description

Attorney Docket No.: 2010581-1440 OLIGONUCLEOTIDE COMPOSITIONS AND METHODS THEREOF CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to United States Provisional Application No.63 / 620,768, filed January 12, 2024, the entirety of which is incorporated herein by reference. BACKGROUND

[0002] Oligonucleotides are useful for many purposes. Various technologies for preparing oligonucleotides have been reported. SUMMARY

[0003] Various chemical modifications have been reported to improve properties and activities of oligonucleotides. For example, 5’-end −P(O)(OH)2 group which may exist in a salt form as −P(O)(O−)2, in some cases together with another chemical moiety, has been incorporated at 5’-end of various oligonucleotides to improve properties and / or activities of the oligonucleotides, e.g., as RNAi agents. In some embodiments, an oligonucleotide comprises the following group attached to its 5’-end sugar carbon atom, in which a phosphonate is bonded to a triazole ring: . In some embodiments, it exists in salt. Various technologies have been reportedgroup. Typically, during oligonucleotide synthesis, −P(O)(OH)2 groups are incorporated as protected groups (e.g., as −P(O)(OMe)2, −P(O)(OEt)2, etc.) which are later deprotected. Among other things, the present disclosure encompasses the recognition that such protected groups can be challenging to deprotect under typical oligonucleotide synthesis conditions. In some embodiments, extra steps, harsher conditions and / or longer reaction time are required. In some embodiments, such protected groups lead to lower oligonucleotide yield and / or purity. In some embodiments, such protected phosphate groups increase operation complexity. In some embodiments, such protected phosphate groups lower manufacturing efficiency. In some embodiments, such protected phosphate groups increase manufacturing cost. In some embodiments, the present disclosure provides to address these challenges. Page 1 of 201 12495950v1Attorney Docket No.: 2010581-1440

[0004] In some embodiments, the present disclosure provides technologies for incorporating −P(O)(OH)2into oligonucleotides with higher yield, higher purity, higher efficiency, lower operation complexity, milder reaction condition, shorter preparation time, and / or lower cost, etc. when compared to using, e.g., −P(O)(OMe)2, or −P(O)(OEt)2. In some embodiments, the present disclosure provides protected −P(O)(OH)2 groups which can be deprotected under oligonucleotide synthesis conditions, e.g., during cleavage and / or deprotection, utilized for oligonucleotides without −P(O)(OH)2groups.

[0005] In some embodiments, the present disclosure provides technologies comprising −P(O)(ORPG)2 wherein each RPGis a group that is labile to oligonucleotide synthesis conditions, e.g., during cleavage and / or deprotection, utilized for oligonucleotides without −P(O)(OH)2 groups. In some embodiments, each RPGis a group that can be removed under oligonucleotide synthesis conditions, e.g., during cleavage and / or deprotection, utilized for oligonucleotides without −P(O)(OH)2 groups. In some embodiments, −P(O)(ORPG)2 is a protected −P(O)(OH)2 group that is converted to −P(O)(OH)2 which may exist in a salt form, e.g., under oligonucleotide synthesis conditions, e.g., during cleavage and / or deprotection, utilized for oligonucleotides without −P(O)(OH)2 groups. In some embodiments, the P atom is bonded to a carbon atom.

[0006] For example, in some embodiments, RPGcomprises 1) an alpha carbon atom bonded to the oxygen to which it is attached, wherein the alpha carbon atom is bonded to a hydrogen, and 2) a beta carbon atom, wherein the beta carbon atom is bonded to a group RPG11that can facilitate removal of RPG(e.g., compared to ethyl), such as an electron-withdrawing group. In some embodiments, RPG11is an electron-withdrawing group. In some embodiments, RPG11is Rsas described herein. In some embodiments, RPG11is −CN. In some embodiments, RPG11is −Ls−Rs11wherein each Lsand Rs11is independently as described herein. In some embodiments, RPGis −CH2−Rs, wherein the −CH2− is independently optionally substituted and Rsis as described herein. In some embodiments, the −CH2− is optionally mono-substituted. In some embodiments, RPGis RP1as described herein. In some embodiments, RPGis RP2as described herein. In some embodiments, RPGis −O−CH2CH2CN.

[0007] In some embodiments, RPGis a group labile to an acid. In some embodiments, RPGis −CH2−O(CO)RPG12, wherein RPG12is trisubstituted methyl and the −CH2− is optionally substituted. In some embodiments, RPGis −CH2−O(CO)RPG12, wherein RPG12is −C(Rs11)3wherein each Rs11is independently as described herein. In some embodiments, RPGis RPG12, wherein RPG12is trisubstituted methyl. In some embodiments, RPG12is −C(Rs11)3wherein each Rs11is independently as described herein. In some embodiments, the carbon of the trisubstituted methyl or −C(Rs11)3is bonded to three carbon atoms. In some embodiments, RPG12is optionally substituted t-butyl. In some embodiments, RPG12is t- butyl. In some embodiments, RPGis RP1or RP2as described herein. In some embodiments, RPGis −O−CH2−O−C(O)−RP, wherein RPis optionally substituted tert-butyl. In some embodiments, RPGis Page 2 of 201 12495950v1Attorney Docket No.: 2010581-1440 −O−CH2−O−C(O)−tBu.

[0008] In some embodiments, −P(O)(ORPG)2has the structure of −P(O)(RP1)(RP2) as described herein (e.g., in formula I or formula I’), wherein each of R1and RP2is independently as described herein.

[0009] In some embodiments, the present disclosure provides oligonucleotides comprising −P(O)(ORPG)2 as described herein. In some embodiments, such oligonucleotides are useful for preparing or delivering oligonucleotides comprising −P(O)(OH)2which may exist in various salt forms. In some embodiments, oligonucleotides comprising −P(O)(ORPG)2as described herein are administered to a subject for preventing or treating conditions, disorders or diseases. In some embodiments, oligonucleotides comprising −P(O)(ORPG)2 as described herein are utilized for preparing oligonucleotides comprising −P(O)(OH)2 which may exist in various salt forms. For example, in some embodiments, the present disclosure provides a compound, wherein the compound is an oligonucleotide comprising , wherein each of RP1and RP2is −O−CH2CH2CN or −O−CH2−O−C(O)−RP, whereintert-butyl. In some embodiments, the present disclosure provides a compound, wherein the compound is an oligonucleotide comprising a moiety of formula O-I or a salt thereof: , wherein:each of RP1and RP2is −O−CH2CH2CN or −O−CH2−O−C(O)−RP, wherein RPis optionally substituted tert-butyl; BA is hydrogen, or an optionally substituted 3-20 membered ring having 0-10 heteroatoms independently selected from silicon, nitrogen, oxygen, phosphorus and sulfur; or BA is an optionally substituted or protected nucleobase; R2sis −F, −Cl, −Br, −I, −CN, −N3, −NO, −NO2, −L2s−R2a, −L2s−OR2a, −L2s−SR2a, −L2s−N(R2a)2, −O−L2s−OR2a, −O−L2s−SR2a, or −O−L2s−N(R2a)2, or R2sis L2sconnecting C2 with C1, C2, C3, C4 or C5; each L2sis independently L; each R2ais independently R’; each L is independently a bivalent, optionally substituted group selected from C1-10 aliphatic and C1-10 heteroaliphatic group having 1-5 heteroatoms independently selected from silicon, nitrogen, oxygen, Page 3 of 201 12495950v1Attorney Docket No.: 2010581-1440 phosphorus and sulfur, wherein one or more methylene units of L are optionally and independently replaced by −Cy−, −O−, −S−, −N(R’)−, −C(O)−, −C(S)−, −C(NR’)−, −C(O)N(R’)−, −N(R’)C(O)N(R’)−, −N(R’)C(O)O−, −S(O)−, −S(O)2−, −S(O)2N(R’)−, −SC(O)−, or −C(O)O−; –Cy– is an optionally substituted bivalent 3-20 membered ring having 0-10 heteroatoms independently selected from silicon, nitrogen, oxygen, phosphorus and sulfur; each R’ is independently −R, −C(O)R, −CO2R, or −S(O)2R, or two or more R’ are taken together with their intervening atom(s) to form an optionally substituted 3-20 membered ring having, in addition to the intervening atom(s), 0-10 heteroatoms independently selected from silicon, nitrogen, oxygen, phosphorus and sulfur; and each R is independently hydrogen, or an optionally substituted group selected from C1-10 aliphatic, C1-10 heteroaliphatic having 1-5 heteroatoms independently selected from silicon, nitrogen, oxygen, phosphorus and sulfur, C6-14 aryl, a 5-14 membered heteroaryl ring having 1-5 heteroatoms independently selected from silicon, nitrogen, oxygen, phosphorus and sulfur, and a 3-15 membered heterocyclic ring having 1-5 heteroatoms independently selected from silicon, nitrogen, oxygen, phosphorus and sulfur.

[0010] In some embodiments, the present disclosure provides nucleoside phosphoramidites comprising −P(O)(ORPG)2. In some embodiments, −P(O)(ORPG)2 is bonded to the sugar of a nucleoside (e.g., 5’ carbon). In some embodiments, it is bonded to another moiety, e.g., an optionally substituted triazole ring (e.g., as in formula I or formula I’) which is bonded to the sugar of a nucleoside (e.g., 5’ carbon). In some embodiments, a phosphoramidite comprises a chiral auxiliary.

[0011] In some embodiments, the provided technology provides a compound of formula I’ or a salt thereof: ,wherein: each of RP1and RP2is −O−CH2CH2CN or −O−CH2−O−C(O)−RP, wherein RPis optionally substituted tert-butyl; Page 4 of 201 12495950v1Attorney Docket No.: 2010581-1440 SU is a , wherein R2sis as described herein); BA is 3-20 membered ring having 0-10 heteroatoms independentlyoxygen, phosphorus and sulfur; or BA is an optionally substituted or protected nucleobase; each of R1, R2, and R3is independently R’, or two or three of R1, R2, and R3are taken together with their intervening atoms to form ; Ring A is an optionally ring having, in addition to the interveningatoms, 0-10 heteroatoms independently selected from silicon, nitrogen, oxygen, phosphorus and sulfur; t is 0-5; each Rsis independently −F, −Cl, −Br, −I, −CN, −N3, −NO, −NO2, −Ls−Rs11, −Ls−ORs11, −Ls−SRs11, −Ls−N(Rs11)2, −O−Ls−ORs11, −O−Ls−SRs11, −O−Ls−N(Rs11)2, −C(Rs11)3 or −Ls−Si(Rs11)3; each Rs11is independently R’; each Lsis independently L; each L is independently a covalent bond, or a bivalent, optionally substituted group selected from C1-10 aliphatic and C1-10 heteroaliphatic group having 1-5 heteroatoms independently selected from silicon, nitrogen, oxygen, phosphorus and sulfur, wherein one or more methylene units of L are optionally and independently replaced by −Cy−, −O−, −S−, −N(R’)−, −C(O)−, −C(S)−, −C(NR’)−, −C(O)N(R’)−, −N(R’)C(O)N(R’)−, −N(R’)C(O)O−, −S(O)−, −S(O)2−, −S(O)2N(R’)−, −SC(O)−, or −C(O)O−; –Cy– is an optionally substituted bivalent 3-20 membered ring having 0-10 heteroatoms independently selected from silicon, nitrogen, oxygen, phosphorus and sulfur; each R’ is independently −R, −C(O)R, −CO2R, or −S(O)2R, or two or more R’ are taken together with their intervening atom(s) to form an optionally substituted 3-20 membered ring having, in addition to the intervening atom(s), 0-10 heteroatoms independently selected from silicon, nitrogen, oxygen, phosphorus and sulfur; and each R is independently hydrogen, or an optionally substituted group selected from C1-10aliphatic, C1-10heteroaliphatic having 1-5 heteroatoms independently selected from silicon, nitrogen, oxygen, phosphorus and sulfur, C6-14aryl, a 5-14 membered heteroaryl ring having 1-5 heteroatoms independently selected from silicon, nitrogen, oxygen, phosphorus and sulfur, and a 3-15 membered heterocyclic ring having 1-5 heteroatoms independently selected from silicon, nitrogen, oxygen, phosphorus and sulfur.

[0012] In some embodiments, the provided technology provides a compound of formula I or a salt Page 5 of 201 12495950v1Attorney Docket No.: 2010581-1440 thereof: ONPNR1P N BA 1 ,wherein: each of RP1and RP2is −O−CH2CH2CN or −O−CH2−O−C(O)−RP, wherein RPis optionally substituted tert-butyl; BA is hydrogen, or an optionally substituted 3-20 membered ring having 0-10 heteroatoms independently selected from silicon, nitrogen, oxygen, phosphorus and sulfur; or BA is an optionally substituted or protected nucleobase; R2sis −F, −Cl, −Br, −I, −CN, −N3, −NO, −NO2, −L2s−R2a, −L2s−OR2a, −L2s−SR2a, −L2s−N(R2a)2, −O−L2s−OR2a, −O−L2s−SR2a, or −O−L2s−N(R2a)2, or R2sis L2sconnecting C2 with C1, C2, C3, C4 or C5; each L2sis independently L; each R2ais independently R’; each L is independently a covalent bond, or a bivalent, optionally substituted group selected from C1-10aliphatic and C1-10heteroaliphatic group having 1-5 heteroatoms independently selected from silicon, nitrogen, oxygen, phosphorus and sulfur, wherein one or more methylene units of L are optionally and independently replaced by −Cy−, −O−, −S−, −N(R’)−, −C(O)−, −C(S)−, −C(NR’)−, −C(O)N(R’)−, −N(R’)C(O)N(R’)−, −N(R’)C(O)O−, −S(O)−, −S(O)2−, −S(O)2N(R’)−, −SC(O)−, or −C(O)O−; –Cy– is an optionally substituted bivalent 3-20 membered ring having 0-10 heteroatoms independently selected from silicon, nitrogen, oxygen, phosphorus and sulfur; each of R1, R2, and R3is independently R’, or two or three of R1, R2, and R3are taken together with their intervening atoms to ; Ring A is an optionallyring having, in addition to the intervening atoms, 0-10 heteroatoms independently selected from silicon, nitrogen, oxygen, phosphorus and sulfur; t is 0-5; each Rsis independently −F, −Cl, −Br, −I, −CN, −N3, −NO, −NO2, −Ls−Rs11, −Ls−ORs11, −Ls−SRs11, −Ls−N(Rs11)2, −O−Ls−ORs11, −O−Ls−SRs11, −O−Ls−N(Rs11)2, −C(Rs11)3or −Ls−Si(Rs11)3; each Rs11is independently R’; Page 6 of 201 12495950v1Attorney Docket No.: 2010581-1440 each Lsis independently L; each R’ is independently −R, −C(O)R, −CO2R, or −S(O)2R, or two or more R’ are taken together with their intervening atom(s) to form an optionally substituted 3-20 membered ring having, in addition to the intervening atom(s), 0-10 heteroatoms independently selected from silicon, nitrogen, oxygen, phosphorus and sulfur; and each R is independently hydrogen, or an optionally substituted group selected from C1-10aliphatic, C1-10heteroaliphatic having 1-5 heteroatoms independently selected from silicon, nitrogen, oxygen, phosphorus and sulfur, C6-14 aryl, a 5-14 membered heteroaryl ring having 1-5 heteroatoms independently selected from silicon, nitrogen, oxygen, phosphorus and sulfur, and a 3-15 membered heterocyclic ring having 1-5 heteroatoms independently selected from silicon, nitrogen, oxygen, phosphorus and sulfur.

[0013] In some embodiments, a compound of formula I or a salt thereof is useful as a nucleoside phosphoramidite for oligonucleotide synthesis. In some embodiments, a compound of formula I’ or a salt thereof is useful as a nucleoside phosphoramidite for oligonucleotide synthesis.

[0014] In some embodiments, the present disclosure provides nucleosides comprising −P(O)(ORPG)2. In some embodiments, −P(O)(ORPG)2 is bonded to the sugar of a nucleoside (e.g., 5’ carbon). In some embodiments, it is bonded to another moiety, e.g., an optionally substituted triazole ring (e.g., as in formula I or formula I’) which is bonded to the sugar of a nucleoside (e.g., 5’ carbon). In some embodiments, the present disclosure provides a compound of formula II’ or a salt thereof: ,wherein: each of RP1and RP2is −O−CH2CH2CN or −O−CH2−O−C(O)−RP, wherein RPis optionally substituted tert-butyl; , wherein R2sis as described herein); and3-20 membered ring having 0-10 heteroatoms independently selected from silicon, nitrogen, oxygen, phosphorus and sulfur; or BA is an optionally substituted or protected nucleobase.

[0015] In some embodiments, the present disclosure provides a compound of formula II or a salt Page 7 of 201 12495950v1Attorney Docket No.: 2010581-1440 thereof: ,wherein: each of RP1and RP2is −O−CH2CH2CN or −O−CH2−O−C(O)−RP, wherein RPis optionally substituted tert-butyl; BA is hydrogen, or an optionally substituted 3-20 membered ring having 0-10 heteroatoms independently selected from silicon, nitrogen, oxygen, phosphorus and sulfur; or BA is an optionally substituted or protected nucleobase; R2sis −F, −Cl, −Br, −I, −CN, −N3, −NO, −NO2, −L2s−R2a, −L2s−OR2a, −L2s−SR2a, −L2s−N(R2a)2, −O−L2s−OR2a, −O−L2s−SR2a, or −O−L2s−N(R2a)2, or R2sis L2sconnecting C2 with C1, C2, C3, C4 or C5; each L2sis independently L; each R2ais independently R’; each L is independently a bivalent, optionally substituted group selected from C1-10aliphatic and C1-10heteroaliphatic group having 1-5 heteroatoms independently selected from silicon, nitrogen, oxygen, phosphorus and sulfur, wherein one or more methylene units of L are optionally and independently replaced by −Cy−, −O−, −S−, −N(R’)−, −C(O)−, −C(S)−, −C(NR’)−, −C(O)N(R’)−, −N(R’)C(O)N(R’)−, −N(R’)C(O)O−, −S(O)−, −S(O)2−, −S(O)2N(R’)−, −SC(O)−, or −C(O)O−; –Cy– is an optionally substituted bivalent 3-20 membered ring having 0-10 heteroatoms independently selected from silicon, nitrogen, oxygen, phosphorus and sulfur; each R’ is independently −R, −C(O)R, −CO2R, or −S(O)2R, or two or more R’ are taken together with their intervening atom(s) to form an optionally substituted 3-20 membered ring having, in addition to the intervening atom(s), 0-10 heteroatoms independently selected from silicon, nitrogen, oxygen, phosphorus and sulfur; and

[0016] each R is independently hydrogen, or an optionally substituted group selected from C1-10 aliphatic, C1-10 heteroaliphatic having 1-5 heteroatoms independently selected from silicon, nitrogen, oxygen, phosphorus and sulfur, C6-14 aryl, a 5-14 membered heteroaryl ring having 1-5 heteroatoms independently selected from silicon, nitrogen, oxygen, phosphorus and sulfur, and a 3-15 membered heterocyclic ring having 1-5 heteroatoms independently selected from silicon, nitrogen, oxygen, phosphorus and sulfur.In some embodiments, the present disclosure provides technologies for preparing Page 8 of 201 12495950v1Attorney Docket No.: 2010581-1440 oligonucleotides and compositions thereof. In some embodiments, oligonucleotides comprise −P(O)(OH)2which may exist in various salt forms. In some embodiments, oligonucleotides comprise −P(O)(ORPG)2as described herein. In some embodiments, the present disclosure provides technologies for preparing phosphoramidites. In some embodiments, the present disclosure provides technologies for preparing nucleosides. DETAILED DESCRIPTION OF CERTAIN EMBODIMENTS

[0017] Technologies of the present disclosure may be understood more readily by reference to the following detailed description of certain embodiments. Definitions

[0018] As used herein, the following definitions shall apply unless otherwise indicated. For purposes of this disclosure, the chemical elements are identified in accordance with the Periodic Table of the Elements, CAS version, Handbook of Chemistry and Physics, 75th Ed. Additionally, general principles of organic chemistry are described in "Organic Chemistry", Thomas Sorrell, University Science Books, Sausalito: 1999, and "March's Advanced Organic Chemistry", 5th Ed., Ed.: Smith, M.B. and March, J., John Wiley & Sons, New York: 2001.

[0019] As used herein in the present disclosure, unless otherwise clear from context, (i) the term “a” or “an” may be understood to mean “at least one”; (ii) the term “or” may be understood to mean “and / or”; (iii) the terms “comprising”, “comprise”, “including” (whether used with “not limited to” or not), and “include” (whether used with “not limited to” or not) may be understood to encompass itemized components or steps whether presented by themselves or together with one or more additional components or steps; (iv) the term “another” may be understood to mean at least an additional / second one or more; (v) the terms “about” and “approximately” may be understood to permit standard variation as would be understood by those of ordinary skill in the art; and (vi) where ranges are provided, endpoints are included.

[0020] Unless otherwise specified, description of oligonucleotides and elements thereof (e.g., base sequence, sugar modifications, internucleotidic linkages, linkage phosphorus stereochemistry, patterns thereof, etc.) is from 5’ to 3’. As those skilled in the art will appreciate, in some embodiments, oligonucleotides may be provided and / or utilized as salt forms, particularly pharmaceutically acceptable salt forms, e.g., sodium salts. As those skilled in the art will also appreciate, in some embodiments, individual oligonucleotides within a composition may be considered to be of the same constitution and / or structure even though, within such composition (e.g., a liquid composition), particular such oligonucleotides might be in different salt form(s) (and may be dissolved and the oligonucleotide chain Page 9 of 201 12495950v1Attorney Docket No.: 2010581-1440 may exist as an anion form when, e.g., in a liquid composition) at a particular moment in time. For example, those skilled in the art will appreciate that, at a given pH, individual internucleotidic linkages along an oligonucleotide chain may be in an acid (H) form, or in one of a plurality of possible salt forms (e.g., a sodium salt, or a salt of a different cation, depending on which ions might be present in the preparation or composition), and will understand that, so long as their acid forms (e.g., replacing all cations, if any, with H+) are of the same constitution and / or structure, such individual oligonucleotides may properly be considered to be of the same constitution and / or structure.

[0021] Aliphatic: As used herein, “aliphatic” means a straight-chain (i.e., unbranched) or branched, substituted or unsubstituted hydrocarbon chain that is completely saturated or that contains one or more units of unsaturation (but not aromatic), or a substituted or unsubstituted monocyclic, bicyclic, or polycyclic hydrocarbon ring that is completely saturated or that contains one or more units of unsaturation (but not aromatic), or combinations thereof. In some embodiments, aliphatic groups contain 1-50 aliphatic carbon atoms. In some embodiments, aliphatic groups contain 1-20 aliphatic carbon atoms. In other embodiments, aliphatic groups contain 1-10 aliphatic carbon atoms. In other embodiments, aliphatic groups contain 1-9 aliphatic carbon atoms. In other embodiments, aliphatic groups contain 1-8 aliphatic carbon atoms. In other embodiments, aliphatic groups contain 1-7 aliphatic carbon atoms. In other embodiments, aliphatic groups contain 1-6 aliphatic carbon atoms. In still other embodiments, aliphatic groups contain 1-5 aliphatic carbon atoms, and in yet other embodiments, aliphatic groups contain 1, 2, 3, or 4 aliphatic carbon atoms. Suitable aliphatic groups include linear or branched, substituted or unsubstituted alkyl, alkenyl, alkynyl groups and hybrids thereof such as (cycloalkyl)alkyl, (cycloalkenyl)alkyl or (cycloalkyl)alkenyl.

[0022] Alkenyl: As used herein, the term “alkenyl” refers to an aliphatic group, as defined herein, having one or more double bonds.

[0023] Alkyl: As used herein, the term “alkyl” is given its ordinary meaning in the art and may include saturated aliphatic groups, including straight-chain alkyl groups, branched-chain alkyl groups, cycloalkyl (alicyclic) groups, alkyl substituted cycloalkyl groups, and cycloalkyl substituted alkyl groups. In some embodiments, alkyl has 1-100 carbon atoms. In certain embodiments, a straight chain or branched chain alkyl has about 1-20 carbon atoms in its backbone (e.g., C1-C20for straight chain, C2-C20for branched chain), and alternatively, about 1-10. In some embodiments, cycloalkyl rings have from about 3-10 carbon atoms in their ring structure where such rings are monocyclic, bicyclic, or polycyclic, and alternatively about 5, 6 or 7 carbons in the ring structure. In some embodiments, an alkyl group may be a lower alkyl group, wherein a lower alkyl group comprises 1-4 carbon atoms (e.g., C1-C4for straight chain lower alkyls).

[0024] Alkynyl: As used herein, the term “alkynyl” refers to an aliphatic group, as defined herein, Page 10 of 201 12495950v1Attorney Docket No.: 2010581-1440 having one or more triple bonds.

[0025] Aryl: The term “aryl", as used herein, used alone or as part of a larger moiety as in “aralkyl,” “aralkoxy,” or “aryloxyalkyl,” refers to monocyclic, bicyclic or polycyclic ring systems having a total of five to thirty ring members, wherein at least one ring in the system is aromatic. In some embodiments, an aryl group is a monocyclic, bicyclic or polycyclic ring system having a total of five to fourteen ring members, wherein at least one ring in the system is aromatic, and wherein each ring in the system contains 3 to 7 ring members. In some embodiments, each monocyclic ring unit is aromatic. In some embodiments, an aryl group is a biaryl group. The term “aryl” may be used interchangeably with the term “aryl ring.” In certain embodiments of the present disclosure, “aryl” refers to an aromatic ring system which includes, but is not limited to, phenyl, biphenyl, naphthyl, binaphthyl, anthracyl and the like, which may bear one or more substituents. Also included within the scope of the term “aryl,” as it is used herein, is a group in which an aromatic ring is fused to one or more non–aromatic rings, such as indanyl, phthalimidyl, naphthimidyl, phenanthridinyl, or tetrahydronaphthyl, and the like.

[0026] Chiral control: As used herein, “chiral control” refers to control of the stereochemical designation of the chiral linkage phosphorus in a chiral internucleotidic linkage within an oligonucleotide. As used herein, a chiral internucleotidic linkage is an internucleotidic linkage whose linkage phosphorus is chiral. In some embodiments, a control is achieved through a chiral element that is absent from the sugar and base moieties of an oligonucleotide, for example, in some embodiments, a control is achieved through use of one or more chiral auxiliaries during oligonucleotide preparation, which chiral auxiliaries often are part of chiral phosphoramidites used during oligonucleotide preparation. In contrast to chiral control, a person having ordinary skill in the art will appreciate that conventional oligonucleotide synthesis which does not use chiral auxiliaries cannot control stereochemistry at a chiral internucleotidic linkage if such conventional oligonucleotide synthesis is used to form the chiral internucleotidic linkage. In some embodiments, the stereochemical designation of each chiral linkage phosphorus in each chiral internucleotidic linkage within an oligonucleotide is controlled.

[0027] Chirally controlled oligonucleotide composition: The terms “chirally controlled oligonucleotide composition”, “chirally controlled nucleic acid composition”, and the like, as used herein, refers to a composition that comprises a plurality of oligonucleotides (or nucleic acids) which share a common base sequence, wherein the plurality of oligonucleotides (or nucleic acids) share the same linkage phosphorus stereochemistry at one or more chiral internucleotidic linkages (chirally controlled or stereodefined internucleotidic linkages, whose chiral linkage phosphorus is Rp or Sp in the composition (“stereodefined”), not a random Rp and Sp mixture as non-chirally controlled internucleotidic linkages). In some embodiments, a chirally controlled oligonucleotide composition comprises a plurality of oligonucleotides (or nucleic acids) that share: 1) a common base sequence, 2) a common pattern of Page 11 of 201 12495950v1Attorney Docket No.: 2010581-1440 backbone linkages, and 3) a common pattern of backbone phosphorus modifications, wherein the plurality of oligonucleotides (or nucleic acids) share the same linkage phosphorus stereochemistry at one or more chiral internucleotidic linkages (chirally controlled or stereodefined internucleotidic linkages, whose chiral linkage phosphorus is Rp or Sp in the composition (“stereodefined”), not a random Rp and Sp mixture as non-chirally controlled internucleotidic linkages). Level of the plurality of oligonucleotides (or nucleic acids) in a chirally controlled oligonucleotide composition is pre-determined / controlled or enriched (e.g., through chirally controlled oligonucleotide preparation to stereoselectively form one or more chiral internucleotidic linkages) compared to a random level in a non-chirally controlled oligonucleotide composition. In some embodiments, about 1%-100%, (e.g., about 5%-100%, 10%-100%, 20%-100%, 30%-100%, 40%-100%, 50%-100%, 60%-100%, 70%-100%, 80-100%, 90-100%, 95-100%, 50%-90%, or about 5%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100%, or at least 5%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99%) of all oligonucleotides in a chirally controlled oligonucleotide composition are oligonucleotides of the plurality. In some embodiments, about 1%-100%, (e.g., about 5%-100%, 10%-100%, 20%-100%, 30%-100%, 40%-100%, 50%-100%, 60%-100%, 70%-100%, 80-100%, 90-100%, 95-100%, 50%-90%, or about 5%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100%, or at least 5%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99%) of all oligonucleotides in a chirally controlled oligonucleotide composition that share the common base sequence, the common pattern of backbone linkages, and the common pattern of backbone phosphorus modifications are oligonucleotides of the plurality. In some embodiments, a level is about 1%-100%, (e.g., about 5%-100%, 10%-100%, 20%-100%, 30%-100%, 40%-100%, 50%-100%, 60%-100%, 70%-100%, 80-100%, 90-100%, 95-100%, 50%-90%, or about 5%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100%, or at least 5%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99%) of all oligonucleotides in a composition, or of all oligonucleotides in a composition that share a common base sequence (e.g., of a plurality of oligonucleotide or an oligonucleotide type), or of all oligonucleotides in a composition that share a common base sequence, a common pattern of backbone linkages, and a common pattern of backbone phosphorus modifications, or of all oligonucleotides in a composition that share a common base sequence, a common patter of base modifications, a common pattern of sugar modifications, a common pattern of internucleotidic linkage types, and / or a common pattern of internucleotidic linkage modifications. In some embodiments, the plurality of oligonucleotides share the same stereochemistry at about 1-50 (e.g., about 1-10, 1-20, 5-10, 5- 20, 10-15, 10-20, 10-25, 10-30, or about 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or Page 12 of 201 12495950v1Attorney Docket No.: 2010581-1440 20, or at least 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20) chiral internucleotidic linkages. In some embodiments, the plurality of oligonucleotides share the same stereochemistry at about 1%-100% (e.g., about 5%-100%, 10%-100%, 20%-100%, 30%-100%, 40%-100%, 50%-100%, 60%- 100%, 70%-100%, 80-100%, 90-100%, 95-100%, 50%-90%, about 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, or 100%, or at least 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, or 99%) of chiral internucleotidic linkages. In some embodiments, oligonucleotides (or nucleic acids) of a plurality share the same pattern of sugar and / or nucleobase modifications, in any. In some embodiments, oligonucleotides (or nucleic acids) of a plurality are various forms of the same oligonucleotide (e.g., acid and / or various salts of the same oligonucleotide). In some embodiments, oligonucleotides (or nucleic acids) of a plurality are of the same constitution. In some embodiments, level of the oligonucleotides (or nucleic acids) of the plurality is about 1%-100%, (e.g., about 5%-100%, 10%-100%, 20%-100%, 30%- 100%, 40%-100%, 50%-100%, 60%-100%, 70%-100%, 80-100%, 90-100%, 95-100%, 50%-90%, or about 5%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100%, or at least 5%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99%) of all oligonucleotides (or nucleic acids) in a composition that share the same constitution as the oligonucleotides (or nucleic acids) of the plurality. In some embodiments, each chiral internucleotidic linkage is a chiral controlled internucleotidic linkage, and the composition is a completely chirally controlled oligonucleotide composition. In some embodiments, oligonucleotides (or nucleic acids) of a plurality are structurally identical. In some embodiments, a chirally controlled internucleotidic linkage has a diastereopurity of at least 80%, 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or 99.5%, typically at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or 99.5%. In some embodiments, a chirally controlled internucleotidic linkage has a diastereopurity of at least 95%. In some embodiments, a chirally controlled internucleotidic linkage has a diastereopurity of at least 96%. In some embodiments, a chirally controlled internucleotidic linkage has a diastereopurity of at least 97%. In some embodiments, a chirally controlled internucleotidic linkage has a diastereopurity of at least 98%. In some embodiments, a chirally controlled internucleotidic linkage has a diastereopurity of at least 99%. In some embodiments, a percentage of a level is or is at least (DS)nc, wherein DS is a diastereopurity as described in the present disclosure (e.g., 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or 99.5% or more) and nc is the number of chiral linkage phosphorus as described in the present disclosure (e.g., 1-50, 1-40, 1-30, 1-25, 1-20, 5-50, 5-40, 5-30, 5-25, 5-20, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25 or more). In some embodiments, a percentage of a level is or is at least (DS)nc, wherein DS is a diastereopurity as described in the present disclosure (e.g., 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or 99.5% or Page 13 of 201 12495950v1Attorney Docket No.: 2010581-1440 more) and nc is the number of chirally controlled internucleotidic linkages as described in the present disclosure (e.g., 1-50, 1-40, 1-30, 1-25, 1-20, 5-50, 5-40, 5-30, 5-25, 5-20, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25 or more). In some embodiments, a percentage of a level is or is at least (DS)nc, wherein DS is 95%-100%. For example, when DS is 99% and nc is 10, the percentage is or is at least 90% ((99%)10≈ 0.90 = 90%). In some embodiments, level of a plurality of oligonucleotides in a composition is represented as the product of the diastereopurity of each chiral linkage phosphorus. In some embodiments, level of a plurality of oligonucleotides in a composition is represented as the product of the diastereopurity of each chirally controlled internucleotidic linkage in the oligonucleotides. In some embodiments, diastereopurity of an internucleotidic linkage connecting two nucleosides in an oligonucleotide (or nucleic acid) is represented by the diastereopurity of an internucleotidic linkage of a dimer connecting the same two nucleosides, wherein the dimer is prepared using comparable conditions, in some instances, identical synthetic cycle conditions (e.g., for the linkage between Nx and Ny in an oligonucleotide ….NxNy….., the dimer is NxNy). In some embodiments, not all chiral internucleotidic linkages are chiral controlled internucleotidic linkages, and the composition is a partially chirally controlled oligonucleotide composition. In some embodiments, a non-chirally controlled internucleotidic linkage has a diastereopurity of less than about 80%, 75%, 70%, 65%, 60%, 55%, or of about 50%, as typically observed in stereorandom oligonucleotide compositions (e.g., as appreciated by those skilled in the art, from traditional oligonucleotide synthesis, e.g., the phosphoramidite method). In some embodiments, oligonucleotides (or nucleic acids) of a plurality are of the same type. In some embodiments, a chirally controlled oligonucleotide composition comprises non- random or controlled levels of individual oligonucleotide or nucleic acids types. For instance, in some embodiments a chirally controlled oligonucleotide composition comprises one and no more than one oligonucleotide type. In some embodiments, a chirally controlled oligonucleotide composition comprises more than one oligonucleotide type. In some embodiments, a chirally controlled oligonucleotide composition comprises multiple oligonucleotide types. In some embodiments, a chirally controlled oligonucleotide composition is a composition of oligonucleotides of an oligonucleotide type, which composition comprises a non-random or controlled level of a plurality of oligonucleotides of the oligonucleotide type.

[0028] Comparable: The term “comparable” is used herein to describe two (or more) sets of conditions or circumstances that are sufficiently similar to one another to permit comparison of results obtained or phenomena observed. In some embodiments, comparable sets of conditions or circumstances are characterized by a plurality of substantially identical features and one or a small number of varied features. Those of ordinary skill in the art will appreciate that sets of conditions are comparable to one another when characterized by a sufficient number and type of substantially identical features to warrant a Page 14 of 201 12495950v1Attorney Docket No.: 2010581-1440 reasonable conclusion that differences in results obtained or phenomena observed under the different sets of conditions or circumstances are caused by or indicative of the variation in those features that are varied.

[0029] Cycloaliphatic: The term “cycloaliphatic,” “carbocycle,” “carbocyclyl,” “carbocyclic radical,” and “carbocyclic ring,” are used interchangeably, and as used herein, refer to saturated or partially unsaturated, but non-aromatic, cyclic aliphatic monocyclic, bicyclic, or polycyclic ring systems, as described herein, having, unless otherwise specified, from 3 to 30 ring members. Cycloaliphatic groups include, without limitation, cyclopropyl, cyclobutyl, cyclopentyl, cyclopentenyl, cyclohexyl, cyclohexenyl, cycloheptyl, cycloheptenyl, cyclooctyl, cyclooctenyl, norbornyl, adamantyl, and cyclooctadienyl. In some embodiments, a cycloaliphatic group has 3–6 carbons. In some embodiments, a cycloaliphatic group is saturated and is cycloalkyl. The term “cycloaliphatic” may also include aliphatic rings that are fused to one or more aromatic or nonaromatic rings, such as decahydronaphthyl or tetrahydronaphthyl. In some embodiments, a cycloaliphatic group is bicyclic. In some embodiments, a cycloaliphatic group is tricyclic. In some embodiments, a cycloaliphatic group is polycyclic. In some embodiments, “cycloaliphatic” refers to C3-C6 monocyclic hydrocarbon, or C8-C10 bicyclic or polycyclic hydrocarbon, that is completely saturated or that contains one or more units of unsaturation, but which is not aromatic, that has a single point of attachment to the rest of the molecule, or a C9-C16 polycyclic hydrocarbon that is completely saturated or that contains one or more units of unsaturation, but which is not aromatic, that has a single point of attachment to the rest of the molecule.

[0030] Heteroaliphatic: The term “heteroaliphatic”, as used herein, is given its ordinary meaning in the art and refers to aliphatic groups as described herein in which one or more carbon atoms are independently replaced with one or more heteroatoms (e.g., oxygen, nitrogen, sulfur, silicon, phosphorus, and the like). In some embodiments, one or more units selected from C, CH, CH2, and CH3 are independently replaced by one or more heteroatoms (including oxidized and / or substituted forms thereof). In some embodiments, a heteroaliphatic group is heteroalkyl. In some embodiments, a heteroaliphatic group is heteroalkenyl.

[0031] Heteroalkyl: The term “heteroalkyl”, as used herein, is given its ordinary meaning in the art and refers to alkyl groups as described herein in which one or more carbon atoms are independently replaced with one or more heteroatoms (e.g., oxygen, nitrogen, sulfur, silicon, phosphorus, and the like). Examples of heteroalkyl groups include, but are not limited to, alkoxy, poly(ethylene glycol)-, alkyl- substituted amino, tetrahydrofuranyl, piperidinyl, morpholinyl, etc.

[0032] Heteroaryl: The terms “heteroaryl” and “heteroar–”, as used herein, used alone or as part of a larger moiety, e.g., “heteroaralkyl,” or “heteroaralkoxy,” refer to monocyclic, bicyclic or polycyclic ring systems having a total of five to thirty ring members, wherein at least one ring in the system is aromatic Page 15 of 201 12495950v1Attorney Docket No.: 2010581-1440 and at least one aromatic ring atom is a heteroatom. In some embodiments, a heteroaryl group is a group having 5 to 10 ring atoms (i.e., monocyclic, bicyclic or polycyclic), in some embodiments 5, 6, 9, or 10 ring atoms. In some embodiments, each monocyclic ring unit is aromatic. In some embodiments, a heteroaryl group has 6, 10, or 14 π electrons shared in a cyclic array; and having, in addition to carbon atoms, from one to five heteroatoms. Heteroaryl groups include, without limitation, thienyl, furanyl, pyrrolyl, imidazolyl, pyrazolyl, triazolyl, tetrazolyl, oxazolyl, isoxazolyl, oxadiazolyl, thiazolyl, isothiazolyl, thiadiazolyl, pyridyl, pyridazinyl, pyrimidinyl, pyrazinyl, indolizinyl, purinyl, naphthyridinyl, and pteridinyl. In some embodiments, a heteroaryl is a heterobiaryl group, such as bipyridyl and the like. The terms “heteroaryl” and “heteroar–”, as used herein, also include groups in which a heteroaromatic ring is fused to one or more aryl, cycloaliphatic, or heterocyclyl rings, where the radical or point of attachment is on the heteroaromatic ring. Non-limiting examples include indolyl, isoindolyl, benzothienyl, benzofuranyl, dibenzofuranyl, indazolyl, benzimidazolyl, benzthiazolyl, quinolyl, isoquinolyl, cinnolinyl, phthalazinyl, quinazolinyl, quinoxalinyl, 4H–quinolizinyl, carbazolyl, acridinyl, phenazinyl, phenothiazinyl, phenoxazinyl, tetrahydroquinolinyl, tetrahydroisoquinolinyl, and pyrido[2,3–b]–1,4–oxazin–3(4H)–one. A heteroaryl group may be monocyclic, bicyclic or polycyclic. The term “heteroaryl” may be used interchangeably with the terms “heteroaryl ring,” “heteroaryl group,” or “heteroaromatic,” any of which terms include rings that are optionally substituted. The term “heteroaralkyl” refers to an alkyl group substituted by a heteroaryl group, wherein the alkyl and heteroaryl portions independently are optionally substituted.

[0033] Heteroatom: The term “heteroatom", as used herein, means an atom that is not carbon or hydrogen. In some embodiments, a heteroatom is boron, oxygen, sulfur, nitrogen, phosphorus, or silicon (including oxidized forms of nitrogen, sulfur, phosphorus, or silicon; charged forms of nitrogen (e.g., quaternized forms, forms as in iminium groups, etc.), phosphorus, sulfur, oxygen; etc.). In some embodiments, a heteroatom is silicon, phosphorus, oxygen, sulfur or nitrogen. In some embodiments, a heteroatom is silicon, oxygen, sulfur or nitrogen. In some embodiments, a heteroatom is oxygen, sulfur or nitrogen.

