Process for the preparation of carboxycyclic anhydrides

Abstract

The present application relates to the preparation method of carboxyl endocyclic anhydride and the preparation product. The preparation method of compound of formula (II) comprises the following steps: reacting compound of formula (I) with a cyclization reagent to generate compound of formula (II) and acid, and using an epoxide compound as an acid scavenger. The present application is a new synthesis method of carboxyl endocyclic anhydride, which has the advantages of low cost, low requirement for reagents, site and equipment, mild conditions, wide substrate application range, high functional group tolerance, recyclable solvent and other high value-added by-products in the synthesis route, less waste liquid discharge, easy scale-up, high industrial and academic value, and the like, and can greatly promote the rapid large-scale production and application of polyamino acid, polyhydroxy acid (polyester), polymercaptan acid (polythioester) and the like.

Description

Technical Field

[0001] This invention relates to methods for preparing compounds, and more specifically to methods for preparing anhydrides within a carboxyl ring. Background Technology

[0002] Polyamino acids (also known as polypeptides, synthetic polypeptides, etc.) are important bio-based polymers that can be used as drugs or drug formulations. They have significant applications in many high-value-added fields such as advanced biomaterials, cosmetics, and asymmetric catalysis, and have huge market potential. For example, polylysine can be used in cell culture, antibacterial materials, and gene transfection materials. Polyglutamic acid and aspartic acid can be used in drug formulations and carriers, as well as medical materials. Several nanomedicines based on polyglutamic acid and polyaspartic acid have entered clinical trials in the United States, Japan, and China. Polyvaline and polyleucine are used industrially as catalysts for the asymmetric Julia-Colonna epoxidation reaction. Polysarcosine can be used in drug formulations and carriers. Glatiramer acetate is a polyamino acid, L-alanine-L-glutamic acid-L-lysine-L-tyrosine polypeptide polymer acetate (prepared by polymerizing four NCAs), with sales reaching $4 billion in 2012, consistently ranking among the top 20 best-selling drugs globally.

[0003] Polyamino acids are mainly prepared through ring-opening polymerization of amino acid N-carboxyl ring anhydrides (hereinafter referred to as NCA); while NCA is usually prepared by cyclization synthesis of the corresponding amino acid (or its derivative). Figure 1 Since Leuch discovered NCA in 1906, it has been over 100 years since its discovery. The cyclizing reagents used have varied, including thionyl chloride, phosgene, triphosgene, PCl3, and PCl5. Currently, triphosgene is the most common (Kricheldorf, HR, Polypeptides and 100 years of chemistry of alpha-amino acid N-carboxyanhydrides. Angew. Chem., Int. Ed. 2006, 45(35), 5752-5784). However, regardless of the cyclizing reagent used, strict anhydrous conditions are required for the synthesis of NCA in both industrial and laboratory settings. This includes the use of expensive anhydrous solvents such as anhydrous tetrahydrofuran (THF), protection with dry nitrogen during the reaction, and heating to 50-60 degrees Celsius in a sealed reagent bottle. The reaction produces a large amount of waste liquid containing high concentrations of hydrochloric acid, which corrodes equipment and increases the difficulty of waste liquid treatment. Even more serious is that the post-processing of NCA is extremely complex and difficult to operate, and the slightest carelessness can lead to the risk of losing everything.

[0004] There is a need in the art for a method to prepare carboxyl ring anhydrides, especially amino acid N-carboxyl ring anhydrides, that overcomes the shortcomings of existing methods. Summary of the Invention

[0005] In their long-term work, the inventors discovered that the traditional synthesis of amino acid N-carboxycyclic anhydrides (NCAs) requires repeated recrystallization in a glove box using anhydrous solvents; and for NCAs that cannot be crystallized, separation using a silica gel column in a glove box using anhydrous solvents is required (Kramer, JR; Deming, TJ, General Method for Purification of alpha-Amino acid-N-carboxyanhydrides Using Flash Chromatography. Biomacromolecules 2010, 11(12), 3668-3672). Because NCA polymerization requires high monomer purity, the above separation steps often need to be repeated multiple times for some NCAs. Furthermore, traditional synthesis methods often require protection of side functional groups such as hydroxyl and thiol groups, necessitating a deprotection step after polymerization to release these functional groups, increasing the number of synthesis steps and costs. Due to these limitations, the industrial production of NCAs is expensive; this further leads to the high cost of downstream polyamino acids, limiting their large-scale production and numerous applications. If NCAs (non-carboxylic acids) could be purified and separated in high yields without nitrogen protection using ordinary solvents outside a glove box, the difficulty and cost of synthesizing polyamino acids would be greatly reduced, thereby promoting their larger-scale and wider application. To address these shortcomings of existing technologies, the inventors provide a method for preparing carboxyl intracyclic anhydrides, particularly N-carboxyl intracyclic anhydrides of amino acids. This method uses an epoxy compound as a hydrochloric acid removal reagent during NCA synthesis. More importantly, this new method makes some monomers that were previously extremely difficult or impossible to synthesize readily available and inexpensive, further facilitating the simple and controllable synthesis of novel polyamino acids and their protein conjugates, demonstrating broad application prospects in the fields of protein drugs and biomaterials.