[0034] Heterocycle: As used herein, the terms “heterocycle,” “heterocyclyl,” “heterocyclic radical,” and “heterocyclic ring", as used herein, are used interchangeably and refer to a monocyclic, bicyclic or polycyclic ring moiety (e.g., 3-30 membered) that is saturated or partially unsaturated and has one or more heteroatom ring atoms. In some embodiments, a heterocyclyl group is a stable 5– to 7–membered monocyclic or 7– to 10–membered bicyclic heterocyclic moiety that is either saturated or partially unsaturated, and having, in addition to carbon atoms, one or more, preferably one to four, heteroatoms, as defined above. When used in reference to a ring atom of a heterocycle, the term "nitrogen" includes substituted nitrogen. As an example, in a saturated or partially unsaturated ring having 0–3 heteroatoms Page 16 of 201 12495950v1Attorney Docket No.: 2010581-1440 selected from oxygen, sulfur and nitrogen, the nitrogen may be N (as in 3,4–dihydro–2H–pyrrolyl), NH (as in pyrrolidinyl), or+NR (as in N–substituted pyrrolidinyl). A heterocyclic ring can be attached to its pendant group at any heteroatom or carbon atom that results in a stable structure and any of the ring atoms can be optionally substituted. Examples of such saturated or partially unsaturated heterocyclic radicals include, without limitation, tetrahydrofuranyl, tetrahydrothienyl, pyrrolidinyl, piperidinyl, pyrrolinyl, tetrahydroquinolinyl, tetrahydroisoquinolinyl, decahydroquinolinyl, oxazolidinyl, piperazinyl, dioxanyl, dioxolanyl, diazepinyl, oxazepinyl, thiazepinyl, morpholinyl, and quinuclidinyl. The terms “heterocycle,” “heterocyclyl,” “heterocyclyl ring,” “heterocyclic group,” “heterocyclic moiety,” and “heterocyclic radical,” are used interchangeably herein, and also include groups in which a heterocyclyl ring is fused to one or more aryl, heteroaryl, or cycloaliphatic rings, such as indolinyl, 3H–indolyl, chromanyl, phenanthridinyl, or tetrahydroquinolinyl. A heterocyclyl group may be monocyclic, bicyclic or polycyclic. The term “heterocyclylalkyl” refers to an alkyl group substituted by a heterocyclyl, wherein the alkyl and heterocyclyl portions independently are optionally substituted.

[0035] Internucleotidic linkage: As used herein, the phrase “internucleotidic linkage” refers generally to a linkage linking nucleoside units of an oligonucleotide or a nucleic acid. In some embodiments, an internucleotidic linkage is a phosphodiester linkage, as extensively found in naturally occurring DNA and RNA molecules (natural phosphate linkage (−OP(=O)(OH)O−), which as appreciated by those skilled in the art may exist as a salt form). In some embodiments, an internucleotidic linkage is a modified internucleotidic linkage (not a natural phosphate linkage). In some embodiments, an internucleotidic linkage is a “modified internucleotidic linkage” wherein at least one oxygen atom or −OH of a phosphodiester linkage is replaced by a different organic or inorganic moiety. In some embodiments, such an organic or inorganic moiety is selected from =S, =Se, =NR’, –SR’, –SeR’, – N(R’)2, B(R’)3, –S–, –Se–, and –N(R’)–, wherein each R’ is independently as defined and described in the present disclosure. In some embodiments, an internucleotidic linkage is a phosphotriester linkage, phosphorothioate linkage (or phosphorothioate diester linkage, −OP(=O)(SH)O−, which as appreciated by those skilled in the art may exist as a salt form), or phosphorothioate triester linkage. In some embodiments, a modified internucleotidic linkage is a phosphorothioate linkage. In some embodiments, an internucleotidic linkage is one of, e.g., PNA (peptide nucleic acid) or PMO (phosphorodiamidate Morpholino oligomer) linkage. In some embodiments, a modified internucleotidic linkage is a non- negatively charged internucleotidic linkage. In some embodiments, a modified internucleotidic linkage is a neutral internucleotidic linkage (e.g., n001 in certain provided oligonucleotides). It is understood by a person of ordinary skill in the art that an internucleotidic linkage may exist as an anion or cation at a given pH due to the existence of acid or base moieties in the linkage.

[0036] Linkage phosphorus: as defined herein, the phrase “linkage phosphorus” is used to indicate Page 17 of 201 12495950v1Attorney Docket No.: 2010581-1440 that the particular phosphorus atom being referred to is the phosphorus atom present in the internucleotidic linkage, which phosphorus atom corresponds to the phosphorus atom of a phosphodiester internucleotidic linkage as occurs in naturally occurring DNA and RNA. In some embodiments, a linkage phosphorus atom is in a modified internucleotidic linkage, wherein each oxygen atom of a phosphodiester linkage is optionally and independently replaced by an organic or inorganic moiety. In some embodiments, a linkage phosphorus atom is chiral (e.g., as in phosphorothioate internucleotidic linkages). In some embodiments, a linkage phosphorus atom is achiral (e.g., as in natural phosphate linkages).

[0037] Modified nucleobase: The terms "modified nucleobase", "modified base" and the like refer to a chemical moiety which is chemically distinct from a nucleobase, but which is capable of performing at least one function of a nucleobase. In some embodiments, a modified nucleobase is a nucleobase which comprises a modification. In some embodiments, a modified nucleobase is capable of at least one function of a nucleobase, e.g., forming a moiety in a polymer capable of base-pairing to a nucleic acid comprising an at least complementary sequence of bases. In some embodiments, a modified nucleobase is substituted A, T, C, G, or U, or a substituted tautomer of A, T, C, G, or U. In some embodiments, a modified nucleobase in the context of oligonucleotides refer to a nucleobase that is not A, T, C, G or U.

[0038] Modified nucleoside: The term "modified nucleoside" refers to a moiety derived from or chemically similar to a natural nucleoside, but which comprises a chemical modification which differentiates it from a natural nucleoside. Non-limiting examples of modified nucleosides include those which comprise a modification at the base and / or the sugar. Non-limiting examples of modified nucleosides include those with a 2’ modification at a sugar. Non-limiting examples of modified nucleosides also include abasic nucleosides (which lack a nucleobase). In some embodiments, a modified nucleoside is capable of at least one function of a nucleoside, e.g., forming a moiety in a polymer capable of base-pairing to a nucleic acid comprising an at least complementary sequence of bases.

[0039] Modified nucleotide: The term “modified nucleotide” includes any chemical moiety which differs structurally from a natural nucleotide but is capable of performing at least one function of a natural nucleotide. In some embodiments, a modified nucleotide comprises a modification at a sugar, base and / or internucleotidic linkage. In some embodiments, a modified nucleotide comprises a modified sugar, modified nucleobase and / or modified internucleotidic linkage. In some embodiments, a modified nucleotide is capable of at least one function of a nucleotide, e.g., forming a subunit in a polymer capable of base-pairing to a nucleic acid comprising an at least complementary sequence of bases.

[0040] Modified sugar: The term “modified sugar” refers to a moiety that can replace a sugar. A modified sugar mimics the spatial arrangement, electronic properties, or some other physicochemical property of a sugar. In some embodiments, as described in the present disclosure, a modified sugar is substituted ribose or deoxyribose. In some embodiments, a modified sugar comprises a 2’-modification. Page 18 of 201 12495950v1Attorney Docket No.: 2010581-1440 Examples of useful 2’-modification are widely utilized in the art and described herein. In some embodiments, a 2’-modification is 2’-F. In some embodiments, a 2’-modification is 2’-OR, wherein R is optionally substituted C1-10aliphatic. In some embodiments, a 2’-modification is 2’-OMe. In some embodiments, a 2’-modification is 2’-MOE. In some embodiments, a modified sugar is a bicyclic sugar (e.g., a sugar used in LNA, BNA, etc.). In some embodiments, in the context of oligonucleotides, a modified sugar is a sugar that is not ribose or deoxyribose as typically found in natural RNA or DNA.

[0041] Nucleic acid: The term “nucleic acid”, as used herein, includes any nucleotides and polymers thereof. The term “polynucleotide”, as used herein, refers to a polymeric form of nucleotides of any length, either ribonucleotides (RNA) or deoxyribonucleotides (DNA) or a combination thereof. These terms refer to the primary structure of the molecules and, thus, include double- and single-stranded DNA, and double- and single-stranded RNA. These terms include, as equivalents, analogs of either RNA or DNA comprising modified nucleotides and / or modified polynucleotides, such as, though not limited to, methylated, protected and / or capped nucleotides or polynucleotides. The terms encompass poly- or oligo-ribonucleotides (RNA) and poly- or oligo-deoxyribonucleotides (DNA); RNA or DNA derived from N-glycosides or C-glycosides of nucleobases and / or modified nucleobases; nucleic acids derived from sugars and / or modified sugars; and nucleic acids derived from phosphate bridges and / or modified internucleotidic linkages. The term encompasses nucleic acids containing any combinations of nucleobases, modified nucleobases, sugars, modified sugars, phosphate bridges or modified internucleotidic linkages. Examples include, and are not limited to, nucleic acids containing ribose moieties, nucleic acids containing deoxy-ribose moieties, nucleic acids containing both ribose and deoxyribose moieties, nucleic acids containing ribose and modified ribose moieties. Unless otherwise specified, the prefix poly- refers to a nucleic acid containing 2 to about 10,000 nucleotide monomer units and wherein the prefix oligo- refers to a nucleic acid containing 2 to about 200 nucleotide monomer units.

[0042] Nucleobase: The term “nucleobase” refers to the parts of nucleic acids that are involved in the hydrogen-bonding that binds one nucleic acid strand to another complementary strand in a sequence specific manner. The most common naturally-occurring nucleobases are adenine (A), guanine (G), uracil (U), cytosine (C), and thymine (T). In some embodiments, a naturally-occurring nucleobases are modified adenine, guanine, uracil, cytosine, or thymine. In some embodiments, a naturally-occurring nucleobases are methylated adenine, guanine, uracil, cytosine, or thymine. In some embodiments, a nucleobase comprises a heteroaryl ring wherein a ring atom is nitrogen, and when in a nucleoside, the nitrogen is bonded to a sugar moiety. In some embodiments, a nucleobase comprises a heterocyclic ring wherein a ring atom is nitrogen, and when in a nucleoside, the nitrogen is bonded to a sugar moiety. In some embodiments, a nucleobase is a “modified nucleobase,” a nucleobase other than adenine (A), guanine (G), uracil (U), cytosine (C), and thymine (T). In some embodiments, a modified nucleobase is substituted A, Page 19 of 201 12495950v1Attorney Docket No.: 2010581-1440 T, C, G or U. In some embodiments, a modified nucleobase is a substituted tautomer of A, T, C, G, or U. In some embodiments, a modified nucleobases is methylated adenine, guanine, uracil, cytosine, or thymine. In some embodiments, a modified nucleobase mimics the spatial arrangement, electronic properties, or some other physicochemical property of the nucleobase and retains the property of hydrogen-bonding that binds one nucleic acid strand to another in a sequence specific manner. In some embodiments, a modified nucleobase can pair with all of the five naturally occurring bases (uracil, thymine, adenine, cytosine, or guanine) without substantially affecting the melting behavior, recognition by intracellular enzymes or activity of the oligonucleotide duplex. As used herein, the term “nucleobase” also encompasses structural analogs used in lieu of natural or naturally-occurring nucleotides, such as modified nucleobases and nucleobase analogs. In some embodiments, a nucleobase is optionally substituted A, T, C, G, or U, or an optionally substituted tautomer of A, T, C, G, or U. In some embodiments, a “nucleobase” refers to a nucleobase unit in an oligonucleotide or a nucleic acid (e.g., A, T, C, G or U as in an oligonucleotide or a nucleic acid).

[0043] Nucleoside: The term “nucleoside” refers to a moiety wherein a nucleobase or a modified nucleobase is covalently bound to a sugar or a modified sugar. In some embodiments, a nucleoside is a natural nucleoside, e.g., adenosine, deoxyadenosine, guanosine, deoxyguanosine, thymidine, uridine, cytidine, or deoxycytidine. In some embodiments, a nucleoside is a modified nucleoside, e.g., a substituted natural nucleoside selected from adenosine, deoxyadenosine, guanosine, deoxyguanosine, thymidine, uridine, cytidine, and deoxycytidine. In some embodiments, a nucleoside is a modified nucleoside, e.g., a substituted tautomer of a natural nucleoside selected from adenosine, deoxyadenosine, guanosine, deoxyguanosine, thymidine, uridine, cytidine, and deoxycytidine. In some embodiments, a “nucleoside” refers to a nucleoside unit in an oligonucleotide or a nucleic acid.

[0044] Nucleotide: The term “nucleotide” as used herein refers to a monomeric unit of a polynucleotide that consists of a nucleobase, a sugar, and one or more internucleotidic linkages (e.g., phosphate linkages in natural DNA and RNA). The naturally occurring bases [guanine, (G), adenine, (A), cytosine, (C), thymine, (T), and uracil (U)] are derivatives of purine or pyrimidine, though it should be understood that naturally and non-naturally occurring base analogs are also included. The naturally occurring sugar is the pentose (five-carbon sugar) deoxyribose (which forms DNA) or ribose (which forms RNA), though it should be understood that naturally and non-naturally occurring sugar analogs are also included. Nucleotides are linked via internucleotidic linkages to form nucleic acids, or polynucleotides. Many internucleotidic linkages are known in the art (such as, though not limited to, phosphate, phosphorothioates, boranophosphates and the like). Artificial nucleic acids include PNAs (peptide nucleic acids), phosphotriesters, phosphorothionates, H-phosphonates, phosphoramidates, boranophosphates, methylphosphonates, phosphonoacetates, thiophosphonoacetates and other variants of the phosphate Page 20 of 201 12495950v1Attorney Docket No.: 2010581-1440 backbone of native nucleic acids, such as those described herein. In some embodiments, a natural nucleotide comprises a naturally occurring base, sugar and internucleotidic linkage. As used herein, the term “nucleotide” also encompasses structural analogs used in lieu of natural or naturally-occurring nucleotides, such as modified nucleotides and nucleotide analogs. In some embodiments, a “nucleotide” refers to a nucleotide unit in an oligonucleotide or a nucleic acid.

[0045] Oligonucleotide: The term "oligonucleotide" refers to a polymer or oligomer of nucleotides, and may contain any combination of natural and non-natural nucleobases, sugars, and internucleotidic linkages.

[0046] Oligonucleotides can be single-stranded or double-stranded. A single-stranded oligonucleotide can have double-stranded regions (formed by two portions of the single-stranded oligonucleotide) and a double-stranded oligonucleotide, which comprises two oligonucleotide chains, can have single-stranded regions for example, at regions where the two oligonucleotide chains are not complementary to each other. Example oligonucleotides include, but are not limited to structural genes, genes including control and termination regions, self-replicating systems such as viral or plasmid DNA, single-stranded and double- stranded RNAi agents and other RNA interference reagents (RNAi agents or iRNA agents), shRNA, antisense oligonucleotides, ribozymes, microRNAs, microRNA mimics, supermirs, aptamers, antimirs, antagomirs, Ul adaptors, triplex-forming oligonucleotides, G-quadruplex oligonucleotides, RNA activators, immuno-stimulatory oligonucleotides, and decoy oligonucleotides.

[0047] Oligonucleotides of the present disclosure can be of various lengths. In particular embodiments, oligonucleotides can range from about 2 to about 200 nucleosides in length. In various related embodiments, oligonucleotides, single-stranded, double-stranded, or triple-stranded, can range in length from about 4 to about 10 nucleosides, from about 10 to about 50 nucleosides, from about 20 to about 50 nucleosides, from about 15 to about 30 nucleosides, from about 20 to about 30 nucleosides in length. In some embodiments, an oligonucleotide is from about 9 to about 39 nucleosides in length. In some embodiments, an oligonucleotide is from about 25 to about 70 nucleosides in length. In some embodiments, an oligonucleotide is from about 26 to about 70 nucleosides in length. In some embodiments, an oligonucleotide is from about 27 to about 70 nucleosides in length. In some embodiments, an oligonucleotide is from about 28 to about 70 nucleosides in length. In some embodiments, an oligonucleotide is from about 29 to about 70 nucleosides in length. In some embodiments, an oligonucleotide is from about 30 to about 70 nucleosides in length. In some embodiments, an oligonucleotide is from about 31 to about 70 nucleosides in length. In some embodiments, an oligonucleotide is from about 32 to about 70 nucleosides in length. In some embodiments, an oligonucleotide is from about 25 to about 60 nucleosides in length. In some embodiments, an oligonucleotide is from about 25 to about 50 nucleosides in length. In some embodiments, an Page 21 of 201 12495950v1Attorney Docket No.: 2010581-1440 oligonucleotide is from about 25 to about 40 nucleosides in length. In some embodiments, an oligonucleotide is from about 30 to about 40 nucleosides in length. In some embodiments, the oligonucleotide is at least 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, or 25 nucleosides in length. In some embodiments, an oligonucleotide is at least 4 nucleosides in length. In some embodiments, an oligonucleotide is at least 5 nucleosides in length. In some embodiments, an oligonucleotide is at least 6 nucleosides in length. In some embodiments, an oligonucleotide is at least 7 nucleosides in length. In some embodiments, an oligonucleotide is at least 8 nucleosides in length. In some embodiments, an oligonucleotide is at least 9 nucleosides in length. In some embodiments, an oligonucleotide is at least 10 nucleosides in length. In some embodiments, an oligonucleotide is at least 11 nucleosides in length. In some embodiments, an oligonucleotide is at least 12 nucleosides in length. In some embodiments, an oligonucleotide is at least 15 nucleosides in length. In some embodiments, an oligonucleotide is at least 15 nucleosides in length. In some embodiments, an oligonucleotide is at least 16 nucleosides in length. In some embodiments, an oligonucleotide is at least 17 nucleosides in length. In some embodiments, an oligonucleotide is at least 18 nucleosides in length. In some embodiments, an oligonucleotide is at least 19 nucleosides in length. In some embodiments, an oligonucleotide is at least 20 nucleosides in length. In some embodiments, an oligonucleotide is at least 25 nucleosides in length. In some embodiments, an oligonucleotide is at least 26 nucleosides in length. In some embodiments, an oligonucleotide is at least 27 nucleosides in length. In some embodiments, an oligonucleotide is at least 28 nucleosides in length. In some embodiments, an oligonucleotide is at least 29 nucleosides in length. In some embodiments, an oligonucleotide is at least 30 nucleosides in length. In some embodiments, an oligonucleotide is at least 31 nucleosides in length. In some embodiments, an oligonucleotide is at least 32 nucleosides in length. In some embodiments, an oligonucleotide is at least 33 nucleosides in length. In some embodiments, an oligonucleotide is at least 34 nucleosides in length. In some embodiments, an oligonucleotide is at least 35 nucleosides in length. In some embodiments, an oligonucleotide is at least 36 nucleosides in length. In some embodiments, an oligonucleotide is at least 37 nucleosides in length. In some embodiments, an oligonucleotide is at least 38 nucleosides in length. In some embodiments, an oligonucleotide is at least 39 nucleosides in length. In some embodiments, an oligonucleotide is at least 40 nucleosides in length. In some embodiments, an oligonucleotide is 25 nucleosides in length. In some embodiments, an oligonucleotide is 26 nucleosides in length. In some embodiments, an oligonucleotide is 27 nucleosides in length. In some embodiments, an oligonucleotide is 28 nucleosides in length. In some embodiments, an oligonucleotide is 29 nucleosides in length. In some embodiments, an oligonucleotide is 30 nucleosides in length. In some embodiments, an oligonucleotide is 31 nucleosides in length. In some embodiments, an oligonucleotide is 32 nucleosides in length. In some embodiments, an oligonucleotide is 33 nucleosides in length. In some embodiments, an oligonucleotide is 34 nucleosides in length. In some Page 22 of 201 12495950v1Attorney Docket No.: 2010581-1440 embodiments, an oligonucleotide is 35 nucleosides in length. In some embodiments, an oligonucleotide is 36 nucleosides in length. In some embodiments, an oligonucleotide is 37 nucleosides in length. In some embodiments, an oligonucleotide is 38 nucleosides in length. In some embodiments, an oligonucleotide is 39 nucleosides in length. In some embodiments, an oligonucleotide is 40 nucleosides in length. In some embodiments, each nucleoside counted in an oligonucleotide length independently comprises a nucleobase comprising a ring having at least one nitrogen ring atom. In some embodiments, each nucleoside counted in an oligonucleotide length independently comprises A, T, C, G, or U, or optionally substituted A, T, C, G, or U, or an optionally substituted tautomer of A, T, C, G or U.

[0048] Optionally Substituted: As described herein, compounds of the disclosure may contain optionally substituted, substituted and / or unsubstituted moieties. In general, the term “substituted,” means that one or more hydrogens of the designated moiety are independently replaced with a substituent. Unless otherwise indicated, an “optionally substituted” group may independently have a substituent at each substitutable position of the group, and when more than one position in any given structure may be substituted with two or more substituents, the substituents may be either the same or different at every position. In some embodiments, an optionally substituted group is unsubstituted. In some embodiments, an optionally substituted group is substituted. Various substituents are described below.

[0049] Monovalent substituents are independently halogen; –(CH2)0–4R°; –(CH2)0–4OR°; −O(CH2)0- 4Ro, –O–(CH2)0–4C(O)OR°; –(CH2)0–4CH(OR°)2; –(CH2)0–4Ph, which may be substituted with R°; −(CH2)0–4O(CH2)0–1Ph which may be substituted with R°; –CH=CHPh, which may be substituted with R°; –(CH2)0–4O(CH2)0–1-pyridyl which may be substituted with R°; –NO2; –CN; –N3; -(CH2)0–4N(R°)2; –(CH2)0–4N(R°)C(O)R°; –N(R°)C(S)R°; –(CH2)0–4N(R°)C(O)N(R°)2; −N(R°)C(S)N(R°)2; –(CH2)0–4N(R°)C(O)OR°; –N(R°)N(R°)C(O)R°; −N(R°)N(R°)C(O)N(R°)2; −N(R°)N(R°)C(O)OR°; –(CH2)0–4C(O)R°; –C(S)R°; –(CH2)0–4C(O)OR°; –(CH2)0–4C(O)SR°; −(CH2)0–4C(O)OSi(R°)3; –(CH2)0–4OC(O)R°; –OC(O)(CH2)0–4SR°, −SC(S)SR°; −(CH2)0–4SC(O)R°; –(CH2)0–4C(O)N(R°)2; –C(S)N(R°)2; –C(S)SR°; −SC(S)SR°, -(CH2)0–4OC(O)N(R°)2; -C(O)N(OR°)R°; –C(O)C(O)R°; –C(O)CH2C(O)R°; −C(NOR°)R°; -(CH2)0–4SSR°; –(CH2)0–4S(O)2R°; –(CH2)0–4S(O)2OR°; –(CH2)0–4OS(O)2R°; −S(O)2N(R°)2; -(CH2)0–4S(O)R°; –N(R°)S(O)2N(R°)2; –N(R°)S(O)2R°; –N(OR°)R°; −C(NH)N(R°)2; – Si(R°)3; –OSi(R°)3; −P(R°)2; −P(OR°)2; −OP(R°)2; −OP(OR°)2; −N(R°)P(R°)2; −B(R°)2; −OB(R°)2; −P(O)(R°)2; −OP(O)(R°)2; −N(R°)P(O)(R°)2; –(C1-4 straight or branched alkylene)O–N(R°)2; or –(C1-4 straight or branched alkylene)C(O)O–N(R°)2; wherein each R° may be independently substituted as defined below and is independently hydrogen, C1-10 (e.g., C1-6, C1-4, etc.) aliphatic, C1-10 (e.g., C1-6, C1-4, etc.) heteroaliphatic having 1-5 heteroatoms independently selected from nitrogen, oxygen, sulfur, silicon and phosphorus, C6-10(e.g., C6, C10, etc.) aryl, 5-10 (e.g., 5-9, 5-6, 5, 6, 9, 10, etc.) membered heteroaryl having Page 23 of 201 12495950v1Attorney Docket No.: 2010581-1440 1-4 heteroatoms independently selected from nitrogen, oxygen and sulfur, −CH2−(C6-10(e.g., C6, C10, etc.) aryl), −O(CH2)0-1(C6-10(e.g., C6, C10, etc.) aryl), −CH2−(5-10 (e.g., 5-9, 5-6, 5, 6, 9, 10, etc.) membered heteroaryl having 1-4 heteroatoms independently selected from nitrogen, oxygen and sulfur), −O(CH2)0-1(5-10 (e.g., 5-9, 5-6, 5, 6, 9, 10, etc.) membered heteroaryl having 1-4 heteroatoms independently selected from nitrogen, oxygen and sulfur), a 3-10 (e.g., 3-6, 5-6, 3, 4, 5, 6, 7, 8, 9, 10, etc.) membered, monocyclic, bicyclic, or polycyclic, saturated, or partially unsaturated ring having 0-5 heteroatoms independently selected from nitrogen, oxygen, sulfur, silicon and phosphorus, or, notwithstanding the definition above, two independent occurrences of R°, taken together with their intervening atom(s), form a 3-10 (e.g., 3-6, 5- 6, 3, 4, 5, 6, 7, 8, 9, 10, etc.) membered, monocyclic, bicyclic, or polycyclic, saturated, partially unsaturated or aromatic ring (for aromatic ring, 5-10 (e.g., 5-9, 5-6, 5, 6, 9, 10, etc.) membered) having, in addition to the intervening atom(s), 0-5 heteroatoms independently selected from nitrogen, oxygen, sulfur, silicon and phosphorus, which may be substituted as defined below.

[0050] Monovalent substituents on R° (or the ring formed by taking two independent occurrences of R° together with their intervening atoms), are independently halogen, –(CH2)0–2R^, –(haloR^), –(CH2)0– 2OH, –(CH2)0–2OR^, –(CH2)0–2CH(OR^)2; –O(haloR^), –CN, –N3, –(CH2)0–2C(O)R^, –(CH2)0–2C(O)OH, – – – – – – – isunsubstituted or where preceded by “halo” is substituted only with one or more halogens, and is independently selected from C1–4aliphatic, –CH2Ph, –O(CH2)0–1Ph, or a 3-6 (e.g., 3-5, 5-6, etc.)-membered saturated, partially unsaturated, or aromatic ring (for aromatic ring, 5- or 6-membered) having 0-4 heteroatoms independently selected from nitrogen, oxygen, and sulfur. Divalent substituents on a saturated carbon atom of R° are independently =O or =S.

[0051] Divalent substituents are independently the following: =O, =S, =NNR*2, =NNHC(O)R*, =NNHC(O)OR*, =NNHS(O)2R*, =NR*, =NOR*, −O(C(R*2))2–3O−, or −S(C(R*2))2–3S−, wherein each independent occurrence of R*is selected from hydrogen, C1-6 aliphatic which may be substituted as defined below, or an unsubstituted 3-6 (e.g., 3-5, 5-6, etc.)-membered saturated, partially unsaturated, or aromatic ring (for aromatic ring, 5- or 6-membered) having 0-4 heteroatoms independently selected from nitrogen, oxygen, and sulfur. Divalent substituents that are bound to vicinal substitutable carbons of an “optionally substituted” group are independently −O(CR*2)2–3O−, wherein each independent occurrence of R*is selected from hydrogen, C1-6aliphatic which may be substituted as defined below, or an unsubstituted 3-6 (e.g., 3-5, 5-6, etc.)-membered saturated, partially unsaturated, or aromatic ring (for aromatic ring, 5- or 6- membered) having 0-4 heteroatoms independently selected from nitrogen, oxygen, and sulfur.

[0052] Substituents on the aliphatic group of R*are independently halogen, –R^, -(haloR^), –OH, −OR^, –O(haloR^), –CN, –C(O)OH, –C(O)OR^, –NH2, –NHR^, –NR^2, or –NO2, wherein each R^is Page 24 of 201 12495950v1Attorney Docket No.: 2010581-1440 unsubstituted or where preceded by “halo” is substituted only with one or more halogens, and is independently C1–4aliphatic, –CH2Ph, –O(CH2)0–1Ph, or a 3-6 (e.g., 3-5, 5-6, etc.)-membered saturated, partially unsaturated, or aromatic ring (for aromatic ring, 5- or 6-membered) having 0-4 heteroatoms independently selected from nitrogen, oxygen, and sulfur.

[0053] Substituents on a substitutable nitrogen are independently –R†, −NR†2, −C(O)R†, –C(O)OR†, – C(O)C(O)R†, –C(O)CH2C(O)R†, –S(O)2R†, –S(O)2NR†2, −C(S)NR†2, –C(NH)NR†2, or –N(R†)S(O)2R†; wherein each R†is independently hydrogen, C1–6aliphatic which may be substituted as defined below, unsubstituted –OPh, or an unsubstituted 3-6 (e.g., 3-5, 5-6, etc.)-membered saturated, partially unsaturated, or aromatic ring (for aromatic ring, 5- or 6-membered) having 0-4 heteroatoms independently selected from nitrogen, oxygen, and sulfur, or, notwithstanding the definition above, two independent occurrences of R†, taken together with their intervening atom(s) form an unsubstituted 3–12 (e.g., 3-10, 3-6, 5-10, 5-6, 3, 4, 5, 6, 7, 8, 9, 10, etc.) membered saturated, partially unsaturated, or aryl mono– or bicyclic ring having 0–4 heteroatoms independently selected from nitrogen, oxygen, and sulfur.

[0054] Substituents on the aliphatic group of R†are independently halogen, −R^, -(haloR^), −OH, – OR^, –O(haloR^), –CN, –C(O)OH, –C(O)OR^, –NH2, –NHR^, –NR^2, or –NO2, wherein each R^is unsubstituted or where preceded by “halo” is substituted only with one or more halogens, and is independently C1–4 aliphatic, –CH2Ph, –O(CH2)0–1Ph, or a 3-6 (e.g., 3-5, 5-6, etc.)-membered saturated, partially unsaturated, or aromatic ring (for aromatic ring, 5- or 6-membered) having 0-4 heteroatoms independently selected from nitrogen, oxygen, and sulfur.

[0055] Partially unsaturated: As used herein, the term “partially unsaturated” refers to a ring moiety that includes at least one double or triple bond. The term “partially unsaturated” is intended to encompass rings having multiple sites of unsaturation, but is not intended to include aryl or heteroaryl moieties, as herein defined.

[0056] Pharmaceutical composition: As used herein, the term “pharmaceutical composition” refers to an active agent, formulated together with one or more pharmaceutically acceptable carriers. In some embodiments, an active agent is present in unit dose amount appropriate for administration in a therapeutic regimen that shows a statistically significant probability of achieving a predetermined therapeutic effect when administered to a relevant population. In some embodiments, pharmaceutical compositions may be specially formulated for administration in solid or liquid form, including those adapted for the following: oral administration, for example, drenches (aqueous or non-aqueous solutions or suspensions), tablets, e.g., those targeted for buccal, sublingual, and systemic absorption, boluses, powders, granules, pastes for application to the tongue; parenteral administration, for example, by subcutaneous, intramuscular, intravenous or epidural injection as, for example, a sterile solution or suspension, or sustained-release formulation; topical application, for example, as a cream, ointment, or a controlled-release patch or spray Page 25 of 201 12495950v1Attorney Docket No.: 2010581-1440 applied to the skin, lungs, or oral cavity; intravaginally or intrarectally, for example, as a pessary, cream, or foam; sublingually; ocularly; transdermally; or nasally, pulmonary, and to other mucosal surfaces.

[0057] Pharmaceutically acceptable: As used herein, the phrase “pharmaceutically acceptable” refers to those compounds, materials, compositions and / or dosage forms which are, within the scope of sound medical judgment, suitable for use in contact with the tissues of human beings and animals without excessive toxicity, irritation, allergic response, or other problem or complication, commensurate with a reasonable benefit / risk ratio.

[0058] Pharmaceutically acceptable carrier: As used herein, the term “pharmaceutically acceptable carrier” means a pharmaceutically-acceptable material, composition or vehicle, such as a liquid or solid filler, diluent, excipient, or solvent encapsulating material, involved in carrying or transporting the subject compound from one organ, or portion of the body, to another organ, or portion of the body. Each carrier must be “acceptable” in the sense of being compatible with the other ingredients of the formulation and not injurious to the patient. Some examples of materials which can serve as pharmaceutically-acceptable carriers include: sugars, such as lactose, glucose and sucrose; starches, such as corn starch and potato starch; cellulose, and its derivatives, such as sodium carboxymethyl cellulose, ethyl cellulose and cellulose acetate; powdered tragacanth; malt; gelatin; talc; excipients, such as cocoa butter and suppository waxes; oils, such as peanut oil, cottonseed oil, safflower oil, sesame oil, olive oil, corn oil and soybean oil; glycols, such as propylene glycol; polyols, such as glycerin, sorbitol, mannitol and polyethylene glycol; esters, such as ethyl oleate and ethyl laurate; agar; buffering agents, such as magnesium hydroxide and aluminum hydroxide; alginic acid; pyrogen-free water; isotonic saline; Ringer’s solution; ethyl alcohol; pH buffered solutions; polyesters, polycarbonates and / or polyanhydrides; and other non-toxic compatible substances employed in pharmaceutical formulations.

[0059] Pharmaceutically acceptable salt: The term “pharmaceutically acceptable salt”, as used herein, refers to salts of such compounds that are appropriate for use in pharmaceutical contexts, i.e., salts which are, within the scope of sound medical judgment, suitable for use in contact with the tissues of humans and lower animals without undue toxicity, irritation, allergic response and the like, and are commensurate with a reasonable benefit / risk ratio. Pharmaceutically acceptable salts are well known in the art. For example, S. M. Berge, et al. describes pharmaceutically acceptable salts in detail in J. Pharmaceutical Sciences, 66: 1-19 (1977). In some embodiments, pharmaceutically acceptable salt include, but are not limited to, nontoxic acid addition salts, which are salts of an amino group formed with inorganic acids such as hydrochloric acid, hydrobromic acid, phosphoric acid, sulfuric acid and perchloric acid or with organic acids such as acetic acid, maleic acid, tartaric acid, citric acid, succinic acid or malonic acid or by using other methods used in the art such as ion exchange. In some embodiments, pharmaceutically acceptable salts include, but are not limited to, adipate, alginate, ascorbate, aspartate, benzenesulfonate, benzoate, Page 26 of 201 12495950v1Attorney Docket No.: 2010581-1440 bisulfate, borate, butyrate, camphorate, camphorsulfonate, citrate, cyclopentanepropionate, digluconate, dodecylsulfate, ethanesulfonate, formate, fumarate, glucoheptonate, glycerophosphate, gluconate, hemisulfate, heptanoate, hexanoate, hydroiodide, 2-hydroxy-ethanesulfonate, lactobionate, lactate, laurate, lauryl sulfate, malate, maleate, malonate, methanesulfonate, 2-naphthalenesulfonate, nicotinate, nitrate, oleate, oxalate, palmitate, pamoate, pectinate, persulfate, 3-phenylpropionate, phosphate, picrate, pivalate, propionate, stearate, succinate, sulfate, tartrate, thiocyanate, p-toluenesulfonate, undecanoate, valerate salts, and the like. In some embodiments, a provided compound comprises one or more acidic groups, e.g., an oligonucleotide, and a pharmaceutically acceptable salt is an alkali, alkaline earth metal, or ammonium (e.g., an ammonium salt of N(R)3, wherein each R is independently defined and described in the present disclosure) salt. Representative alkali or alkaline earth metal salts include sodium, lithium, potassium, calcium, magnesium, and the like. In some embodiments, a pharmaceutically acceptable salt is a sodium salt. In some embodiments, a pharmaceutically acceptable salt is a potassium salt. In some embodiments, a pharmaceutically acceptable salt is a calcium salt. In some embodiments, pharmaceutically acceptable salts include, when appropriate, nontoxic ammonium, quaternary ammonium, and amine cations formed using counterions such as halide, hydroxide, carboxylate, sulfate, phosphate, nitrate, alkyl having from 1 to 6 carbon atoms, sulfonate and aryl sulfonate. In some embodiments, a provided compound comprises more than one acid groups, for example, an oligonucleotide may comprise two or more acidic groups (e.g., in natural phosphate linkages and / or modified internucleotidic linkages). In some embodiments, a pharmaceutically acceptable salt, or generally a salt, of such a compound comprises two or more cations, which can be the same or different. In some embodiments, in a pharmaceutically acceptable salt (or generally, a salt), all ionizable hydrogen (e.g., in an aqueous solution with a pKa no more than about 11, 10, 9, 8, 7, 6, 5, 4, 3, or 2; in some embodiments, no more than about 7; in some embodiments, no more than about 6; in some embodiments, no more than about 5; in some embodiments, no more than about 4; in some embodiments, no more than about 3) in the acidic groups are replaced with cations. In some embodiments, each phosphorothioate and phosphate group independently exists in its salt form (e.g., if sodium salt, −O−P(O)(SNa)−O− and −O−P(O)(ONa)−O−, respectively). In some embodiments, each phosphorothioate and phosphate internucleotidic linkage independently exists in its salt form (e.g., if sodium salt, −O−P(O)(SNa)−O− and −O−P(O)(ONa)−O−, respectively). In some embodiments, a pharmaceutically acceptable salt is a sodium salt of an oligonucleotide. In some embodiments, a pharmaceutically acceptable salt is a sodium salt of an oligonucleotide, wherein each acidic phosphate and modified phosphate group (e.g., phosphorothioate, phosphate, etc.), if any, exists as a salt form (all sodium salt).

[0060] Predetermined: By predetermined (or pre-determined) is meant deliberately selected or non- random or controlled, for example as opposed to randomly occurring, random, or achieved without control. Page 27 of 201 12495950v1Attorney Docket No.: 2010581-1440 Those of ordinary skill in the art, reading the present specification, will appreciate that the present disclosure provides technologies that permit selection of particular chemistry and / or stereochemistry features to be incorporated into oligonucleotide compositions, and further permits controlled preparation of oligonucleotide compositions having such chemistry and / or stereochemistry features. Such provided compositions are “predetermined” as described herein. Compositions that may contain certain oligonucleotides because they happen to have been generated through a process that are not controlled to intentionally generate the particular chemistry and / or stereochemistry features are not “predetermined” compositions. In some embodiments, a predetermined composition is one that can be intentionally reproduced (e.g., through repetition of a controlled process). In some embodiments, a predetermined level of a plurality of oligonucleotides in a composition means that the absolute amount, and / or the relative amount (ratio, percentage, etc.) of the plurality of oligonucleotides in the composition is controlled. In some embodiments, a predetermined level of a plurality of oligonucleotides in a composition is achieved through chirally controlled oligonucleotide preparation.