[0006] Furthermore, the method of the present invention can be used not only to cyclize amino acids to generate amino acid N-carboxyl intracyclic anhydrides (NCA), but also to cyclize amino acid derivatives to generate carboxyl intracyclic anhydrides, as shown in the following formula.

[0007]

[0008] Where X = NH, O or S, the corresponding products are NCA, OCA and SCA.

[0009] R' can be H, Boc, or Cbz.

[0010] In one aspect, the present invention provides a preparation method comprising reacting an amino acid, hydroxy acid, mercapto acid, or a derivative thereof with a protected group (such as amino, mercapto, hydroxy, or carboxyl, e.g., α-amino or ε-amino) with a cyclizing agent to generate an N-, O-, or S-carboxycyclic intracyclic anhydride and an acid, and using an epoxy compound as an acid remover, provided that the amino acid, hydroxy acid, or mercapto acid, or a derivative thereof, is capable of forming the corresponding carboxycyclic intracyclic anhydride.

[0011] In one aspect, the present invention provides a method for preparing a compound of formula (II), the method comprising reacting a compound of formula (I) with a cyclizing agent to generate a compound of formula (II) and an acid, and using an epoxy compound as an acid scavenger.

[0012]

[0013] in:

[0014] R1 is -R4-R5-R6, where R4 is H and C is arbitrarily substituted. 1-6 Straight-chain or branched alkyl groups (e.g., C4 groups substituted with hydroxyl or thiol groups) 1-6 Straight-chain or branched alkyl groups), optionally substituted C 1-6 Alkoxy, carboxyl, amino, carbonylamino (-CO-NH2), guanidinyl, optionally substituted phenyl (e.g., substituted with hydroxyl or alkyl), optionally substituted benzyl (e.g., substituted with hydroxyl or alkyl), indolyl, imidazolyl, guanidinyl or carbonylalkoxy;

[0015] R5 is absent, oxy (-O-), selenyl (-Se-), thio (-S-), carbonyl (-CO-), ester (carbonyloxy, -COO-), ester imino (-COO-NH-) (or oxycarbonyl imino), imino, amino, carbonylamino (-CO-NH2), carbonylimino (-CO-NH-), benzyl ester (BnCOO-), optionally substituted phenyl (e.g., substituted with hydroxyl), optionally substituted benzyl (e.g., substituted with hydroxyl), indole, imidazolyl, guanidinyl, carbonylalkoxy, or carboxyl;

[0016] R6 represents non-existent, H, or C with optional substitution. 1-6 Straight-chain or branched alkyl groups (e.g., C4 groups substituted with hydroxyl or thiol groups) 1-6 Straight-chain or branched alkyl groups), optionally substituted C 1-6Alkoxy, hydroxy, carboxyl, thioalkyl, amino, carbonylamino, guanidinyl, optionally substituted phenyl (e.g., hydroxyl-substituted), amino protecting group, hydroxyl protecting group or carboxyl protecting group, optionally substituted benzyl (e.g., hydroxyl-substituted), optionally substituted phenylalkyl, optionally substituted benzylalkyl, indolyl, imidazolyl, guanidinyl, carbonylalkoxy, benzyl ester, benzyliminocarbonylalkyl or -[O(CH2)] m1 ] m2 -R7,

[0017] Where R7 is H, and C is optionally substituted. 1-6 Straight-chain or branched alkyl groups (e.g., C4 groups substituted with hydroxyl or thiol groups) 1-6 Straight-chain or branched alkyl groups), optionally substituted C 1-6 Alkoxy, carbonyl alkyl, or imino alkyl; m1 and m2 are each independent integers from 1 to 6;

[0018] R2 is N, O, or S, or R1 and R2 together with the carbon atoms attached to them form a 3-7 membered ring, which is optionally substituted with a halogen, mercapto, or hydroxyl group, such as an indolyl, imidazolyl, pyrrolidinyl, mercaptopyrrolidinyl, or hydroxypyrrolidinyl; when R2 is O or S, the H attached to R2 is optionally substituted with a hydroxyl or mercapto protecting group.

[0019] R3 indicates the absence of H, halogen, or optional substitution of C. 1-6 Straight-chain or branched alkyl groups (e.g., C4 groups substituted with hydroxyl or thiol groups) 1-6 Straight-chain or branched alkyl groups), optionally substituted C 2-6 Straight-chain or branched alkenyl or ynyl, C 1-6 Alkoxy, cycloalkyl, aromatic or heterocyclic groups, wherein one or more hydrogen atoms are optionally substituted with halogen, oxygen or nitrogen, or oc or Cbz.

[0020] In one embodiment, the epoxy compound used as an acid scavenger has the structure of formula (III):

[0021]

[0022] Wherein: R and R' are each independently H, halogen, or optionally substituted C. 1-6 Straight-chain or branched alkyl groups, optionally substituted C 2-6 Straight-chain or branched alkenyl or alkynyl, alkoxy or cycloalkyl; wherein one or more hydrogen atoms are optionally halogenated, C 1-6 The alkyl, oxygen, or nitrogen groups are either straight-chain or branched; or one of R and R' forms a five- to seven-membered ring together with the two carbon atoms in the epoxide group.

[0023] In one embodiment, the epoxy compound is selected from one or more of the following: ethylene oxide, propylene oxide, 1,2-epoxybutane, dimethyl ethylene oxide, cyclohexane oxide, and their halogen-substituted derivatives, such as epichlorohydrin.

[0024] In one embodiment, the cyclizing agent is selected from one or more of the following: phosgene, diphosgene, triphosgene, phosphorus trichloride, and phosphorus pentachloride.

[0025] In one implementation, R1 is H, with optional substituted C. 1-6 Straight-chain or branched alkyl groups, optionally substituted aromatic groups, or BnNHCOCH2CH2SeCH2CH2; preferably, the optionally substituted C 1-6 Straight-chain or branched alkyl groups are straight-chain or branched C14 groups. 1-6 Alkyl, C 1-6 Alkyl hydroxyl, C 1-6 Alkyl mercapto, C 1-6 alkyl carboxyl group, C 1-6 Alkylamino, C 1-6 Alkyl carbonyl amino, C 1-6 alkyl aromatic group, C 1-6 alkyl heterocyclic group, C 1-6 Alkylguanidine, C 1-6 Alkyl thio C 1-6 Alkyl, C 1-6 Alkyloxy C 1-6 Alkyl group. Preferably, the aromatic or heterocyclic group is optionally substituted, for example, by a hydroxyl or mercapto group. Preferably, the amino, hydroxyl, or carboxyl group is protected.

[0026] In one embodiment, R1 is H, CH3, CH(CH3)2, CH2CH(CH3)2, CH(CH3)CH2CH3, CH2-C6H5, methylindolyl (e.g., 3-methylindolyl), CH2-C6H4-OH, CH2-COOH, CH2-CONH2, (CH2)2-COOH, (CH2)4-NH2, (CH2)2-CONH2, (CH2)2-S-CH3, CH2-OH, CH(CH3)-OH, CH2-SH, methylimidazolyl, BnCO2NH(CH2)4, BnCO2(CH2)2, CH2-CH2-CH2-CN3H4, BnNHCOCH2CH2SeCH2CH2, CH3O(CH2CH2O)3COCH2CH2, SHC(CH3)2, C6H5, or C(CH3)3OCH3 or trifluoroacetyliminobutyl. These groups may also be optionally substituted, for example, by halogen, alkyl, hydroxyl, mercapto, carboxyl, or aryl groups. In one embodiment, the amino, hydroxyl, or carboxyl group on R1 may be protected. The selection of protecting groups and methods of protection for these groups are known to those skilled in the art.

[0027] In one embodiment, R2 is N or O. In one embodiment, R3 is absent, H, or methyl. In one embodiment, R1 and R2, together with the carbon atoms attached to them, form a pyrrolidinyl or hydroxypyrrolidinyl group, optionally with the imino group protected. Those skilled in the art will understand that groups such as amino, imino, carboxyl, hydroxyl, or mercapto groups can be protected. The selection of protecting groups and methods of protection for these groups are known to those skilled in the art. For example, N-tert-butoxycarbonylglycine, N-tert-butoxycarbonylsarcosine, or... L -N-tert-Butoxycarbonylproline.