[0061] Protecting group: The term “protecting group,” as used herein, is well known in the art and includes those described in detail in Protecting Groups in Organic Synthesis, T. W. Greene and P. G. M. Wuts, 3rdedition, John Wiley & Sons, 1999, the entirety of which is incorporated herein by reference. Also included are those protecting groups specially adapted for nucleoside and nucleotide chemistry described in Current Protocols in Nucleic Acid Chemistry, edited by Serge L. Beaucage et al.06 / 2012, the entirety of Chapter 2 is incorporated herein by reference. Suitable amino–protecting groups include methyl carbamate, ethyl carbamante, 9–fluorenylmethyl carbamate (Fmoc), 9–(2–sulfo)fluorenylmethyl carbamate, 9–(2,7– dibromo)fluoroenylmethyl carbamate, 2,7–di–t–butyl–[9–(10,10–dioxo–10,10,10,10– tetrahydrothioxanthyl)]methyl carbamate (DBD–Tmoc), 4–methoxyphenacyl carbamate (Phenoc), 2,2,2– trichloroethyl carbamate (Troc), 2–trimethylsilylethyl carbamate (Teoc), 2–phenylethyl carbamate (hZ), 1– (1–adamantyl)–1–methylethyl carbamate (Adpoc), 1,1–dimethyl–2–haloethyl carbamate, 1,1–dimethyl– 2,2–dibromoethyl carbamate (DB–t–BOC), 1,1–dimethyl–2,2,2–trichloroethyl carbamate (TCBOC), 1– methyl–1–(4–biphenylyl)ethyl carbamate (Bpoc), 1–(3,5–di–t–butylphenyl)–1–methylethyl carbamate (t– Bumeoc), 2–(2’– and 4’–pyridyl)ethyl carbamate (Pyoc), 2–(N,N–dicyclohexylcarboxamido)ethyl carbamate, t–butyl carbamate (BOC), 1–adamantyl carbamate (Adoc), vinyl carbamate (Voc), allyl carbamate (Alloc), 1–isopropylallyl carbamate (Ipaoc), cinnamyl carbamate (Coc), 4–nitrocinnamyl carbamate (Noc), 8–quinolyl carbamate, N–hydroxypiperidinyl carbamate, alkyldithio carbamate, benzyl carbamate (Cbz), p–methoxybenzyl carbamate (Moz), p–nitobenzyl carbamate, p–bromobenzyl carbamate, p–chlorobenzyl carbamate, 2,4–dichlorobenzyl carbamate, 4–methylsulfinylbenzyl carbamate (Msz), 9– anthrylmethyl carbamate, diphenylmethyl carbamate, 2–methylthioethyl carbamate, 2–methylsulfonylethyl carbamate, 2–(p–toluenesulfonyl)ethyl carbamate, [2–(1,3–dithianyl)]methyl carbamate (Dmoc), 4– Page 28 of 201 12495950v1Attorney Docket No.: 2010581-1440 methylthiophenyl carbamate (Mtpc), 2,4–dimethylthiophenyl carbamate (Bmpc), 2–phosphonioethyl carbamate (Peoc), 2–triphenylphosphonioisopropyl carbamate (Ppoc), 1,1–dimethyl–2–cyanoethyl carbamate, m–chloro–p–acyloxybenzyl carbamate, p–(dihydroxyboryl)benzyl carbamate, 5– benzisoxazolylmethyl carbamate, 2–(trifluoromethyl)–6–chromonylmethyl carbamate (Tcroc), m– nitrophenyl carbamate, 3,5–dimethoxybenzyl carbamate, o–nitrobenzyl carbamate, 3,4–dimethoxy–6– nitrobenzyl carbamate, phenyl(o–nitrophenyl)methyl carbamate, phenothiazinyl–(10)–carbonyl derivative, N’–p–toluenesulfonylaminocarbonyl derivative, N’–phenylaminothiocarbonyl derivative, t–amyl carbamate, S–benzyl thiocarbamate, p–cyanobenzyl carbamate, cyclobutyl carbamate, cyclohexyl carbamate, cyclopentyl carbamate, cyclopropylmethyl carbamate, p–decyloxybenzyl carbamate, 2,2– dimethoxycarbonylvinyl carbamate, o–(N,N–dimethylcarboxamido)benzyl carbamate, 1,1–dimethyl–3– (N,N–dimethylcarboxamido)propyl carbamate, 1,1–dimethylpropynyl carbamate, di(2–pyridyl)methyl carbamate, 2–furanylmethyl carbamate, 2–iodoethyl carbamate, isoborynl carbamate, isobutyl carbamate, isonicotinyl carbamate, p–(p’–methoxyphenylazo)benzyl carbamate, 1–methylcyclobutyl carbamate, 1– methylcyclohexyl carbamate, 1–methyl–1–cyclopropylmethyl carbamate, 1–methyl–1–(3,5– dimethoxyphenyl)ethyl carbamate, 1–methyl–1–(p–phenylazophenyl)ethyl carbamate, 1–methyl–1– phenylethyl carbamate, 1–methyl–1–(4–pyridyl)ethyl carbamate, phenyl carbamate, p–(phenylazo)benzyl carbamate, 2,4,6–tri–t–butylphenyl carbamate, 4–(trimethylammonium)benzyl carbamate, 2,4,6– trimethylbenzyl carbamate, formamide, acetamide, chloroacetamide, trichloroacetamide, trifluoroacetamide, phenylacetamide, 3–phenylpropanamide, picolinamide, 3–pyridylcarboxamide, N– benzoylphenylalanyl derivative, benzamide, p–phenylbenzamide, o–nitophenylacetamide, o– nitrophenoxyacetamide, acetoacetamide, (N’–dithiobenzyloxycarbonylamino)acetamide, 3–(p– hydroxyphenyl)propanamide, 3–(o–nitrophenyl)propanamide, 2–methyl–2–(o– nitrophenoxy)propanamide, 2–methyl–2–(o–phenylazophenoxy)propanamide, 4–chlorobutanamide, 3– methyl–3–nitrobutanamide, o–nitrocinnamide, N–acetylmethionine derivative, o–nitrobenzamide, o– (benzoyloxymethyl)benzamide, 4,5–diphenyl–3–oxazolin–2–one, N–phthalimide, N–dithiasuccinimide (Dts), N–2,3–diphenylmaleimide, N–2,5–dimethylpyrrole, N–1,1,4,4–tetramethyldisilylazacyclopentane adduct (STABASE), 5–substituted 1,3–dimethyl–1,3,5–triazacyclohexan–2–one, 5–substituted 1,3– dibenzyl–1,3,5–triazacyclohexan–2–one, 1–substituted 3,5–dinitro–4–pyridone, N–methylamine, N– allylamine, N–[2–(trimethylsilyl)ethoxy]methylamine (SEM), N–3–acetoxypropylamine, N–(1– isopropyl–4–nitro–2–oxo–3–pyroolin–3–yl)amine, quaternary ammonium salts, N–benzylamine, N–di(4– methoxyphenyl)methylamine, N–5–dibenzosuberylamine, N–triphenylmethylamine (Tr), N–[(4– methoxyphenyl)diphenylmethyl]amine (MMTr), N–9–phenylfluorenylamine (PhF), N–2,7–dichloro–9– fluorenylmethyleneamine, N–ferrocenylmethylamino (Fcm), N–2–picolylamino N’–oxide, N–1,1– dimethylthiomethyleneamine, N–benzylideneamine, N–p–methoxybenzylideneamine, N– Page 29 of 201 12495950v1Attorney Docket No.: 2010581-1440 diphenylmethyleneamine, N–[(2–pyridyl)mesityl]methyleneamine, N–(N’,N’– dimethylaminomethylene)amine, N,N’–isopropylidenediamine, N–p–nitrobenzylideneamine, N– salicylideneamine, N–5–chlorosalicylideneamine, N–(5–chloro–2– hydroxyphenyl)phenylmethyleneamine, N–cyclohexylideneamine, N–(5,5–dimethyl–3–oxo–1– cyclohexenyl)amine, N–borane derivative, N–diphenylborinic acid derivative, N– [phenyl(pentacarbonylchromium– or tungsten)carbonyl]amine, N–copper chelate, N–zinc chelate, N– nitroamine, N–nitrosoamine, amine N–oxide, diphenylphosphinamide (Dpp), dimethylthiophosphinamide (Mpt), diphenylthiophosphinamide (Ppt), dialkyl phosphoramidates, dibenzyl phosphoramidate, diphenyl phosphoramidate, benzenesulfenamide, o–nitrobenzenesulfenamide (Nps), 2,4– dinitrobenzenesulfenamide, pentachlorobenzenesulfenamide, 2–nitro–4–methoxybenzenesulfenamide, triphenylmethylsulfenamide, 3–nitropyridinesulfenamide (Npys), p–toluenesulfonamide (Ts), benzenesulfonamide, 2,3,6,–trimethyl–4–methoxybenzenesulfonamide (Mtr), 2,4,6– trimethoxybenzenesulfonamide (Mtb), 2,6–dimethyl–4–methoxybenzenesulfonamide (Pme), 2,3,5,6– tetramethyl–4–methoxybenzenesulfonamide (Mte), 4–methoxybenzenesulfonamide (Mbs), 2,4,6– trimethylbenzenesulfonamide (Mts), 2,6–dimethoxy–4–methylbenzenesulfonamide (iMds), 2,2,5,7,8– pentamethylchroman–6–sulfonamide (Pmc), methanesulfonamide (Ms), β– trimethylsilylethanesulfonamide (SES), 9–anthracenesulfonamide, 4–(4’,8’– dimethoxynaphthylmethyl)benzenesulfonamide (DNMBS), benzylsulfonamide, trifluoromethylsulfonamide, and phenacylsulfonamide.

[0062] Suitably protected carboxylic acids further include, but are not limited to, silyl–, alkyl–, alkenyl–, aryl–, and arylalkyl–protected carboxylic acids. Examples of suitable silyl groups include trimethylsilyl, triethylsilyl, t–butyldimethylsilyl, t–butyldiphenylsilyl, triisopropylsilyl, and the like. Examples of suitable alkyl groups include methyl, benzyl, p–methoxybenzyl, 3,4–dimethoxybenzyl, trityl, t–butyl, tetrahydropyran–2–yl. Examples of suitable alkenyl groups include allyl. Examples of suitable aryl groups include optionally substituted phenyl, biphenyl, or naphthyl. Examples of suitable arylalkyl groups include optionally substituted benzyl (e.g., p–methoxybenzyl (MPM), 3,4–dimethoxybenzyl, O– nitrobenzyl, p–nitrobenzyl, p–halobenzyl, 2,6–dichlorobenzyl, p–cyanobenzyl), and 2– and 4–picolyl.

[0063] Suitable hydroxyl protecting groups include methyl, methoxylmethyl (MOM), methylthiomethyl (MTM), t–butylthiomethyl, (phenyldimethylsilyl)methoxymethyl (SMOM), benzyloxymethyl (BOM), p–methoxybenzyloxymethyl (PMBM), (4–methoxyphenoxy)methyl (p–AOM), guaiacolmethyl (GUM), t–butoxymethyl, 4–pentenyloxymethyl (POM), siloxymethyl, 2– methoxyethoxymethyl (MEM), 2,2,2–trichloroethoxymethyl, bis(2–chloroethoxy)methyl, 2– (trimethylsilyl)ethoxymethyl (SEMOR), tetrahydropyranyl (THP), 3–bromotetrahydropyranyl, tetrahydrothiopyranyl, 1–methoxycyclohexyl, 4–methoxytetrahydropyranyl (MTHP), 4– Page 30 of 201 12495950v1Attorney Docket No.: 2010581-1440 methoxytetrahydrothiopyranyl, 4–methoxytetrahydrothiopyranyl S,S–dioxide, 1–[(2–chloro–4– methyl)phenyl]–4–methoxypiperidin–4–yl (CTMP), 1,4–dioxan–2–yl, tetrahydrofuranyl, tetrahydrothiofuranyl, 2,3,3a,4,5,6,7,7a–octahydro–7,8,8–trimethyl–4,7–methanobenzofuran–2–yl, 1– ethoxyethyl, 1–(2–chloroethoxy)ethyl, 1–methyl–1–methoxyethyl, 1–methyl–1–benzyloxyethyl, 1– methyl–1–benzyloxy–2–fluoroethyl, 2,2,2–trichloroethyl, 2–trimethylsilylethyl, 2–(phenylselenyl)ethyl, t– butyl, allyl, p–chlorophenyl, p–methoxyphenyl, 2,4–dinitrophenyl, benzyl, p–methoxybenzyl, 3,4– dimethoxybenzyl, o–nitrobenzyl, p–nitrobenzyl, p–halobenzyl, 2,6–dichlorobenzyl, p–cyanobenzyl, p– phenylbenzyl, 2–picolyl, 4–picolyl, 3–methyl–2–picolyl N–oxido, diphenylmethyl, p,p’– dinitrobenzhydryl, 5–dibenzosuberyl, triphenylmethyl, α–naphthyldiphenylmethyl, p– methoxyphenyldiphenylmethyl, di(p–methoxyphenyl)phenylmethyl, tri(p–methoxyphenyl)methyl, 4–(4’– bromophenacyloxyphenyl)diphenylmethyl, 4,4’,4’’–tris(4,5–dichlorophthalimidophenyl)methyl, 4,4’,4’’– tris(levulinoyloxyphenyl)methyl, 4,4’,4’’–tris(benzoyloxyphenyl)methyl, 3–(imidazol–1–yl)bis(4’,4’’– dimethoxyphenyl)methyl, 1,1–bis(4–methoxyphenyl)–1’–pyrenylmethyl, 9–anthryl, 9–(9– phenyl)xanthenyl, 9–(9–phenyl–10–oxo)anthryl, 1,3–benzodithiolan–2–yl, benzisothiazolyl S,S–dioxido, trimethylsilyl (TMS), triethylsilyl (TES), triisopropylsilyl (TIPS), dimethylisopropylsilyl (IPDMS), diethylisopropylsilyl (DEIPS), dimethylthexylsilyl, t–butyldimethylsilyl (TBDMS), t–butyldiphenylsilyl (TBDPS), tribenzylsilyl, tri–p–xylylsilyl, triphenylsilyl, diphenylmethylsilyl (DPMS), t– butylmethoxyphenylsilyl (TBMPS), formate, benzoylformate, acetate, chloroacetate, dichloroacetate, trichloroacetate, trifluoroacetate, methoxyacetate, triphenylmethoxyacetate, phenoxyacetate, p– chlorophenoxyacetate, 3–phenylpropionate, 4–oxopentanoate (levulinate), 4,4–(ethylenedithio)pentanoate (levulinoyldithioacetal), pivaloate, adamantoate, crotonate, 4–methoxycrotonate, benzoate, p– phenylbenzoate, 2,4,6–trimethylbenzoate (mesitoate), alkyl methyl carbonate, 9–fluorenylmethyl carbonate (Fmoc), alkyl ethyl carbonate, alkyl 2,2,2–trichloroethyl carbonate (Troc), 2– (trimethylsilyl)ethyl carbonate (TMSEC), 2–(phenylsulfonyl) ethyl carbonate (Psec), 2– (triphenylphosphonio) ethyl carbonate (Peoc), alkyl isobutyl carbonate, alkyl vinyl carbonate alkyl allyl carbonate, alkyl p–nitrophenyl carbonate, alkyl benzyl carbonate, alkyl p–methoxybenzyl carbonate, alkyl 3,4–dimethoxybenzyl carbonate, alkyl o–nitrobenzyl carbonate, alkyl p–nitrobenzyl carbonate, alkyl S– benzyl thiocarbonate, 4–ethoxy–1–napththyl carbonate, methyl dithiocarbonate, 2–iodobenzoate, 4– azidobutyrate, 4–nitro–4–methylpentanoate, o–(dibromomethyl)benzoate, 2–formylbenzenesulfonate, 2– (methylthiomethoxy)ethyl, 4–(methylthiomethoxy)butyrate, 2–(methylthiomethoxymethyl)benzoate, 2,6– dichloro–4–methylphenoxyacetate, 2,6–dichloro–4–(1,1,3,3–tetramethylbutyl)phenoxyacetate, 2,4– bis(1,1–dimethylpropyl)phenoxyacetate, chlorodiphenylacetate, isobutyrate, monosuccinoate, (E)–2– methyl–2–butenoate, o–(methoxycarbonyl)benzoate, α–naphthoate, nitrate, alkyl N,N,N’,N’– tetramethylphosphorodiamidate, alkyl N–phenylcarbamate, borate, dimethylphosphinothioyl, alkyl 2,4– Page 31 of 201 12495950v1Attorney Docket No.: 2010581-1440 dinitrophenylsulfenate, sulfate, methanesulfonate (mesylate), benzylsulfonate, and tosylate (Ts). For protecting 1,2– or 1,3–diols, the protecting groups include methylene acetal, ethylidene acetal, 1–t– butylethylidene ketal, 1–phenylethylidene ketal, (4–methoxyphenyl)ethylidene acetal, 2,2,2– trichloroethylidene acetal, acetonide, cyclopentylidene ketal, cyclohexylidene ketal, cycloheptylidene ketal, benzylidene acetal, p–methoxybenzylidene acetal, 2,4–dimethoxybenzylidene ketal, 3,4– dimethoxybenzylidene acetal, 2–nitrobenzylidene acetal, methoxymethylene acetal, ethoxymethylene acetal, dimethoxymethylene ortho ester, 1–methoxyethylidene ortho ester, 1–ethoxyethylidine ortho ester, 1,2–dimethoxyethylidene ortho ester, α–methoxybenzylidene ortho ester, 1–(N,N– dimethylamino)ethylidene derivative, α–(N,N’–dimethylamino)benzylidene derivative, 2– oxacyclopentylidene ortho ester, di–t–butylsilylene group (DTBS), 1,3–(1,1,3,3– tetraisopropyldisiloxanylidene) derivative (TIPDS), tetra–t–butoxydisiloxane–1,3–diylidene derivative (TBDS), cyclic carbonates, cyclic boronates, ethyl boronate, and phenyl boronate.

[0064] In some embodiments, a hydroxyl protecting group is acetyl, t-butyl, tbutoxymethyl, methoxymethyl, tetrahydropyranyl, 1 -ethoxyethyl, 1 -(2-chloroethoxy)ethyl, 2- trimethylsilylethyl, p- chlorophenyl, 2,4-dinitrophenyl, benzyl, benzoyl, p-phenylbenzoyl, 2,6- dichlorobenzyl, diphenylmethyl, p-nitrobenzyl, triphenylmethyl (trityl), 4,4'-dimethoxytrityl, trimethylsilyl, triethylsilyl, t- butyldimethylsilyl, t-butyldiphenylsilyl, triphenylsilyl, triisopropylsilyl, benzoylformate, chloroacetyl, trichloroacetyl, trifiuoroacetyl, pivaloyl, 9- fluorenylmethyl carbonate, mesylate, tosylate, triflate, trityl, monomethoxytrityl (MMTr), 4,4'-dimethoxytrityl, (DMTr) and 4,4',4''-trimethoxytrityl (TMTr), 2- cyanoethyl (CE or Cne), 2-(trimethylsilyl)ethyl (TSE), 2-(2-nitrophenyl)ethyl, 2-(4-cyanophenyl)ethyl 2- (4-nitrophenyl)ethyl (NPE), 2-(4-nitrophenylsulfonyl)ethyl, 3,5-dichlorophenyl, 2,4-dimethylphenyl, 2- nitrophenyl, 4-nitrophenyl, 2,4,6-trimethylphenyl, 2-(2-nitrophenyl)ethyl, butylthiocarbonyl, 4,4',4''- tris(benzoyloxy)trityl, diphenylcarbamoyl, levulinyl, 2-(dibromomethyl)benzoyl (Dbmb), 2- (isopropylthiomethoxymethyl)benzoyl (Ptmt), 9-phenylxanthen-9-yl (pixyl) or 9-(p- methoxyphenyl)xanthine-9-y1 (MOX). In some embodiments, each of the hydroxyl protecting groups is, independently selected from acetyl, benzyl, t- butyldimethylsilyl, t-butyldiphenylsilyl and 4,4'- dimethoxytrityl. In some embodiments, the hydroxyl protecting group is selected from the group consisting of trityl, monomethoxytrityl and 4,4'-dimethoxytrityl group. In some embodiments, a phosphorous linkage protecting group is a group attached to the phosphorous linkage (e.g., an internucleotidic linkage) throughout oligonucleotide synthesis. In some embodiments, a protecting group is attached to a sulfur atom of an phosphorothioate group. In some embodiments, a protecting group is attached to an oxygen atom of an internucleotide phosphorothioate linkage. In some embodiments, a protecting group is attached to an oxygen atom of the internucleotide phosphate linkage. In some embodiments a protecting group is 2- cyanoethyl (CE or Cne), 2-trimethylsilylethyl, 2-nitroethyl, 2-sulfonylethyl, methyl, benzyl, o-nitrobenzyl, Page 32 of 201 12495950v1Attorney Docket No.: 2010581-1440 2-(p-nitrophenyl)ethyl (NPE or Npe), 2-phenylethyl, 3-(N-tert-butylcarboxamido)-1-propyl, 4-oxopentyl, 4-methylthio-l-butyl, 2-cyano-1,1-dimethylethyl, 4-N-methylaminobutyl, 3-(2-pyridyl)-1-propyl, 2-[N- methyl-N-(2-pyridyl)]aminoethyl, 2-(N-formyl,N-methyl)aminoethyl, or 4-[N-methyl-N-(2,2,2- trifluoroacetyl)amino]butyl.

[0065] Subject: As used herein, the term “subject” or “test subject” refers to any organism to which a compound (e.g., an oligonucleotide) or composition is administered in accordance with the present disclosure e.g., for experimental, diagnostic, prophylactic and / or therapeutic purposes. Typical subjects include animals (e.g., mammals such as mice, rats, rabbits, non-human primates, and humans; insects; worms; etc.) and plants. In some embodiments, a subject is a human. In some embodiments, a subject may be suffering from and / or susceptible to a disease, disorder and / or condition.

[0066] Substantially: As used herein, the term “substantially” refers to the qualitative condition of exhibiting total or near-total extent or degree of a characteristic or property of interest. A base sequence which is substantially identical or complementary to a second sequence is not fully identical or complementary to the second sequence, but is mostly or nearly identical or complementary to the second sequence. In some embodiments, an oligonucleotide with a substantially complementary sequence to another oligonucleotide or nucleic acid forms duplex with the oligonucleotide or nucleic acid in a similar fashion as an oligonucleotide with a fully complementary sequence. In addition, one of ordinary skill in the biological and / or chemical arts will understand that biological and chemical phenomena rarely, if ever, go to completion and / or proceed to completeness or achieve or avoid an absolute result. The term “substantially” is therefore used herein to capture the potential lack of completeness inherent in many biological and / or chemical phenomena.

[0067] Sugar: The term “sugar” refers to a monosaccharide or polysaccharide in closed and / or open form. In some embodiments, sugars are monosaccharides. In some embodiments, sugars are polysaccharides. Sugars include, but are not limited to, ribose, deoxyribose, pentofuranose, pentopyranose, and hexopyranose moieties. As used herein, the term “sugar” also encompasses structural analogs used in lieu of conventional sugar molecules, such as glycol, polymer of which forms the backbone of the nucleic acid analog, glycol nucleic acid (“GNA”), etc. As used herein, the term “sugar” also encompasses structural analogs used in lieu of natural or naturally-occurring nucleotides, such as modified sugars and nucleotide sugars. In some embodiments, a sugar is a RNA or DNA sugar (ribose or deoxyribose). In some embodiments, a sugar is a modified ribose or deoxyribose sugar, e.g., 2’-modified, 5’-modified, etc. As described herein, in some embodiments, when used in oligonucleotides and / or nucleic acids, modified sugars may provide one or more desired properties, activities, etc. In some embodiments, a sugar is optionally substituted ribose or deoxyribose. In some embodiments, a “sugar” refers to a sugar unit in an oligonucleotide or a nucleic acid. Page 33 of 201 12495950v1Attorney Docket No.: 2010581-1440

[0068] Susceptible to: An individual who is “susceptible to” a disease, disorder and / or condition is one who has a higher risk of developing the disease, disorder and / or condition than does a member of the general public. In some embodiments, an individual who is susceptible to a disease, disorder and / or condition is predisposed to have that disease, disorder and / or condition. In some embodiments, an individual who is susceptible to a disease, disorder and / or condition may not have been diagnosed with the disease, disorder and / or condition. In some embodiments, an individual who is susceptible to a disease, disorder and / or condition may exhibit symptoms of the disease, disorder and / or condition. In some embodiments, an individual who is susceptible to a disease, disorder and / or condition may not exhibit symptoms of the disease, disorder and / or condition. In some embodiments, an individual who is susceptible to a disease, disorder, and / or condition will develop the disease, disorder, and / or condition. In some embodiments, an individual who is susceptible to a disease, disorder, and / or condition will not develop the disease, disorder, and / or condition.

[0069] Therapeutic agent: As used herein, the term “therapeutic agent” in general refers to any agent that elicits a desired effect (e.g., a desired biological, clinical, or pharmacological effect) when administered to a subject. In some embodiments, an agent is considered to be a therapeutic agent if it demonstrates a statistically significant effect across an appropriate population. In some embodiments, an appropriate population is a population of subjects suffering from and / or susceptible to a disease, disorder or condition. In some embodiments, an appropriate population is a population of model organisms. In some embodiments, an appropriate population may be defined by one or more criterion such as age group, gender, genetic background, preexisting clinical conditions, prior exposure to therapy. In some embodiments, a therapeutic agent is a substance that alleviates, ameliorates, relieves, inhibits, prevents, delays onset of, reduces severity of, and / or reduces incidence of one or more symptoms or features of a disease, disorder, and / or condition in a subject when administered to the subject in an effective amount. In some embodiments, a “therapeutic agent” is an agent that has been or is required to be approved by a government agency before it can be marketed for administration to humans. In some embodiments, a “therapeutic agent” is an agent for which a medical prescription is required for administration to humans. In some embodiments, a therapeutic agent is a provided compound, e.g., a provided oligonucleotide.

[0070] Therapeutically effective amount: As used herein, the term “therapeutically effective amount” means an amount of a substance (e.g., a therapeutic agent, composition, and / or formulation) that elicits a desired biological response when administered as part of a therapeutic regimen. In some embodiments, a therapeutically effective amount of a substance is an amount that is sufficient, when administered to a subject suffering from or susceptible to a disease, disorder, and / or condition, to treat, diagnose, prevent, and / or delay the onset of the disease, disorder, and / or condition. As will be appreciated by those of ordinary skill in this art, the effective amount of a substance may vary depending on such factors as the desired Page 34 of 201 12495950v1Attorney Docket No.: 2010581-1440 biological endpoint, the substance to be delivered, the target cell or tissue, etc. For example, the effective amount of compound in a formulation to treat a disease, disorder, and / or condition is the amount that alleviates, ameliorates, relieves, inhibits, prevents, delays onset of, reduces severity of and / or reduces incidence of one or more symptoms or features of the disease, disorder, and / or condition. In some embodiments, a therapeutically effective amount is administered in a single dose; in some embodiments, multiple unit doses are required to deliver a therapeutically effective amount.

[0071] Treat: As used herein, the term “treat,” “treatment,” or “treating” refers to any method used to partially or completely alleviate, ameliorate, relieve, inhibit, prevent, delay onset of, reduce severity of, and / or reduce incidence of one or more symptoms or features of a disease, disorder, and / or condition. Treatment may be administered to a subject who does not exhibit signs of a disease, disorder, and / or condition. In some embodiments, treatment may be administered to a subject who exhibits only early signs of the disease, disorder, and / or condition, for example for the purpose of decreasing the risk of developing pathology associated with the disease, disorder, and / or condition.

[0072] Unsaturated: The term "unsaturated," as used herein, means that a moiety has one or more units of unsaturation.

[0073] As those skilled in the art will appreciate, methods and compositions described herein relating to provided compounds (e.g., oligonucleotides) generally also apply to pharmaceutically acceptable salts of such compounds. Description of Certain Embodiments

[0074] Certain embodiments are described below as examples.

[0075] Among other things, the present disclosure encompass the recognition that traditional technologies for incorporating −P(O)(OH)2 groups into compounds, e.g., utilization of protected groups such as −P(O)(OMe)2, −P(O)(OEt)2, etc., often utilize deprotection conditions that can reduce efficiency and / or increase cost of manufacturing. For example, when −P(O)(OMe)2, −P(O)(OEt)2, etc., are utilized to incorporate −P(O)(OH)2 into oligonucleotides, removal of the methyl or ethyl groups may require extra steps and / or harsher reaction conditions which can lead to lower manufacturing efficiency, lower oligonucleotide yields and / or purity, and / or increased cost compared to manufacturing of reference oligonucleotides without −P(O)(OH)2(e.g., otherwise identical oligonucleotides without −P(O)(OH)2).

[0076] In some embodiments, the present disclosure provides technologies for incorporating −P(O)(OH)2into compounds, e.g., oligonucleotides which technologies can provide higher yield, higher purity, higher efficiency, lower operation complexity, milder reaction condition, shorter preparation time, and / or lower cost, etc. when compared to using, e.g., −P(O)(OMe)2, or −P(O)(OEt)2. In some embodiments, the present disclosure provides protected −P(O)(OH)2groups which can be deprotected Page 35 of 201 12495950v1Attorney Docket No.: 2010581-1440 under oligonucleotide synthesis conditions, e.g., during cleavage and / or deprotection, utilized for oligonucleotides without −P(O)(OH)2groups. In some embodiments, provided technologies are useful for preparing stereorandom oligonucleotide compositions. In some embodiments, provided technologies are useful for stereoselective oligonucleotide synthesis. In some embodiments, a stereoselective oligonucleotide synthesis stereoselectively and independently prepares one stereochemical configuration of each of one or more or all chiral linkage phosphorus in an oligonucleotide over the other. In some embodiments, provided technologies are useful for preparing chirally controlled oligonucleotide compositions. In some embodiments, a chiral auxiliary is utilized during stereoselective oligonucleotide synthesis. Certain useful stereoselective oligonucleotide synthesis technologies including chiral auxiliaries, cycles, conditions, etc. are described in US 10167309, US 11643657, US 11718638, US 11608355 and US 20230089442, the entirety of each of which is independently incorporated herein by reference.

[0077] For example, in some embodiments, provided technologies utilizes −P(O)(ORPG)2 as described herein for prepare compounds including oligonucleotides. In some embodiments, −P(O)(ORPG)2 are converted into −P(O)(OH)2 during manufacturing or after administration to a subject.

[0078] In some embodiments, the present disclosure provides technologies comprising −P(O)(ORPG)2 wherein each RPGis a group that is labile to oligonucleotide synthesis conditions, e.g., during cleavage, deprotection and / or chiral auxiliary removal, utilized for reference oligonucleotides without −P(O)(OH)2 groups. In some embodiments, each RPGis a group that can be removed under oligonucleotide synthesis conditions for reference oligonucleotides without −P(O)(OH)2 groups. In some embodiments, −P(O)(ORPG)2 is a protected −P(O)(OH)2 group that is converted to −P(O)(OH)2 which may exist in a salt form, e.g., under oligonucleotide synthesis conditions. In some embodiments, as exemplified herein the P atom is bonded to a carbon atom.

[0079] In some embodiments, RPGcomprises 1) an alpha carbon atom bonded to the oxygen to which it is attached, wherein the alpha carbon atom is bonded to a hydrogen, and 2) a beta carbon atom, wherein the beta carbon atom is bonded to a group RPG11that can facilitate removal of RPG(e.g., compared to ethyl), such as an electron-withdrawing group. In some embodiments, RPG11is an electron- withdrawing group (e.g., as described in US 20230089442). In some embodiments, RPG11is Rsas described herein. In some embodiments, RPG11is −CN. In some embodiments, RPG11is −Ls−Rs11wherein each Lsand Rs11is independently as described herein. In some embodiments, RPGis −CH2−Rs, wherein the −CH2− is independently optionally substituted and Rsis as described herein. In some embodiments, the −CH2− is optionally mono-substituted. In some embodiments, RPGis RP1as described herein. In some embodiments, RPGis RP2as described herein. In some embodiments, RPGis −O−CH2CH2CN.

[0080] In some embodiments, RPGis −CH2−O(CO)RPG12, wherein RPG12is trisubstituted methyl and Page 36 of 201 12495950v1Attorney Docket No.: 2010581-1440 the −CH2− is optionally substituted. In some embodiments, RPGis −CH2−O(CO)RPG12, wherein RPG12is −C(Rs11)3wherein each Rs11is independently as described herein. In some embodiments, RPGis RPG12, wherein RPG12is trisubstituted methyl. In some embodiments, RPG12is −C(Rs11)3wherein each Rs11is independently as described herein. In some embodiments, the carbon of the trisubstituted methyl or −C(Rs11)3 is bonded to three carbon atoms. In some embodiments, RPG12is optionally substituted t-butyl. In some embodiments, RPG12is t-butyl. In some embodiments, RPGis RP1or RP2as described herein. In some embodiments, RPGis −O−CH2−O−C(O)−RP, wherein RPis optionally substituted tert-butyl. In some embodiments, RPGis −O−CH2−O−C(O)−tBu.

[0081] In some embodiments, −P(O)(ORPG)2 has the structure of −P(O)(RP1)(RP2) as described herein (e.g., in formula I or formula I’), wherein each of R1and RP2is independently as described herein.

[0082] In some embodiments, RPGis labile under a basic condition. In some embodiments, RPGis labile under an acidic condition. In some embodiments, −P(O)(ORPG)2 is converted into −P(O)(OH)2 under an acidic condition. In some embodiments, −P(O)(ORPG)2 is converted into −P(O)(OH)2 under a basic condition. In some embodiments, a condition is utilized in oligonucleotide synthesis for a reference oligonucleotide which does not have a −P(O)(OH)2 group but is otherwise identical. In some embodiments, a condition is a cleavage and / or deprotection condition in oligonucleotide synthesis. In some embodiments, a condition is a chiral auxiliary removal, cleavage and / or deprotection condition in oligonucleotide synthesis.

[0083] As those skilled in the art appreciate, acidic and / or basic groups, e.g., −P(O)(OH)2, may exist in various forms including various salt forms. In some embodiments, an acidic and / or basic group, e.g., −P(O)(OH)2, is in a salt form. In some embodiments, an acidic and / or basic group, e.g., −P(O)(OH)2, is in a pharmaceutically acceptable salt form.

[0084] In some embodiments, as described below, the present disclosure provides technologies, e.g., compounds (e.g., nucleosides, phosphoramidites, oligonucleotides, reaction reagents, etc.), methods, etc., that are useful for, among other things, oligonucleotide synthesis. Phosphoramidites

[0085] Various phosphoramidites can be utilized for oligonucleotide preparation, e.g., those described in US 10167309, US 11643657, US 11718638, US 11608355, US 20230089442, etc. In some embodiments, the present disclosure provides phosphoramidites comprising −P(O)(ORPG)2as described herein. In some embodiments, a phosphoramidite comprises −P(O)(ORPG)2which is bonded to a sugar moiety of a nucleoside. In some embodiments, a phosphoramidite comprises −P(O)(ORPG)2which is bonded to a moiety, e.g., an optionally substituted triazole ring, that is bonded to a sugar moiety of a nucleoside. In some embodiments, a sugar is a natural sugar. In some embodiments, a sugar is a Page 37 of 201 12495950v1Attorney Docket No.: 2010581-1440 modified sugar. In some embodiments, a nucleobase in a phosphoramidite is an optionally substituted natural nucleobase. In some embodiments, a nucleobase in a phosphoramidite is optionally protected A, T, C, G, U, or 5mC (e.g., for oligonucleotide synthesis). In some embodiments, a phosphoramidite is abasic.

[0086] In some embodiments, the present disclosure provides a compound having the structure of (RPGO)2P(O)−L5E−SU(−BA)−OP(OR1)N(R2)(R3) or a salt thereof, wherein L5Eis L as described herein, SU is a sugar as described herein, and each other variable is independently as described herein. In some embodiments, such a compound is utilized as a phosphoramidite for oligonucleotide synthesis. In some embodiments, L5Eis an optionally substituted triazole ring.

[0087] In some embodiments, the provided technology provides a compound of formula P’ or a salt thereof: ONPGNR O P , wherein each variable isembodiments, such a compound is utilized as a phosphoramidite for oligonucleotide synthesis.

[0088] In some embodiments, the provided technology provides a compound of formula P or a salt thereof: , wherein each variable isembodiments, such a compound is utilized as a phosphoramidite for oligonucleotide synthesis.

[0089] In some embodiments, the provided technology provides a compound of formula I’ or a salt thereof: Page 38 of 201 12495950v1Attorney Docket No.: 2010581-1440 ,wherein each variable is as some embodiments, such a compound is utilized as a phosphoramidite for oligonucleotide synthesis.

[0090] In some embodiments, the provided technology provides a compound of formula I or a salt thereof: ONP1NR P BA 1 ,wherein each variable is independently as described herein. In some embodiments, such a compound is utilized as a phosphoramidite for oligonucleotide synthesis.

[0091] Certain embodiments of certain variables utilized in various formulae are described below. RP1

[0092] In some embodiments, RP1is −O−CH2CH2CN. In some embodiments, RP1is −O−CH2−O−C(O)−RP, wherein RPis optionally substituted tert-butyl. In some embodiments, RP1is −O−CH2−O−C(O)−tBu. RP2

[0093] In some embodiments, RP2is −O−CH2CH2CN. In some embodiments, RP2is −O−CH2−O−C(O)−RP, wherein RPis optionally substituted tert-butyl. In some embodiments, RP2is −O−CH2−O−C(O)−tBu.

[0094] In some embodiments, RP1and RP2are the same. In some embodiments, RP1and RP2are different. In some embodiments, each of RP1and RP2is −O−CH2CH2CN. In some embodiments, each of RP1and RP2is independently −O−CH2−O−C(O)−RP, wherein RPis optionally substituted tert-butyl. In some embodiments, each of RP1and RP2is −O−CH2−O−C(O)−tBu. RPPage 39 of 201 12495950v1Attorney Docket No.: 2010581-1440

[0095] In some embodiments, RPis substituted tert-butyl. In some embodiments, RPis tert-butyl. BA

[0096] In some embodiments, BA is hydrogen.

[0097] In some embodiments, BA is an optionally substituted 3-20 (e.g., 3-15, 3-10, 3-6, 5-10, 5-6, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, etc.) membered ring having 0-10 (e.g., 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 1-10, 0-5, 1-5, etc.) heteroatoms independently selected from silicon, nitrogen, oxygen, phosphorus and sulfur. In some embodiments, BA is an optionally substituted 3-20 (e.g., 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 3-15, 3-14, 3-10, 5-10, 3-7, 3-6, etc.) membered ring having 0-5 (e.g., 1, 2, 3, 4, 5, 1-5, 1-4, 1-2, etc.) heteroatoms independently selected from oxygen, nitrogen and sulfur. In some embodiments, BA is an optionally substituted 3-20 (e.g., 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 3-15, 3-14, 3-10, 5-10, 3-7, 3-6, etc.) membered ring having 0-5 (e.g., 1, 2, 3, 4, 5, 1-5, 1-4, 1-2, etc.) heteroatoms independently selected from nitrogen and oxygen. In some embodiments, BA is an optionally substituted ring having at least one nitrogen atom. In some embodiments, BA is an optionally substituted 5-15 membered ring. In some embodiments, BA is an optionally substituted 5-10 membered ring. In some embodiments, BA is an optionally substituted 5-9 membered ring. In some embodiments, BA is an optionally substituted 9-membered ring. In some embodiments, BA is an optionally substituted 10-membered ring. In some embodiments, an optionally substituted 5-membered ring. In some embodiments, BA is an optionally substituted 6-membered ring. In some embodiments, BA is an optionally substituted monocyclic ring. In some embodiments, BA is an optionally substituted bicyclic ring. In some embodiments, BA is bonded to C1 of a sugar at a nitrogen atom.

[0098] In some embodiments, BA is an optionally substituted group, wherein the group is a tautomer thereof. In somewherein BA is a protected nucleobase. In some embodiments, BA is an optionally protected nucleobase selected from A, T, C, G, U and 5mU. In some embodiments, protection is suitable for oligonucleotide synthesis.

[0099] In some embodiments, BA is an optionally substituted or protected nucleobase. Various nucleobases are as described herein and can be utilized as BA. SU

[0100] In some embodiments, SU is a sugar as described herein. In some embodiments, SU is Page 40 of 201 12495950v1Attorney Docket No.: 2010581-1440 , wherein a nucleobase, BA, etc. is bonded at C1. In some embodiments, SU is , wherein a nucleobase, BA, etc. as described herein, is bonded at C1. In someembodiments, SU is optionally , wherein a nucleobase, BA, etc. as described herein, is bonded at C1.R2s

[0101] In some embodiments, Rs2is −H. In some embodiments, R2sis −F.

[0102] In some embodiments, R2sis −Cl. In some embodiments, R2sis −Br. In some embodiments, R2sis −I. In some embodiments, R2sis −CN. In some embodiments, R2sis −N3. In some embodiments, R2sis −NO. In some embodiments, R2sis −NO2.

[0103] In some embodiments, R2sis −L2s−R2a. In some embodiments, Rs2is R2a. In some embodiments, Rs2is R. In some embodiments, R2sis −O−L2s’−R2a, wherein L2s’is a covalent bond, or a bivalent, optionally substituted group selected from C1-10 aliphatic and C1-10 heteroaliphatic group having 1-4 heteroatoms independently selected from silicon, nitrogen, oxygen, phosphorus and sulfur, wherein one or more methylene units of L2s’are optionally and independently replaced by −Cy−, −O−, −S−, −N(R’)−, −C(O)−, −C(S)−, −C(NR’)−, −C(O)N(R’)−, −N(R’)C(O)N(R’)−, −N(R’)C(O)O−, −S(O)−, −S(O)2−, −S(O)2N(R’)−, −SC(O)−, or −C(O)O−. In some embodiments, L2s’is a covalent bond. In some embodiments, L2s’is an optionally substituted bivalent C1-10 aliphatic group. In some embodiments, L2s’is a bivalent C1-10 aliphatic group. In some embodiments, L2s’is an optionally substituted bivalent linear C1- 10 aliphatic group. In some embodiments, L2s’is a bivalent linear C1-10 aliphatic group. In some embodiments, L2s’is an optionally substituted C1-10 alkylene group. In some embodiments, L2s’is a C1-10 alkylene group. In some embodiments, L2s’is optionally substituted −(CH2)1-10−. In some embodiments, L2s’is −(CH2)1-10−. In some embodiments, L2s’is an optionally substituted bivalent C1-10 heteroaliphatic group having 1-4 heteroatoms independently selected from silicon, nitrogen, oxygen, phosphorus and sulfur. In some embodiments, one or more methylene units are independently replaced as described herein. For example, in some embodiments, R2sis −O(CH2)0-10R2a, wherein each −CH2− is optionally substituted. In some embodiments, R2ais optionally substituted C1-10 aliphatic. In some embodiments, Page 41 of 201 12495950v1Attorney Docket No.: 2010581-1440 R2ais optionally substituted C1-10alkyl. In some embodiments, R2ais optionally substituted linear C1-10alkyl. In some embodiments, R2ais C1-10alkyl. In some embodiments, R2ais C1-10linear alkyl. In some embodiments, R2sis −O(CH2)0-15CH3. In some embodiments, R2sis −O(CH2)15CH3.

[0104] In some embodiments, R2sis −L2s−OR2a. In some embodiments, R2sis −OR2a. In some embodiments, R2sis −OMe.

[0105] In some embodiments, R2sis −L2s−SR2a. In some embodiments, R2sis −SR2a.

[0106] In some embodiments, R2sis −L2s−N(R2a)2. In some embodiments, R2sis −N(R2a)2.

[0107] In some embodiments, R2sis −O−L2s−OR2a. In some embodiments, R2sis −O−L2s−SR2a. In some embodiments, R2sis or −O−L2s−N(R2a)2. In some embodiments, L2sis an optionally substituted bivalent C2-10 aliphatic group. In some embodiments, L2sis a bivalent C2-10 aliphatic group. In some embodiments, L2sis a bivalent linear C2-10 aliphatic group. In some embodiments, L2sis a bivalent linear C2-10 alkylene group. In some embodiments, R2sis −OCH2CH2OCH3.

[0108] In some embodiments, R2sis L2sconnecting C2 with C1, C2, C3, C4 or C5 wherein Lsis L as described herein. For example, in some embodiments, L is (C2)−O−(unsubstituted methylene)−. In some embodiments, L is (C2)−O−(substituted methylene)−. In some embodiments, L is (C2)−O−(substituted methylene)−, wherein the methylene group is substituted with methyl. In some embodiments, L is (C2)−O−(substituted methylene)−, wherein the methylene group is substituted with ethyl. In some embodiments, the carbon atom of the methylene group is R. In some embodiments, the carbon atom of the methylene group is S.