[0028] In one embodiment, the compound of formula (I) is an amino acid or a derivative thereof, such as an amino acid protected by Boc or Cbz, selected from the group consisting of: glycine, alanine, valine, leucine, isoleucine, methionine, proline, tryptophan, serine, tyrosine, cysteine, phenylalanine, asparagine, glutamine, threonine, aspartic acid, glutamic acid, lysine, arginine, histidine, ε-nitrobenzyloxycarbonyllysine, benzyl glutamate, sarcosine, hydroxyproline, (S)-2-amino-4-((3-(benzylamino)-3-oxypropyl)selenoyl)butyric acid, γ-(2-(2- (2-(2-methoxyethoxy)ethoxy)glutamic acid, penicillamine, L-phenyllactic acid, L-mandelic acid, or oxy-tert-butyl-serine or ε-nitro-trifluoroacetyl-L-lysine. The compound of formula (II) can be the corresponding intracyclic carboxyl anhydride, such as N- or O-carboxyl intracyclic anhydride. In one embodiment, the amino or hydroxyl groups on the side chains of certain amino acids, such as lysine or glutamic acid, need to be protected, for example, ε-nitro-trifluoroacetyl-L-lysine, ε-nitro-benzyloxycarbonyl-lysine, benzyl glutamate, or γ-(2-(2-(2-(2-methoxyethoxy)ethoxy)glutamic acid).

[0029] In one implementation, the method is carried out under atmospheric conditions.

[0030] In another embodiment, the method is carried out at room temperature or under conditions without heating.

[0031] In one embodiment, the preparation method further includes crystallization and / or column chromatography steps.

[0032] In another aspect, the present invention provides a method for forming a copolymer, which may include the steps of forming a compound of formula (II) and forming a copolymer. Preferably, R1 is a group containing a carboxyl group, such as COOHCH2CH2. For example, the compound of formula (I) is glutamic acid, and the compound of formula (II) is... L -Glutamic acid nitrogen-carboxylic acid anhydride. Preferably, the copolymer is a poly(glutamic acid nitrogen-carboxylic acid anhydride). L -Glutamic acid.

[0033] The copolymer can be represented by the following formula:

[0034] n is an integer greater than or equal to 2, such as 10, 20, 30, 40, 50, 60, 70, 80, or 90. For example, the copolymer is... Where n is 20.

[0035] In another aspect, the present invention provides a method for preparing a compound of formula (V), the method comprising reacting a compound of formula (IV) with a cyclizing agent to generate a compound of formula (V) and an acid, and using an epoxide compound as an acid scavenger.

[0036]

[0037] Where R represents N, O, or S; R1 represents non-existent, H, halogen, or optionally substituted C. 1-6 Straight-chain or branched alkyl groups, optionally substituted C 2-6 Straight-chain or branched alkenyl or ynyl, C 1-6 Alkoxy, cycloalkyl, aromatic, or heterocyclic groups, wherein one or more hydrogen atoms are optionally substituted with halogen, oxygen, or nitrogen, or Boc or Cbz; R2 is H, optionally substituted C 1-6 Straight-chain or branched alkyl groups (e.g., C4 groups substituted with hydroxyl or thiol groups) 1-6 (Straight-chain or branched alkyl) or optionally substituted C 1-6 Alkoxy or carbonyloxyalkyl, such as methyl ester, ethyl ester, propyl ester; when R is O or S, the H connected to R is optionally replaced by a hydroxyl or mercapto protecting group.

[0038] In one embodiment, the epoxy compound used as an acid scavenger has the structure of formula (III):

[0039]

[0040] Wherein: R and R' are each independently H, halogen, or optionally substituted C. 1-6 Straight-chain or branched alkyl groups, optionally substituted C 2-6 Straight-chain or branched alkenyl or alkynyl, alkoxy or cycloalkyl; wherein one or more hydrogen atoms are optionally halogenated, C 1-6 The alkyl, oxygen, or nitrogen groups are either straight-chain or branched; or one of R and R' forms a five- to seven-membered ring together with the two carbon atoms in the epoxide group.

[0041] In one embodiment, the epoxy compound is selected from one or more of the following: ethylene oxide, propylene oxide, 1,2-epoxybutane, dimethyl ethylene oxide, cyclohexane oxide, and their halogen-substituted derivatives, such as epichlorohydrin.

[0042] In one embodiment, the cyclizing agent is selected from one or more of the following: phosgene, diphosgene, triphosgene, phosphorus trichloride, and phosphorus pentachloride.

[0043] In one embodiment, the method is carried out under atmospheric conditions, and / or the method is carried out at room temperature or under unheated conditions.

[0044] In one embodiment, the preparation method further includes crystallization and / or column chromatography steps.

[0045] In one implementation, the compound of formula (IV) is

[0046] β-alanine, 3-amino-3-(4-methylphenyl)propionic acid, or 3-amino-3-(4-chlorophenyl)propionic acid, and the compound of formula (V) is

[0047] β-alanine nitrogen-carboxylic acid anhydride, 3-amino-3-(4-chlorophenyl)propionic acid nitrogen-carboxylic acid anhydride or 3-amino-3-(4-methylphenyl)propionic acid nitrogen-carboxylic acid anhydride.

[0048] In another aspect, the present invention provides a method for forming a copolymer, which may include the steps of forming a compound of formula (V) and forming a copolymer.

[0049] In one implementation, the copolymer is n is an integer greater than or equal to 2, such as 10, 20, 30, 40, 50, 60, 70, 80, or 90. For example, the copolymer is a polyamino acid. For example, the copolymer is... Where n is 50.

[0050] The polymerization steps described above may include adding N,N-dimethylformyl and benzylamine initiators to the reactants, for example, mixing N,N-dimethylformyl and benzylamine initiators with compounds of formula (II) or (V).

[0051] The compounds of formulas (I) and (IV) above may include all the starting amino acids or amino acid derivatives in the examples. The compounds of formulas (II) and (V) above may include all the reaction products in the examples, namely N- or O-carboxylic anhydrides, especially amino acid-N-carboxylic anhydrides.

[0052] In another aspect, the present invention provides compounds prepared according to the preparation method of the present invention.

[0053] In one embodiment, the compound of formula (II) has one of the following structures:

[0054]

[0055] In another aspect, the present invention provides the use of the amino acid N-carboxyl ring anhydrides prepared herein in the preparation of polyamino acids. In the carboxyl ring anhydrides prepared herein, such as amino acid N-carboxyl ring anhydrides, epoxides can be used as scavenging agents.

[0056] This invention also provides a method for preparing carboxyl-cyclic anhydrides of amino acids or their derivatives, the method comprising reacting an amino acid or its derivative with a cyclizing agent to generate a carboxyl-cyclic anhydride and an acid of the amino acid or its derivative, and using an epoxide compound as an acid-removing agent. In one embodiment, the amino acid or its derivative is selected from the group consisting of: glycine, alanine, valine, leucine, isoleucine, methionine, proline, tryptophan, serine, tyrosine, cysteine, phenylalanine, asparagine, glutamine, threonine, aspartic acid, glutamic acid, lysine, arginine, histidine, ε-nitrobenzyloxycarbonyl lysine, benzyl glutamate, sarcosine, hydroxyproline, (S)-2-amino-4-((3-(benzylamino)-3-oxypropyl)selenoyl)butyric acid, penicillamine, L-phenyllactic acid, L-mandelic acid, or oxy-tert-butyl-serine, L-aspartic acid-1-methyl ester or The derivatives can also be the corresponding Boc or Cbz-protected amino acids of the aforementioned 20 natural amino acids. The method of this invention is applicable to amino acids, hydroxy acids, or mercapto acids, and certain groups thereof, such as amino, hydroxy, or carboxyl groups, for example, α-amino or ε-amino-protected derivatives, provided they can form the corresponding intracyclic carboxyl anhydrides, such as N-, S-, or O-carboxyl intracyclic anhydrides. Those skilled in the art can readily determine whether these require protection and the groups and methods for protecting these groups.

[0057] The present invention may also include a method or step of forming polyamino acids from the anhydrides within the N-carboxyl ring of the above-mentioned amino acids.

[0058] In this invention, the epoxide compound may be added prior to the addition of the cyclizing agent. The method of this invention may also include a step of removing a protecting group, such as Boc or Cbz.