[0109] In some embodiments, C2 and C4 are connected through −O−CH2−, wherein the −CH2− is optionally substituted. In some embodiments, C2 and C4 are connected through −O−CH2−. In some embodiments, C2 and C4 are connected through −O−CH(CH3)−. In some embodiments, C2 and C4 are connected through −O−CH(CH2OMe)−. In some embodiments, the configuration of the chiral carbon in L2sis R. In some embodiments, the configuration of the chiral carbon in L2sis S. In some embodiments, the −O− is bonded to C2. In some embodiments, a sugar is a LNA sugar. L2s

[0110] In some embodiments, L2sis a covalent bond. In some embodiments, L2sis an optionally substituted bivalent C1-10aliphatic group wherein one or more methylene units of L are optionally and independently replaced by −Cy−, −O−, −S−, −N(R’)−, −C(O)−, −C(S)−, −C(NR’)−, −C(O)N(R’)−, −N(R’)C(O)N(R’)−, −N(R’)C(O)O−, −S(O)−, −S(O)2−, −S(O)2N(R’)−, −SC(O)−, or −C(O)O−. In some embodiments, L2sis an optionally substituted bivalent C1-5aliphatic group wherein one or more methylene units of L are optionally and independently replaced by −Cy−, −O−, −S−, −N(R’)−, −C(O)−, −C(S)−, −C(NR’)−, −C(O)N(R’)−, −N(R’)C(O)N(R’)−, −N(R’)C(O)O−, −S(O)−, −S(O)2−, −S(O)2N(R’)−, −SC(O)−, or −C(O)O−. In some embodiments, L2sis an optionally substituted bivalent C1-5aliphatic Page 42 of 201 12495950v1Attorney Docket No.: 2010581-1440 group wherein one or more methylene units of L are optionally and independently replaced by −O−, −S−, −N(R’)−, −C(O)−, −C(S)−, −C(NR’)−, −C(O)N(R’)−, −N(R’)C(O)N(R’)−, −N(R’)C(O)O−, −S(O)−, −S(O)2−, −S(O)2N(R’)−, −SC(O)−, or −C(O)O−. In some embodiments, L2sis an optionally substituted bivalent C1-10aliphatic group. In some embodiments, L2sis an optionally substituted bivalent C2-10aliphatic group. In some embodiments, L2sis a bivalent C2-10 aliphatic group. In some embodiments, L2sis a bivalent linear C2-10aliphatic group. In some embodiments, L2sis a bivalent linear C1-10alkylene group. In some embodiments, L2sis a bivalent linear C2-10alkylene group. In some embodiments, L2sis optionally substituted −O−CH2−. R2a

[0111] As defined herein, R2ais R’ as described herein. In some embodiments, R2ais R as described herein. In some embodiments, R2ais −H. In some embodiments, R2ais C1-6 aliphatic. In some embodiments, R2ais C1-6 alkyl. In some embodiments, R2ais methyl.

[0112] In some embodiments, two or more R2aare R’ and are taken together with their intervening atom(s) to form an optionally substituted 3-20 membered ring having, in addition to the intervening atom(s), 0-5 heteroatoms independently selected from oxygen, nitrogen, sulfur. In some embodiments, two R2aattached to the same atom are R’ and are taken together with the atom to which they are attached to form an optionally substituted 3-20 (e.g., 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19 or 20, 3-20, 5-9, etc.) membered ring having, in addition to the intervening atom(s), 0-5 heteroatoms independently selected from oxygen, nitrogen, sulfur. In some embodiments, a formed ring is as described herein. L

[0113] Certain embodiments for L are described below. Various variables, e.g., L2s, Ls, etc., can be L, and embodiments for L can also be applied to such variables that can be L.

[0114] In some embodiments, L is a covalent bond. In some embodiments, L is a bivalent, optionally substituted C1-10 (e.g., C1-6, C2-8, C1, C2, C3, C4, C5, C6, C7, C8, C9, C10, etc.) aliphatic group wherein one or more methylene units of L are optionally and independently replaced by −Cy−, −O−, −S−, −N(R’)−, −C(O)−, −C(S)−, −C(NR’)−, −C(O)N(R’)−, −N(R’)C(O)N(R’)−, −N(R’)C(O)O−, −S(O)−, −S(O)2−, −S(O)2N(R’)−, −SC(O)−, or −C(O)O−. In some embodiments, L is a bivalent, optionally substituted C1-6aliphatic group wherein one or more methylene units of L are optionally and independently replaced by −Cy−, −O−, −S−, −N(R’)−, −C(O)−, −C(S)−, −C(NR’)−, −C(O)N(R’)−, −N(R’)C(O)N(R’)−, −N(R’)C(O)O−, −S(O)−, −S(O)2−, −S(O)2N(R’)−, −SC(O)−, or −C(O)O−. In some embodiments, L is a bivalent, optionally substituted C1-5aliphatic group wherein one or more methylene units of L are optionally and independently replaced by −Cy−, −O−, −S−, −N(R’)−, −C(O)−, −C(S)−, −C(NR’)−, −C(O)N(R’)−, −N(R’)C(O)N(R’)−, −N(R’)C(O)O−, −S(O)−, −S(O)2−, −S(O)2N(R’)−, Page 43 of 201 12495950v1Attorney Docket No.: 2010581-1440 −SC(O)−, or −C(O)O−. In some embodiments, each methylene unit are replaced. In some embodiments, at least one methylene unit is not replaced. In some embodiments, L comprises at least one chain carbon atom. In some embodiments, L is −O−. In some embodiments, L is −S−. In some embodiments, L is −N(R’)−. In some embodiments, L is −C(O)−.

[0115] In some embodiments, no methylene unit is replaced. In some embodiments, L is a bivalent, optionally substituted C1-10(e.g., C1-6, C2-8, C1, C2, C3, C4, C5, C6, C7, C8, C9, C10, etc.) aliphatic group. In some embodiments, L is optionally substituted C1-6aliphatic group. In some embodiments, L is bivalent, optionally substituted C1-10 (e.g., C1-6, C2-8, C1, C2, C3, C4, C5, C6, C7, C8, C9, C10, etc.) alkylene. In some embodiments, L is optionally substituted C1-6 alkylene. In some embodiments, L is linear. In some embodiments, L is branched. In some embodiments, L is substituted. In some embodiments, L is not substituted.

[0116] In some embodiments, L is a bivalent, optionally substituted C1-10 heteroaliphatic (e.g., C1-6, C2-8, C1, C2, C3, C4, C5, C6, C7, C8, C9, C10, etc.) group having 1-5 heteroatoms independently selected from silicon, nitrogen, oxygen, phosphorus and sulfur, wherein one or more methylene units of L are optionally and independently replaced by −Cy−, −O−, −S−, −N(R’)−, −C(O)−, −C(S)−, −C(NR’)−, −C(O)N(R’)−, −N(R’)C(O)N(R’)−, −N(R’)C(O)O−, −S(O)−, −S(O)2−, −S(O)2N(R’)−, −SC(O)−, or −C(O)O−. In some embodiments, L is a bivalent, optionally substituted C1-6 heteroaliphatic group having 1-5 heteroatoms independently selected from silicon, nitrogen, oxygen, phosphorus and sulfur, wherein one or more methylene units of L are optionally and independently replaced by −Cy−, −O−, −S−, −N(R’)−, −C(O)−, −C(S)−, −C(NR’)−, −C(O)N(R’)−, −N(R’)C(O)N(R’)−, −N(R’)C(O)O−, −S(O)−, −S(O)2−, −S(O)2N(R’)−, −SC(O)−, or −C(O)O−. In some embodiments, L is linear. In some embodiments, L is branched. In some embodiments, L is substituted. In some embodiments, L is not substituted.

[0117] In some embodiments, a methylene unit is replaced by −Cy− as described herein. −Cy−

[0118] As used herein, −Cy− is an optionally substituted bivalent 3-20 (e.g., 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 3-15, 3-14, 3-10, 5-10, 3-7, 3-6, etc.) membered ring having 0-10 (e.g., 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 1-10, 0-5, 1-5, etc.) heteroatoms independently selected from silicon, nitrogen, oxygen, phosphorus and sulfur. In some embodiments, each heteroatom is independently selected from nitrogen, oxygen and sulfur. In some embodiments, −Cy− is an optionally substituted bivalent 3-20 (e.g., 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 3-15, 3-14, 3-10, 5-10, 3-7, 3-6, etc.) membered ring having 0-10 (e.g., 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 1-10, 0-5, 1-5, etc.) heteroatoms independently selected from oxygen, nitrogen, and sulfur. In some embodiments, −Cy− is monocyclic. In some embodiments, −Cy− is bicyclic. In some embodiments, −Cy− is polycyclic. In some Page 44 of 201 12495950v1Attorney Docket No.: 2010581-1440 embodiments, each monocyclic ring unit is independently an optionally substituted 3-10 (e.g., 3, 4, 5, 6, 7, 8, 9, 10, 3-8, 3-7, 3-6, 5-8, etc.) membered ring having 0-5 (e.g., 1, 2, 3, 4, 5, 1-5, 1-4, 1-2, etc.) heteroatoms independently selected from silicon, nitrogen, oxygen, phosphorus and sulfur and 1-10 (e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 1-5, 1-4, etc.) carbon atoms. In some embodiments, a monocyclic ring unit is an optionally substituted saturated ring. In some embodiments, a monocyclic ring unit is an optionally substituted partially unsaturated ring. In some embodiments, a monocyclic ring unit is an optionally substituted aromatic ring. In some embodiments, a monocyclic ring unit is an optionally substituted phenyl ring. In some embodiments, a monocyclic ring unit is an optionally substituted 5-membered heteroaromatic having 1-4 (e.g., 1, 2, 3, 4, 1-3, 1-2, etc.) heteroatoms independently selected from nitrogen, oxygen and sulfur. In some embodiments, a monocyclic ring unit is an optionally substituted 6- membered heteroaromatic having 1-4 (e.g., 1, 2, 3, 4, 1-3, 1-2, etc.) heteroatoms independently selected from nitrogen, oxygen and sulfur. Each monocyclic ring unit is independently optionally substituted. In some embodiments, a monocyclic ring unit is unsaturated. In some embodiments, a monocyclic ring unit is saturated. In some embodiments, −Cy− is an optionally substituted saturated ring. In some embodiments, −Cy− is an optionally substituted partially unsaturated ring. In some embodiments, −Cy− is an optionally substituted aromatic ring.

[0119] In some embodiments, −Cy− is an optionally substituted bivalent 3-10 (e.g., 3, 4, 5, 6, 7, 8, 9, or 10) membered monocyclic cycloaliphatic ring. In some embodiments, −Cy− is an optionally substituted 3-10 (e.g., 3, 4, 5, 6, 7, 8, 9, or 10) membered monocyclic cycloalkyl ring. In some embodiments, −Cy− is an optionally substituted 3-10 (e.g., 3, 4, 5, 6, 7, 8, 9, or 10) membered monocyclic heteroaliphatic ring having 1-5 heteroatoms. In some embodiments, −Cy− is an optionally substituted 3-10 (e.g., 3, 4, 5, 6, 7, 8, 9, or 10) membered monocyclic heteroalkyl ring having 1-5 heteroatoms. In some embodiments, −Cy− is an optionally substituted bivalent 5-15 (e.g., 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, or 15) membered bicyclic or polycyclic cycloaliphatic group. In some embodiments, −Cy− is an optionally substituted bivalent 5-15 (e.g., 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, or 15) membered bicyclic or polycyclic cycloalkyl group. In some embodiments, −Cy− is an optionally substituted 5-15 (e.g., 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, or 15) membered bicyclic or polycyclic heteroaliphatic ring having 1-5 heteroatoms. In some embodiments, −Cy− is an optionally substituted 5-15 (e.g., 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, or 15) membered bicyclic or polycyclic heterocyclyl ring having 1-5 heteroatoms. In some embodiments, a cycloaliphatic, cycloalkyl, heteroaliphatic or heteroalkyl ring is 3-membered. In some embodiments, it is 4-membered. In some embodiments, it is 5-membered. In some embodiments, it is 6- membered. In some embodiments, it is 7-membered. In some embodiments, it is 8-membered. In some embodiments, it is 9-membered. In some embodiments, it is 10-membered. In some embodiments, it is 11-membered. In some embodiments, it is 12-membered. In some embodiments, −Cy− is optionally Page 45 of 201 12495950v1Attorney Docket No.: 2010581-1440 substituted phenylene. In some embodiments, −Cy− is an optionally substituted bivalent 10-membered bicyclic aryl ring. In some embodiments, −Cy− is an optionally substituted 5-membered heteroaryl ring having 1-4 heteroatoms. In some embodiments, −Cy− is an optionally substituted 6-membered heteroaryl ring having 1-4 heteroatoms. In some embodiments, −Cy− is an optionally substituted 9-membered bicyclic heteroaryl ring having 1-5 heteroatoms. In some embodiments, −Cy− is an optionally substituted 10-membered bicyclic heteroaryl ring having 1-5 heteroatoms. In some embodiments, a heteroaliphatic, heterocyclyl or heteroaryl ring contains no more than 1 heteroatom. In some embodiments, each heteroatom is independently selected from nitrogen, oxygen and sulfur.

[0120] In some embodiments, −Cy− is an optionally substituted 4-7 membered ring having 0-3 heteroatoms. In some embodiments, −Cy− is an optionally substituted 6-membered aryl ring. In some embodiments, an aryl ring is substituted. In some embodiments, it is substituted with one or more halogen. In some embodiments, it is substituted with one or more −F. In some embodiments, it is not substituted. In some embodiments, it is optionally . In some embodiments, it is. In some embodiments, it is optionally . In some embodiments, it is. In some embodiments, it is optionally . In some embodiments, it is. In some embodiments, −Cy− is an optionally substituted 5-membered heteroaryl ring havingIn some embodiments, a heteroatom is nitrogen. In some embodiments, a heteroatom is oxygen. In some embodiments, a heteroatom is sulfur. In some embodiments, −Cy− is optionally . In some embodiments, −Cy− is .

[0121] In some embodiments, R1is R’ as described herein and is not −H. In some embodiments, R1is R as described herein. In some embodiments, R1is optionally substituted C1-6aliphatic. In some embodiments, R1is optionally substituted methyl. In some embodiments, R1is optionally substituted ethyl. In some embodiments, R1is optionally substituted ethyl, wherein the methylene unit boned to the oxygen is optionally monosubstituted, and the methyl is substituted with an electron-withdrawing group, e.g., −CN. Certain electron-withdrawing groups are described in US 10167309, US 11643657, US Page 46 of 201 12495950v1Attorney Docket No.: 2010581-1440 11718638, US 11608355 or US 20230089442, the electron-withdrawing groups of each of which are incorporated herein by reference. In some embodiments, R1is −OCH2CH2CN. R2

[0122] In some embodiments, R2is R’ as described herein and is not −H. In some embodiments, R2is R as described herein. In some embodiments, R2is not −H. In some embodiments, R2is optionally substituted C1-10aliphatic. In some embodiments, R2is optionally substituted C1-10alkyl. In some embodiments, R2is C1-6aliphatic. In some embodiments, R2is C1-6alkyl. In some embodiments, R2is isopropyl. R3

[0123] In some embodiments, R3is R’ as described herein and is not −H. In some embodiments, R3is R as described herein. In some embodiments, R3is not −H. In some embodiments, R3is optionally substituted C1-10 aliphatic. In some embodiments, R3is optionally substituted C1-10 alkyl. In some embodiments, R2is C1-6 aliphatic. In some embodiments, R2is C1-6 alkyl. In some embodiments, R3is isopropyl.

[0124] In some embodiments, R2and R3are the same. In some embodiments, they are different.

[0125] In some embodiments, −P(OR1)N(R2)(R3) is −P(OCH2CH2CN)N[CH(CH3)2]2.

[0126] In some embodiments, two or three of R1, R2, and R3are taken together with their intervening atoms to form wherein each variable is independently as described herein. In some embodiments,taken together with their intervening atoms to form a ring as described herein. In some embodiments, R2and R3are taken together with their intervening atoms to from a ring as described herein. In some embodiments, R1, R2and R3are taken together with their intervening atoms to form a ring as described herein. Ring A

[0127] As defined herein, Ring A is an optionally substituted 3-20 (e.g., 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 3-15, 3-14, 3-10, 5-10, 3-7, 3-6, etc.) membered ring having, in addition to the intervening atoms, 0-10 (e.g., 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 1-10, 0-5, 1-5, etc.) heteroatoms independently selected from silicon, nitrogen, oxygen, phosphorus and sulfur. In some embodiments, Ring A is an optionally substituted 3-20 (e.g., 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 3-15, 3-14, 3-10, 5-10, 3-7, 3-6, etc.) membered ring having 0-10 (e.g., 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 1-10, 0-5, 1-5, etc.) heteroatoms independently selected from silicon, nitrogen, oxygen, phosphorus and sulfur. In some embodiments, Ring A has no additional heteroatoms. In some embodiments, Ring has 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 additional heteroatoms.

[0128] In some embodiments, Ring A is not substituted (as appreciated by those skilled in the art, Page 47 of 201 12495950v1Attorney Docket No.: 2010581-1440 not including Rs). In some embodiments, Ring A is substituted (as appreciated by those skilled in the art, not including Rs).

[0129] In some embodiments, Ring A is monocyclic. In some embodiments, Ring A is bicyclic. In some embodiments, Ring A is polycyclic. In some embodiments, each monocyclic ring unit is independently an optionally substituted 3-10 (e.g., 3, 4, 5, 6, 7, 8, 9, 10, 3-8, 3-7, 3-6, 4-6, 5-6, 5-8, etc.) membered ring having 0-5 (e.g., 1, 2, 3, 4, 5, 1-5, 1-4, 1-2, etc.) heteroatoms independently selected from silicon, nitrogen, oxygen, phosphorus and sulfur and 1-10 (e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 1-5, 1-4, etc.) carbon atoms. In some embodiments, each monocyclic ring unit is independently an optionally substituted 4-10 (e.g., 4, 5, 6, 7, 8, 9, 10, 5-7, 5-6) membered ring having 0-5 (e.g., 1, 2, 3, 4, 5, 1-5, 1-4, 1-2, etc.) heteroatoms independently selected from silicon, nitrogen, oxygen, phosphorus and sulfur and 1-10 (e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 1-5, 1-4, etc.) carbon atoms. In some embodiments, each monocyclic ring unit is independently an optionally substituted 3-10 membered. In some embodiments, each monocyclic ring unit is independently an optionally substituted 3-7 membered. In some embodiments, each monocyclic ring unit is independently an optionally substituted 4-6 membered. In some embodiments, each monocyclic ring unit is independently an optionally substituted 5-6 membered. In some embodiments, each monocyclic ring unit is independently an optionally substituted 5-membered. In some embodiments, a monocyclic ring unit is an optionally substituted saturated ring. In some embodiments, a monocyclic ring unit is an optionally substituted partially unsaturated ring. In some embodiments, a monocyclic ring unit is an optionally substituted aromatic ring. In some embodiments, a monocyclic ring unit is an optionally substituted phenyl ring. In some embodiments, a monocyclic ring unit is an optionally substituted 5-membered heteroaromatic having 1-4 (e.g., 1, 2, 3, 4, 1-3, 1-2, etc.) heteroatoms independently selected from nitrogen, oxygen and sulfur. In some embodiments, a monocyclic ring unit is an optionally substituted 6-membered heteroaromatic having 1-4 (e.g., 1, 2, 3, 4, 1-3, 1-2, etc.) heteroatoms independently selected from nitrogen, oxygen and sulfur. Each monocyclic ring unit is independently optionally substituted. In some embodiments, a monocyclic ring unit is unsaturated. In some embodiments, a monocyclic ring unit is saturated.

[0130] In some embodiments, a monocyclic ring unit comprising the nitrogen atom to which R2and R3are bond is an optionally substituted saturated 4-10 (e.g., 4-8, 4-6, 4, 5, 6, 7, 8, 9, 10, etc.) membered ring having 0-2 heteroatoms in addition to the nitrogen atom independently selected from nitrogen, oxygen and sulfur. In some embodiments, a monocyclic ring unit comprising the nitrogen atom to which R2and R3are bond is an optionally substituted saturated 4-10 (e.g., 4-8, 4-6, 4, 5, 6, 7, 8, 9, 10, etc.) membered ring having no heteroatoms in addition to the nitrogen atom independently selected from nitrogen, oxygen and sulfur. In some embodiments, it is 4-membered. In some embodiments, it is 5- membered. In some embodiments, it is 6-membered. In some embodiments, it is 7-membered. In some Page 48 of 201 12495950v1Attorney Docket No.: 2010581-1440 embodiments, it is 8-membered.

[0131] In some embodiments, Ring A is an optionally substituted saturated ring. In some embodiments, Ring A is an optionally substituted partially unsaturated ring. In some embodiments, Ring A is an optionally substituted aromatic ring.

[0132] In some embodiments, Ring A is an optionally substituted monocyclic 3-10 (e.g., 3-6, 5-10, 5-6, 3, 4, 5, 6, 7, 8, 9, 10, etc.) membered, monocyclic, bicyclic or polycyclic ring having, in addition to the intervening atom(s), 0-4 heteroatoms independently selected from nitrogen, oxygen and sulfur. In some embodiments, Ring A is an optionally substituted bicyclic or polycyclic 6-20 (e.g., 6-15, 6-10, 8-20, 8-15, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, etc.) membered, monocyclic, bicyclic or polycyclic ring having, in addition to the intervening atom(s), 0-4 heteroatoms independently selected from nitrogen, oxygen and sulfur. In some embodiments, Ring A is 3-9, 3-8, 3-7, 3-6, 4-10, 4-9, 4-8, 4-7, 4-6, 5-10, 5-9, 5-8, 5-7, 5-6, or 3, 4, 5, 6, 7, 8, 9, or 10-membered. In some embodiments, Ring A is 3-9 membered. In some embodiments, Ring A is 3-7 membered. In some embodiments, Ring A is 4-10 membered. In some embodiments, Ring A is 4-7 membered. In some embodiments, Ring A is 5-10 membered. In some embodiments, Ring A is 5-7 membered. In some embodiments, Ring A is 3- membered. In some embodiments, Ring A is 4-membered. In some embodiments, Ring A is 5- membered. In some embodiments, Ring A is 6-membered. In some embodiments, Ring A is 7- membered. In some embodiments, Ring A is 8-membered. In some embodiments, Ring A is 9- membered. In some embodiments, Ring A is 10-membered. In some embodiments, Ring A is 11- membered. In some embodiments, Ring A is 12-membered. In some embodiments, Ring A is monocyclic. In some embodiments, Ring A is bicyclic. In some embodiments, Ring A is an optionally substituted bicyclic 7-12 membered ring. In some embodiments, Ring A is an optionally substituted bicyclic 8-10 membered ring. In some embodiments, Ring A is an optionally substituted bicyclic 7- membered ring. In some embodiments, Ring A is an optionally substituted bicyclic 8-membered ring. In some embodiments, Ring A is an optionally substituted bicyclic 9-membered ring. In some embodiments, Ring A is an optionally substituted bicyclic 10-membered ring. In some embodiments, Ring A is polycyclic. In some embodiments, Ring A has no additional heteroatoms. In some embodiments, Ring A has 0-6, e.g., 0, 1-6, 1-5, 1-3, or 1, 2, 3, 4, 5, or 6 additional heteroatoms. In some embodiments, Ring A comprises one or more aromatic ring. In some embodiments, Ring A is bicyclic or polycyclic, and each monocyclic ring unit is independently 3-10 (e.g., 3-9, 3-8, 3-7, 3-6, 4-10, 4-9, 4-8, 4- 7, 4-6, 5-10, 5-9, 5-8, 5-7, 5-6, or 3, 4, 5, 6, 7, 8, 9, or 10) membered, saturated, partially unsaturated or aromatic and having 0-5 (e.g., 0, 1-5, 1-3, 1, 2, 3, 4, or 5) heteroatoms. In some embodiments, a monocyclic ring unit is saturated. In some embodiments, a monocyclic ring unit is partially unsaturated. In some embodiments, a monocyclic ring unit is aromatic. In some embodiments, a monocyclic ring unit Page 49 of 201 12495950v1Attorney Docket No.: 2010581-1440 is heteroaromatic. Those skilled in the art appreciate that intervening atom(s), e.g., of groups taken together to form a ring, are typically atoms on the shortest path connecting such groups if multiple paths exist.

[0133] In some embodiments, a monocyclic ring unit comprising the phosphorus, nitrogen and oxygen atoms is saturated. In some embodiments, a monocyclic ring unit comprising the phosphorus, nitrogen and oxygen atoms is partially saturated. In some embodiments, it is 4-membered. In some embodiments, it is 5-membered. In some embodiments, it is 6-membered. In some embodiments, it is 7- membered. In some embodiments, it has one or more additional heteroatoms independently selected from silicon, nitrogen, oxygen, phosphorus and sulfur. In some embodiments, the phosphorus, nitrogen and oxygen atoms are the only heteroatoms in that monocyclic ring unit.

[0134] In some embodiments, a monocyclic ring unit comprising the nitrogen atom to which R2and R3are bond is an optionally substituted partially unsaturated 4-10 (e.g., 4-8, 4-6, 4, 5, 6, 7, 8, 9, 10, etc.) membered ring having 0-2 heteroatoms in addition to the nitrogen atom independently selected from nitrogen, oxygen and sulfur. In some embodiments, a monocyclic ring unit comprising the nitrogen atom to which R2and R3are bond is an optionally substituted partially unsaturated 4-10 (e.g., 4-8, 4-6, 4, 5, 6, 7, 8, 9, 10, etc.) membered ring having no heteroatoms in addition to the nitrogen atom independently selected from nitrogen, oxygen and sulfur. In some embodiments, it is 4-membered. In some embodiments, it is 5-membered. In some embodiments, it is 6-membered. In some embodiments, it is 7- membered. In some embodiments, it is 8-membered.

[0135] In some embodiments, Ring A comprises optionally , wherein each Lais independently a covalent bond or a bivalent C1-5aliphatic group whereinmethylene units of each Laare optionally and independently replaced by −O−, −S−, or −NH. In some embodiments, Ring A is optionally, wherein each Lais independently a covalent bond or a bivalent C1-5aliphatic group wherein one or more methylene units of each Laare optionally and independently replaced by −O−, −S−, or −NH. In some embodiments, Ring A comprises optionally , wherein each Lais independently a covalent bond or a bivalent C1-5aliphatic group whereinmethylene units of each Laare optionally and independently replaced by −O−, −S−, or −NH. In some Page 50 of 201 12495950v1Attorney Docket No.: 2010581-1440 embodiments, Ring A is optionally , wherein each Lais independently a covalent bond or a bivalent C1-5 aliphatic group wherein methylene units of each Laare optionally andindependently replaced by −O−, −S−, or embodiments, Lais a covalent bond. In some embodiments, Lais not a covalent bond. In some embodiments, Lais −CH2−. In some embodiments, Lais –(CH2)2−. In some embodiments, Lais –(CH2)3−. In some embodiments, Lais –(CH2)4−. In some embodiments, Lais –(CH2)5−. In some embodiments, a methylene unit is replaced with −O−. In some embodiments, a methylene unit is replaced with −S−. In some embodiments, a methylene unit is replaced with −NH−.

[0136] In some embodiments, Ring A is optionally . In some embodiments,Ring A is optionally . In some embodiments, Ring A is optionally substituted.In some embodiments, an occurrence of Rsis bonded to a carbon atom bonded to the oxygen of −P(OR1)N(R2)(R3). In some embodiments, −P(OR1)N(R2)(R3) , wherein each of Rs1andRs2is independently Rsas described herein. In some embodiments, −P(OR1)N(R2) Insome embodiments, −P(OR1)N(R2)(R3) . In some embodiments, −P(OR1)N(R2)(R3) isPage 51 of 201 12495950v1Attorney Docket No.: 2010581-1440

[0138] In some embodiments, one of Rs1and Rs2is −H. In some embodiments, Rs1and Rs2are independently not −H. In some embodiments, Rs1is R as described herein. In some embodiments, Rs1is not hydrogen. In some embodiments, Rs1is hydrogen. In some embodiments, Rs1is hydrogen and Rs2is not hydrogen. In some embodiments, Rs1is optionally substituted C1-6aliphatic. In some embodiments, Rs1is methyl. In some embodiments, Rs1is optionally substituted phenyl. In some embodiments, Rs1is phenyl. In some embodiments, Rs2is R as described herein. In some embodiments, Rs2is not hydrogen. In some embodiments, Rs2is hydrogen. In some embodiments, Rs2is optionally substituted C1-6aliphatic. In some embodiments, wherein Rs2is methyl. In some embodiments, Rs2is optionally substituted phenyl. In some embodiments, wherein Rs2is phenyl.

[0139] In some embodiments, −P(OR1)N(R2)(R3) is wherein each variable is independently as described herein. In some is of such a structure thatis a chiral auxiliary, e.g., described in US 10167309, US 11643657, US 11718638, US 11608355 or US 20230089442, the chiral auxiliaries of each of which are incorporated herein by reference. For example, in some embodiments, it . In some embodiments, it is. In some embodiments, it . In some embodiments, it isIn some embodiments, it is . In some embodiments, it isIn some embodiments, it . In some embodiments, Insome some embodiments, it . In some embodiments, itPage 52 of 201 12495950v1Attorney Docket No.: 2010581-1440 is . In some embodiments, it . In someembodiments, it . In some embodiments, it . t

[0140] In some t is 0. In some 5. In some embodiments, t is 1. In some embodiments, t is 2. In some embodiments, t is 3. In some embodiments, t is 4. In some embodiments, t is 5. Rs

[0141] In some embodiments, Rsis −F. In some embodiments, Rsis −Cl. In some embodiments, Rsis −Br. In some embodiments, Rsis −I. In some embodiments, Rsis −CN. In some embodiments, Rsis −N3. In some embodiments, Rsis −NO. In some embodiments, Rsis −NO2.

[0142] In some embodiments, Rsis −Ls−Rs11wherein each of Lsand Rs11is independently as described herein. In some embodiments, Rsis Rs11as described herein.

[0143] In some embodiments, Rsis R’ as described herein. For example, in some embodiments, R’ is −C(O)R wherein R is as described herein. In some embodiments, R’ is −CO2R wherein R is as described herein. In some embodiments, R’ is −S(O)2R wherein R is as described herein. In some embodiments, R is C1-6 aliphatic. In some embodiments, R is C1-6 alkyl. In some embodiments, R is optionally substituted phenyl. In some embodiments, Rsis −S(O)2R wherein R is optionally substituted C1-6 aliphatic. In some embodiments, Rsis −S(O)2Me. In some embodiments, Rsis −S(O)2t-Bu. In some embodiments, Rsis −S(O)2R wherein R is optionally substituted phenyl. In some embodiments, Rsis −S(O)2Ph.

[0144] In some embodiments, Rsis R as described herein. For example, in some embodiments, R is not −H. In some embodiments, R is optionally substituted C1-6aliphatic. In some embodiments, R is optionally substituted C1-6alkyl. In some embodiments, R is methyl. In some embodiments, R is optionally substituted phenyl. In some embodiments, R is phenyl.

[0145] In some embodiments, Rsis −Ls−ORs11wherein each of Lsand Rs11is independently as described herein. In some embodiments, Rsis −ORs11wherein Rs11is as described herein. In some embodiments, Rsis −CH2ORs11wherein Rs11is as described herein.

[0146] In some embodiments, Rsis −Ls−SRs11wherein each of Lsand Rs11is independently as described herein. In some embodiments, Rsis −SRs11wherein Rs11is as described herein. In some embodiments, Rsis −CH2SRs11wherein Rs11is as described herein. Page 53 of 201 12495950v1Attorney Docket No.: 2010581-1440

[0147] In some embodiments, Rsis −Ls−N(Rs11)2wherein each of Lsand Rs11is independently as described herein. In some embodiments, Rsis −N(Rs11)2wherein each of Lsand Rs11is independently as described herein. In some embodiments, Rsis −CH2N(Rs11)2wherein each of Lsand Rs11is independently as described herein.

[0148] In some embodiments, Rsis −C(Rs11)3 wherein each Rs11is independently as described herein. In some embodiments, Rsis −CH(Rs11)2wherein each Rs11is independently as described herein. In some embodiments, two or more Rs11are taken together with the carbon atom to which they are attached to form an optionally substituted 3-20 (e.g., 3-15, 3-10, 3-6, 5-10, 5-6, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, etc.) membered ring having 0-10 (e.g., 0, 1-10, 1-5, 1-4, 1-3, 1-2, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, etc.) heteroatoms independently selected from silicon, nitrogen, oxygen, phosphorus and sulfur. In some embodiments, Rsis optionally .

[0149] In some embodiments, Rsis −Ls−Sis11R is independently as described herein. In some embodiments, each Rs11is independently R’ as described herein and is not −H. In some embodiments, each Rs11is independently R as described herein and is not −H. In some embodiments, at least one Rs11is optionally substituted C1-10aliphatic. In some embodiments, at least one Rs11is optionally substituted C1-10alkyl. In some embodiments, at least one Rs11is methyl. In some embodiments, at least one Rs11is optionally substituted phenyl. In some embodiments, at least one Rs11is phenyl. In some embodiments, each Rs11is independently an optionally substituted group selected from C1-10aliphatic and 6-10 membered aryl. In some embodiments, each Rs11is independently an optionally substituted group selected from C1-10alkyl and 6-10 membered aryl. In some embodiments, each Rs11is independently an optionally substituted group selected from C1-6alkyl and 6-10 phenyl. In some embodiments, Rs11is −SiPh2Me. Rs11

[0150] As used herein, Rs11is R’ as described herein. For example, in some embodiments, R’ is R as described herein. In some embodiments, R’ is −C(O)R wherein R is as described herein. In some embodiments, R’ is −CO2R wherein R is as described herein. In some embodiments, R’ is −S(O)2R wherein R is as described herein. Rs11is −H. In some embodiments, Rs11is not −H. In some embodiments, two or more Rs11on the same atom are taken together with their intervening atom(s) to form an optionally substituted 3-20 membered ring having, in addition to the intervening atom(s), 0-10 heteroatoms independently selected from silicon, nitrogen, oxygen, phosphorus and sulfur. Certain embodiments of rings are described herein. Page 54 of 201 12495950v1Attorney Docket No.: 2010581-1440 Ls

[0151] As used herein, Lsis L as described herein. For example, in some embodiments, L is a covalent bond. In some embodiments, L is optionally substituted −CH2−. In some embodiments, L is −CH2−. In some embodiments, L is monosubstituted −CH2−. R’

[0152] Certain embodiments for R’ are described below. Various variables, e.g., R2a, R1, R2, R3, Rs, Rs11, etc., can be R’, and embodiments for R’ can also be applied to such variables that can be R’.

[0153] In some embodiments, R’ is R as described herein. In some embodiments, R’ is −H. In some embodiments, R’ is not −H.

[0154] In some embodiments, R’ is −C(O)R wherein R is as described herein. In some embodiments, R’ is −CO2R wherein R is as described herein. In some embodiments, R’ is −S(O)2R wherein R is as described herein. In some embodiments, as described herein, R is not −H.

[0155] In some embodiments, two or more R’ are taken together with their intervening atom(s) to form an optionally substituted 3-20 (e.g., 3-15, 3-10, 3-6, 5-10, 5-6, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, etc.) membered ring having, in addition to the intervening atom(s), 0-10 (e.g., 0, 1- 10, 1-5, 1-4, 1-3, 1-2, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, etc.) heteroatoms independently selected from silicon, nitrogen, oxygen, phosphorus and sulfur. In some embodiments, two or more R’ on the same atom are taken together with the atom to which they are attached to form an optionally substituted 3-20 (e.g., 3-15, 3-10, 3-6, 5-10, 5-6, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, etc.) membered ring having, in addition to the intervening atom(s), 0-10 (e.g., 0, 1-10, 1-5, 1-4, 1-3, 1-2, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, etc.) heteroatoms independently selected from silicon, nitrogen, oxygen, phosphorus and sulfur. In some embodiments, two R’ on the same atom are taken together with the atom to which they are attached to form an optionally substituted 3-20 (e.g., 3-15, 3-10, 3-6, 5-10, 5-6, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, etc.) membered ring having, in addition to the intervening atom(s), 0-10 (e.g., 0, 1-10, 1-5, 1-4, 1-3, 1-2, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, etc.) heteroatoms independently selected from silicon, nitrogen, oxygen, phosphorus and sulfur.

[0156] In some embodiments, each R’ is independently −R, −C(O)R, −CO2R, or −S(O)2R, or two or more R’ on the same atom are taken together with the atom to which they are attached to form an optionally substituted 3-20 membered ring having, in addition to the intervening atom(s), 0-5 heteroatoms independently selected from silicon, nitrogen, oxygen, phosphorus and sulfur. Ring

[0157] Compounds of the present disclosure may contain various rings. In some embodiments, a variable, e.g., R or a variable that can be R, can be of a ring as described herein. In some embodiments, two variables, e.g., two R’ groups, may be taken together with their intervening atom(s) to form a ring as Page 55 of 201 12495950v1Attorney Docket No.: 2010581-1440 described herein. In some embodiments, a ring is monovalent. In some embodiments, a ring is bivalent. In some embodiments, a ring structure can be polyvalent. Rings are optionally substituted. In some embodiments, a ring is unsubstituted. In some embodiments, a ring is substituted.

[0158] Certain embodiments and features of rings are described below as examples.

[0159] In some embodiments, a ring is an optionally substituted 3-20 (e.g., 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 3-15, 3-14, 3-10, 5-10, 3-7, 3-6, etc.) membered ring having 0-10 (e.g., 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 1-10, 0-5, 1-5, etc.) heteroatoms independently selected from silicon, nitrogen, oxygen, phosphorus and sulfur. In some embodiments, each heteroatom is independently selected from nitrogen, oxygen and sulfur. In some embodiments, a ring is an optionally substituted 3-20 (e.g., 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 3-15, 3-14, 3-10, 5-10, 3-7, 3-6, etc.) membered ring having 0-10 (e.g., 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 1-10, 0-5, 1-5, etc.) heteroatoms independently selected from oxygen, nitrogen, and sulfur. In some embodiments, a ring is monocyclic. In some embodiments, a ring is bicyclic. In some embodiments, a ring is polycyclic.

[0160] In some embodiments, each monocyclic ring unit is independently an optionally substituted 3-10 (e.g., 3, 4, 5, 6, 7, 8, 9, 10, 3-8, 3-7, 3-6, 5-8, etc.) membered ring having 0-5 (e.g., 1, 2, 3, 4, 5, 1-5, 1-4, 1-2, etc.) heteroatoms independently selected from silicon, nitrogen, oxygen, phosphorus and sulfur and 1-10 (e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 1-5, 1-4, etc.) carbon atoms. In some embodiments, a monocyclic ring unit is an optionally substituted saturated ring. In some embodiments, a monocyclic ring unit is an optionally substituted partially unsaturated ring. In some embodiments, a monocyclic ring unit is an optionally substituted aromatic ring. In some embodiments, a monocyclic ring unit is an optionally substituted phenyl ring. In some embodiments, a monocyclic ring unit is an optionally substituted 5- membered heteroaromatic having 1-4 (e.g., 1, 2, 3, 4, 1-3, 1-2, etc.) heteroatoms independently selected from nitrogen, oxygen and sulfur. In some embodiments, a monocyclic ring unit is an optionally substituted 6-membered heteroaromatic having 1-4 (e.g., 1, 2, 3, 4, 1-3, 1-2, etc.) heteroatoms independently selected from nitrogen, oxygen and sulfur. Each monocyclic ring unit is independently optionally substituted. In some embodiments, a monocyclic ring unit is unsaturated. In some embodiments, a monocyclic ring unit is saturated.

[0161] In some embodiments, a ring is an optionally substituted saturated ring. In some embodiments, a ring is an optionally substituted partially unsaturated ring. In some embodiments, a ring is an optionally substituted aromatic ring.

[0162] In some embodiments, a ring is an optionally substituted 3-10 membered, monocyclic, bicyclic or polycyclic ring having, in addition to the intervening atom(s), 0-4 heteroatoms independently selected from nitrogen, oxygen and sulfur. In some embodiments, a ring is 3-9, 3-8, 3-7, 3-6, 4-10, 4-9, 4-8, 4-7, 4-6, 5-10, 5-9, 5-8, 5-7, 5-6, or 3, 4, 5, 6, 7, 8, 9, or 10-membered. In some embodiments, a ring Page 56 of 201 12495950v1Attorney Docket No.: 2010581-1440 is 3-9 membered. In some embodiments, a ring is 3-7 membered. In some embodiments, a ring is 4-10 membered. In some embodiments, a ring is 4-7 membered. In some embodiments, a ring is 5-10 membered. In some embodiments, a ring is 5-7 membered. In some embodiments, a ring is 3-membered. In some embodiments, a ring is 4-membered. In some embodiments, a ring is 5-membered. In some embodiments, a ring is 6-membered. In some embodiments, a ring is 7-membered. In some embodiments, a ring is 8-membered. In some embodiments, a ring is 9-membered. In some embodiments, a ring is 10-membered. In some embodiments, a ring is monocyclic. In some embodiments, a ring is bicyclic. In some embodiments, a ring is polycyclic. In some embodiments, a ring has no heteroatoms. In some embodiments, a ring has 1-6, e.g., 1-5, 1-3, or 1, 2, 3, 4, 5, or 6 heteroatoms. In some embodiments, a ring formed by two or more groups taken together with their intervening atom(s) has no heteroatoms in addition to the intervening atom(s). In some embodiments, a ring formed by two or more groups taken together with their intervening atom(s) has 1-6, e.g., 1-5, 1-3, or 1, 2, 3, 4, 5, or 6 heteroatoms in addition to the intervening atom(s). In some embodiments, a ring is saturated. In some embodiments, a ring is partially unsaturated. In some embodiments, a ring comprises one or more aromatic ring. In some embodiments, a ring is bicyclic or polycyclic, and each monocyclic ring unit is independently 3-10 (e.g., 3-9, 3-8, 3-7, 3-6, 4-10, 4-9, 4-8, 4-7, 4-6, 5-10, 5-9, 5-8, 5-7, 5-6, or 3, 4, 5, 6, 7, 8, 9, or 10) membered, saturated, partially unsaturated or aromatic and having 0-5 (e.g., 0, 1- 5, 1-3, 1, 2, 3, 4, or 5) heteroatoms. In some embodiments, each heteroatom is independently selected from nitrogen, oxygen and sulfur. In some embodiments, a monocyclic ring unit is saturated. In some embodiments, a monocyclic ring unit is partially unsaturated. In some embodiments, a monocyclic ring unit is aromatic. In some embodiments, a monocyclic ring unit is heteroaromatic. Those skilled in the art appreciate that intervening atom(s), e.g., of groups taken together to form a ring, are typically atoms on the shortest path connecting such groups if multiple paths exist.

[0163] In some embodiments, a ring has one or more heteroatoms. In some embodiments, a ring comprises a nitrogen atom. In some embodiments, a ring comprises an oxygen atom. In some embodiments, a ring comprises a sulfur atom. R

[0001] Various variables in the present disclosure can independently be R. Certain embodiments for R are described below as examples. Those skilled in the art reading the present disclosure appreciate that embodiments that are described for a variable that can be R and fall within the definition of R can be embodiments for R as well. Those skilled in the art reading the present disclosure further appreciate that embodiments for R, e.g., those described for R, those described for a variable that can be R and within the definition of R, etc., can be embodiments for a variable that can be R.