[0059] The present invention also provides a method for synthesizing a polymer, comprising preparing a compound of formula (II) and / or preparing a compound of formula (V) using the methods described above, and polymerizing one or more compounds of the same or different formula (II) and / or one or more compounds of the same or different formula (V) to form a polymer. Preferably, the polymer is a polyamino acid. For example, the degree of polymerization is 4, 5, 6, 7, 8, 9, 10, 20, 30, 40, 50, 60, 70, 80 or 90.

[0060] This invention also provides a method for preparing an L-alanine-L-glutamic acid-L-lysine-L-tyrosine polypeptide polymer, comprising reacting L-alanine, an L-glutamic acid derivative, an L-lysine derivative, or L-tyrosine with a cyclizing agent to generate the corresponding amino acid N-carboxyl ring anhydride and acid, wherein an epoxide compound is used as an acid-removing agent in the preparation of one or more corresponding amino acid N-carboxyl ring anhydrides; then, the corresponding amino acid N-carboxyl ring anhydride is polymerized to form an L-alanine-L-glutamic acid-L-lysine-L-tyrosine polypeptide polymer. Preferably, the cyclizing agent is selected from one or more of the following: phosgene, diphosgene, triphosgene, phosphorus trichloride, and phosphorus pentachloride. Preferably, the epoxide compound is an epoxide compound as defined above. Preferably, the above derivative is an amino acid protected by a carboxyl or amino group. For example, an L-glutamic acid derivative is... L - Glutamic acid benzyl ester, and / or L-lysine derivatives are nitrogen-ε-trifluoroacetyl- L -Lysine.

[0061] The advantages of the method of the present invention include:

[0062] 1. Compared to other deacidifying agents, epoxy compounds react with hydrochloric acid in THF at an extremely fast rate, almost instantaneously at room temperature, which can not only completely remove acid but also remove chloride ions.

[0063] 2. Epoxy compounds are cheaper than pinene and limonene, resulting in lower costs.

[0064] 3. The products formed by the reaction of epoxides with hydrochloric acid, 1-chloro-2-propanol or 2-chloro-1-propanol, can be easily separated and purified for sale as chemical raw materials. These characteristics determine that this method is not only inexpensive but also achieves near-zero emissions, minimizes environmental pollution, and can create some high-value-added byproducts.

[0065] 4. Whether it is the synthesis itself or the subsequent recrystallization / column chromatography, anhydrous solvents and glove boxes can be completely eliminated. Inexpensive analytical grade common solvents can be used throughout the process to obtain high-purity NCA monomers in high yield under normal experimental conditions.

[0066] 5. No heating or nitrogen protection is required, and the process is faster than conventional methods.

[0067] 6. It has good universality and functional group compatibility. For some monomers that cannot be obtained by ordinary methods or are extremely difficult to synthesize, this method can successfully prepare them and obtain clear characterization evidence. Attached Figure Description

[0068] Figure 1 Existing methods for synthesizing NCA and their polymerization to prepare polyamino acids.

[0069] Figure 2 GatheringL SEC characterization of 1-glutamic acid. Detailed Implementation

[0070] As used in this article, "amino acid" can refer to an amino acid with the structure H2N-R x Compounds with -COOH, where R x It is an organic group, and NH2 may optionally be combined with Rx (e.g., as in the case of proline). An amino acid derivative refers to a compound obtained by substituting atoms of an amino acid. Amino acids include any known amino acid, including but not limited to α-amino acids, β-amino acids, γ-amino acids, δ-amino acids, etc. In some embodiments, the term may refer to either α- or β-amino acids. In this document, amino acids may be any of the 20 naturally occurring amino acids, such as glycine, alanine, valine, leucine, isoleucine, methionine, proline, tryptophan, serine, tyrosine, cysteine, phenylalanine, asparagine, glutamine, threonine, aspartic acid, glutamic acid, lysine, arginine, or histidine. Alternatively, amino acid derivatives refer to compounds obtained by substituting atoms of amino acids, such as ε-nitro-benzyloxycarbonyl lysine, benzyl glutamate, sarcosine, hydroxyproline, (S)-2-amino-4-((3-(benzylamino)-3-oxypropyl)seleno)butyric acid, γ-(2-(2-(2-(2-methoxyethoxy)ethoxy)glutamic acid, penicillamine, phenyllactic acid, mandelic acid, or oxy-tert-butyl-serine, or amino acids protected by protecting groups such as Boc or Cbz, for example, various naturally occurring amino acids protected by Boc or Cbz. Protecting group protection can be on α-amino, hydroxyl, thiol, or carboxyl groups, or on corresponding groups on the side chain. The protection may be performed, or both simultaneously. The aforementioned amino acid may be an L-amino acid or a D-amino acid. In one embodiment, R1 is H, CH3, CH(CH3)2, CH2CH(CH3)2, CH(CH3)CH2CH3, CH2-C6H5, indole (C8NH6), CH2-C6H4-OH, CH2-COOH, CH2-CONH2, (CH2)2-COOH, (CH2)4-NH2, (CH2)2-CONH2, (CH2)2-S-CH3, CH2-OH, CH(CH3)-OH, CH2-SH, -C3H6, imidazole, or guanidine.