[0002] In some embodiments, R is −H. In some embodiments, R is not −H. In some embodiments, Page 57 of 201 12495950v1Attorney Docket No.: 2010581-1440 R is optionally substituted C1-10(e.g., C1-6, C2-8, C1, C2, C3, C4, C5, C6, C7, C8, C9, C10, etc.) aliphatic. In some embodiments, R is optionally substituted C1-8aliphatic. In some embodiments, R is optionally substituted C1-6aliphatic. In some embodiments, R is optionally substituted C1-10(e.g., C1-6, C2-8, C1, C2, C3, C4, C5, C6, C7, C8, C9, C10, etc.) alkyl. In some embodiments, R is optionally substituted C1-8alkyl. In some embodiments, R is optionally substituted C1-6 aliphatic. In some embodiments, R is optionally substituted C1-6alkyl. In some embodiments, R is optionally substituted −CH2−C3-6cycloaliphatic. In some embodiments, R is optionally substituted −CH2−C3-6cycloaliphatic. In some embodiments, R is optionally substituted −CH2−C3-6 cycloalkyl. In some embodiments, R is methyl. In some embodiments, R is ethyl. In some embodiments, R is isopropyl. In some embodiments, R is −CF3. In some embodiments, R is −CH2CF3. In some embodiments, R is butyl. In some embodiments, R is t-butyl.

[0003] In some embodiments, R is optionally substituted 3-10 membered (e.g., 3-9, 3-8, 3-7, 3-6, 5- 7, 4, 5, 6, 7, 8, 9, 10, etc.) cycloaliphatic. In some embodiments, R is optionally substituted C3-10 cycloalkyl. In some embodiments, R is optionally substituted cyclopropyl. In some embodiments, R is optionally substituted cyclobutyl. In some embodiments, R is optionally substituted cyclopentyl. In some embodiments, R is optionally substituted cyclohexyl.

[0004] In some embodiments, R is optionally substituted C1-10 (e.g., C1-6, C2-8, C1, C2, C3, C4, C5, C6, C7, C8, C9, C10, etc.) heteroaliphatic having 1-5 (e.g., 1-4, 1-3, 1-2, 1, 2, 3, 4, 5, etc.) heteroatoms independently selected from silicon, nitrogen, oxygen, phosphorus and sulfur. In some embodiments, R is optionally substituted C1-6 (e.g., C1-6, C2-8, C1, C2, C3, C4, C5, C6, C7, C8, C9, C10, etc.) heteroaliphatic having 1-5 (e.g., 1-4, 1-3, 1-2, 1, 2, 3, 4, 5, etc.) heteroatoms independently selected from silicon, nitrogen, oxygen, phosphorus and sulfur. In some embodiments, R is optionally substituted C1-10 (e.g., C1- 6, C2-8, C1, C2, C3, C4, C5, C6, C7, C8, C9, C10, etc.) heteroaliphatic having 1-5 (e.g., 1-4, 1-3, 1-2, 1, 2, 3, 4, 5, etc.) heteroatoms independently selected from oxygen, nitrogen and sulfur. In some embodiments, R is optionally substituted C1-6 (e.g., C1-6, C2-8, C1, C2, C3, C4, C5, C6, C7, C8, C9, C10, etc.) heteroaliphatic having 1-5 (e.g., 1-4, 1-3, 1-2, 1, 2, 3, 4, 5, etc.) heteroatoms independently selected from oxygen, nitrogen and sulfur. In some embodiments, R is optionally substituted C1-6 heteroaliphatic having 1-3 heteroatoms independently selected from nitrogen, oxygen and sulfur. In some embodiments, R is optionally substituted C1-6heteroaliphatic having 1-3 heteroatoms independently selected from nitrogen, oxygen and sulfur C1-6heteroaliphatic having 1 heteroatom independently selected from nitrogen, oxygen and sulfur. In some embodiments, R is heteroalkyl.

[0005] In some embodiments, R is optionally substituted 3-15 (e.g., 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 3-10, 3-7, 4-10, 4-6, etc.) membered heterocyclic ring having 1-5 (e.g., 1-4, 1-3, 1-2, 1, 2, 3, 4, 5, etc.) heteroatoms independently selected from silicon, nitrogen, oxygen, phosphorus and sulfur. In some embodiments, R is optionally substituted 3-15 (e.g., 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 3-10, 3-7, 4- Page 58 of 201 12495950v1Attorney Docket No.: 2010581-1440 10, 4-6, etc.) membered heterocyclic ring having 1-5 (e.g., 1-4, 1-3, 1-2, 1, 2, 3, 4, 5, etc.) heteroatoms independently selected from oxygen, nitrogen and sulfur. In some embodiments, R is optionally substituted 3-10 (e.g., 3-9, 3-8, 3-7, 3-6, 5-7, 4, 5, 6, 7, 8, 9, 10, etc.) membered heterocyclyl having 1-4 (e.g., 1, 2, 3, 4, 1-2, etc.) heteroatoms independently selected from nitrogen, oxygen and sulfur. In some embodiments, R is optionally substituted 3-membered heterocyclyl having 1-2 heteroatoms independently selected from nitrogen, oxygen and sulfur. In some embodiments, R is optionally substituted 3- membered heterocyclyl having one heteroatom independently selected from nitrogen, oxygen and sulfur. In some embodiments, R is optionally substituted 4-membered heterocyclyl having 1-2 heteroatoms independently selected from nitrogen, oxygen and sulfur. In some embodiments, R is optionally substituted 5-membered heterocyclyl having 1-3 heteroatoms independently selected from nitrogen, oxygen and sulfur. In some embodiments, R is optionally substituted 6-membered heterocyclyl having 1- 3 heteroatoms independently selected from nitrogen, oxygen and sulfur. In some embodiments, R is optionally substituted 7-membered heterocyclyl having 1-3 heteroatoms independently selected from nitrogen, oxygen and sulfur. In some embodiments, R is optionally substituted 8-membered heterocyclyl having 1-3 heteroatoms independently selected from nitrogen, oxygen and sulfur. In some embodiments, R is optionally substituted 9-membered heterocyclyl having 1-3 heteroatoms independently selected from nitrogen, oxygen and sulfur. In some embodiments, R is optionally substituted 10-membered heterocyclyl having 1-3 heteroatoms independently selected from nitrogen, oxygen and sulfur. In some embodiments, there is one carbon atom in a heterocyclyl ring. In some embodiments, there are two or more (e.g., 2-14, 2-9, 2-6, 2-4, 3-10, 3-5, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, etc.) carbon atoms in a heterocyclyl ring.

[0006] In some embodiments, R is optionally substituted phenyl. In some embodiments, R is phenyl. In some embodiments, R is optionally substituted naphthyl. In some embodiments, R is optionally substituted 1-naphthyl. In some embodiments, R is optionally substituted 2-naphthyl. In some embodiments, R is naphthyl.

[0007] In some embodiments, R is optionally substituted 5-14 (e.g., 5, 6, 9, 10, 14, etc.) membered heteroaryl having 1-6 (e.g., 1-5, 1-4, 1, 2, 3, 4, 5, 6, etc.) heteroatoms independently selected from silicon, nitrogen, oxygen, phosphorus and sulfur. In some embodiments, R is optionally substituted 5-14 (e.g., 5, 6, 9, 10, 14, etc.) membered heteroaryl having 1-6 (e.g., 1-5, 1-4, 1, 2, 3, 4, 5, 6, etc.) heteroatoms independently selected from oxygen, nitrogen and sulfur. In some embodiments, R is optionally substituted 5-10 (e.g., 5, 6, 9, 10, etc.) membered heteroaryl having 1-6 (e.g., 1-5, 1-4, 1, 2, 3, 4, 5, 6, etc.) heteroatoms independently selected from oxygen, nitrogen and sulfur. In some embodiments, R is optionally substituted 5-10 membered heteroaryl having 1-4 heteroatoms independently selected from nitrogen, oxygen and sulfur. In some embodiments, a heteroaryl ring is monocyclic and is 5-membered. Page 59 of 201 12495950v1Attorney Docket No.: 2010581-1440 In some embodiments, a heteroaryl ring is monocyclic and is 6-membered. In some embodiments, a heteroaryl ring is bicyclic and is 9-membered. In some embodiments, a heteroaryl ring is bicyclic and is 10-membered. In some embodiments, a heteroaryl ring is tricyclic and is 14-membered. In some embodiments, R is optionally substituted 5-membered heteroaryl having 1-4 heteroatoms independently selected from nitrogen, oxygen and sulfur. In some embodiments, R is optionally substituted 5- membered heteroaryl having 1 heteroatom selected from nitrogen, oxygen and sulfur. In some embodiments, R is optionally substituted 6-membered heteroaryl having 1-4 heteroatoms independently selected from nitrogen, oxygen and sulfur. In some embodiments, R is optionally substituted 6- membered heteroaryl having 1 heteroatom selected from nitrogen, oxygen and sulfur. In some embodiments, R is optionally substituted bicyclic 8-10 membered aromatic ring having 1-6 heteroatoms nitrogen, oxygen and sulfur. In some embodiments, R is optionally substituted bicyclic 9-membered aromatic ring having 1-6 heteroatoms nitrogen, oxygen and sulfur. In some embodiments, R is optionally substituted bicyclic 10-membered aromatic ring having 1-6 heteroatoms nitrogen, oxygen and sulfur. In some embodiments, R is optionally substituted bicyclic 9-membered aromatic ring having 1 heteroatom selected from nitrogen, oxygen and sulfur. In some embodiments, R is optionally substituted bicyclic 10- membered aromatic ring having 1 heteroatom nitrogen, oxygen and sulfur. In some embodiments, at least one heteroatom is nitrogen. In some embodiments, at least one heteroatom is oxygen. In some embodiments, at least one heteroatom is sulfur. In some embodiments, each heteroatom is the same. In some embodiments, at least one heteroatom is different from another heteroatom.

[0008] As described herein, various groups may be optionally substituted. Substituents are routinely utilized in chemistry including in development of various therapeutics. Many substituents can be utilized in accordance with the present disclosure. In some embodiments, an optionally substituted group is unsubstituted. In some embodiments, an optionally substituted group is substituted. Substituents are preferably those that result in the formation of compounds for a desired property, activity, use, etc., as described herein. In some embodiments, compounds are stable for therapeutic use as described herein. The term “stable,” as used herein, refers to compounds that are not substantially altered when subjected to conditions to allow for their production, detection, and, in certain embodiments, their recovery, purification, and use for one or more of the purposes disclosed herein. In some embodiments, a substituent is a hydrocarbon group. In some embodiments, a substituent comprises a heteroatom. In some embodiments, a substituent comprises multiple heteroatoms. In some embodiments, each atom in a substituent is independently selected from hydrogen, carbon, halogen, nitrogen, oxygen, sulfur, phosphorus and silicon. In some embodiments, each atom in a substituent is independently selected from hydrogen, carbon, halogen, nitrogen, oxygen, and sulfur. In some embodiments, each atom in a substituent is independently selected from hydrogen, carbon, fluorine, chlorine, bromine, iodine, nitrogen, oxygen, and sulfur. In some Page 60 of 201 12495950v1Attorney Docket No.: 2010581-1440 embodiments, the total number of carbon and non-halogen heteroatom(s) in a substituent is about or no more than about 1; in some embodiments, it is no more than about 2; in some embodiments, it is no more than about 3; in some embodiments, it is no more than about 4; in some embodiments, it is no more than about 5; in some embodiments, it is no more than about 6; in some embodiments, it is no more than about 7; in some embodiments, it is no more than about 8; in some embodiments, it is no more than about 9; in some embodiments, it is no more than about 10; in some embodiments, it is no more than about 11; in some embodiments, it is no more than about 12; in some embodiments, it is no more than about 13; in some embodiments, it is no more than about 14; in some embodiments, it is no more than about 15; in some embodiments, it is no more than about 20. In some embodiments, the total number of carbon and non- halogen heteroatom(s) in each substituent is independently no more than about 20. In some embodiments, the total number of carbon and non-halogen heteroatom(s) in each substituent is independently no more than about 15. In some embodiments, the total number of carbon and non-halogen heteroatom(s) in each substituent is independently no more than about 10. In some embodiments, the total number of carbon and non-halogen heteroatom(s) in each substituent is independently no more than about 6. Nucleosides

[0164] Various nucleosides can be utilized for oligonucleotide preparation, e.g., those described in US 10167309, US 11643657, US 11718638, US 11608355, US 20230089442, etc. In some embodiments, the present disclosure provides nucleosides comprising −P(O)(ORPG)2 as described herein. In some embodiments, a nucleoside comprises −P(O)(ORPG)2 which is bonded to the sugar moiety of the nucleoside. In some embodiments, a phosphoramidite comprises −P(O)(ORPG)2 which is bonded to a moiety, e.g., an optionally substituted triazole ring, that is bonded to the sugar moiety of the nucleoside. In some embodiments, a sugar is a natural sugar. In some embodiments, a sugar is a modified sugar. In some embodiments, a nucleobase is an optionally substituted natural nucleobase. In some embodiments, a nucleobase is optionally protected A, T, C, G, U, or 5mC (e.g., for oligonucleotide synthesis). In some embodiments, a nucleoside is abasic.

[0165] In some embodiments, the provided technology provides a compound of formula (RPG)2P(O)−L5E−SU(−BA)−OH wherein each other variable is independently as described herein. In some embodiments, such a compound is utilized as a nucleoside, e.g., for phosphoramidite preparation.

[0166] In some embodiments, the provided technology provides a compound of formula N or a salt thereof: Page 61 of 201 12495950v1Attorney Docket No.: 2010581-1440 , wherein each variable is embodiments, such a compound isutilized as a nucleoside, e.g., for

[0167] In some embodiments, the provided technology provides a compound of formula N’ or a salt thereof: , wherein each variable is embodiments, such a compound isutilized as a nucleoside, e.g., for phosphoramidite preparation.

[0168] In some embodiments, the provided technology provides a compound of formula II or a salt thereof: , wherein each variable isembodiments, such a compound is utilized as a nucleoside, e.g., for phosphoramidite preparation.

[0169] In some embodiments, the provided technology provides a compound of formula II’ or a salt thereof: ,wherein each variable is independently as described herein. In some embodiments, such a compound is utilized as a nucleoside, e.g., for phosphoramidite preparation. Page 62 of 201 12495950v1Attorney Docket No.: 2010581-1440

[0170] In some embodiments, provided nucleosides can react with phosphorus-containing agents, e.g., compounds of formula V or salts thereof to provide phosphoramidites.

[0171] In some embodiments, the provided technology provides a compound of formula III or a salt thereof: ,wherein each variable is independently as described herein. In some embodiments, such a compound is utilized as a nucleoside, e.g., for phosphoramidite preparation. In some embodiments, such a compound is utilized to prepare for, e.g., a compound of formula II or formula II’, or a salt thereof.

[0172] In some embodiments, the provided technology provides a compound of formula III’ or a salt thereof: ,wherein each variable is independently as described herein. In some embodiments, such a compound is utilized as a nucleoside, e.g., for phosphoramidite preparation. In some embodiments, such a compound is utilized to prepare for, e.g., a compound of formula II or formula II’, or a salt thereof. Nucleobases

[0173] Various nucleobases may be utilized in phosphoramidites, nucleosides, oligonucleotides, etc., in accordance with the present disclosure. In some embodiments, a nucleobase is a natural nucleobase, the most commonly occurring ones being A, T, C, G and U. In some embodiments, a nucleobase is a modified nucleobase in that it is not A, T, C, G or U. In some embodiments, a nucleobase is optionally substituted A, T, C, G or U, or a substituted tautomer of A T, C, G or U. In some embodiments, a nucleobase is optionally substituted A, T, C, G or U, e.g., 5mC, 5-hydroxymethyl C, etc. In some embodiments, a nucleobase is alkyl-substituted A, T, C, G or U. In some embodiments, a nucleobase is A. In some embodiments, a nucleobase is T. In some embodiments, a nucleobase is C. In some embodiments, a nucleobase is G. In some embodiments, a nucleobase is U. In some embodiments, a nucleobase is 5mC. In some embodiments, a nucleobase is substituted A, T, C, G or U. In some embodiments, a nucleobase is a substituted tautomer of A, T, C, G or U. In some embodiments, substitution protects certain functional groups in nucleobases to minimize undesired reactions during oligonucleotide synthesis. Suitable Page 63 of 201 12495950v1Attorney Docket No.: 2010581-1440 technologies for nucleobase protection in oligonucleotide synthesis are widely known in the art and may be utilized in accordance with the present disclosure.

[0174] In some embodiments, a nucleobase is a natural nucleobase or a modified nucleobase derived from a natural nucleobase. Examples include uracil, thymine, adenine, cytosine, and guanine optionally having their respective amino groups protected by acyl protecting groups, 2-fluorouracil, 2-fluorocytosine, 5-bromouracil, 5-iodouracil, 2,6-diaminopurine, azacytosine, pyrimidine analogs such as pseudoisocytosine and pseudouracil and other modified nucleobases such as 8-substituted purines, xanthine, or hypoxanthine (the latter two being the natural degradation products). Certain examples of modified nucleobases are disclosed in Chiu and Rana, RNA, 2003, 9, 1034-1048, Limbach et al. Nucleic Acids Research, 1994, 22, 2183-2196 and Revankar and Rao, Comprehensive Natural Products Chemistry, vol.7, 313. In some embodiments, a modified nucleobase is substituted uracil, thymine, adenine, cytosine, or guanine. In some embodiments, a modified nucleobase is a functional replacement, e.g., in terms of hydrogen bonding and / or base pairing, of uracil, thymine, adenine, cytosine, or guanine. In some embodiments, a nucleobase is optionally substituted uracil, thymine, adenine, cytosine, 5-methylcytosine, or guanine. In some embodiments, a nucleobase is uracil, thymine, adenine, cytosine, 5-methylcytosine, or guanine.

[0175] In some embodiments, a modified base is optionally substituted adenine, cytosine, guanine, thymine, or uracil, or a tautomer thereof. In some embodiments, a modified nucleobase is a modified adenine, cytosine, guanine, thymine or uracil, modified by one or more modifications by which: a nucleobase is modified by one or more optionally substituted groups independently selected from acyl, halogen, amino, azide, alkyl, alkenyl, alkynyl, aryl, heteroalkyl, heteroalkenyl, heteroalkynyl, heterocyclyl, heteroaryl, carboxyl, hydroxyl, biotin, avidin, streptavidin, substituted silyl, and combinations thereof; one or more atoms of a nucleobase are independently replaced with a different atom selected from carbon, nitrogen and sulfur; one or more double bonds in a nucleobase are independently hydrogenated; or one or more aryl or heteroaryl rings are independently inserted into a nucleobase.

[0176] In some embodiments, a modified nucleobase is a modified nucleobase reported in, e.g., WO2017 / 210647. In some embodiments, modified nucleobases are expanded-size nucleobases in which one or more aryl and / or heteroaryl rings, such as phenyl rings, have been added. Certain examples of modified nucleobases, including nucleobase replacements, are described in the Glen Research catalog (Glen Research, Sterling, Virginia); Krueger AT et al., Acc. Chem. Res., 2007, 40, 141-150; Kool, ET, Acc. Chem. Res., 2002, 35, 936-943; Benner S.A., et al., Nat. Rev. Genet., 2005, 6, 553-543; Romesberg, F.E., et al., Curr. Opin. Chem. Biol., 2003, 7, 723-733; or Hirao, I., Curr. Opin. Chem. Biol., 2006, 10, 622-627. Page 64 of 201 12495950v1Attorney Docket No.: 2010581-1440 In some embodiments, an expanded-size nucleobase is an expanded-size nucleobase described in, e.g., WO2017 / 210647. In some embodiments, modified nucleobases are moieties such as corrin- or porphyrin- derived rings. Certain porphyrin-derived base replacements have been described in, e.g., Morales-Rojas, H and Kool, ET, Org. Lett., 2002, 4, 4377-4380. In some embodiments, a porphyrin-derived ring is a porphyrin-derived ring described in, e.g., WO2017 / 219647. In some embodiments, a modified nucleobase is a modified nucleobase described in, e.g., WO2017 / 219647. In some embodiments, a modified nucleobase is fluorescent. Examples of such fluorescent modified nucleobases include phenanthrene, pyrene, stillbene, isoxanthine, isozanthopterin, terphenyl, terthiophene, benzoterthiophene, coumarin, lumazine, tethered stillbene, benzo-uracil, naphtho-uracil, etc., and those described in e.g., WO2017 / 210647. In some embodiments, a nucleobase or modified nucleobase is selected from: C5- propyne T, C5-propyne C, C5-Thiazole, phenoxazine, 2-thio-thymine, 5-triazolylphenyl-thymine, diaminopurine, and N2-aminopropylguanine.

[0177] In some embodiments, a modified nucleobase is selected from 5-substituted pyrimidines, 6- azapyrimidines, alkyl or alkynyl substituted pyrimidines, alkyl substituted purines, and N-2, N-6 and O-6 substituted purines. In certain embodiments, modified nucleobases are selected from 2- aminopropyladenine, 5-hydroxymethyl cytosine, xanthine, hypoxanthine, 2-aminoadenine, 6-N- methylguanine, 6-N- methyladenine, 2-propyladenine, 2-thiouracil, 2-thiothymine and 2-thiocytosine, 5- propynyl (−C≡C-CH3) uracil, 5-propynylcytosine, 6-azouracil, 6-azocytosine, 6-azothymine, 5- ribosyluracil (pseudouracil), 4- thiouracil, 8-halo, 8-amino, 8-thiol, 8-thioalkyl, 8-hydroxyl, 8-aza and other 8-substituted purines, 5-halo, particularly 5-bromo, 5-trifluoromethyl, 5-halouracil, and 5-halocytosine, 7- methylguanine, 7-methyladenine, 2-F-adenine, 2-aminoadenine, 7-deazaguanine, 7-deazaadenine, 3- deazaguanine, 3-deazaadenine, 6-N- benzoyladenine, 2-N-isobutyrylguanine, 4-N-benzoylcytosine, 4-N- benzoyluracil, 5-methyl 4-N-benzoylcytosine, 5-methyl 4-N-benzoyluracil, universal bases, hydrophobic bases, promiscuous bases, size-expanded bases, and fluorinated bases. In some embodiments, modified nucleobases are tricyclic pyrimidines, such as l,3-diazaphenoxazine-2-one, l,3-diazaphenothiazine-2-one or 9-(2-aminoethoxy)-l,3-diazaphenoxazine-2- one (G-clamp). In some embodiments, modified nucleobases are those in which the purine or pyrimidine base is replaced with other heterocycles, for example, 7-deaza- adenine, 7-deazaguanosine, 2-aminopyridine or 2- pyridone. In some embodiments, modified nucleobases are those disclosed in US 3687808, The Concise Encyclopedia Of Polymer Science And Engineering, Kroschwitz, J.I., Ed., John Wiley & Sons, 1990, 858-859; Englisch et al., Angewandte Chemie, International Edition, 1991, 30, 613; Sanghvi, Y.S., Chapter 15, Antisense Research and Applications, Crooke, S.T. and Lebleu, B., Eds., CRC Press, 1993, 273-288; or in Chapters 6 and 15, Antisense Drug Technology, Crooke S.T., Ed., CRC Press, 2008, 163-166 and 442-443.

[0178] In some embodiments, modified nucleobases and methods thereof are those described in US Page 65 of 201 12495950v1Attorney Docket No.: 2010581-1440 20030158403, US 3687808, US 4845205, US 5130302, US 5134066, US 5 175273, US 5367066, US 5432272, US 5434257, US 5457187, US 5459255, US 5484908, US 5502177, US 5525711, US 5552540, US 5587469, US 5594 121, US 5596091, US 5614617, US 5645985, US 5681941, US 5750692, US 5763588, US 5830653, or US 6005096.

[0179] In some embodiments, a modified nucleobase is substituted. In some embodiments, a modified nucleobase is substituted such that it contains, e.g., heteroatoms, alkyl groups, or linking moieties connected to fluorescent moieties, biotin or avidin moieties, or other protein or peptides. In some embodiments, a modified nucleobase is a “universal base” that is not a nucleobase in the most classical sense, but that functions similarly to a nucleobase. One example of a universal base is 3-nitropyrrole.

[0180] In some embodiments, nucleosides that can be utilized in provided technologies comprise modified nucleobases and / or modified sugars, e.g., 4-acetylcytidine; 5-(carboxyhydroxylmethyl)uridine; 2’-O-methylcytidine; 5-carboxymethylaminomethyl-2-thiouridine; 5-carboxymethylaminomethyluridine; dihydrouridine; 2’-O-methylpseudouridine; beta,D-galactosylqueosine; 2’-O-methylguanosine; N6- isopentenyladenosine; 1-methyladenosine; 1-methylpseudouridine; 1-methylguanosine; l-methylinosine; 2,2-dimethylguanosine; 2-methyladenosine; 2-methylguanosine; N7-methylguanosine; 3-methyl-cytidine; 5-methylcytidine; 5-hydroxymethylcytidine; 5-formylcytosine; 5-carboxylcytosine; N6-methyladenosine; 7-methylguanosine; 5-methylaminoethyluridine; 5-methoxyaminomethyl-2-thiouridine; beta,D- mannosylqueosine; 5-methoxycarbonylmethyluridine; 5-methoxyuridine; 2-methylthio-N6- isopentenyladenosine; N-((9-beta,D-ribofuranosyl-2-methylthiopurine-6-yl)carbamoyl)threonine; N-((9- beta,D-ribofuranosylpurine-6-yl)-N-methylcarbamoyl)threonine; uridine-5-oxyacetic acid methylester; uridine-5-oxyacetic acid (v); pseudouridine; queosine; 2-thiocytidine; 5-methyl-2-thiouridine; 2- thiouridine; 4-thiouridine; 5-methyluridine; 2’-O-methyl-5-methyluridine; and 2’-O-methyluridine.

[0181] In some embodiments, a nucleobase, e.g., a modified nucleobase comprises one or more biomolecule binding moieties such as e.g., antibodies, antibody fragments, biotin, avidin, streptavidin, receptor ligands, or chelating moieties. In other embodiments, a nucleobase is 5-bromouracil, 5-iodouracil, or 2,6-diaminopurine. In some embodiments, a nucleobase comprises substitution with a fluorescent or biomolecule binding moiety. In some embodiments, a substituent is a fluorescent moiety. In some embodiments, a substituent is biotin or avidin.

[0182] Certain examples of nucleobases and related methods are described in US 3687808, 4845205, US 513030, US 5134066, US 5175273, US 5367066, US 5432272, US 5457187, US 5457191, US 5459255, US 5484908, US 5502177, US 5525711, US 5552540, US 5587469, US 5594121, US 5596091, US 5614617, US 5681941, US 5750692, US 6015886, US 6147200, US 6166197, US 6222025, US 6235887, US 6380368, US 6528640, US 6639062, US 6617438, US 7045610, US 7427672, US or US 7495088.

[0183] In some embodiments, an oligonucleotide comprises a nucleobase, sugar, nucleoside, and / or Page 66 of 201 12495950v1Attorney Docket No.: 2010581-1440 internucleotidic linkage which is described in any of: Gryaznov, S; Chen, J.-K. J. Am. Chem. Soc. 1994, 116, 3143; Hendrix et al.1997 Chem. Eur. J.3: 110; Hyrup et al.1996 Bioorg. Med. Chem.4: 5; Jepsen et al. 2004 Oligo. 14: 130-146; Jones et al. J. Org. Chem. 1993, 58, 2983; Koizumi et al. 2003 Nuc. Acids Res.12: 3267-3273; Koshkin et al.1998 Tetrahedron 54: 3607-3630; Kumar et al.1998 Bioo. Med. Chem. Let.8: 2219-2222; Lauritsen et al.2002 Chem. Comm.5: 530-531; Lauritsen et al.2003 Bioo. Med. Chem. Lett.13: 253-256; Mesmaeker et al. Angew. Chem., Int. Ed. Engl.1994, 33, 226; Morita et al.2001 Nucl. Acids Res. Supp.1: 241-242; Morita et al.2002 Bioo. Med. Chem. Lett.12: 73-76; Morita et al.2003 Bioo. Med. Chem. Lett. 2211-2226; Nielsen et al. 1997 Chem. Soc. Rev. 73; Nielsen et al. 1997 J. Chem. Soc. Perkins Transl. 1: 3423-3433; Obika et al. 1997 Tetrahedron Lett. 38 (50): 8735–8; Obika et al. 1998 Tetrahedron Lett. 39: 5401-5404; Pallan et al. 2012 Chem. Comm. 48: 8195-8197; Petersen et al. 2003 TRENDS Biotech. 21: 74-81; Rajwanshi et al. 1999 Chem. Commun. 1395-1396; Schultz et al. 1996 Nucleic Acids Res. 24: 2966; Seth et al. 2009 J. Med. Chem. 52: 10-13; Seth et al. 2010 J. Med. Chem. 53: 8309-8318; Seth et al.2010 J. Org. Chem.75: 1569-1581; Seth et al.2012 Bioo. Med. Chem. Lett.22: 296-299; Seth et al. 2012 Mol. Ther-Nuc. Acids. 1, e47; Seth, Punit P; Siwkowski, Andrew; Allerson, Charles R; Vasquez, Guillermo; Lee, Sam; Prakash, Thazha P; Kinberger, Garth; Migawa, Michael T; Gaus, Hans; Bhat, Balkrishen; et al. From Nucleic Acids Symposium Series (2008), 52(1), 553-554; Singh et al. 1998 Chem. Comm. 1247-1248; Singh et al. 1998 J. Org. Chem. 63: 10035-39; Singh et al. 1998 J. Org. Chem. 63: 6078-6079; Sorensen 2003 Chem. Comm. 2130-2131; Ts'o et al. Ann. N. Y. Acad. Sci. 1988, 507, 220; Van Aerschot et al. 1995 Angew. Chem. Int. Ed. Engl. 34: 1338; Vasseur et al. J. Am. Chem. Soc.1992, 114, 4006; WO 2007090071; or WO 2016 / 079181.

[0184] In some embodiments, an oligonucleotide comprises a modified nucleobase, nucleoside or nucleotide which is described in any of: Feldman et al.2017 J. Am. Chem. Soc.139: 11427-11433, Feldman et al. 2017 Proc. Natl. Acad. Sci. USA 114: E6478-E6479, Hwang et al. 2009 Nucl. Acids Res. 37: 4757- 4763, Hwang et al. 2008 J. Am. Chem. Soc. 130: 14872-14882, Lavergne et al. 2012 Chem. Eur. J. 18: 1231-1239, Lavergne et al. 2013 J. Am. Chem. Soc. 135: 5408-5419, Ledbetter et al. 2018 J. Am. Chem. Soc.140: 758-765, Malyshev et al.2009 J. Am. Chem. Soc.131: 14620-14621, Seo et al.2009 Chem. Bio. Chem. 10: 2394-2400, e.g., d3FB, d2Py analogs, d2Py, d3MPy, d4MPy, d5MPy, d34DMPy, d35DMPy, d45DMPy, d5FM, d5PrM, d5SICS, dFEMO, dMMO2, dNaM, dNM01, dTPT3, nucleotides with 2’-azido, 2’-chloro, 2’-amino or arabinose sugars, isocarbostiryl-, napthyl- and azaindole-nucleotides, and modifications and derivatives and functionalized versions thereof, e.g., those in which the sugar comprises a 2’-modification and / or other modification, and dMMO2 derivatives with meta-chlorine, -bromine, - iodine, -methyl, or -propinyl substituents.

[0185] In some embodiments, a nucleobase comprises at least one optionally substituted ring which comprises a heteroatom ring atom. In some embodiments, a nucleobase comprises at least one optionally Page 67 of 201 12495950v1Attorney Docket No.: 2010581-1440 substituted ring which comprises a nitrogen ring atom. In some embodiments, such a ring is aromatic. In some embodiments, a nucleobase is bonded to a sugar through a heteroatom. In some embodiments, a nucleobase is bonded to a sugar through a nitrogen atom. In some embodiments, a nucleobase is bonded to a sugar through a ring nitrogen atom.

[0186] In some embodiments, an oligonucleotide comprises a nucleobase or modified nucleobase as described in US 10167309, US 11643657, US 11718638, US 11608355 and US 20230089442.

[0187] In some embodiments, a nucleobase is an optionally substituted purine base residue. In some embodiments, a nucleobase is a protected purine base residue. In some embodiments, a nucleobase is an optionally substituted adenine residue. In some embodiments, a nucleobase is a protected adenine residue. In some embodiments, a nucleobase is an optionally substituted guanine residue. In some embodiments, a nucleobase is a protected guanine residue. In some embodiments, a nucleobase is an optionally substituted cytosine residue. In some embodiments, a nucleobase is a protected cytosine residue. In some embodiments, a nucleobase is an optionally substituted thymine residue. In some embodiments, a nucleobase is a protected thymine residue. In some embodiments, a nucleobase is an optionally substituted uracil residue. In some embodiments, a nucleobase is a protected uracil residue. In some embodiments, a nucleobase is an optionally substituted 5-methylcytosine residue. In some embodiments, a nucleobase is a protected 5-methylcytosine residue.

[0188] In some embodiments, a provided oligonucleotide comprises a modified nucleobase described in, e.g., US 5552540, US 6222025, US 6528640, US 4845205, US 5681941, US 5750692, US 6015886, US 5614617, US 6147200, US 5457187, US 6639062, US 7427672, US 5459255, US 5484908, US 7045610, US 3687808, US 5502177, US 55257116235887, US 5175273, US 6617438, US 5594121, US 6380368, US 5367066, US 5587469, US 6166197, US 5432272, US 7495088, US 5134066, or US 5596091. In some embodiments, a nucleobase is described in WO 2020 / 154344, WO 2020 / 154343, WO 2020 / 154342, WO 2020 / 165077, WO 2020 / 201406, WO 2020 / 216637, or WO 2020 / 252376, and can be utilized in accordance with the present disclosure.

[0189] In some embodiments, a nucleobase is a protected base residue as used in oligonucleotide preparation. In some embodiments, a nucleobase is a base residue illustrated in US 2011 / 0294124, US 2015 / 0211006, US 2015 / 0197540, WO 2015 / 107425, WO 2017 / 192679, WO 2018 / 022473, WO 2018 / 098264, WO 2018 / 223056, WO 2018 / 223073, WO 2018 / 223081, WO 2018 / 237194, WO 2019 / 032607, WO 2019 / 055951, WO 2019 / 075357, WO 2019 / 200185, WO 2019 / 217784, WO 2019 / 032612, or WO 2020 / 191252. Sugars

[0190] Various sugars, including modified sugars, can be utilized in accordance with the present Page 68 of 201 12495950v1Attorney Docket No.: 2010581-1440 disclosure in, e.g., phosphoramidites, nucleosides, oligonucleotides, etc.

[0191] The most common naturally occurring nucleosides comprise ribose sugars (e.g., in RNA) or deoxyribose sugars (e.g., in DNA) linked to the nucleobases adenosine (A), cytosine (C), guanine (G), thymine (T) or uracil (U). In some embodiments, a sugar, e.g., in a phosphoramidite, a nucleoside, an oligonucleotide, etc., is a natural DNA sugar (in DNA nucleic acids or oligonucleotides, having the structure , wherein a nucleobase is attached to the 1’ position, and the 3’ and 5’ positions are linkages (as appreciated by those skilled in the art, if at the 5’-end ofthe 5’ position may be connected to a 5’-end group, and if at the 3’-end of an oligonucleotide, the 3’ position may be connected to a 3’-end group (e.g., −OH). In some embodiments, a sugar is a natural RNA sugar (in RNA nucleic acids or oligonucleotides, having the structure of , wherein a nucleobase is attached to the 1’ position, and the 3’ and 5’ positions arelinkages (as appreciated by those skilled in the art, if at the 5’-end of an oligonucleotide, the 5’ position may be connected to a 5’-end group (e.g., −OH), and if at the 3’-end of an oligonucleotide, the 3’ position may be connected to a 3’-end group (e.g., −OH). In some embodiments, a sugar is a modified sugar in that it is not a natural DNA sugar or a natural RNA sugar. Among other things, modified sugars may provide improved stability. In some embodiments, modified sugars can be utilized to alter and / or optimize one or more hybridization characteristics. In some embodiments, modified sugars can be utilized to alter and / or optimize target nucleic acid recognition. In some embodiments, modified sugars can be utilized to optimize Tm. In some embodiments, modified sugars can be utilized to improve oligonucleotide activities.

[0192] Sugars can be bonded to internucleotidic linkages at various positions. For example, internucleotidic linkages can be bonded to the 2’, 3’, 4’ or 5’ positions of sugars. In some embodiments, as most commonly in natural nucleic acids, an internucleotidic linkage connects with one sugar at the 5’ position and another sugar at the 3’ position unless otherwise indicated.

[0193] In some embodiments, a sugar is an optionally substituted natural DNA or RNA sugar. In some embodiments, a sugar is optionally . In some embodiments, the 2’ position isPage 69 of 201 12495950v1Attorney Docket No.: 2010581-1440 optionally substituted. In some embodiments, a sugar . In some embodiments, a sugar has, wherein each of R1s, R2s, R3s, R4s, and R5sis sugar modification (e.g., those described in USUS 20180216108, US 20180216107, US 9598458, WO 2017 / 062862, WO 2018 / 067973, WO 2017 / 160741, WO 2017 / 192679, WO 2017 / 210647, WO 2018 / 098264, WO 2018 / 022473, WO 2018 / 223056, WO 2018 / 223073, WO 2018 / 223081, WO 2018 / 237194, WO 2019 / 032607, WO 2019 / 032612, WO 2019 / 055951, WO 2019 / 075357, WO 2019 / 200185, WO 2019 / 217784, WO 2019 / 032612, WO 2020 / 191252, WO 2021 / 071858, or WO 2022 / 099159, the substituents, sugar modifications, descriptions of R1s, R2s, R3s, R4s, and R5s, and modified sugars of each of which are independently incorporated herein by reference). In some embodiments, each of R1s, R2s, R3s, R4s, and R5sis independently Rs, wherein each Rsis independently −F, −Cl, −Br, −I, −CN, −N3, −NO, −NO2, −Ls−R’, −Ls−OR’, −Ls−SR’, −Ls−N(R’)2, −O−Ls−OR’, −O−Ls−SR’, or −O−Ls−N(R’)2, wherein each R’ is independently as described herein, and each Lsis independently a covalent bond or optionally substituted bivalent C1-6 aliphatic or heteroaliphatic having 1- 4 heteroatoms; or two Rsare taken together to form a bridge −Ls−. In some embodiments, R’ is optionally substituted C1-10 aliphatic. In some embodiments, a sugar has the structure . In someembodiments, a sugar has the structure . In some embodiments, a sugar has the structure. In some embodiments, a sugar has the structure . In some embodiments, a sugar has thePage 70 of 201 12495950v1Attorney Docket No.: 2010581-1440 structure . In some embodiments, a sugar has the . In some substituted C1-6 aliphatic. In some is optionallysubstituted some embod5s6 iments, R is optionally substituted embodiments, a In the 6 R2sis −OMe. In some embodiments, a modified nucleoside is mA, mT, mC, m5mC, mG, mU, etc., in which R2sis −OMe. In some embodiments, R2sis −OCH2CH2OMe. In some embodiments, R2sis −OCH2CH2OH. In some embodiments, a 2’-F modified sugar has the structure . In some embodiments, a 2’-OMe modified sugar has the structure . In some embodiments, a 2’-MOE modified sugarhas the structure of ..

[0194] In some embodiments, a sugar has the structure , wherein R2sand R4sare taken sstogether to form −L−, wherein L is a covalent bond or bivalent C1-6aliphatic or heteroaliphatic having 1-4 heteroatoms. In some embodiments, each heteroatom is independently selected Page 71 of 201 12495950v1Attorney Docket No.: 2010581-1440 from nitrogen, oxygen or sulfur). In some embodiments, Lsis optionally substituted C2−O−CH2−C4. In some embodiments, Lsis C2−O−CH2−C4. In some embodiments, Lsis C2−O−(R)-CH(CH2CH3)−C4. In some embodiments, Lsis C2−O−(S)-CH(CH2CH3)−C4.

[0195] In some embodiments, a sugar has the , wherein each variableis independently as described herein. In some embodiments, a sugar has the structure , wherein each variable is independently as described herein. In some embodiments, R5sembodiments, a sugar has the , wherein each variable is independently as described herein. In some In some embodiments, R3sis −H. In someembodiments, a sugar .

[0196] In some embodiments, a sugar is optionally , wherein Xsis −S−, −Se−, or optionally substituted −CH2−. In some embodiments, thesubstituted. In some embodiments, a sugar . In some embodiments, a sugar has the structure of, wherein each of R1s, R2s, R3s, R4s, and R5sis independently −H, a(e.g., those described in US 9394333, US 9744183, US 9605019, US 9982257, US 20170037399, US 20180216108, US 20180216107, US 9598458, WO 2017 / 062862, WO 2018 / 067973, WO 2017 / 160741, WO 2017 / 192679, WO 2017 / 210647, WO 2018 / 098264, WO 2018 / 022473, WO 2018 / 223056, WO 2018 / 223073, WO 2018 / 223081, WO 2018 / 237194, WO 2019 / 032607, WO 2019 / 032612, WO 2019 / 055951, WO 2019 / 075357, WO Page 72 of 201 12495950v1Attorney Docket No.: 2010581-1440 2019 / 200185, WO 2019 / 217784, WO 2019 / 032612, WO 2020 / 191252, WO 2021 / 071858, and / or WO 2022 / 099159, the substituents, descriptions of R1s, R2s, R3s, R4s, and R5s, and modified sugars of each of which are independently incorporated herein by reference). In some embodiments, each of R1s, R2s, R3s, R4s, and R5sis independently Rs, wherein each Rsis independently −F, −Cl, −Br, −I, −CN, −N3, −NO, −NO2, −Ls−R’, −Ls−OR’, −Ls−SR’, −Ls−N(R’)2, −O−Ls−OR’, −O−Ls−SR’, or −O−Ls−N(R’)2, wherein each R’ is independently as described herein, and each Lsis independently a covalent bond or optionally substituted bivalent C1-6aliphatic or heteroaliphatic having 1-4 heteroatoms; or two Rsare taken together to form a bridge −Ls−. In some embodiments, R’ is optionally substituted C1-10 aliphatic. In some embodiments, a sugar has the structure . In some embodiments, a sugar has the structure .In some embodiments, a sugar has the In some embodiments, a sugar has the. In some embodiments, a sugar has the . In someembodiments, a sugar has the structure . In some embodiments, a sugar has the structureIn some embodiments,some embodiments, R5sis optionally substituted C1-6aliphatic.C1-6alkyl. In some embodiments, R5sis optionally substituted methyl. In some embodiments, R5sis methyl. In some embodiments, a sugar has the structure of . In some embodiments, a sugar has the structure of . In some embodiments,Page 73 of 201 12495950v1Attorney Docket No.: 2010581-1440 2’-is −OCH2CH2OMe. In some embodiments, R2sis −OCH2CH2OH. In some embodiments, a modified sugar has the structure . In some embodiments, a modified sugar has the structure of. In some embodiments, a modified sugar having the structure . Insome embodiments, a modified sugar having the structure . In some embodiments, Xsis −S−. In some embodiments, Xsis optionally substitutedembodiments, Xsis −CH2−. In some embodiments, a modified sugar having the structure . In some embodiments, amodified sugar having the structure .

[0197] , orPage 74 of 201 12495950v1Attorney Docket No.: 2010581-1440 , wherein each R2sis independently −H, −F, −OH or −ORak, wherein Rakis optionally and each of the other variables is independently as described herein. In someof R1s, R3s, R4s, and R5sis independently −H. In some embodiments, each of R1s, R3sand R4s, and one of R5s, are independently −H, and the other R5sis independently C1-6 aliphatic. In some embodiments, an occurrence of R5sis C1-6 aliphatic, e.g., methyl. In some embodiments, R2sis −H. In some embodiments, R2sis −F. In some embodiments, R2sis --ORak. In some embodiments, R2sis −OMe. In some embodiments, R2sis −OCH2CH2CH3. In some embodiments, at least one occurrence of R2sis −H. In some embodiments, at least one occurrence of R2sis not −H. In some embodiments, Xsis −O−. In some embodiments, Xsis −S−. In some embodiments, Xsis optionally substituted −CH2−. In some embodiments, Xsis −CH2−.

[0198] In some embodiments, a sugar has the , wherein R2sand R4sare taken together to form −Ls−, wherein Lsis a covalent bondbivalent C1-6aliphatic or heteroaliphatic having 1-4 heteroatoms. In some embodiments, each heteroatom is independently selected from nitrogen, oxygen or sulfur). In some embodiments, Lsis optionally substituted C2−O−CH2−C4. In some embodiments, Lsis C2−O−CH2−C4. In some embodiments, Lsis C2−O−(R)- CH(CH2CH3)−C4. In some embodiments, Lsis C2−O−(S)-CH(CH2CH3)−C4. In some embodiments, Xsis −S−. In some embodiments, Xsis optionally substituted −CH2−. In some embodiments, Xsis −CH2−. In some embodiments, Xsis −Se−.

[0199] In some embodiments, a sugar has the , wherein each variableis independently as described herein. In some embodiments, a sugar has the structure , wherein each variable is independently as described herein. In some embodiments,embodiments, a sugar has the , wherein each variable is independently as12495950v1Attorney Docket No.: 2010581-1440 described herein. In some embodiments, R3sis −OH. In some embodiments, R3sis −H. In some embodiments, Xsis −S−. In some embodiments, Xsis optionally substituted −CH2−. In some embodiments, Xsis −CH2−.

[0200] In some embodiments, a nucleoside comprising a modified sugar has the structure of or a salt form thereof, wherein BAsis −H or an optionally substituted or protected BA), and R2sis as described herein. In some embodiments, R2sis −OH, halogen, orC1-C6alkoxy. In some embodiments, BAsis −H. In some embodiments, BAsis an optionally substituted or protected nucleobase. In some embodiments, BAsis BA. In some embodiments, R2sis −F. In some embodiments, a nucleoside comprising a modified sugar has the structure of or a salt form thereof, wherein each variable is independently as described herein. In some R2sis −H, −OH, halogen, or o2sptionally substituted C1-C6alkoxy. In some embodiments, R is −H. In some embodiments, R2sis −F. In some embodiments, a nucleoside comprising a modified sugar has the structure of , wherein each variable is as described herein. In some embodiments, anucleoside comprising a modified sugar has the structure or a salt form thereof, wherein each variable is independently as described herein. InR2sis −H, −OH, halogen, or optionally substituted C1-C6alkoxy. In some embodiments, R2sis −H. In some embodiments, R2sis −F. In some embodiments, a nucleoside comprising a modified sugar has the or a salt form thereof, wherein R2s’is Rs, and each of Rs, R2sand BAsisIn some embodiments, each of R2sand R2s’is independently −H, −OH, halogen, or optionally substituted C1- C6 alkoxy. In some embodiments, R2sis −H. In some embodiments, R2sis −OH. In some embodiments, R2sis halogen. In some embodiments, R2sis −F. In some embodiments, R2sis optionally substituted C1-C6 alkoxy. In some embodiments, R2s’is −H. In some embodiments, R2s’is −OH. In some embodiments, R2s’is halogen. In some embodiments, R2s’is −F. In some embodiments, R2s’is optionally substituted C1-C6 alkoxy. In some embodiments, BAsis −H. In some embodiments, BAsis an optionally substituted or Page 76 of 201 12495950v1Attorney Docket No.: 2010581-1440 protected nucleobase. In some embodiments, BAsis BA. In some embodiments, nucleobases such as BA are optionally substituted or protected for oligonucleotide synthesis. Certain such nucleosides including sugars and nucleobases and uses thereof are described in WO 2020 / 154342. In some embodiments, an oligonucleotide comprises arabinoside, 2’-deoxy-2’-fluoro-arabinoside, 2’-OR arabinoside, adeoxycytidine, DNA-abasic, RNA-abasic, or 2’-OR abasic, wherein R is not hydrogen (e.g., optionally substituted C1-6aliphatic). In some embodiments, 2’-OR is 2’-OMe. In some embodiments, 2’-OR is 2’- MOE. In some embodiments, an oligonucleotide comprises 2’-O-methyl-arabinocytidine (amC). In some embodiments, oligonucleotides comprise such nucleosides. In some embodiments, monomers comprise such nucleosides. In some embodiments, phosphoramidites comprise such nucleosides (in some embodiments, one connecting site (e.g., a −CH2− connecting site) is bonded to an optionally substituted −OH, e.g., (−ODMTr), and one connecting site (e.g., a ring connecting site) is bonded to O which is also bonded to P of a phosphoramidite). In some embodiments, one or more or each of a 5’ immediate nucleoside (e.g., N1), an opposite nucleoside (N0) and a 3’ immediate nucleoside (e.g., N-1) is independently such a nucleoside. In some embodiments, 5’-N1N0N-1-3’ is amCCA. In some embodiments, a sugar has , wherein each variable is as described herein and C1’ is bonded to aa sugar is an arabinose. In some embodiments, a sugar has the structure is at

[0202] In some embodiments, a sugar is optionally , wherein position a is bonded to a nucleobase, Xsis −O−, −S−, −Se− or optionallyIn some embodiments, a . In some embodiments, a sugar is optionally , whereinPage 77 of 201 12495950v1Attorney Docket No.: 2010581-1440 position a is bonded to a nucleobase, Xsis −O−, −S−, −Se− or optionally substituted −CH2−. In some embodiments, a sugar . In some embodiments, Xsis −O−. In some embodiments, Xsis −S−. In some In some embodiments, Xsis optionally substituted −CH2−. In ssome embodiments, X embodiments, n is 0. In some embodiments, n is 1. In some embodiments, n is 2. In some embodiments, n is 3.

[0203] In some embodiments, a modified sugar comprises an optionally substituted 6-membered ring having 0-1 oxygen atom. In some embodiments, a modified sugar comprises an optionally substituted 6- membered ring having an oxygen atom. For example, in some embodiments, a modified sugar has the structure of optionally , wherein position a is bonded to a nucleobase. In someembodiments, a modified sugar has the , wherein position a is bonded to anucleobase. in some embodiments, a modified sugar has the structure of optionally , wherein position a is bonded to a nucleobase. In some embodiments, a modified sugar, wherein position a is bonded to a nucleobase. In some embodiments, a modified sugar hasthe structure of optionally , wherein position a is bonded to a nucleobase. In someembodiments, a modified sugar has the , wherein position a is bonded to a nucleobase. In some embodiments, astructure of optionally substituted , wherein position a is bonded to a nucleobase. In some embodiments, a modified sugar hasthe structure of , wherein position a is bonded to a nucleobase. In some embodiments, aPage 78 of 201 12495950v1Attorney Docket No.: 2010581-1440 modified sugar has the structure of optionally , wherein position a is bonded to anucleobase. In some embodiments, a modified sugar has the structure , wherein position a is bonded to a nucleobase.

[0204] In some embodiments, a nucleoside comprising a sugar the structure of salt form thereof, wherein each of R6sand R7sis independently Rs, BAsis −H or an or protected nucleobase (e.g., BA), and Rsis independently as described herein. Insome embodiments, R6sis −H, −OH or halogen, and R7sis −H, −OH, halogen or optionally substituted C1- C6alkoxy. In some embodiments, BAsis −H. In some embodiments, BAsis an optionally substituted or protected nucleobase. In some embodiments, BAsis BA. In some embodiments, a nucleoside comprising a modified sugar has the a salt form thereof, wherein each of R8sand R9sis independently Rs, and each ofas described herein. In some embodiments, R8sis −H or halogen, and R9sis −H, −OH, halogen, or optionally substituted C1-C6 alkoxy. In some embodiments, a nucleoside comprising a modified sugar has the structure of or a salt form thereof, wherein each of R10sand R11sis independently Rs, and each of Rsand BAsis independently as described herein. In some embodiments, R10sis −H or halogen, and R11sis −H, −OH, halogen, or optionally substituted C1-C6 alkoxy. In some embodiments, a nucleoside comprising a modified sugar has the structure a salt form thereof, wherein BAsis as described herein. In some embodiments, anucleoside comprising a modified sugar has the a salt form thereof, wherein BAsis as described herein. Those skilled inembodiments, the Page 79 of 201 12495950v1Attorney Docket No.: 2010581-1440 nitrogen may be directly bonded to linkage phosphorus. In some embodiments, a halogen is −F. In some embodiments, BAsis −H. In some embodiments, BAsis an optionally substituted or protected nucleobase. In some embodiments, BAsis BA. In some embodiments, nucleobases such as BA are optionally substituted or protected for oligonucleotide synthesis. In some embodiments, an oligonucleotide comprises alpha-homo-DNA, beta-homo-DNA moieties. In some embodiments, an oligonucleotide comprises an alpha- or beta-homo-DNA sugar. In some embodiments, an oligonucleotide comprises an alpha-homo- DNA sugar. In some embodiments, an oligonucleotide comprises a beta-homo-DNA sugar. Certain such nucleosides including sugars and nucleobases and uses thereof are described in WO 2020 / 154343. In some embodiments, oligonucleotides comprise such nucleosides. In some embodiments, monomers comprise such nucleosides. In some embodiments, phosphoramidites comprise such nucleosides (in some embodiments, one connecting site (e.g., a −CH2− connecting site) is bonded to an optionally substituted −OH, e.g., −ODMTr, and one connecting site (e.g., a ring connecting site) is bonded to P of a phosphoramidite (e.g., when the connecting ring atom is N) or to O which is also bonded to P of a phosphoramidite(e.g., when the connecting ring atom is C)). In some embodiments, one or more or each of a 5’ immediate nucleoside (e.g., N1), an opposite nucleoside (N0) and a 3’ immediate nucleoside (e.g., N-1) is independently such a nucleoside.

[0205] In some embodiments, a modified sugar has the structure , wherein positiona is bonded to a nucleobase. In some embodiments, a modified sugar has the structure , wherein position a is bonded to a nucleobase. In some embodiments, a modified, wherein position a is bonded to a nucleobase, position b is bonded to an internucleotidic−H or optionally substituted C1-6 aliphatic. In some embodiments, a modified sugar has the , wherein position a is bonded to a nucleobase, position b is bonded to anis −H or C1-6 aliphatic. In some embodiments, a modified sugar has the Page 80 of 201 12495950v1Attorney Docket No.: 2010581-1440 structure , wherein position a is bonded to a nucleobase, position b is bonded to an R’’ is −H or C1-6 aliphatic. In some embodiments, R” is methyl.

[0206] a nucleoside comprising a modified sugar has the structure of or a salt form thereof, wherein each variable is as described herein. In some embodiments, anucleoside comprising a modified sugar has the structure or a salt form thereof, wherein each variable is as described herein. In some embodiments,comprising a modified sugar has the structure of or a salt form thereof, wherein each variable is as described herein. In someembodiments, a nucleoside comprising a modified sugar has the a salt form thereof, wherein R12sis Rs, and each of Rsand BAsisIn some embodiments, R12sis −H, −OH, halogen, optionally substituted C1-6 alkyl, optionally substituted C1-6 heteroalkyl, or optionally substituted C1-6 alkoxy. In some embodiments, a halogen is −F. In some embodiments, a nucleoside comprising a modified sugar has the structure or a saltform thereof, wherein each variable is as described herein. In some a comprising a modified sugar has the a salt form thereof, wherein R13sis Rs, and each of Rsand BAsisembodiments, R13sis −H or optionally substituted C1-C6 alkyl. In some embodiments, a nucleoside comprising a modified sugar has the structure Page 81 of 201 12495950v1Attorney Docket No.: 2010581-1440 a salt form thereof, wherein each variable is as described herein. In someembodiments, a nucleotide comprising a modified sugar has the salt form thereof, wherein each variable is as described herein. In some slinkage. In some embodiments, BA is −H. In some embodiments, an or protected nucleobase. In some embodiments, BAsis BA. In some embodiments, nucleobases such as BA are optionally substituted or protected for oligonucleotide synthesis. Certain such nucleosides and nucleotides including sugars and nucleobases and uses thereof are described in WO 2020 / 154344. In some embodiments, oligonucleotides comprise such nucleosides. In some embodiments, oligonucleotides comprise such nucleosides (in some embodiments, one connecting site (e.g., a −CH2− connecting site) is bonded to an optionally substituted −OH, e.g., (−ODMTr), and one connecting site (e.g., a ring connecting site) is bonded to O which is also bonded to P of a phosphoramidite. In some embodiments, one or more or each of a 5’ immediate nucleoside (e.g., N1), an opposite nucleoside (N0) and a 3’ immediate nucleoside (e.g., N-1) is independently such a nucleoside.

[0207] In some embodiments, a sugar is an acyclic sugar, e.g. a UNA sugar. In some embodiments, a sugar is optionally substituted . In some embodiments, the 2’ position is optionallysubstituted. In some embodiments, a . In some embodiments, a sugar has thesome embodiments, R2sis −OH. In some ,carbon atom bonded to a nucleobase. In someis Page 82 of 201 12495950v1Attorney Docket No.: 2010581-1440 , wherein “*” indicates the carbon atom bonded to a nucleobase. In some embodiments, thebonded to a nitrogen atom of a nucleobase and is of R configuration (e.g., sm18). In some embodiments, an oligonucleotide comprises a sugar described herein.

[0208] a is bonded to asugar is . In some embodiments, Xsis −O−. In some embodiments, Xsis −S−. In someIn some embodiments, Xsis optionally substituted −CH2−. In some embodiments, Xsis −CH2−. In some embodiments, n is 0. In some embodiments, n is 1. In some embodiments, n is 2. In some embodiments, n is 3.

[0209] In some embodiments, a sugar is connected not through 5’ and 3’ positions. Those skilled in the art appreciate that for such sugars, 5’ can refer to the side / direction toward 5’-end of an oligonucleotide, and 3’ can refer to the side / direction toward to 3’-end of an oligonucleotide.

[0210] In some embodiments, each of R1s, R2s, R3s, R4s, and R5sis independently Rs, wherein Rsis independently −H, halogen, −CN, −N3, −NO, −NO2, −Ls−R’, −Ls−Si(R’)3, −Ls−OR’, −Ls−SR’, −Ls−N(R’)2, −O−Ls−R’, −O−Ls−Si(R)3, −O−Ls−OR’, −O−Ls−SR’, or −O−Ls−N(R’)2; wherein Lsis LBas described herein, and each other variable is independently as described herein. In some embodiments, each of R1sand R2sis independently Rs. In some embodiments, Rsis −H. In some embodiments, Rsis not −H. In some embodiments, Lsis a covalent bond. In some embodiments, each of R2sand R4sare independently −H, −F, −OR, −N(R)2. In some embodiments, R2sis −H, −F, −OR, −N(R)2. In some embodiments, R4sis −H. In some embodiments, R2sand R4sform 2’−O−Ls−, wherein Lsis optionally substituted C1-6 alkylene. In some embodiments, Lsis optionally substituted −CH2−. In some embodiments, Lsis optionally substituted −CH2−.

[0211] In some embodiments, R is hydrogen. In some embodiments, R is not hydrogen. In some embodiments, R is an optionally substituted group selected from C1-10 aliphatic, C1-10 heteroaliphatic having 1-10 heteroatoms independently selected from silicon, nitrogen, oxygen, phosphorus and sulfur, C6-14 aryl, a 5-14 membered heteroaryl ring having 1-10 heteroatoms independently selected from silicon, nitrogen, oxygen, phosphorus and sulfur, and a 3-15 membered heterocyclic ring having 1-5 heteroatoms independently selected from silicon, nitrogen, oxygen, phosphorus and sulfur. Page 83 of 201 12495950v1Attorney Docket No.: 2010581-1440

[0212] In some embodiments, R is optionally substituted C1-10aliphatic. In some embodiments, R is optionally substituted C1-6aliphatic. In some embodiments, R is optionally substituted C1-6alkyl. In some embodiments, R is optionally substituted hexyl, pentyl, butyl, propyl, ethyl or methyl. In some embodiments, R is optionally substituted hexyl. In some embodiments, R is optionally substituted pentyl. In some embodiments, R is optionally substituted butyl. In some embodiments, R is optionally substituted propyl. In some embodiments, R is optionally substituted ethyl. In some embodiments, R is optionally substituted methyl. In some embodiments, R is hexyl. In some embodiments, R is pentyl. In some embodiments, R is butyl. In some embodiments, R is propyl. In some embodiments, R is ethyl. In some embodiments, R is methyl. In some embodiments, R is isopropyl. In some embodiments, R is n-propyl. In some embodiments, R is tert-butyl. In some embodiments, R is sec-butyl. In some embodiments, R is n-butyl. In some embodiments, R is −(CH2)2OCH3.

[0213] In some embodiments, R is optionally substituted phenyl. In some embodiments, R is phenyl.

[0214] In some embodiments, R2sis a 2’-modification as described in the present disclosure, and R4sis −H. In some embodiments, R2sis −OR, wherein R is not hydrogen. In some embodiments, R2sis −F. In some embodiments, R2sis −OMe. In some embodiments, R2sis −OCH2CH2CH3. In some embodiments, R2sis selected from −H, −F, and −OR, wherein R is optionally substituted C1-6 alkyl. In some embodiments, R2sis selected from −H, −F, and −OMe.

[0215] In some embodiments, a sugar is a bicyclic sugar, e.g., sugars wherein R2sand R4sare taken to form an optionally substituted ring as described in the present disclosure. In some embodiments, a sugar is selected from LNA sugars, BNA sugars, cEt sugars, etc. In some embodiments, a bridge is between the 2’ and 4’-carbon atoms (corresponding to R2sand R4staken together with their intervening atoms to form an optionally substituted ring as described herein). In some embodiments, a bridge is 2’−La−Lb−4’, wherein Lais −O−, −S− or N(R), and Lbis an optionally substituted C1-4 bivalent aliphatic chain, e.g., methylene.

[0216] In some embodiments, a sugar is a 2’-OMe, 2’-MOE, 2’-F, a LNA (locked nucleic acid) sugar, an ENA (ethylene bridged nucleic acid) sugar, a BNA(NMe) (Methylamino bridged nucleic acid) sugar, 2’-F ANA (2’-F arabinose), alpha-DNA (alpha-D-ribose), 2’ / 5’ ODN (e.g., 2’ / 5’ linked oligonucleotide), Inv (inverted sugar, e.g., inverted desoxyribose), AmR (Amino-Ribose), ThioR (Thio-ribose), HNA (hexose nucleic acid), CeNA (cyclohexene nucleic acid), or MOR (Morpholino) sugar.

[0217] Those skilled in the art after reading the present disclosure will appreciate that various types of sugar modifications are known and can be utilized in accordance with the present disclosure. In some embodiments, a sugar modification is a 2’-modification (e.g., R2s). In some embodiments, a 2’-modification is 2’-F. In some embodiments, a 2’-modification is 2’-OR, wherein R is not hydrogen. In some embodiments, a 2’-modification is 2’-OR, wherein R is optionally substituted C1-6aliphatic. In some embodiments, a 2’-modification is 2’-OR, wherein R is optionally substituted C1-6alkyl. In some Page 84 of 201 12495950v1Attorney Docket No.: 2010581-1440 embodiments, a 2’-modification is 2’-OMe. In some embodiments, a 2’-modification is 2’-MOE. In some embodiments, a 2’-modification is −O−Lb− or −Lb−Lb− which connects the 2’-carbon of a sugar moiety to another carbon of a sugar moiety. In some embodiments, a 2’-modification is 2’−O−Lb−4’ or 2’−Lb−Lb−4’ which connects the 2’-carbon of a sugar moiety to the 4’-carbon of a sugar moiety. In some embodiments, a 2’-modification is S-cEt. In some embodiments, a modified sugar is an LNA sugar. In some embodiments, −Lb− is −C(R)2−. In some embodiments, a 2’-modification is (C2−O−C(R)2−C4), wherein each R is independently as described in the present disclosure. In some embodiments, a 2’-modification is a LNA sugar modification (C2−O−CH2−C4). In some embodiments, a 2’-modification is (C2−O−CHR−C4), wherein R is as described in the present disclosure. In some embodiments, a 2’- modification is (C2−O−(R)-CHR−C4), wherein R is as described in the present disclosure and is not hydrogen. In some embodiments, a 2’-modification is (C2−O−(S)-CHR−C4), wherein R is as described in the present disclosure and is not hydrogen. In some embodiments, R is optionally substituted C1-6 aliphatic. In some embodiments, R is optionally substituted C1-6 alkyl. In some embodiments, R is unsubstituted C1- 6 alkyl. In some embodiments, R is methyl. In some embodiments, R is ethyl. In some embodiments, a 2’-modification is (C2−O−CHR−C4), wherein R is optionally substituted C1-6 aliphatic. In some embodiments, a 2’-modification is (C2−O−CHR−C4), wherein R is optionally substituted C1-6 alkyl. In some embodiments, a 2’-modification is (C2−O−CHR−C4), wherein R is methyl. In some embodiments, a 2’-modification is (C2−O−CHR−C4), wherein R is ethyl. In some embodiments, a 2’-modification is (C2−O−(R)-CHR−C4), wherein R is optionally substituted C1-6 aliphatic. In some embodiments, a 2’- modification is (C2−O−(R)-CHR−C4), wherein R is optionally substituted C1-6 alkyl. In some embodiments, a 2’-modification is (C2−O−(R)-CHR−C4), wherein R is methyl. In some embodiments, a 2’-modification is (C2−O−(R)-CHR−C4), wherein R is ethyl. In some embodiments, a 2’-modification is (C2−O−(S)-CHR−C4), wherein R is optionally substituted C1-6 aliphatic. In some embodiments, a 2’- modification is (C2−O−(S)-CHR−C4), wherein R is optionally substituted C1-6 alkyl. In some embodiments, a 2’-modification is (C2−O−(S)-CHR−C4), wherein R is methyl. In some embodiments, a 2’-modification is (C2−O−(S)-CHR−C4), wherein R is ethyl. In some embodiments, a 2’-modification is C2−O−(R)-CH(CH2CH3)−C4. In some embodiments, a 2’-modification is C2−O−(S)-CH(CH2CH3)−C4. In some embodiments, a sugar is a natural DNA sugar. In some embodiments, a sugar is a natural RNA sugar. In some embodiments, a sugar is an optionally substituted natural DNA sugar. In some embodiments, a sugar is a natural DNA sugar optionally substituted at 2’. In some embodiments, a sugar is a natural DNA sugar substituted at 2’ (2’-modification). In some embodiments, a sugar is a natural DNA sugar modified at 2’ (2’-modification).

[0218] In some embodiments, a sugar is an optionally substituted ribose or deoxyribose. In some embodiments, a sugar is an optionally modified ribose or deoxyribose, wherein one or more hydroxyl Page 85 of 201 12495950v1Attorney Docket No.: 2010581-1440 groups of the ribose or deoxyribose moiety is optionally and independently replaced by halogen, R’, – N(R’)2, –OR’, or –SR’, wherein each R’ is as described herein. In some embodiments, a sugar is an optionally substituted deoxyribose, wherein the 2’ position of the deoxyribose is optionally substituted. In some embodiments, a sugar is an optionally substituted deoxyribose, wherein the 2’ position of the deoxyribose is optionally substituted with halogen, R’, –N(R’)2, –OR’, or –SR’, wherein each R’ is independently described in the present disclosure. In some embodiments, a sugar is an optionally substituted deoxyribose, wherein the 2’ position of the deoxyribose is optionally substituted with halogen. In some embodiments, a sugar is an optionally substituted deoxyribose, wherein the 2’ position of the deoxyribose is optionally substituted with one or more –F. In some embodiments, a sugar is an optionally substituted deoxyribose, wherein the 2’ position of the deoxyribose is optionally substituted with –OR’, wherein each R’ is independently described in the present disclosure. In some embodiments, a sugar is an optionally substituted deoxyribose, wherein the 2’ position of the deoxyribose is optionally substituted with –OR’, wherein each R’ is independently optionally substituted C1–C6 aliphatic. In some embodiments, a sugar is an optionally substituted deoxyribose, wherein the 2’ position of the deoxyribose is optionally substituted with –OR’, wherein each R’ is independently an optionally substituted C1–C6 alkyl. In some embodiments, a sugar is an optionally substituted deoxyribose, wherein the 2’ position of the deoxyribose is optionally substituted with –OMe. In some embodiments, a sugar is an optionally substituted deoxyribose, wherein the 2’ position of the deoxyribose is optionally substituted with –O–methoxyethyl.

[0219] In some embodiments, provided oligonucleotides comprise one or more modified sugars. In some embodiments, provided oligonucleotides comprise one or more modified sugars and one or more natural sugars.

[0220] Examples of bicyclic sugars include sugars of alpha-L-methyleneoxy (4'-CH2-O-2’) LNA, beta-D-methyleneoxy (4'-CH2-O-2’) LNA, ethyleneoxy (4' -(CH2)2-O-2’) LNA, aminooxy (4' -CH2-O- N(R)-2’) LNA, and oxyamino (4'-CH2-N(R)-O-2’) LNA. In some embodiments, a bicyclic sugar, e.g., a LNA or BNA sugar, is sugar having at least one bridge between two sugar carbons. In some embodiments, a bicyclic sugar in a nucleoside may have the stereochemical configurations of alpha-L-ribofuranose or beta-D-ribofuranose.

[0221] In some embodiments, a bicyclic sugar may be further defined by isomeric configuration. For example, a sugar comprising a 4’-(CH2)-O-2’ bridge may be in the alpha-L configuration or in the beta-D configuration. In some embodiments, a 4’ to 2’ bridge is a -L-4’-(CH2)-O-2’, b-D-4'-CH2-O-2’, 4'-(CH2)2- O-2’, 4'-CH2-O-N(R’)-2’, 4'-CH2-N(R’)-O-2’, 4'-CH(R’)-O-2’, 4'-CH(CH3)-O-2’, 4'-CH2-S-2’, 4'-CH2- N(R’)-2’, 4'-CH2-CH(R’)-2’, 4'-CH2-CH(CH3)-2’, and 4'-(CH2)3-2’, wherein each R’ is as described in the present disclosure. In some embodiments, R’ is −H, a protecting group or optionally substituted C1-C12alkyl. In some embodiments, R’ is −H or optionally substituted C1-C12alkyl. Page 86 of 201 12495950v1Attorney Docket No.: 2010581-1440

[0222] In some embodiments, a bicyclic sugar is a sugar of alpha-L-methyleneoxy (4'-CH2-O-2’) BNA, beta-D-methyleneoxy (4'-CH2-O-2’) BNA, ethyleneoxy (4'-(CH2)2-O-2’) BNA, aminooxy (4'-CH2- O-N(R)-2’) BNA, oxyamino (4'-CH2-N(R)-O-2’) BNA, methyl(methyleneoxy) (4'-CH(CH3)-O-2’) BNA (also referred to as constrained ethyl or cEt), methylene-thio (4'-CH2-S-2’) BNA, methylene-amino (4'- CH2-N(R)-2’) BNA, methyl carbocyclic (4'-CH2-CH(CH3)-2’) BNA, propylene carbocyclic (4'-(CH2)3-2’) BNA, or vinyl BNA.

[0223] In some embodiments, a sugar modification is a modification described in US 9006198. In some embodiments, a modified sugar is described in US 9006198. In some embodiments, a sugar modification is a modification described in US 9394333, US 9744183, US 9605019, US 9982257, US 20170037399, US 20180216108, US 20180216107, US 9598458, WO 2017 / 062862, WO 2018 / 067973, WO 2017 / 160741, WO 2017 / 192679, WO 2017 / 210647, WO 2018 / 098264, WO 2018 / 022473, WO 2018 / 223056, WO 2018 / 223073, WO 2018 / 223081, WO 2018 / 237194, WO 2019 / 032607, WO 2019 / 032612, WO 2019 / 055951, WO 2019 / 075357, WO 2019 / 200185, WO 2019 / 217784, WO 2019 / 032612, WO 2020 / 191252, WO 2021 / 071858, and / or WO 2022 / 099159, the sugar modifications and modified sugars of each of which are independently incorporated herein by reference.

[0224] In some embodiments a modified sugar is one described in US 5658873, US 5118800, US 5393878, US 5514785, US 5627053, US 7034133;7084125, US 7399845, US 5319080, US 5591722, US 5597909, US 5466786, US 6268490, US 6525191, US 5519134, US 5576427, US 6794499, US 6998484, US 7053207, US 4981957, US 5359044, US 6770748, US 7427672, US 5446137, US 6670461, US 7569686, US 7741457, US 8022193, US 8030467, US 8278425, US 5610300, US 5646265, US 8278426, US 5567811, US 5700920, US 8278283, US 5639873, US 5670633, US 8314227, US 2008 / 0039618, US 2009 / 0012281, WO 2021 / 030778, WO 2020 / 154344, WO 2020 / 154343, WO 2020 / 154342, WO 2020 / 165077, WO 2020 / 201406, WO 2020 / 216637, or WO 2020 / 252376.

[0225] In some embodiments, a sugar modification is 2’-OMe, 2’-MOE, 2’-LNA, 2’-F, 5’-vinyl, or S- cEt. In some embodiments, a modified sugar is a sugar of FRNA, FANA, or morpholino. In some embodiments, an oligonucleotide comprises a nucleic acid analog, e.g., GNA, LNA, PNA, TNA, F-HNA (F-THP or 3’-fluoro tetrahydropyran), MNA (mannitol nucleic acid, e.g., Leumann 2002 Bioorg. Med. Chem.10: 841-854), ANA (anitol nucleic acid), or morpholino, or a portion thereof. In some embodiments, a sugar is as in flexible nucleic acids or serinol nucleic acids. In some embodiments, a sugar modification replaces a natural sugar with another cyclic or acyclic moiety. Examples of such moieties are widely known in the art, e.g., those used in morpholino, glycol nucleic acids, etc. and may be utilized in accordance with the present disclosure. As appreciated by those skilled in the art, when utilized with modified sugars, in some embodiments internucleotidic linkages may be modified, e.g., as in morpholino, PNA, etc. In some embodiments, a sugar is a (R)-GNA sugar. In some embodiments, a sugar is a (S)-GNA sugar. In some Page 87 of 201 12495950v1Attorney Docket No.: 2010581-1440 embodiments, a nucleoside having a GNA sugar is utilized as N-1, N0and / or N1. In some embodiments, N0is a nucleoside having a GNA sugar. In some embodiments, a sugar is bicyclic sugar. In some embodiments, a sugar is a LNA sugar. In some embodiments, a sugar is an acyclic sugar. In some embodiments, a sugar is a UNA sugar. In some embodiments, a nucleoside having a UNA sugar is utilized as N-1, N0 and / or N1. In some embodiments, N0 is a nucleoside having a UNA sugar. In some embodiments, a nucleoside is abasic. In some embodiments, an abasic sugar is utilized as N-1, N0and / or N1. In some embodiments, N0is a nucleoside having an abasic sugar.

[0226] In some embodiments, a sugar is a 6’-modified bicyclic sugar that have either (R) or (S)- chirality at the 6-position, e.g., those described in US 7399845. In some embodiments, a sugar is a 5’- modified bicyclic sugar that has either (R) or (S)-chirality at the 5-position, e.g., those described in US 20070287831.

[0227] In some embodiments, a modified sugar contains one or more substituents at the 2’ position (typically one substituent, and often at the axial position) independently selected from –F; –CF3, –CN, –N3, –NO, –NO2, –OR’, –SR’, or –N(R’)2, wherein each R’ is independently described in the present disclosure; –O–(C1–C10 alkyl), –S–(C1–C10 alkyl), –NH–(C1–C10 alkyl), or –N(C1–C10 alkyl)2; –O–(C2–C10 alkenyl), – S–(C2–C10 alkenyl), –NH–(C2–C10 alkenyl), or –N(C2–C10 alkenyl)2; –O–(C2–C10 alkynyl), –S–(C2–C10 alkynyl), –NH–(C2–C10 alkynyl), or –N(C2–C10 alkynyl)2; or –O––(C1–C10 alkylene)–O––(C1–C10 alkyl), – O–(C1–C10 alkylene)–NH–(C1–C10 alkyl) or –O–(C1–C10 alkylene)–NH(C1–C10 alkyl)2, –NH–(C1–C10 alkylene)–O–(C1–C10 alkyl), or –N(C1–C10 alkyl)–(C1–C10 alkylene)–O–(C1–C10 alkyl), wherein each of the alkyl, alkylene, alkenyl and alkynyl is independently and optionally substituted. In some embodiments, a substituent is –O(CH2)nOCH3, –O(CH2)nNH2, MOE, DMAOE, or DMAEOE, wherein n is from 1 to about 10. In some embodiments, a modified sugar is one described in WO 2001 / 088198; and Martin et al., Helv. Chim. Acta, 1995, 78, 486-504. In some embodiments, a modified sugar comprises one or more groups selected from a substituted silyl group, an RNA cleaving group, a reporter group, a fluorescent label, an intercalator, a group for improving the pharmacokinetic properties of a nucleic acid, a group for improving the pharmacodynamic properties of a nucleic acid, or other substituents having similar properties. In some embodiments, modifications are made at one or more of the 2’, 3’, 4’, or 5’ positions, including the 3’ position of the sugar on the 3’-terminal nucleoside or in the 5’ position of the 5’-terminal nucleoside.

[0228] In some embodiments, the 2’-OH of a ribose is replaced with a group selected from –H, –F; – CF3, –CN, –N3, –NO, –NO2, –OR’, –SR’, or –N(R’)2, wherein each R’ is independently described in the present disclosure; –O–(C1–C10alkyl), –S–(C1–C10alkyl), –NH–(C1–C10alkyl), or –N(C1–C10alkyl)2; –O– (C2–C10alkenyl), –S–(C2–C10alkenyl), –NH–(C2–C10alkenyl), or –N(C2–C10alkenyl)2; –O–(C2–C10alkynyl), –S–(C2–C10alkynyl), –NH–(C2–C10alkynyl), or –N(C2–C10alkynyl)2; or –O–(C1–C10alkylene)– O––(C1–C10alkyl), –O–(C1–C10alkylene)–NH–(C1–C10alkyl) or –O–(C1–C10alkylene)–NH(C1–C10Page 88 of 201 12495950v1Attorney Docket No.: 2010581-1440 alkyl)2, –NH–(C1–C10alkylene)–O–(C1–C10alkyl), or –N(C1–C10alkyl)–(C1–C10alkylene)–O–(C1–C10alkyl), wherein each of the alkyl, alkylene, alkenyl and alkynyl is independently and optionally substituted. In some embodiments, the 2’–OH is replaced with –H (deoxyribose). In some embodiments, the 2’–OH is replaced with –F. In some embodiments, the 2’–OH is replaced with –OR’. In some embodiments, the 2’– OH is replaced with –OMe. In some embodiments, the 2’–OH is replaced with –OCH2CH2OMe.

[0229] In some embodiments, a sugar modification is a 2’-modification. Commonly used 2’- modifications include but are not limited to 2’–OR, wherein R is not hydrogen and is as described in the present disclosure. In some embodiments, a modification is 2’−OR, wherein R is optionally substituted C1- 6 aliphatic. In some embodiments, a modification is 2’−OR, wherein R is optionally substituted C1-6 alkyl. In some embodiments, a modification is 2’−OMe. In some embodiments, a modification is 2’-MOE. In some embodiments, a 2’-modification is S-cEt. In some embodiments, a modified sugar is an LNA sugar. In some embodiments, a 2’-modification is −F. In some embodiments, a 2’-modification is FANA. In some embodiments, a 2’-modification is FRNA. In some embodiments, a sugar modification is a 5’- modification, e.g., 5’-Me. In some embodiments, a sugar modification changes the size of the sugar ring. In some embodiments, a sugar modification is the sugar moiety in FHNA.

[0230] In some embodiments, a sugar modification replaces a sugar moiety with another cyclic or acyclic moiety. Examples of such moieties are widely known in the art, including but not limited to those used in morpholino (optionally with its phosphorodiamidate linkage), glycol nucleic acids, etc.

[0231] Modified sugars include cyclobutyl or cyclopentyl moieties in place of a pentofuranosyl sugar. Representative examples of such modified sugars include those described in US 4,981,957, US 5,118,800, US 5,319,080, or US 5,359,044. In some embodiments, the oxygen atom within the ribose ring is replaced by nitrogen, sulfur, selenium, or carbon. In some embodiments, −O− is replaced with −N(R’)−, −S−, −Se− or −C(R’)2−. In some embodiments, a modified sugar is a modified ribose wherein the oxygen atom within the ribose ring is replaced with nitrogen, and wherein the nitrogen is optionally substituted with an alkyl group (e.g., methyl, ethyl, isopropyl, etc.).

[0232] An example of modified sugars is glycerol, which is part of glycerol nucleic acids (GNAs), e.g., as described in Zhang, R et al., J. Am. Chem. Soc., 2008, 130, 5846-5847; Zhang L, et al., J. Am. Chem. Soc., 2005, 127, 4174-4175 and Tsai CH et al., PNAS, 2007, 14598-14603.

[0233] A flexible nucleic acid (FNA) is based on a mixed acetal aminal of formyl glycerol, e.g., as described in Joyce GF et al., PNAS, 1987, 84, 4398-4402 and Heuberger BD and Switzer C, J. Am. Chem. Soc., 2008, 130, 412-413.

[0234] In some embodiments, one or more hydroxyl group in a sugar is optionally and independently replaced with halogen, R’ –N(R’)2, –OR’, or –SR’, wherein each R’ is independently described in the present disclosure. Page 89 of 201 12495950v1Attorney Docket No.: 2010581-1440

[0235] In some embodiments, a modified nucleoside is a modified nucleoside described in WO 2018 / 022473, WO 2018 / 098264, WO 2018 / 223056, WO 2018 / 223073, WO 2018 / 223081, WO 2018 / 237194, WO 2019 / 032607, WO 2019 / 055951, WO 2019 / 075357, WO 2019 / 200185, WO 2019 / 217784, WO 2019 / 032612, WO 2020 / 191252, WO 2021 / 071858, and / or WO 2022 / 099159, the modified nucleosides of each of which are independently incorporated herein by reference.

[0236] In some embodiments, a sugar modification is 5’-vinyl (R or S), 5’-methyl (R or S), 2'-SH, 2’- F, 2’-OCH3, 2’-OCH2CH3, 2’-OCH2CH2F or 2’-O(CH2)20CH3. In some embodiments, a substituent at the 2’ position, e.g., a 2’-modification, is allyl, amino, azido, thio, −O−allyl, −O−C1-C10 alkyl, −OCF3, −OCH2F, −O(CH2)2SCH3, −O(CH2)2ON(R’)2, −OCH2C(O)N(R’)2, and −OCH2C(O)N(R’)(CH2)2N(R’)2, wherein each allyl, amino and alkyl is optionally substituted, and each R’ is independently as described in the present disclosure. In some embodiments, each R’ is independently −H or optionally substituted C1- C10 alkyl.

[0237] In some embodiments, bicyclic sugars comprise a bridge, e.g., −Lb−Lb−, −L−, etc. between two sugar carbons, e.g., between the 4’ and the 2’ ribosyl ring carbon atoms. In some embodiments, a bridge is 4'−(CH2)−O−2’ (e.g., LNA sugars), 4'−(CH2)−S−2’, 4’−(CH2)2−O−2’ (e.g., ENA sugars), 4’−CH(R’)−O−2’ (e.g., 4’−CH(CH3)−O−2’, 4’−CH(CH2OCH3)−O−2’, and examples in US 7399845, etc.), 4’−CH(R’)2−O−2’ (e.g., 4’−C(CH3)(CH3)−O−2’ and examples in WO 2009006478, etc.), 4’-CH2-N(OR’)- 2’ (e.g., 4’-CH2-N(OCH3)-2’, examples in WO 2008150729, etc.), 4’−CH2−O−N(R’)−2’ (e.g., 4’−CH2−O−N(CH3)−2’, examples in US 20040171570, etc.), 4’−CH2−N(R’)−O−2’ [e.g., wherein R is −H, C1-C12 alkyl, or a protecting group (e.g., see US 7427672)], 4’−C(R’)2−C(H)(R’)−2’ (e.g., 4'−CH2−C(H)(CH3)−2’, examples in Chattopadhyaya et al., J. Org. Chem., 2009, 74, 118-134, etc.), or 4’−C(R’)2−C(=C(R’)2)−2’ (e.g., 4’−CH2−C(=CH2)−2’, examples in WO 2008154401, etc.).