[0071] As used herein, “epoxide” refers to a class of compounds having a three-membered cyclic ether structure. For example, an epoxide can have the structure shown in formula (III): Wherein: R and R' are each independently H, halogen, or optionally substituted C. 1-6 Straight-chain or branched alkyl groups, optionally substituted C 2-6Straight-chain or branched alkenyl or alkynyl, alkoxy or cycloalkyl; wherein one or more hydrogen atoms are optionally halogenated, C 1-6 The alkyl group is straight-chain or branched, and it is substituted with oxygen or nitrogen; or, one of R and R' forms a five- to seven-membered ring together with the two carbon atoms in the epoxide group. Specifically, the epoxide compound can be ethylene oxide, propylene oxide, 1,2-epoxide butane, dimethyl ethylene oxide, cyclohexyl epoxide, and their halogen-substituted derivatives, such as chlorinated, brominated, or fluorinated ethylene oxide, propylene oxide, 1,2-epoxide butane, dimethyl ethylene oxide, or cyclohexyl epoxide.

[0072] As used herein, "cyclizing agent" refers to an agent that catalyzes the cyclization of amino acids or their derivatives (e.g., those shown in Formula I) as illustrated herein to form a carboxyl anhydride. For example, cyclizing agents may be selected from phosgene, diphosgene, triphosgene, phosphorus trichloride, and phosphorus pentachloride.

[0073] As used herein, "halogen" refers to a fluorine, chlorine, bromine, or iodine atom. In some embodiments, the halogen may be a chlorine atom.

[0074] As used herein, "alkyl" refers to a straight-chain or branched saturated hydrocarbon having 1 to 30 carbon atoms, which may optionally be substituted, with a variety of degrees of substitution permitted as further described herein. Examples of "alkyl" as used herein include, but are not limited to, methyl, ethyl, n-propyl, isopropyl, isobutyl, n-butyl, sec-butyl, tert-butyl, isopentyl, n-pentyl, neopentyl, n-hexyl, and 2-ethylhexyl. In some cases, one or more carbon atoms in an alkyl group may be substituted with heteroatoms and are referred to as "heteroalkyl" respectively. Non-limiting examples include alkoxy groups, which refer to groups in which a carbon atom in an alkyl group is replaced by an oxygen atom. Alkyl groups may be C16-3 ... 1-6 Alkyl group. "C" 1-6 "Alkyl" means an alkyl group having 1 to 6 carbon atoms, and includes, for example, methyl, ethyl, n-propyl, isopropyl, isobutyl, n-butyl, sec-butyl, tert-butyl, isopentyl, n-pentyl, neopentyl, and n-hexyl. 1-6 "Alkoxy" indicates C 1-6 An alkyl group is a group in which one or more carbon atoms are replaced by oxygen, such as methoxy, ethoxy, n-butoxy, tert-butoxy, pentoxy, or hexoxy. "alkyl" or "alkoxy" can also be replaced by halogen, alkyl group, hydroxyl group, mercapto group, carboxyl group, aryl group, etc. Alkoxy can refer to C... 1-6 Alkyl group.

[0075] As used herein, “alkenyl” refers to a straight-chain or branched non-aromatic hydrocarbon having 2 to 30 carbon atoms and one or more carbon-carbon double bonds, which may optionally be substituted, with a variety of degrees of substitution permitted as further described herein. Examples of “alkenyl” as used herein include, but are not limited to, vinyl, 2-propenyl, 2-butenyl, and 3-butenyl. In some cases, one or more carbon atoms in an alkenyl or alkenylyl group may be substituted with heteroatoms (e.g., selected from nitrogen, oxygen, or sulfur where feasible), and are referred to as “heteroalkenyl” respectively. “Alkenyl” may also be substituted with halogens, alkyl groups, hydroxyl groups, mercapto groups, carboxyl groups, aryl groups, etc.