[0238] In some embodiments, a sugar is a tetrahydropyran or THP sugar. In some embodiments, a modified nucleoside is tetrahydropyran nucleoside or THP nucleoside which is a nucleoside having a six- membered tetrahydropyran sugar substituted for a pentofuranosyl residue in typical natural nucleosides. THP sugars and / or nucleosides include those used in hexitol nucleic acid (HNA), anitol nucleic acid (ANA), mannitol nucleic acid (MNA) (e.g., Leumann, Bioorg. Med. Chem., 2002, 10, 841-854) or fluoro HNA (F- HNA).

[0239] In some embodiments, sugars comprise rings having more than 5 atoms and / or more than one heteroatom, e.g., morpholino sugars which are described in e.g., Braasch et al., Biochemistry, 2002, 41, 4503-4510; US 5698685; US 5166315; US 5185444; US 5034506; etc.).

[0240] In some embodiments, a nucleoside has a six-membered cyclohexenyl in place of the pentofuranosyl residue in naturally occurring nucleosides. Example cyclohexenyl nucleosides and preparation and uses thereof are described in, e.g., WO 2010036696; Robeyns et al., J. Am. Chem. Soc., Page 90 of 201 12495950v1Attorney Docket No.: 2010581-1440 2008, 130(6), 1979-1984; Horvath et al., Tetrahedron Letters, 2007, 48, 3621-3623; Nauwelaerts et al., J. Am. Chem. Soc., 2007, 129(30), 9340-9348; Gu et al., Nucleosides, Nucleotides & Nucleic Acids, 2005, 24(5-7), 993-998; Nauwelaerts et al., Nucleic Acids Research, 2005, 33(8), 2452-2463; Robeyns et al., Acta Crystallographica, Section F: Structural Biology and Crystallization Communications, 2005, F61(6), 585- 586; Gu et al., Tetrahedron, 2004, 60(9), 2111-2123; Gu et al., Oligonucleotides, 2003, 13(6), 479-489; Wang et al., J. Org. Chem., 2003, 68, 4499-4505; Verbeure et al., Nucleic Acids Research, 2001, 29(24), 4941-4947; Wang et al., J. Org. Chem., 2001, 66, 8478-82; Wang et al., Nucleosides, Nucleotides & Nucleic Acids, 2001, 20(4-7), 785-788; Wang et al., J. Am. Chem., 2000, 122, 8595-8602; WO 2006047842; WO 2001049687; etc.

[0241] Many monocyclic, bicyclic and tricyclic ring systems are suitable as sugar surrogates (modified sugars) and may be utilized in accordance with the present disclosure. See, e.g., Leumann, Christian J. Bioorg. & Med. Chem., 2002, 10, 841-854. Such ring systems can undergo various additional substitutions to further enhance their properties and / or activities.

[0242] In some embodiments, a 2’-modified sugar is a furanosyl sugar modified at the 2’ position. In some embodiments, a 2’-modification is halogen, −R’ (wherein R’ is not −H), −OR’ (wherein R’ is not −H), −SR’, −N(R’)2, optionally substituted −CH2−CH=CH2, optionally substituted alkenyl, or optionally substituted alkynyl. In some embodiments, a 2’-modifications is selected from −O[(CH2)nO]mCH3, −O(CH2)nNH2, −O(CH2)nCH3, −O(CH2)nF, −O(CH2)nONH2, −OCH2C(=O)N(H)CH3, and −O(CH2)nON[(CH2)nCH3]2, wherein each n and m is independently from 1 to about 10. In some embodiments, a 2’-modification is optionally substituted C1-C12 alkyl, optionally substituted alkenyl, optionally substituted alkynyl, optionally substituted alkaryl, optionally substituted aralkyl, optionally substituted −O−alkaryl, optionally substituted −O−aralkyl, −SH, −SCH3, −OCN, −Cl, −Br, −CN, −F, −CF3, −OCF3, −SOCH3, −SO2CH3, −ONO2, −NO2, −N3, −NH2, optionally substituted heterocycloalkyl, optionally substituted heterocycloalkaryl, optionally substituted aminoalkylamino, optionally substituted polyalkylamino, substituted silyl, a reporter group, an intercalator, a group for improving pharmacokinetic properties, a group for improving the pharmacodynamic properties, and other substituents. In some embodiments, a 2’-modification is a 2’-MOE modification (e.g., see Baker et al., J. Biol. Chem., 1997, 272, 11944-12000). In some cases, a 2’-MOE modification has been reported as having improved binding affinity compared to unmodified sugars and to some other modified nucleosides, such as 2’- O-methyl, 2’- O-propyl, and 2’-O-aminopropyl. Oligonucleotides having the 2’-MOE modification have also been reported to be capable of inhibiting gene expression with promising features for in vivo use (see, e.g., Martin, Helv. Chim. Acta, 1995, 78, 486-504; Altmann et al., Chimia, 1996, 50, 168-176; Altmann et al., Biochem. Soc. Trans., 1996, 24, 630-637; and Altmann et al., Nucleosides Nucleotides, 1997, 16, 917-926; etc.). Page 91 of 201 12495950v1Attorney Docket No.: 2010581-1440

[0243] In some embodiments, a 2’-modified or 2’-substituted sugar or nucleoside is a sugar or nucleoside comprising a substituent at the 2’ position of the sugar which is other than −H (typically not considered a substituent) or −OH. In some embodiments, a 2’-modified sugar is a bicyclic sugar comprising a bridge connecting two carbon atoms of the sugar ring one of which is the 2’ carbon. In some embodiments, a 2’-modification is non-bridging, e.g., allyl, amino, azido, thio, optionally substituted −O−allyl, optionally substituted −O−C1-C10alkyl, −OCF3, −O(CH2)2OCH3, 2’-O(CH2)2SCH3, −O(CH2)2ON(Rm)(Rn), or −OCH2C(=O)N(Rm)(Rn), where each Rmand Rnis independently −H or optionally substituted C1-C10 alkyl.

[0244] Certain modified sugars, their preparation and uses are described in US 4981957, US 5118800, US 5319080, US 5359044, US 5393878, US 5446137, US 5466786, US 5514785, US 5519134, US 5567811, US 5576427, US 5591722, US 5597909, US 5610300, US 5627053, US 5639873, US 5646265, US 5670633, US 5700920, US 5792847, US 6600032 and WO 2005121371.

[0245] In some embodiments, a sugar is the sugar of N-methanocarba, LNA, cMOE BNA, cEt BNA, α-L-LNA or related analogs, HNA, Me-ANA, MOE-ANA, Ara-FHNA, FHNA, R-6'-Me-FHNA, S-6'-Me- FHNA, ENA, or c-ANA. In some embodiments, a modified internucleotidic linkage is C3-amide (e.g., sugar that has the amide modification attached to the C3’, Mutisya et al. 2014 Nucleic Acids Res. 2014 Jun 1; 42(10): 6542–6551), formacetal, thioformacetal, MMI [e.g., methylene(methylimino), Peoc'h et al. 2006 Nucleosides and Nucleotides 16 (7-9)], a PMO (phosphorodiamidate linked morpholino) linkage (which connects two sugars), or a PNA (peptide nucleic acid) linkage. In some embodiments, examples of internucleotidic linkages and / or sugars are described in Allerson et al. 2005 J. Med. Chem. 48: 901-4; BMCL 201121: 1122; BMCL 201121: 588; BMCL 201222: 296; Chattopadhyaya et al. 2007 J. Am. Chem. Soc.129: 8362; Chem. Bio. Chem.201314: 58; Curr. Prot. Nucl. Acids Chem.20111.24.1; Egli et al.2011 J. Am. Chem. Soc.133: 16642; Hendrix et al.1997 Chem. Eur. J.3: 110; Hyrup et al.1996 Bioorg. Med. Chem. 4: 5; Imanishi 1997 Tet. Lett. 38: 8735; J. Am. Chem. Soc. 1994, 116, 3143; J. Med. Chem. 200952: 10; J. Org. Chem.201075: 1589; Jepsen et al.2004 Oligo.14: 130-146; Jones et al. J. Org. Chem. 1993, 58, 2983; Jung et al. 2014 ACIEE 53: 9893; Kodama et al. 2014 AGDS; Koizumi 2003 BMC 11: 2211; Koizumi et al.2003 Nuc. Acids Res.12: 3267-3273; Koshkin et al.1998 Tetrahedron 54: 3607-3630; Kumar et al.1998 Bioo. Med. Chem. Let.8: 2219-2222; Lauritsen et al.2002 Chem. Comm. 5: 530-531; Lauritsen et al.2003 Bioo. Med. Chem. Lett.13: 253-256; Lima et al.2012 Cell 150: 883-894; Mesmaeker et al. Angew. Chem., Int. Ed. Engl. 1994, 33, 226; Migawa et al. 2013 Org. Lett. 15: 4316; Mol. Ther. Nucl. Acids 20121: e47; Morita et al. 2001 Nucl. Acids Res. Supp. 1: 241-242; Morita et al. 2002 Bioo. Med. Chem. Lett. 12: 73-76; Morita et al. 2003 Bioo. Med. Chem. Lett. 2211-2226; Murray et al. 2012 Nucl. Acids Res. 40: 6135; Nielsen et al. 1997 Chem. Soc. Rev. 73; Nielsen et al. 1997 J. Chem. Soc. Perkins Transl. 1: 3423-3433; Obika et al. 1997 Tetrahedron Lett. 38 (50): 8735–8; Obika et al. 1998 Page 92 of 201 12495950v1Attorney Docket No.: 2010581-1440 Tetrahedron Lett. 39: 5401-5404; Obika et al. 2008 J. Am. Chem. Soc. 130: 4886; Obika et al. 2011 Org. Lett.13: 6050; Oestergaard et al.2014 JOC 79: 8877; Pallan et al.2012 Biochem.51: 7; Pallan et al.2012 Chem. Comm. 48: 8195-8197; Petersen et al. 2003 TRENDS Biotech. 21: 74-81; Prakash et al. 2010 J. Med. Chem. 53: 1636; Prakash et al. 2015 Nucl. Acids Res. 43: 2993-3011; Prakash et al. 2016 Bioorg. Med. Chem. Lett. 26: 2817-2820; Rajwanshi et al. 1999 Chem. Commun. 1395-1396; Schultz et al. 1996 Nucleic Acids Res.24: 2966; Seth et al.2008 Nucl. Acid Sym. Ser.52: 553; Seth et al.2009 J. Med. Chem. 52: 10-13; Seth et al.2010 J. Am. Chem. Soc.132: 14942; Seth et al.2010 J. Med. Chem. 53: 8309-8318; Seth et al.2010 J. Org. Chem.75: 1569-1581; Seth et al.2011 BMCL 21: 4690; Seth et al.2012 Bioo. Med. Chem. Lett. 22: 296-299; Seth et al. 2012 Mol. Ther-Nuc. Acids. 1, e47; Seth et al., Nucleic Acids Symposium Series (2008), 52(1), 553-554; Singh et al. 1998 Chem. Comm. 1247-1248; Singh et al. 1998 J. Org. Chem.63: 10035-39; Singh et al.1998 J. Org. Chem.63: 6078-6079; Sorensen 2003 Chem. Comm. 2130-2131; Starrup et al. 2010 Nucl. Acids Res. 38: 7100; Swayze et al. 2007 Nucl. Acids Res. 35: 687; Ts'o et al. Ann. N. Y. Acad. Sci. 1988, 507, 220; Van Aerschot et al. 1995 Angew. Chem. Int. Ed. Engl. 34: 1338; Vasseur et al. J. Am. Chem. Soc. 1992, 114, 4006; WO 2007090071; WO 2016079181; US 6326199; US 6066500; or US 6440739.

[0246] Various additional sugars useful for preparing oligonucleotides or analogs thereof are known in the art and may be utilized in accordance with the present disclosure. Internucleotidic linkages

[0247] Among other things, the present disclosure provides various internucleotidic linkages, including various modified internucleotidic linkages, that may be utilized together with other structural elements, e.g., various sugars as described herein, to provide oligonucleotides and compositions thereof.

[0248] Various internucleotidic linkages may be utilized in oligonucleotides in accordance with the present disclosure. In some embodiments, an oligonucleotide comprises one or more types of internucleotidic linkage. In some embodiments, an oligonucleotide comprises two or more types of internucleotidic linkage. In some embodiments, an oligonucleotide comprises at least three types of internucleotidic linkages. In some embodiments, a linkage contains a linkage phosphorus atom bonded to an oxygen atom which oxygen atom is not bonded to or is not part of a backbone sugar (“a PO linkage”, e.g., a natural phosphate linkage). In some embodiments, a linkage contains a linkage phosphorus atom bonded to a sulfur atom which sulfur atom is not bonded to or is not part of a backbone sugar (“a PS linkage”, e.g., a phosphorothioate internucleotidic linkage). In some embodiments, a linkage contains a linkage phosphorus atom bonded to a nitrogen atom which nitrogen atom is not bonded to or is not part of a backbone sugar (“a PN linkage”, e.g., n001). In some embodiments, an oligonucleotide comprises one or more PS linkages. In some embodiments, an oligonucleotide comprises one or more PO linkages. In Page 93 of 201 12495950v1Attorney Docket No.: 2010581-1440 some embodiments, an oligonucleotide comprises one or more PN linkages. In some embodiments, an oligonucleotide comprises one or more PS and one or more PO linkages. In some embodiments, an oligonucleotide comprises one or more PS and one or more PN linkages. In some embodiments, an oligonucleotide comprises one or more PS, one or more PN and one or more PO linkages. In some embodiments, a PS linkage is a phosphorothioate linkage. In some embodiments, each PS linkage is independently a phosphorothioate linkage. In some embodiments, a PO linkage is a natural phosphate linkage. In some embodiments, each PO linkage is independently a natural phosphate linkage. In some embodiments, a PN linkage is a phosphoryl guanidine linkage. In some embodiments, each PN linkage is independently a phosphoryl guanidine linkage.

[0249] In some embodiments, provided oligonucleotides comprise both one or more modified internucleotidic linkages and one or more natural phosphate linkages. As widely known by those skilled in the art, natural phosphate linkages are widely found in natural DNA and RNA molecules; they have the structure of −OP(O)(OH)O−, connect sugars in the nucleosides in DNA and RNA, and may be in various salt forms, for example, at physiological pH (about 7.4), natural phosphate linkages are predominantly exist in salt forms with the anion being −OP(O)(O−)O−. A modified internucleotidic linkage, or a non-natural phosphate linkage, is an internucleotidic linkage that is not natural phosphate linkage or a salt form thereof. Modified internucleotidic linkages, depending on their structures, may also be in their salt forms. For example, as appreciated by those skilled in the art, phosphorothioate internucleotidic linkages which have the structure of −OP(O)(SH)O− may be in various salt forms, e.g., at physiological pH (about 7.4) with the anion being −OP(O)(S−)O−.

[0250] In some embodiments, an oligonucleotide comprises an internucleotidic linkage which is a modified internucleotidic linkage, e.g., phosphorothioate, phosphorodithioate, methylphosphonate, phosphoroamidate, thiophosphate, 3’-thiophosphate, or 5’-thiophosphate. In some embodiments, a modified internucleotidic linkage is a PN linkage. In some embodiments, a modified internucleotidic linkage is a PS linkage. In some embodiments, a modified internucleotidic linkage is a PO linkage (e.g., other than a natural phosphate linkage). In some embodiments, each modified internucleotidic linkage is independently a PN internucleotidic linkage or a PS internucleotidic linkage. In some embodiments, an oligonucleotide comprises one or more PN internucleotidic linkages, one or more PS internucleotidic linkages, and one or more PO internucleotidic linkages. In some embodiments, one or more PN internucleotidic linkages are independently phosphoryl guanidine internucleotidic linkages. In some embodiments, one or more PN internucleotidic linkages are independently n001. In some embodiments, one or more PS internucleotidic linkages are independently phosphorothioate internucleotidic linkages. In some embodiments, each PS internucleotidic linkage is independently a phosphorothioate internucleotidic linkage. In some embodiments, one or more PO internucleotidic linkages are independently natural Page 94 of 201 12495950v1Attorney Docket No.: 2010581-1440 phosphate linkages. In some embodiments, each PO internucleotidic linkage is independently a natural phosphate linkage.

[0251] In some embodiments, a modified internucleotidic linkage is a chiral internucleotidic linkage which comprises a chiral linkage phosphorus. In some embodiments, a chiral internucleotidic linkage is a phosphorothioate linkage. In some embodiments, a chiral internucleotidic linkage is a non-negatively charged internucleotidic linkage. In some embodiments, a chiral internucleotidic linkage is a neutral internucleotidic linkage. In some embodiments, a chiral internucleotidic linkage is chirally controlled with respect to its chiral linkage phosphorus. In some embodiments, a chiral internucleotidic linkage is stereochemically pure with respect to its chiral linkage phosphorus. In some embodiments, a chiral internucleotidic linkage is not chirally controlled. In some embodiments, a pattern of backbone chiral centers comprises or consists of positions and linkage phosphorus configurations of chirally controlled internucleotidic linkages (Rp or Sp) and positions of achiral internucleotidic linkages (e.g., natural phosphate linkages).

[0252] In some embodiments, an internucleotidic linkage comprises a P-modification, wherein a P- modification is a modification at a linkage phosphorus. In some embodiments, a modified internucleotidic linkage is a moiety which does not comprise a phosphorus but serves to link two sugars or two moieties that each independently comprises a nucleobase, e.g., as in peptide nucleic acid (PNA).

[0253] In some embodiments, an internucleotidic linkage is described in US 10167309, US 11643657, US 11718638, US 11608355, US 20230089442, US 20220306573, or US 20230203087, the internucleotidic linkages of each of which incorporated herein by reference.

[0254] In some embodiments, a modified internucleotidic linkage (e.g., a non-negatively charged internucleotidic linkage) comprises optionally substituted triazolyl. In some embodiments, a modified internucleotidic linkage (e.g., a non-negatively charged internucleotidic linkage) comprises optionally substituted alkynyl. In some embodiments, a modified internucleotidic linkage comprises a triazole or alkyne moiety. In some embodiments, a triazole moiety, e.g., a triazolyl group, is optionally substituted. In some embodiments, a triazole moiety, e.g., a triazolyl group) is substituted. In some embodiments, a triazole moiety is unsubstituted. In some embodiments, a modified internucleotidic linkage comprises an optionally substituted cyclic guanidine moiety. In some embodiments, a modified internucleotidic linkage has the is optionally chirally controlled, wherein R1is −L−R’, wherein each L and R’herein. In some embodiments, each R1is independently R’. In some embodiments, each R’ is independently R. In some embodiments, two R1are R and are taken Page 95 of 201 12495950v1Attorney Docket No.: 2010581-1440 together to form a ring as described herein. In some embodiments, two R1on two different nitrogen atoms are R and are taken together to form a ring as described herein. In some embodiments, R1is independently optionally substituted C1-6aliphatic as described herein. In some embodiments, R1is methyl. In some embodiments, two R’ on the same nitrogen atom are R and are taken together to form a ring as described herein. In some embodiments, a modified internucleotidic linkage has theis optionally chirally controlled. In some embodiments, a modified internucleotidic linkagemoiety and has the structure is O or S. In somenegatively charged internucleotidic linkage is stereochemically controlled.

[0255] In some embodiments, a non-negatively charged internucleotidic linkage or a neutral internucleotidic linkage is an internucleotidic linkage comprising a triazole moiety. In some embodiments, a non-negatively charged internucleotidic linkage or a non-negatively charged internucleotidic linkage comprises an optionally substituted triazolyl group. In some embodiments, an internucleotidic linkage comprising a triazole moiety (e.g., an optionally substituted triazolyl group) has the structure of . In some embodiments, an internucleotidic linkage comprising a triazole moiety hasthe structure . In some embodiments, an internucleotidic linkage comprising atriazole moiety has the In some embodiments, anPage 96 of 201 12495950v1Attorney Docket No.: 2010581-1440 internucleotidic linkage comprising an alkyne moiety (e.g., an optionally substituted alkynyl group) has the formula , wherein W is O or S. In some embodiments, an internucleotidic linkage, e.g., a non- internucleotidic linkage, a neutral internucleotidic linkage, comprises a cyclicembodiments, an internucleotidic linkage comprising a cyclic guanidine moiety has the some embodiments, a non-negatively charged internucleotidiclinkage, or a neutral internucleotidic linkage, is or comprising a structure selected, wherein W is O or S.

[0256] In some embodiments, an internucleotidic linkage comprises a Tmg Insome embodiments, an internucleotidic linkage comprises a Tmg group andof (the “Tmg internucleotidic linkage”). In some embodiments, neutral internucleotidiclinkages of PNA and PMO, and an Tmg internucleotidic linkage.

[0257] In some embodiments, a non-negatively charged internucleotidic linkage comprises an optionally substituted 3-20 membered heterocyclyl or heteroaryl group having 1-10 heteroatoms. In some embodiments, a non-negatively charged internucleotidic linkage comprises an optionally substituted 3-20 membered heterocyclyl or heteroaryl group having 1-10 heteroatoms, wherein at least one heteroatom is nitrogen. In some embodiments, such a heterocyclyl or heteroaryl group is of a 5-membered ring. In some embodiments, such a heterocyclyl or heteroaryl group is of a 6-membered ring.

[0258] In some embodiments, a non-negatively charged internucleotidic linkage comprises an optionally substituted 5-20 membered heteroaryl group having 1-10 heteroatoms. In some embodiments, Page 97 of 201 12495950v1Attorney Docket No.: 2010581-1440 a non-negatively charged internucleotidic linkage comprises an optionally substituted 5-20 membered heteroaryl group having 1-10 heteroatoms, wherein at least one heteroatom is nitrogen. In some embodiments, a non-negatively charged internucleotidic linkage comprises an optionally substituted 5-6 membered heteroaryl group having 1-4 heteroatoms, wherein at least one heteroatom is nitrogen. In some embodiments, a non-negatively charged internucleotidic linkage comprises an optionally substituted 5- membered heteroaryl group having 1-4 heteroatoms, wherein at least one heteroatom is nitrogen. In some embodiments, a heteroaryl group is directly bonded to a linkage phosphorus. In some embodiments, a non- negatively charged internucleotidic linkage comprises an optionally substituted triazolyl group. In some embodiments, a non-negatively charged internucleotidic linkage comprises an unsubstituted triazolyl group, . In some embodiments, a non-negatively charged internucleotidic linkage comprises asubstituted triazolyl group, .

[0259] In some negatively charged internucleotidic linkage comprises anoptionally substituted 5-20 membered heterocyclyl group having 1-10 heteroatoms. In some embodiments, a non-negatively charged internucleotidic linkage comprises an optionally substituted 5-20 membered heterocyclyl group having 1-10 heteroatoms, wherein at least one heteroatom is nitrogen. In some embodiments, a non-negatively charged internucleotidic linkage comprises an optionally substituted 5-6 membered heterocyclyl group having 1-4 heteroatoms, wherein at least one heteroatom is nitrogen. In some embodiments, a non-negatively charged internucleotidic linkage comprises an optionally substituted 5- membered heterocyclyl group having 1-4 heteroatoms, wherein at least one heteroatom is nitrogen. In some embodiments, at least two heteroatoms are nitrogen. In some embodiments, a heterocyclyl group is directly bonded to a linkage phosphorus. In some embodiments, a heterocyclyl group is bonded to a linkage phosphorus through a linker, e.g., =N− when the heterocyclyl group is part of a guanidine moiety who directed bonded to a linkage phosphorus through its =N−. In some embodiments, a non-negatively charged internucleotidic linkage comprises an optionally substituted group. In some embodiments, a non- negatively charged internucleotidic linkage comprises an substituted group. In some embodiments, a non-negatively charged internucleotidic linkage group, whereinPage 98 of 201 12495950v1Attorney Docket No.: 2010581-1440 each R1is independently −L−R. In some embodiments, each R1is independently optionally substituted C1-6alkyl. In some embodiments, each R1is independently methyl.

[0260] In some embodiments, a modified internucleotidic linkage, e.g., a non-negatively charged internucleotidic linkage, comprises a triazole or alkyne moiety, each of which is optionally substituted. In some embodiments, a modified internucleotidic linkage comprises a triazole moiety. In some embodiments, a modified internucleotidic linkage comprises a unsubstituted triazole moiety. In someembodiments, a modified internucleotidic linkage comprises a substituted triazole In some embodiments, a modified internucleotidic linkage comprises an alkyl moiety. In some embodiments, amodified internucleotidic linkage comprises an optionally substituted alkynyl group. In some embodiments, a modified internucleotidic linkage comprises an unsubstituted alkynyl In someembodiments, a modified internucleotidic linkage comprises a substituted alkynyl group. In some embodiments, an alkynyl group is directly bonded to a linkage phosphorus.

[0261] In some embodiments, a non-negatively charged internucleotidic linkage has the structure of thehas the some embodiments, a non-negatively charged internucleotidiclinkage has the structure . In some embodiments, a non-negatively chargedinternucleotidic linkage has the In some embodiments, a non-negativelycharged internucleotidic linkage has the . In some embodiments, a non-Page 99 of 201 12495950v1Attorney Docket No.: 2010581-1440 negatively charged internucleotidic linkage has the . In some embodiments,a non-negatively charged internucleotidic linkage has the In someembodiments, a non-negatively charged internucleotidic linkage has the . In some embodiments, a non-negatively charged internucleotidic ofO a non-negatively charged internucleotidic linkage has the structure embodiments, a non-negatively charged internucleotidic linkage has the . In some embodiments, W is O. In some embodiments, W is S. In somelinkage is a non-negatively charged internucleotidic linkage described above.

[0262] In some embodiments, an oligonucleotide comprises a neutral internucleotidic linkage and a chirally controlled internucleotidic linkage. In some embodiments, an oligonucleotide comprises a neutral internucleotidic linkage and a chirally controlled internucleotidic linkage which is not the neutral internucleotidic linkage. In some embodiments, an oligonucleotide comprises a neutral internucleotidic linkage and a chirally controlled phosphorothioate internucleotidic linkage. In some embodiments, the present disclosure provides an oligonucleotide comprising one or more non-negatively charged internucleotidic linkages and one or more phosphorothioate internucleotidic linkages, wherein each phosphorothioate internucleotidic linkage in the oligonucleotide is independently a chirally controlled internucleotidic linkage. In some embodiments, the present disclosure provides an oligonucleotide comprising one or more neutral internucleotidic linkages and one or more phosphorothioate internucleotidic linkage, wherein each phosphorothioate internucleotidic linkage in the oligonucleotide is independently a Page 100 of 201 12495950v1Attorney Docket No.: 2010581-1440 chirally controlled internucleotidic linkage. In some embodiments, an oligonucleotide comprises at least 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20 or more chirally controlled phosphorothioate internucleotidic linkages. In some embodiments, non-negatively charged internucleotidic linkage is chirally controlled. In some embodiments, non-negatively charged internucleotidic linkage is not chirally controlled. In some embodiments, a neutral internucleotidic linkage is chirally controlled. In some embodiments, a neutral internucleotidic linkage is not chirally controlled. In some embodiments, an oligonucleotide comprises one or more (e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10) chirally controlled and one or more (e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10) non-chirally controlled chiral internucleotidic linkages. In some embodiments, an oligonucleotide comprises one or more (e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10) chirally controlled and one or more (e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10) non-chirally controlled non-negatively charged internucleotidic linkages (in some embodiments, each of which is independently n001). In some embodiments, a neutral internucleotidic linkage is chirally controlled. In some embodiments, a neutral internucleotidic linkage is not chirally controlled. In some embodiments, an oligonucleotide comprises one or more (e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10) chirally controlled and one or more (e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10) non-chirally controlled neutral internucleotidic linkages (in some embodiments, each of which is independently n001).

[0263] In some embodiments, an internucleotidic linkage has the structure of −O−P(=W)[−N(R’)2]−O−, wherein W is O or S, and each variable is independently as described herein. In some embodiments, an internucleotidic linkage has the structure of −O−P(=W)(−NHR’)−O−, wherein each variable is independently as described herein. In some embodiments, an internucleotidic linkage has the structure of −O−P(=W)(−NHSO2R)−O−, wherein each variable is independently as described herein. In some embodiments, R is methyl. In some embodiments, an internucleotidic linkage is −O−P(=O)(−NHSO2CH3)−O−. In some embodiments, an internucleotidic linkage has the structure of −O−P(=W)[−N=C(–R’)2]−O−, wherein each variable is independently as described herein. In some embodiments, an internucleotidic linkage has the structure of −O−P(=W)[−N=C[N(R’)2]2]−O−, wherein each variable is independently as described herein. In some embodiments, an internucleotidic linkage has the structure of −OP(=W)(−N=C(R’)2)−O−, wherein each variable is independently as described herein. In some embodiments, an internucleotidic linkage has the structure of −OP(=W)(−N(R’)2)−O−, wherein each variable is independently as described herein. In some embodiments, W is O. In some embodiments, W is S. In some embodiments, such an internucleotidic linkage is a non-negatively charged internucleotidic linkage. In some embodiments, such an internucleotidic linkage is a neutral internucleotidic linkage.

[0264] In some embodiments, an internucleotidic linkage has the structure of −P(=W)[−N(R’)2]−O−, wherein each variable is independently as described herein. In some embodiments, an internucleotidic linkage has the structure of −P(=W)(−NHR’)−O−, wherein each variable is independently as described Page 101 of 201 12495950v1Attorney Docket No.: 2010581-1440 herein. In some embodiments, an internucleotidic linkage has the structure of −P(=W)(−NHSO2R)−O−, wherein each variable is independently as described herein. In some embodiments, R is methyl. In some embodiments, an internucleotidic linkage is −P(=O)(−NHSO2CH3)−O−. In some embodiments, an internucleotidic linkage has the structure of −P(=W)[−N=C(–LL–R’)2]−O−, wherein each variable is independently as described herein. In some embodiments, an internucleotidic linkage has the structure of −P(=W)[−N=C[N(R’)2]2]−O−, wherein each variable is independently as described herein. In some embodiments, an internucleotidic linkage has the structure of −P(=W)(−N=C(R’)2)−O−, wherein each variable is independently as described herein. In some embodiments, an internucleotidic linkage has the structure of −P(=W)(−N(R’)2)−O−, wherein each variable is independently as described herein. In some embodiments, W is O. In some embodiments, W is S. In some embodiments, such an internucleotidic linkage is a non-negatively charged internucleotidic linkage. In some embodiments, such an internucleotidic linkage is a neutral internucleotidic linkage. In some embodiments, P of such an internucleotidic linkage is bonded to N of a sugar.

[0265] In some embodiments, a linkage is a phosphoryl guanidine internucleotidic linkage. In some embodiments, a linkage is a thio-phosphoryl guanidine internucleotidic linkage. Oligonucleotides

[0266] In some embodiments, provided technologies are useful for preparing or delivering oligonucleotides comprising −P(O)(OH)2 which may exist in various salt forms. In some embodiments, the present disclosure provides oligonucleotides comprising −P(O)(ORPG)2 as described herein. In some embodiments, oligonucleotides comprising −P(O)(ORPG)2 as described herein are administered to a subject for preventing or treating conditions, disorders or diseases. In some embodiments, oligonucleotides comprising −P(O)(ORPG)2 as described herein are utilized for preparing oligonucleotides comprising −P(O)(OH)2 which may exist in various salt forms. For example, in some embodiments, the present disclosure provides a compound, wherein the compound is an oligonucleotide comprising , wherein each of RP1and RP2is −O−CH2CH2CN or −O−CH2−O−C(O)−RP, whereintert-butyl. In some embodiments, the present disclosure provides a compound, wherein the compound is an oligonucleotide comprising a moiety of formula O or a salt thereof: Page 102 of 201 12495950v1Attorney Docket No.: 2010581-1440 ,wherein each variable is as some embodiments, the present disclosure provides a compound, wherein the compound is an oligonucleotide comprising a moiety of formula O-I or a salt thereof:,wherein each variable is independently as described herein. In some embodiments, the present disclosure provides a compound, wherein the compound is an oligonucleotide comprising a moiety of formula O-I’ or a salt thereof: ,wherein each variable is independently as described herein.

[0267] As those skilled in the art appreciate, oligonucleotides may comprise various sugars, nucleobases, internucleotidic linkages as described herein. In some embodiments, an oligonucleotide comprises a PS linkage. In some embodiments, an oligonucleotide comprises a PN linkage. In some embodiments, an oligonucleotide comprises a PO linkage. In some embodiments, an oligonucleotide comprises a PS linkage and a PN linkage. In some embodiments, an oligonucleotide comprises a PS linkage and a PO linkage. In some embodiments, an oligonucleotide comprises a PO linkage, a PS linkage and a PN linkage. In some embodiments, the number of PS internucleotidic linkages in an oligonucleotide is about 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19 or 20 or more. In some embodiments, the number of PN internucleotidic linkages in an oligonucleotide is about 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19 or 20 or more. In some embodiments, the number of PO internucleotidic linkages in an oligonucleotide is about 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, Page 103 of 201 12495950v1Attorney Docket No.: 2010581-1440 17, 18, 19 or 20 or more. In some embodiments, each PS linkage is a phosphorothioate internucleotidic linkage. In some embodiments, each PN linkage is independently a non-negatively charged internucleotidic linkage. In some embodiments, each PN linkage is independently a neutral internucleotidic linkage. In some embodiments, each PN linkage is independently a phosphoryl guanidine internucleotidic linkage. In some embodiments, each PN linkage is independently n001.

[0268] In some embodiments, each PS internucleotidic linkage is independently chirally controlled. In some embodiments, each PN internucleotidic linkage is independently chirally controlled. In some embodiments, each chiral linkage phosphorus is independently chirally controlled.

[0269] In some embodiments, an oligonucleotide has a length of about 10-200 (e.g., about 10-20, 10- 30, 10-40, 10-50, 10-60, 10-70, 10-80, 10-90, 10-100, 10-120, 10-150, 20-30, 20-40, 20-50, 20-60, 20-70, 20-80, 20-90, 20-100, 20-120, 20-150, 20-200, 25-30, 25-40, 25-50, 25-60, 25-70, 25-80, 25-90, 25-100, 25-120, 25-150, 25-200, 30-40, 30-50, 30-60, 30-70, 30-80, 30-90, 30-100, 30-120, 30-150, 30-200, 10, 20, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 45, 50, 60, etc.) nucleobases. In some embodiments, the base sequence of an oligonucleotide is about 10-60 nucleobases in length. In some embodiments, a base sequence is about 15-50 nucleobases in length. In some embodiments, a base sequence is from about 15 to about 35 nucleobases in length. In some embodiments, an oligonucleotide is about 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60 or more nucleobases in length. In some embodiments, each nucleobase counted in the length is independently optionally substituted or protected A, T, C, G, U or a tautomer thereof.

[0270] In some embodiments, oligonucleotides are provided as salt forms. In some embodiments, oligonucleotides are provided as salts comprising negatively-charged internucleotidic linkages (e.g., phosphorothioate internucleotidic linkages, natural phosphate linkages, etc.) existing as their salt forms. In some embodiments, oligonucleotides are provided as pharmaceutically acceptable salts. In some embodiments, oligonucleotides are provided as metal salts. In some embodiments, oligonucleotides are provided as sodium salts. In some embodiments, oligonucleotides are provided as ammonium salts. In some embodiments, oligonucleotides are provided as metal salts, e.g., sodium salts, wherein each negatively-charged internucleotidic linkage is independently in a salt form (e.g., for sodium salts, −O−P(O)(SNa)−O− for a phosphorothioate internucleotidic linkage, −O−P(O)(ONa)−O− for a natural phosphate linkage, etc.).

[0271] In some embodiments, oligonucleotides are chiral controlled, comprising one or more chirally controlled internucleotidic linkages. In some embodiments, provided oligonucleotides are stereochemically pure. In some embodiments, provided oligonucleotides or compositions thereof are substantially pure of other stereoisomers. In some embodiments, the present disclosure provides chirally controlled Page 104 of 201 12495950v1Attorney Docket No.: 2010581-1440 oligonucleotide compositions.

[0272] As described herein, oligonucleotides of the present disclosure can be provided in high purity (e.g., 50%-100%). In some embodiments, oligonucleotides of the present disclosure are of high stereochemical purity (e.g., 50%-100%). In some embodiments, oligonucleotides in provided compositions are of high stereochemical purity (e.g., high percentage (e.g., 50%-100%) of a stereoisomer compared to the other stereoisomers of the same oligonucleotide). In some embodiments, a percentage is at least or about 50%. In some embodiments, a percentage is at least or about 60%. In some embodiments, a percentage is at least or about 70%. In some embodiments, a percentage is at least or about 75%. In some embodiments, a percentage is at least or about 80%. In some embodiments, a percentage is at least or about 85%. In some embodiments, a percentage is at least or about 90%. In some embodiments, a percentage is at least or about 95%.

[0273] In some embodiments, oligonucleotides of the present disclosure are at least 50%, 60%, 70%, 75%, 80%, 85%, 90%, 95%, or 99% stereochemically pure at linkage phosphorus of chiral internucleotidic linkages. In some embodiments, oligonucleotides of the present disclosure are prepared stereoselectively and are substantially free of stereoisomers. In some embodiments, in provided compositions comprising a plurality of oligonucleotides which share the same base sequence of the same pattern of chiral linkage phosphorus stereochemistry (e.g., comprising one or more of Rp and / or Sp, wherein each chiral linkage phosphorus is independently Rp or Sp), at least 50%, 60%, 70%, 75%, 80%, 85%, 90%, 95%, or 99% of all oligonucleotides in the composition that share the same base sequence as oligonucleotides of the plurality share the same pattern of chiral linkage phosphorus stereochemistry or are oligonucleotides of the plurality. In some embodiments, in provided compositions comprising a plurality of oligonucleotides which share the same base sequence of the same pattern of chiral linkage phosphorus stereochemistry, at least 50%, 60%, 70%, 75%, 80%, 85%, 90%, 95%, or 99% of all oligonucleotides in the composition that share the same constitution as oligonucleotides of the plurality share the same pattern of chiral linkage phosphorus stereochemistry or are oligonucleotides of the plurality. In some embodiments, diastereomeric excess of each chiral phosphorus is independently about or at least about 90%. In some embodiments, diastereomeric excess of each chiral phosphorus is independently about or at least about 95%. In some embodiments, diastereomeric excess of each chiral phosphorus is independently about or at least about 97%. In some embodiments, diastereomeric excess of each chiral phosphorus is independently about or at least about 98%. In some embodiments, diastereomeric purity is about or at least about (DS)nc, wherein DS is about 90-100%, and nc is the number of chiral linkage phosphorus. In some embodiments, DS is about 90% or more. In some embodiments, DS is about 95% or more. In some embodiments, DS is about 96% or more. In some embodiments, DS is about 97% or more. In some embodiments, DS is about 98% or more. In some embodiments, DS is about 99% or more. In some embodiments, diastereomeric purity is represented Page 105 of 201 12495950v1Attorney Docket No.: 2010581-1440 as the product of the diastereopurity of each chiral linkage phosphorus. Oligonucleotide Compositions

[0274] Among other things, the present disclosure provides various oligonucleotide compositions. In some embodiments, the present disclosure provides oligonucleotide compositions of oligonucleotides described herein. In some embodiments, an oligonucleotide composition comprises a plurality of oligonucleotides described in the present disclosure. In some embodiments, an oligonucleotide composition is chirally controlled. In some embodiments, an oligonucleotide composition is not chirally controlled (stereorandom).

[0275] Linkage phosphorus of natural phosphate linkages is achiral. Linkage phosphorus of many modified internucleotidic linkages, e.g., phosphorothioate internucleotidic linkages, are chiral. In some embodiments, during preparation of oligonucleotide compositions (e.g., in traditional phosphoramidite oligonucleotide synthesis), configurations of chiral linkage phosphorus are not purposefully designed or controlled, creating non-chirally controlled (stereorandom) oligonucleotide compositions (substantially racemic preparations) which are complex, random mixtures of various stereoisomers (diastereoisomers) - for oligonucleotides with n chiral internucleotidic linkages (linkage phosphorus being chiral), typically 2^n stereoisomers (e.g., when n is 10, 2^10 =1,032; when n is 20, 2^20 = 1,048,576). These stereoisomers have the same constitution, but differ with respect to the pattern of stereochemistry of their linkage phosphorus.

[0276] In some embodiments, stereorandom oligonucleotide compositions have sufficient properties and / or activities for certain purposes and / or applications. In some embodiments, stereorandom oligonucleotide compositions can be cheaper, easier and / or simpler to produce than chirally controlled oligonucleotide compositions. However, stereoisomers within stereorandom compositions may have different properties, activities, and / or toxicities, resulting in inconsistent therapeutic effects and / or unintended side effects by stereorandom compositions, particularly compared to certain chirally controlled oligonucleotide compositions of oligonucleotides of the same constitution.

[0277] In some embodiments, the present disclosure encompasses technologies for designing and preparing chirally controlled oligonucleotide compositions. In some embodiments, a chirally controlled oligonucleotide composition comprises a controlled / pre-determined (not random as in stereorandom compositions) level of a plurality of oligonucleotides, wherein the oligonucleotides share the same linkage phosphorus stereochemistry at one or more chiral internucleotidic linkages (chirally controlled internucleotidic linkages). In some embodiments, the oligonucleotides share the same pattern of backbone chiral centers (stereochemistry of linkage phosphorus). In some embodiments, a pattern of backbone chiral centers is as described in the present disclosure. In some embodiments, oligonucleotides of a plurality are structural identical. Page 106 of 201 12495950v1Attorney Docket No.: 2010581-1440

[0278] In some embodiments, the present disclosure provides a chirally controlled oligonucleotide composition comprising a plurality of oligonucleotides, wherein the oligonucleotides share: 1) a common constitution, and 2) share the same linkage phosphorus stereochemistry at one or more (e.g., 1-50, 1-40, 1-30, 1-25, 1-20, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25 or more) chiral internucleotidic linkages (chirally controlled internucleotidic linkages), wherein the composition is enriched, relative to a substantially racemic preparation of oligonucleotides of the common constitution, for oligonucleotides of the plurality.

[0279] In some embodiments, the present disclosure provides a chirally controlled oligonucleotide composition comprising a plurality of oligonucleotides, wherein the oligonucleotides share: 1) a common constitution, and 2) share the same linkage phosphorus stereochemistry at one or more (e.g., 1-50, 1-40, 1-30, 1-25, 1-20, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25 or more) chiral internucleotidic linkages (chirally controlled internucleotidic linkages), wherein stereochemical purity of the linkage phosphorus of each chirally controlled internucleotidic linkage is independently 80%-100% (e.g., 85-100%, 90-100%, about or at least about 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or 99.5%).

[0280] In some embodiments, at least one chiral internucleotidic linkage is chirally controlled. In some embodiments, at least 2 internucleotidic linkages are independently chirally controlled. In some embodiments, the number of chirally controlled internucleotidic linkages is at least 3. In some embodiments, it is at least 4. In some embodiments, it is at least 5. In some embodiments, it is at least 6. In some embodiments, it is at least 7. In some embodiments, it is at least 8. In some embodiments, it is at least 9. In some embodiments, it is at least 10. In some embodiments, it is at least 11. In some embodiments, it is at least 12. In some embodiments, it is at least 13. In some embodiments, it is at least 14. In some embodiments, it is at least 15. In some embodiments, it is at least 20. In some embodiments, it is at least 25. In some embodiments, it is at least 30.

[0281] In some embodiments, at least 5%-100% (e.g., about 10%-100%, 20-100%, 30%-100%, 40%- 100%, 50%-80%, 50%-85%, 50%-90%, 50%-95%, 60%-80%, 60%-85%, 60%-90%, 60%-95%, 60%- 100%, 65%-80%, 65%-85%, 65%-90%, 65%-95%, 65%-100%, 70%-80%, 70%-85%, 70%-90%, 70%- 95%, 70%-100%, 75%-80%, 75%-85%, 75%-90%, 75%-95%, 75%-100%, 80%-85%, 80%-90%, 80%- 95%, 80%-100%, 85%-90%, 85%-95%, 85%-100%, 90%-95%, 90%-100%, 10%, 20%, 30%, 40%, 50%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, or 100%, etc.) of all chiral linkage phosphorus are chirally controlled. In some embodiments, at least 5%-100% (e.g., about 10%-100%, 20-100%, 30%-100%, 40%- 100%, 50%-80%, 50%-85%, 50%-90%, 50%-95%, 60%-80%, 60%-85%, 60%-90%, 60%-95%, 60%- Page 107 of 201 12495950v1Attorney Docket No.: 2010581-1440 100%, 65%-80%, 65%-85%, 65%-90%, 65%-95%, 65%-100%, 70%-80%, 70%-85%, 70%-90%, 70%- 95%, 70%-100%, 75%-80%, 75%-85%, 75%-90%, 75%-95%, 75%-100%, 80%-85%, 80%-90%, 80%- 95%, 80%-100%, 85%-90%, 85%-95%, 85%-100%, 90%-95%, 90%-100%, 10%, 20%, 30%, 40%, 50%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, or 100%, etc.) of all phosphorothioate internucleotidic linkages are chirally controlled. In some embodiments, each phosphorothioate internucleotidic linkage is independently chirally controlled. In some embodiments, a percentage is at least 50%. In some embodiments, a percentage is at least 60%. In some embodiments, a percentage is at least 70%. In some embodiments, a percentage is at least 80%. In some embodiments, a percentage is at least 90%. In some embodiments, a percentage is at least 90%. In some embodiments, each chiral internucleotidic linkage is chirally controlled. In some embodiments, each phosphorothioate internucleotidic linkage is chirally controlled.

[0282] In some embodiments, no more than 1-10, e.g., no more than 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10, chiral internucleotidic linkages are not chirally controlled. In some embodiments, no more than 1 chiral internucleotidic linkages is not chirally controlled. In some embodiments, no more than 2 chiral internucleotidic linkages are not chirally controlled. In some embodiments, no more than 3 chiral internucleotidic linkages are not chirally controlled. In some embodiments, no more than 4 chiral internucleotidic linkages are not chirally controlled. In some embodiments, no more than 5 chiral internucleotidic linkages are not chirally controlled. In some embodiments, the number of non-chirally controlled internucleotidic linkages is 1. In some embodiments, it is 2. In some embodiments, it is 3. In some embodiments, it is 4. In some embodiments, it is 5.

[0283] In some embodiments, the present disclosure provides a composition comprising a plurality of oligonucleotides, wherein each oligonucleotide of the plurality is independently a particular oligonucleotide or a salt thereof. In some embodiments, the present disclosure provides a composition comprising a plurality of oligonucleotides, wherein each oligonucleotide of the plurality is independently a particular oligonucleotide or a pharmaceutically acceptable salt thereof. In some embodiments, such a composition is enriched relative to a substantially racemic preparation of a particular oligonucleotide. As appreciated by those skilled in the art, oligonucleotides of the plurality share a common sequence which is the base sequence of the particular oligonucleotide. In some embodiments, at least about 5%-100%, 10%-100%, 20-100%, 30%-100%, 40%-100%, 50%-100%, 5%-90%, 10%-90%, 20-90%, 30%-90%, 40%-90%, 50%- 90%, 5%-85%, 10%-85%, 20-85%, 30%-85%, 40%-85%, 50%-85%, 5%-80%, 10%-80%, 20-80%, 30%- 80%, 40%-80%, 50%-80%, 5%-75%, 10%-75%, 20-75%, 30%-75%, 40%-75%, 50%-75%, 5%-70%, 10%- 70%, 20-70%, 30%-70%, 40%-70%, 50%-70%, 5%-65%, 10%-65%, 20-65%, 30%-65%, 40%-65%, 50%- 65%, 5%-60%, 10%-60%, 20-60%, 30%-60%, 40%-60%, 50%-60%, 5%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% of all oligonucleotides Page 108 of 201 12495950v1Attorney Docket No.: 2010581-1440 in the composition that share the base sequence of a the particular oligonucleotide are oligonucleotide of the plurality. In some embodiments, at least about 5%-100%, 10%-100%, 20-100%, 30%-100%, 40%- 100%, 50%-100%, 5%-90%, 10%-90%, 20-90%, 30%-90%, 40%-90%, 50%-90%, 5%-85%, 10%-85%, 20-85%, 30%-85%, 40%-85%, 50%-85%, 5%-80%, 10%-80%, 20-80%, 30%-80%, 40%-80%, 50%-80%, 5%-75%, 10%-75%, 20-75%, 30%-75%, 40%-75%, 50%-75%, 5%-70%, 10%-70%, 20-70%, 30%-70%, 40%-70%, 50%-70%, 5%-65%, 10%-65%, 20-65%, 30%-65%, 40%-65%, 50%-65%, 5%-60%, 10%-60%, 20-60%, 30%-60%, 40%-60%, 50%-60%, 5%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% of all oligonucleotides in the composition that share the constitution of the particular oligonucleotide or a salt thereof are oligonucleotide of the plurality. In some embodiments, a percentage is at least 10%. In some embodiments, a percentage is at least 20%. In some embodiments, a percentage is at least 30%. In some embodiments, a percentage is at least 40%. In some embodiments, a percentage is at least 50%. In some embodiments, it is at least 60%. In some embodiments, it is at least 70%. In some embodiments, it is at least 80%. In some embodiments, it is at least 90%. In some embodiments, it is at least 95%. In some embodiments, it is about 5-100%. In some embodiments, it is about 10-100%. In some embodiments, it is about 20-100%. In some embodiments, it is about 30-90%. In some embodiments, it is about 30-80%. In some embodiments, it is about 30-70%. In some embodiments, it is about 40-90%. In some embodiments, it is about 40-80%. In some embodiments, it is about 40-70%.

[0284] In some embodiments, an enrichment relative to a substantially racemic preparation is that at least about 5%-100%, 10%-100%, 20-100%, 30%-100%, 40%-100%, 50%-100%, 5%-90%, 10%-90%, 20- 90%, 30%-90%, 40%-90%, 50%-90%, 5%-85%, 10%-85%, 20-85%, 30%-85%, 40%-85%, 50%-85%, 5%- 80%, 10%-80%, 20-80%, 30%-80%, 40%-80%, 50%-80%, 5%-75%, 10%-75%, 20-75%, 30%-75%, 40%- 75%, 50%-75%, 5%-70%, 10%-70%, 20-70%, 30%-70%, 40%-70%, 50%-70%, 5%-65%, 10%-65%, 20- 65%, 30%-65%, 40%-65%, 50%-65%, 5%-60%, 10%-60%, 20-60%, 30%-60%, 40%-60%, 50%-60%, 5%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% of all oligonucleotides in the composition, or all oligonucleotides in the composition that share the common base sequence of a plurality, or all oligonucleotides in the composition that share the common constitution of a plurality, are oligonucleotide of the plurality. In some embodiments, a percentage is at least 10%. In some embodiments, a percentage is at least 20%. In some embodiments, a percentage is at least 30%. In some embodiments, a percentage is at least 40%. In some embodiments, a percentage is at least 50%. In some embodiments, it is at least 60%. In some embodiments, it is at least 70%. In some embodiments, it is at least 80%. In some embodiments, it is at least 90%. In some embodiments, it is at least 95%. In some embodiments, it is about 5-100%. In some embodiments, it is about 10-100%. In some embodiments, it is about 20-100%. In some embodiments, it is about 30-90%. In some embodiments, it is Page 109 of 201 12495950v1Attorney Docket No.: 2010581-1440 about 30-80%. In some embodiments, it is about 30-70%. In some embodiments, it is about 40-90%. In some embodiments, it is about 40-80%. In some embodiments, it is about 40-70%.

[0285] In some embodiments, at least about 5%-100%, 10%-100%, 20-100%, 30%-100%, 40%- 100%, 50%-100%, 5%-90%, 10%-90%, 20-90%, 30%-90%, 40%-90%, 50%-90%, 5%-85%, 10%-85%, 20-85%, 30%-85%, 40%-85%, 50%-85%, 5%-80%, 10%-80%, 20-80%, 30%-80%, 40%-80%, 50%-80%, 5%-75%, 10%-75%, 20-75%, 30%-75%, 40%-75%, 50%-75%, 5%-70%, 10%-70%, 20-70%, 30%-70%, 40%-70%, 50%-70%, 5%-65%, 10%-65%, 20-65%, 30%-65%, 40%-65%, 50%-65%, 5%-60%, 10%-60%, 20-60%, 30%-60%, 40%-60%, 50%-60%, 5%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% of all oligonucleotides in the composition that share the common base sequence of a plurality are oligonucleotide of the plurality. In some embodiments, a percentage is at least 10%. In some embodiments, a percentage is at least 20%. In some embodiments, a percentage is at least 30%. In some embodiments, a percentage is at least 40%. In some embodiments, a percentage is at least 50%. In some embodiments, it is at least 60%. In some embodiments, it is at least 70%. In some embodiments, it is at least 80%. In some embodiments, it is at least 90%. In some embodiments, it is at least 95%. In some embodiments, it is about 5-100%. In some embodiments, it is about 10-100%. In some embodiments, it is about 20-100%. In some embodiments, it is about 30-90%. In some embodiments, it is about 30-80%. In some embodiments, it is about 30-70%. In some embodiments, it is about 40-90%. In some embodiments, it is about 40-80%. In some embodiments, it is about 40-70%.

[0286] Levels of oligonucleotides of a plurality in chirally controlled oligonucleotide compositions are controlled. In contrast, in non-chirally controlled (or stereorandom, racemic) oligonucleotide compositions (or preparations), levels of oligonucleotides are random and not controlled. In some embodiments, an enrichment relative to a substantially racemic preparation is a level described herein.

[0287] In some embodiments, a level as a percentage (e.g., a co...

Claims

Attorney Docket No.: 2010581-1440 CLAIMS 1. A compound, wherein the compound is a compound of formula I’ or a salt thereof: , wherein: each of RP1and RP2is or (O)−RP, wherein RPis optionally substituted tert-butyl; SU is a sugar; BA is hydrogen, or an optionally substituted 3-20 membered ring having 0-10 heteroatoms independently selected from silicon, nitrogen, oxygen, phosphorus and sulfur; or BA is an optionally substituted or protected nucleobase; each of R1, R2, and R3is independently R’, or two or three of R1, R2, and R3are taken together with their intervening atoms to form ; Ring A is an optionallyring having, in addition to the intervening atoms, 0-10 heteroatoms independently selected from silicon, nitrogen, oxygen, phosphorus and sulfur; t is 0-5; each Rsis independently −F, −Cl, −Br, −I, −CN, −N3, −NO, −NO2, −Ls−Rs11, −Ls−ORs11, −Ls−SRs11, −Ls−N(Rs11)2, −O−Ls−ORs11, −O−Ls−SRs11, −O−Ls−N(Rs11)2, −C(Rs11)3or −Ls−Si(Rs11)3; each Rs11is independently R’; each Lsis independently L; each L is independently a covalent bond, or a bivalent, optionally substituted group selected from C1-10aliphatic and C1-10heteroaliphatic group having 1-5 heteroatoms independently selected from silicon, nitrogen, oxygen, phosphorus and sulfur, wherein one or more methylene units of L are optionally and independently replaced by −Cy−, −O−, −S−, −N(R’)−, −C(O)−, −C(S)−, −C(NR’)−, −C(O)N(R’)−, −N(R’)C(O)N(R’)−, −N(R’)C(O)O−, −S(O)−, −S(O)2−, −S(O)2N(R’)−, −SC(O)−, or −C(O)O−; –Cy– is an optionally substituted bivalent 3-20 membered ring having 0-10 heteroatoms independently selected from silicon, nitrogen, oxygen, phosphorus and sulfur; each R’ is independently −R, −C(O)R, −CO2R, or −S(O)2R, or two or more R’ are taken together with their intervening atom(s) to form an optionally substituted 3-20 membered ring having, in addition to Page 184 of 201 12495950v1Attorney Docket No.: 2010581-1440 the intervening atom(s), 0-10 heteroatoms independently selected from silicon, nitrogen, oxygen, phosphorus and sulfur; and each R is independently hydrogen, or an optionally substituted group selected from C1-10aliphatic, C1-10heteroaliphatic having 1-5 heteroatoms independently selected from silicon, nitrogen, oxygen, phosphorus and sulfur, C6-14 aryl, a 5-14 membered heteroaryl ring having 1-5 heteroatoms independently selected from silicon, nitrogen, oxygen, phosphorus and sulfur, and a 3-15 membered heterocyclic ring having 1-5 heteroatoms independently selected from silicon, nitrogen, oxygen, phosphorus and sulfur.

2. A compound, wherein the compound is a compound of formula I or a salt thereof: ,wherein: each of RP1and RP2is −O−CH2CH2CN or −O−CH2−O−C(O)−RP, wherein RPis optionally substituted tert-butyl; BA is hydrogen, or an optionally substituted 3-20 membered ring having 0-10 heteroatoms independently selected from silicon, nitrogen, oxygen, phosphorus and sulfur; or BA is an optionally substituted or protected nucleobase; R2sis −F, −Cl, −Br, −I, −CN, −N3, −NO, −NO2, −L2s−R2a, −L2s−OR2a, −L2s−SR2a, −L2s−N(R2a)2, −O−L2s−OR2a, −O−L2s−SR2a, or −O−L2s−N(R2a)2, or R2sis L2sconnecting C2 with C1, C2, C3, C4 or C5; each L2sis independently L; each R2ais independently R’; each L is independently a covalent bond, or a bivalent, optionally substituted group selected from C1-10aliphatic and C1-10heteroaliphatic group having 1-5 heteroatoms independently selected from silicon, nitrogen, oxygen, phosphorus and sulfur, wherein one or more methylene units of L are optionally and independently replaced by −Cy−, −O−, −S−, −N(R’)−, −C(O)−, −C(S)−, −C(NR’)−, −C(O)N(R’)−, −N(R’)C(O)N(R’)−, −N(R’)C(O)O−, −S(O)−, −S(O)2−, −S(O)2N(R’)−, −SC(O)−, or −C(O)O−; –Cy– is an optionally substituted bivalent 3-20 membered ring having 0-10 heteroatoms independently selected from silicon, nitrogen, oxygen, phosphorus and sulfur; Page 185 of 201 12495950v1Attorney Docket No.: 2010581-1440 each of R1, R2, and R3is independently R’, or two or three of R1, R2, and R3are taken together with their intervening atoms to form ; Ring A is an optionally substituted 3-20 membered ring having, in addition to the intervening atoms, 0-10 heteroatoms independently selected from silicon, nitrogen, oxygen, phosphorus and sulfur; t is 0-5; each Rsis independently −F, −Cl, −Br, −I, −CN, −N3, −NO, −NO2, −Ls−Rs11, −Ls−ORs11, −Ls−SRs11, −Ls−N(Rs11)2, −O−Ls−ORs11, −O−Ls−SRs11, −O−Ls−N(Rs11)2, −C(Rs11)3or −Ls−Si(Rs11)3; each Rs11is independently R’; each Lsis independently L; each R’ is independently −R, −C(O)R, −CO2R, or −S(O)2R, or two or more R’ are taken together with their intervening atom(s) to form an optionally substituted 3-20 membered ring having, in addition to the intervening atom(s), 0-10 heteroatoms independently selected from silicon, nitrogen, oxygen, phosphorus and sulfur; and each R is independently hydrogen, or an optionally substituted group selected from C1-10 aliphatic, C1-10 heteroaliphatic having 1-5 heteroatoms independently selected from silicon, nitrogen, oxygen, phosphorus and sulfur, C6-14aryl, a 5-14 membered heteroaryl ring having 1-5 heteroatoms independently selected from silicon, nitrogen, oxygen, phosphorus and sulfur, and a 3-15 membered heterocyclic ring having 1-5 heteroatoms independently selected from silicon, nitrogen, oxygen, phosphorus and sulfur.

3. The compound of any one of the preceding claims, wherein R1is −CH2CH2CN.

4. The compound of any one of the preceding claims, wherein R2is optionally substituted C1-6 aliphatic (e.g., isopropyl).

5. The compound of any one of the preceding claims, wherein R3is optionally substituted C1-6 aliphatic (e.g., isopropyl).

6. The compound of claim 1, wherein −P(OR1)N(R2)(R3) is −P(OCH2CH2CN)N[CH(CH3)2]2.

7. The compound of claim 1, wherein two or three of R1, R2, and R3are taken together with their intervening atoms to .

8. The compound of claim 7,an optionally substituted polycyclic ring.

9. The compound of claim 7, wherein Ring A is an optionally substituted bicyclic 7-12 membered ring.

10. The compound of claim 7, wherein Ring A comprises an optionally substituted 5- or 6- membered ring comprising the phosphorus, oxygen and nitrogen atoms of −P(OR1)N(R2)(R3). Page 186 of 201 12495950v1Attorney Docket No.: 2010581-1440 11. The compound of claim 10, wherein the ring comprising the phosphorus, oxygen and nitrogen atoms of −P(OR1)N(R2)(R3) does not have any other ring heteroatoms.

12. The compound of claim 7, wherein each monocyclic ring unit of Ring A is independently an optionally substituted 3-7 membered ring.

13. The compound of claim 7, wherein Ring A is or comprises optionally, wherein each Lais independently a covalent bond or a bivalent C1-5aliphaticone or more methylene units of each Laare optionally and independently −O−, −S−, or −NH.

14. The compound of claim 7, wherein Ring A is or comprises optionally .

15. The compound of claim 7, wherein Ring A is or comprises optionally .

16. The compound of claim 7, wherein Ring A is or comprises optionally .

17. The compound of any one of claims 7-16, wherein t is 1-5.

18. The compound of any one of claims 7-16, wherein an occurrence of Rsis bonded to a carbon atom bonded to the oxygen of −P(OR1)N(R2)(R3).

19. The compound of claim 1, wherein , wherein each of Rs1and Rs2is independently Rs.

20. The compound of claim 1, wherein −P(OR1)N(R2)(R3) .

21. The compound of any one of claims 7-20, wherein anof Lsis optionally substituted −CH2−.

22. The compound of any one of claims 7-20, wherein an occurrence of Lsis a covalent bond.

23. The compound of any one of claims 7-22, wherein an occurrence of Rsis −Ls−Si(Rs11)3.

24. The compound of claim 23, wherein each Rs11is not hydrogen. Page 187 of 201 12495950v1Attorney Docket No.: 2010581-1440 25. The compound of claim 23, wherein each Rs11is independently an optionally substituted group selected from C1-6aliphatic and phenyl.

26. The compound of claim 23, wherein −Si(Rs11)3is −Si(CH3)(Ph)2.

27. The compound of any one of claims 7-22, wherein Rsis −Ls−Rs11.

28. The compound of claim 27, wherein Rs11is −S(O)2R wherein R is optionally substituted C1-6 aliphatic.

29. The compound of claim 27, wherein Rs11is −S(O)2R wherein R is t-Bu.

30. The compound of claim 27, wherein Rs11is −S(O)2R wherein R is methyl.

31. The compound of claim 27, wherein Rs11is −S(O)2R.

32. The compound of any one of claims 7-20, wherein an occurrence of Rsis −C(Rs11)3.

33. The compound of any one of claims 7-20, wherein an occurrence of Rsis −CH(Rs11)2.

34. The compound of claim 33, wherein the two Rs11are taken together with the carbon atom to which they are attached to form an optionally substituted 3-20 membered ring having 0-5 heteroatoms independently selected from silicon, nitrogen, oxygen, phosphorus and sulfur.

35. The compound of claim 20, wherein Rs2is optionally substituted C1-6 aliphatic, or Rs2is optionally substituted phenyl. .P . or.Page 188 of 201 12495950v1Attorney Docket No.: 2010581-1440 40. The compound of claim 1, or.

41. The compound of claim 1, wherein −P(OR1)N(R2)(R3) ,.

42. A compound, wherein the compound is an oligonucleotide , wherein each of RP1and RP2is −O−CH2CH2CN or −O−CH2−O−Coptionally substituted tert-butyl.

43. A compound, wherein the compound is an oligonucleotide comprising a moiety of formula O-I or a salt thereof: ONN1 ,wherein: each of RP1and RP2is −O−CH2CH2CN or −O−CH2−O−C(O)−RP, wherein RPis optionally substituted tert-butyl; BA is hydrogen, or an optionally substituted 3-20 membered ring having 0-10 heteroatoms independently selected from silicon, nitrogen, oxygen, phosphorus and sulfur; or BA is an optionally substituted or protected nucleobase; R2sis −F, −Cl, −Br, −I, −CN, −N3, −NO, −NO2, −L2s−R2a, −L2s−OR2a, −L2s−SR2a, −L2s−N(R2a)2, −O−L2s−OR2a, −O−L2s−SR2a, or −O−L2s−N(R2a)2, or R2sis L2sconnecting C2 with C1, C2, C3, C4 or C5; each L2sis independently L; Page 189 of 201 12495950v1Attorney Docket No.: 2010581-1440 each R2ais independently R’; each L is independently a bivalent, optionally substituted group selected from C1-10aliphatic and C1-10heteroaliphatic group having 1-5 heteroatoms independently selected from silicon, nitrogen, oxygen, phosphorus and sulfur, wherein one or more methylene units of L are optionally and independently replaced by −Cy−, −O−, −S−, −N(R’)−, −C(O)−, −C(S)−, −C(NR’)−, −C(O)N(R’)−, −N(R’)C(O)N(R’)−, −N(R’)C(O)O−, −S(O)−, −S(O)2−, −S(O)2N(R’)−, −SC(O)−, or −C(O)O−; –Cy– is an optionally substituted bivalent 3-20 membered ring having 0-10 heteroatoms independently selected from silicon, nitrogen, oxygen, phosphorus and sulfur; each R’ is independently −R, −C(O)R, −CO2R, or −S(O)2R, or two or more R’ are taken together with their intervening atom(s) to form an optionally substituted 3-20 membered ring having, in addition to the intervening atom(s), 0-10 heteroatoms independently selected from silicon, nitrogen, oxygen, phosphorus and sulfur; and each R is independently hydrogen, or an optionally substituted group selected from C1-10 aliphatic, C1-10 heteroaliphatic having 1-5 heteroatoms independently selected from silicon, nitrogen, oxygen, phosphorus and sulfur, C6-14 aryl, a 5-14 membered heteroaryl ring having 1-5 heteroatoms independently selected from silicon, nitrogen, oxygen, phosphorus and sulfur, and a 3-15 membered heterocyclic ring having 1-5 heteroatoms independently selected from silicon, nitrogen, oxygen, phosphorus and sulfur.

44. A compound, wherein the compound is a compound of formula II’ or a salt thereof: ,wherein: each of RP1and RP2is −O−CH2CH2CN or −O−CH2−O−C(O)−RP, wherein RPis optionally substituted tert-butyl; SU is a sugar; and BA is hydrogen, or an optionally substituted 3-20 membered ring having 0-10 heteroatoms independently selected from silicon, nitrogen, oxygen, phosphorus and sulfur; or BA is an optionally substituted or protected nucleobase.

45. A compound, wherein the compound is a compound of formula II or a salt thereof: Page 190 of 201 12495950v1Attorney Docket No.: 2010581-1440 ,wherein: each of RP1and RP2is −O−CH2CH2CN or −O−CH2−O−C(O)−RP, wherein RPis optionally substituted tert-butyl; BA is hydrogen, or an optionally substituted 3-20 membered ring having 0-10 heteroatoms independently selected from silicon, nitrogen, oxygen, phosphorus and sulfur; or BA is an optionally substituted or protected nucleobase; R2sis −F, −Cl, −Br, −I, −CN, −N3, −NO, −NO2, −L2s−R2a, −L2s−OR2a, −L2s−SR2a, −L2s−N(R2a)2, −O−L2s−OR2a, −O−L2s−SR2a, or −O−L2s−N(R2a)2, or R2sis L2sconnecting C2 with C1, C2, C3, C4 or C5; each L2sis independently L; each R2ais independently R’; each L is independently a bivalent, optionally substituted group selected from C1-10 aliphatic and C1-10 heteroaliphatic group having 1-5 heteroatoms independently selected from silicon, nitrogen, oxygen, phosphorus and sulfur, wherein one or more methylene units of L are optionally and independently replaced by −Cy−, −O−, −S−, −N(R’)−, −C(O)−, −C(S)−, −C(NR’)−, −C(O)N(R’)−, −N(R’)C(O)N(R’)−, −N(R’)C(O)O−, −S(O)−, −S(O)2−, −S(O)2N(R’)−, −SC(O)−, or −C(O)O−; –Cy– is an optionally substituted bivalent 3-20 membered ring having 0-10 heteroatoms independently selected from silicon, nitrogen, oxygen, phosphorus and sulfur; each R’ is independently −R, −C(O)R, −CO2R, or −S(O)2R, or two or more R’ are taken together with their intervening atom(s) to form an optionally substituted 3-20 membered ring having, in addition to the intervening atom(s), 0-10 heteroatoms independently selected from silicon, nitrogen, oxygen, phosphorus and sulfur; and each R is independently hydrogen, or an optionally substituted group selected from C1-10aliphatic, C1-10heteroaliphatic having 1-5 heteroatoms independently selected from silicon, nitrogen, oxygen, phosphorus and sulfur, C6-14aryl, a 5-14 membered heteroaryl ring having 1-5 heteroatoms independently selected from silicon, nitrogen, oxygen, phosphorus and sulfur, and a 3-15 membered heterocyclic ring having 1-5 heteroatoms independently selected from silicon, nitrogen, oxygen, phosphorus and sulfur.

46. The compound of any one of the preceding claims, wherein RP1and RP2are −O−CH2CH2CN. Page 191 of 201 12495950v1Attorney Docket No.: 2010581-1440 47. The compound of any one of the preceding claims, wherein RP1and RP2are −O−CH2−O−C(O)−tBu.

48. A compound, wherein the compound is a compound of formula III or formula III’, or a salt thereof: , , wherein:BA is hydrogen, or an optionally substituted 3-20 membered ring having 0-10 heteroatoms independently selected from silicon, nitrogen, oxygen, phosphorus and sulfur; or BA is an optionally substituted or protected nucleobase; SU is a sugar; R2sis −F, −Cl, −Br, −I, −CN, −N3, −NO, −NO2, −L2s−R2a, −L2s−OR2a, −L2s−SR2a, −L2s−N(R2a)2, −O−L2s−OR2a, −O−L2s−SR2a, or −O−L2s−N(R2a)2, or R2sis L2sconnecting C2 with C1, C2, C3, C4 or C5; each L2sis independently L; each R2ais independently R’; each L is independently a bivalent, optionally substituted group selected from C1-10 aliphatic and C1-10 heteroaliphatic group having 1-5 heteroatoms independently selected from silicon, nitrogen, oxygen, phosphorus and sulfur, wherein one or more methylene units of L are optionally and independently replaced by −Cy−, −O−, −S−, −N(R’)−, −C(O)−, −C(S)−, −C(NR’)−, −C(O)N(R’)−, −N(R’)C(O)N(R’)−, −N(R’)C(O)O−, −S(O)−, −S(O)2−, −S(O)2N(R’)−, −SC(O)−, or −C(O)O−; –Cy– is an optionally substituted bivalent 3-20 membered ring having 0-10 heteroatoms independently selected from silicon, nitrogen, oxygen, phosphorus and sulfur; each R’ is independently −R, −C(O)R, −CO2R, or −S(O)2R, or two or more R’ are taken together with their intervening atom(s) to form an optionally substituted 3-20 membered ring having, in addition to the intervening atom(s), 0-10 heteroatoms independently selected from silicon, nitrogen, oxygen, phosphorus and sulfur; and each R is independently hydrogen, or an optionally substituted group selected from C1-10 aliphatic, C1-10 heteroaliphatic having 1-5 heteroatoms independently selected from silicon, nitrogen, Page 192 of 201 12495950v1Attorney Docket No.: 2010581-1440 oxygen, phosphorus and sulfur, C6-14aryl, a 5-14 membered heteroaryl ring having 1-5 heteroatoms independently selected from silicon, nitrogen, oxygen, phosphorus and sulfur, and a 3-15 membered heterocyclic ring having 1-5 heteroatoms independently selected from silicon, nitrogen, oxygen, phosphorus and sulfur.

49. The compound of any one of the preceding claims, wherein BA is an optionally substituted 3- 20 membered ring having 0-10 heteroatoms independently selected from silicon, nitrogen, oxygen, phosphorus and sulfur.

50. The compound of any one of the preceding claims, wherein BA is bonded to C1 at a nitrogen atom.

51. The compound of any one of claims 1-50, wherein BA is an optionally substituted group, or 52.nucleobase.

53. The compound of claim 52, wherein the nucleobase is selected from A, T, C, G, U and 5mU.

54. The compound of any one of the preceding claims, wherein R2sis −H.

55. The compound of any one of claims 1-53, wherein R2sis −F.

56. The compound of any one of claims 1-53, wherein R2sis −OR2a.

57. The compound of claim 56, wherein R2ais methyl.

58. The compound of any one of claims 1-53, wherein L2sis not a covalent bond.

59. The compound of any one of claims 1-53, wherein L2sis optionally substituted C1-10 alkylene.

60. The compound of any one of claims 1-53, wherein R2sis −L2s−R2a.

61. The compound of claim 60, wherein L2sis −O−L2s’−R2a, wherein L2s’is optionally substituted −(CH2)1-10−.

62. The compound of any one of claims 1-53, wherein R2sis −O−L2s−OR2a.

63. The compound of claim 62, wherein R2ais −OMe.

64. The compound of claim 62, wherein R2sis −OCH2CH2OMe.

65. The compound of any one of claims 1-53, wherein R2sis L2sconnecting C2 with C1, C2, C3, C4 or C5. Page 193 of 201 12495950v1Attorney Docket No.: 2010581-1440 66. The compound of any one of claims 1-53 and 65, wherein L is (C2)−O−(unsubstituted methylene)−.

67. The compound of any one of claims 1-53 and 65, wherein L is (C2)−O−(substituted methylene)− 68. The compound of claim 67, wherein the carbon atom of the methylene group is R.

69. The compound of claim 67, wherein the carbon atom of the methylene group is S.

70. A compound, wherein the compound is a compound of formula IV or a salt thereof: ,wherein: each of RP1and RP2is −O−CH2CH2CN or −O−CH2−O−C(O)−RP, wherein RPis optionally substituted tert-butyl.

71. The compound of claim 70, wherein RP1and RP2are −O−CH2CH2CN.

72. The compound of claim 70, wherein RP1and RP2are −O−CH2−O−C(O)−tBu.

73. The compound of any one of the preceding claims, wherein the purity of the compound is about or more than 50%, 60%, 70%, 75%, 80%, 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99%.

74. A method for preparing an oligonucleotide, comprising into−P(O)(OH)2(e.g., a salt form thereof).

75. A method for preparing an oligonucleotide, comprising coupling a compound of any one of claims 1-41, 45-47, and 49-69, wherein the compound is a compound of formula I or formula I’, or a salt thereof, to an oligonucleotide.

76. A method for preparing an oligonucleotide, comprising reacting a compound of any one of claims 1-41, 45-47, and 49-69, wherein the compound is a compound of formula I or formula I’, or a salt thereof, with a compound comprising a −OH group.

77. The method of claim 76, wherein the −OH group is 5’-OH of an oligonucleotide.

78. The method of any one of claims 75-77, wherein the oligonucleotide preparation comprises utilizing a solid support. Page 194 of 201 12495950v1Attorney Docket No.: 2010581-1440 79. The method of any one of claims 75-78, comprising preparing a compound of any one of claims 42, 46-47, and 49-69, wherein the compound is a compound of formula O-I or a salt thereof.

80. The method of any one of claims 75-78, comprising into −P(O)(OH)2 (e.g., a salt form thereof).

81. The method of claim 80, wherein RP1and RP2are −OCH2CH2CN, and the conversion is performed in the presence of a base.

82. The method of claim 80, wherein RP1and RP2are −OCH2OC(O)tBu.

83. The method of any one of claims 75-82, wherein the conversion occurs during cleavage and deprotection that removes base protection groups and / or chiral auxiliaries and / or cleaves the oligonucleotide from a solid support.

84. The method of any one of claims 75-83, wherein the oligonucleotide prepared is a compound of any one of claims 42, 46-47, and 49-69, wherein the compound is a compound of formula O-I or a salt thereof.

85. A method for preparing a compound of any one of claims 1-41, 45-47, and 49-69, wherein the compound is a compound of formula I or formula I’, or a salt thereof, comprising reacting a compound of any one of claims 45-47 and 49-69, wherein the compound is a compound of formula II or formula II’, or a salt thereof, with a compound of formula V or a salt thereof: , wherein:LG is a leaving group; each of R1, R2, and R3is independently R’, or two or three of R1, R2, and R3are taken together with their intervening atoms to form ; Ring A is an optionally substituted 3-20 membered ring having, in addition to the intervening atoms, 0-10 heteroatoms independently selected from silicon, nitrogen, oxygen, phosphorus and sulfur; t is 0-5; each Rsis independently −F, −Cl, −Br, −I, −CN, −N3, −NO, −NO2, −Ls−Rs11, −Ls−ORs11, −Ls−SRs11, −Ls−N(Rs11)2, −O−Ls−ORs11, −O−Ls−SRs11, −O−Ls−N(Rs11)2, −C(Rs11)3or −Ls−Si(Rs11)3; Page 195 of 201 12495950v1Attorney Docket No.: 2010581-1440 each Rs11is independently R’; each Lsis independently L; each L is independently a bivalent, optionally substituted group selected from C1-10aliphatic and C1-10heteroaliphatic group having 1-5 heteroatoms independently selected from silicon, nitrogen, oxygen, phosphorus and sulfur, wherein one or more methylene units of L are optionally and independently replaced by −Cy−, −O−, −S−, −N(R’)−, −C(O)−, −C(S)−, −C(NR’)−, −C(O)N(R’)−, −N(R’)C(O)N(R’)−, −N(R’)C(O)O−, −S(O)−, −S(O)2−, −S(O)2N(R’)−, −SC(O)−, or −C(O)O−; −Cy− is an optionally substituted bivalent 3-20 membered ring having 0-10 heteroatoms independently selected from silicon, nitrogen, oxygen, phosphorus and sulfur; each R’ is independently −R, −C(O)R, −CO2R, or −S(O)2R, or two or more R’ are taken together with their intervening atom(s) to form an optionally substituted 3-20 membered ring having, in addition to the intervening atom(s), 0-10 heteroatoms independently selected from silicon, nitrogen, oxygen, phosphorus and sulfur; and each R is independently hydrogen, or an optionally substituted group selected from C1-10 aliphatic, C1-10 heteroaliphatic having 1-5 heteroatoms independently selected from silicon, nitrogen, oxygen, phosphorus and sulfur, C6-14 aryl, a 5-14 membered heteroaryl ring having 1-5 heteroatoms independently selected from silicon, nitrogen, oxygen, phosphorus and sulfur, and a 3-15 membered heterocyclic ring having 1-5 heteroatoms independently selected from silicon, nitrogen, oxygen, phosphorus and sulfur.

86. The method of claim 85, wherein LG is −Cl.

87. The method of any one of claims 85-86, wherein the reaction is performed in the presence of a base.

88. The method of any one of claims 85-87, wherein R1, R2and R3of formula V are as described in any one of claims 3-41.

89. The method of any one of claims 75-84, comprising a method of any one of claims 85-88.

90. A method for preparing a compound of any one of claims 45-47 and 49-69, wherein the compound is a compound of formula II or formula II’, or a salt thereof, comprising reacting a compound of any one of claims 48-69, wherein the compound is a compound of formula III or formula III’, or a salt thereof, with a compound of any one of claims 70-73.

91. The method of claim 90, wherein the reaction is in the presence of a base.

92. The method of claim 91, wherein the base is DIEA.

93. The method of any one of claims 90-92, wherein the reaction is in the presence of copper salt.

94. The method of any one of claims 90-92, wherein the reaction is in the presence of CuI.

95. The method of any one of claims 75-89, comprising a method of any one of claims 90-94. Page 196 of 201 12495950v1Attorney Docket No.: 2010581-1440 96. A method for preparing a compound of any one of claims 70-73, comprising oxidizing a compound of formula VI or a salt thereof: RP1P ,wherein: each of RP1and RP2is −O−CH2CH2CN or −O−CH2−O−C(O)−RP, wherein RPis optionally substituted tert-butyl.

97. The method of claim 96, wherein the oxidant is mCPBA.

98. The method of claim 96 or 97, wherein RP1and RP2are −O−CH2CH2CN.

99. The method of any one of claims 75-95, comprising a method of any one of claims 96-98.

100. A method for preparing a compound of formula VI or a salt thereof: RP1P ,comprising reacting ≡−MgBr with a compound of formula VII or a salt thereof: ,wherein: LG is a leaving group; and each of RP1and RP2is −O−CH2CH2CN or −O−CH2−O−C(O)−RP, wherein RPis optionally substituted tert-butyl.

101. The method of claim 100, wherein LG is −Cl.

102. The method of any one of claims 100-101, wherein each of RP1and RP2is −O−CH2CH2CN.

103. The method of any one of claims 75-99, comprising a method of any one of claims 100-102.

104. A method for preparing a compound of formula VII or a salt thereof: ,wherein LG is −Cl, comprising reacting HO−CH2CH2−CN with PCl3 in the presence of a base. Page 197 of 201 12495950v1Attorney Docket No.: 2010581-1440 105. The method of claim 104, wherein the base is TEA.

106. The method of any one of claims 75-103, comprising a method of any one of claims 104-105.

107. A method for preparing a compound of any one of claims 70-73, wherein each of RP1and RP2is −O−CH2−O−C(O)−RP, wherein RPis optionally substituted tert-butyl, comprising reacting a compound of formula IX or a salt thereof: ,with a compound having the structure of formula X or a salt thereof: LG−CH2−O−C(O)−RP, X wherein: RPis optionally substituted tert-butyl; LG is a leaving group; each of RP3and RP4is independently −O−RSP, wherein RSPis an optionally substituted optionally substituted C1-6 aliphatic.

108. The method of claim 107, wherein each of RP3and RP4is −OMe.

109. The method of any one of claims 107-108, wherein LG is −I.

110. The method of any one of claims 75-95, comprising a method of any one of claims 107-109.

111. A method for preparing a compound of formula IX or a salt thereof: ,comprising reacting ≡−MgBr with a compound of formula XI or a salt thereof: ,wherein: LG is a leaving group each of RP3and RP4is independently −O−RSP, wherein each RSPis independently optionally substituted C1-6 aliphatic. Page 198 of 201 12495950v1Attorney Docket No.: 2010581-1440 112. The method of claim 111, wherein each of RP3and RP4is −OMe.

113. The method of any one of claims 111-112, wherein LG is −Cl.

114. The method of any one of claims 75-95 and 107-110, comprising a method of any one of claims 111-113.

115. A method for preparing a compound of any one of claims 48-69, wherein the compound is a compound of formula III or formula III’, or a salt thereof, comprising reacting a compound of formula XII or formula XII’ or a salt thereof: ,, XII’ wherein LG is a leaving group, with an azide.

116. The method of claim 115, wherein LG is −I.

117. The method of any one of claims 115-116, wherein the azide is sodium azide.

118. The method of any one of claims 75-114, comprising a method of any one of claims 115-117.

119. A method for preparing a compound of formula XII or XII’ or a salt thereof: , ,wherein LG is −I, comprising reacting a compound of formula XIII or formula XIII’ or a salt thereof: ,Page 199 of 201 12495950v1Attorney Docket No.: 2010581-1440 , XIII’ with I2.

120. The method of any one of claims 115-119, wherein the reaction is performed in the presence of a phosphine.

121. The method of any one of claims 115-119, wherein the reaction is performed in the presence of a PPh3.

122. The method of any one of claims 119-121, wherein the reaction is performed in the presence of a base.

123. The method of any one of claims 119-121, wherein the reaction is performed in the presence of a heteroaryl base, wherein the heteroaryl ring comprises −N= or −N(R)−.

124. The method of any one of claims 119-121, wherein the reaction is performed in the presence of a heteroaryl base, wherein the heteroaryl ring comprises −N= or −NH−.

125. The method of any one of claims 119-121, wherein the reaction is performed in the presence of imidazole.

126. The method of any one of claims 75-118, comprising a method of any one of claims 119-125.

127. A compound or method of any one of Embodiments 1-205. Page 200 of 201 12495950v1