[0076] As used herein, the aryl group can be a phenyl, biphenyl, or naphthyl aryl group, and can be mono, di, or trisubstituted, for example, by halogen, hydroxyl, alkyl, methyl, mercapto, carboxyl, etc. Substituents derived from the aryl group can be substituted, just like the aryl group, such as aralkyl, aryloxy, arylthio, or arylacyl groups.

[0077] As used herein, heteroaryl groups can be aromatic monocyclic or bicyclic heterocyclic groups containing 5 to 7 or 8 to 12 ring atoms, of which 1 to 2 ring atoms are sulfur or oxygen atoms or 1 to 4 ring atoms are nitrogen atoms. These can be understood as thiophene, benzo[b]thiophene, furanyl, pyranyl, pyranyl, benzofuranyl, pyrroloyl, imidazolyl, pyrazolyl, pyridinyl, pyrimidinyl, pyridazinyl, indazole, isoindolyl, indolyl, purine, quinolinyl, isoquinolinyl, 2,3-diazanaphthyl, 1,5-diazanaphthyl, quinoxalinyl, quinazolinyl, borazinyl, pteridinyl, oxazolyl, isoxazolyl, thiazolyl, or isothiazolyl. Heteroaryl groups can also be substituted with halogens, alkyl groups, hydroxyl groups, mercapto groups, carboxyl groups, aryl groups, etc.

[0078] As used herein, “substitution” means replacing one or more hydrogen atoms of a specified module with one or more specified substituents, with a variety of degrees of substitution permitted unless otherwise stated, provided that the substitution produces a stable or chemically viable compound. “Optional substitution” means that a group may or may not be substituted. Substitution may be with halogens, alkyl groups, hydroxyl groups, mercapto groups, carboxyl groups, or aryl groups.

[0079] The method of the present invention

[0080] The inventors discovered that high concentrations of hydrochloric acid are generated during NCA synthesis. If water is encountered during the synthesis and purification process, the hydrochloric acid will catalyze the decomposition or polymerization of NCA, leading to synthesis failure. For this reason, existing literature and patents report the addition of acid-scavenging agents such as organic amines (e.g., triethylamine) (Gkikas, M.; Avery, RK; Olsen, BD, Thermoresponsive and Mechanical Properties of Poly(L-proline)Gels. Biomacromolecules 2016, 17(2), 399-406), pinene (Fabrice Cornille, BSY; Jean-Luc Copier, A.; Jean-Pierre Senet, B.; Yves Robin, VLPPROCESS FOR THEPREPARATION OF N-CARBOXYANHYDRIDES. US 6,479,665 B2, 2002), and limonene (Smeets, NMB; van der Weide, PLJ; Meuldijk, J.; Vekemans, JAJM; Hulshof, LA, AScalable Synthesis of l-Leucine-N-carboxyanhydride. Org. Process). The method (Res.Dev.2005,9(6),757-763) etc. However, the inventors found that since amine is a base, an excess will cause NCA polymerization, and an insufficient amount is not enough to completely eliminate the side effects of hydrochloric acid. Therefore, the amount added is not easy to control in actual operation. Moreover, the triethylamine chloride byproduct produced by triethylamine and hydrochloric acid has good solubility in water and organic solvents and is not easy to remove. Furthermore, triethylamine cannot remove nucleophilic chloride ions and can still induce NCA decomposition, so the effect is not ideal (Biomacromolecules2011,12,6,2396–2406; J.Org.Chem.1965,30,4,1158–1161). However, the reaction between pinene and hydrochloric acid in tetrahydrofuran (the most common solvent for NCA synthesis) is slow (J.Am.Chem.Soc.1941,63,3,860–862), and the hydrochloric acid produced cannot be removed in a timely and effective manner during the synthesis process. Therefore, anhydrous solvents and nitrogen protection are still required.Meanwhile, pinene and citric acid are also relatively expensive, increasing the cost of industrial production (Smeets, NMB; van der Weide, PLJ; Meuldijk, J.; Vekemans, JAJM; Hulshof, LA, A Scalable Synthesis of l-Leucine-N-carboxyanhydride. Org. Process Res. Dev. 2005, 9(6), 757-763).

[0081] After long-term exploration, the inventors discovered that using epoxy compounds such as propylene oxide (PO) as the hydrochloric acid removal reagent in the NCA synthesis process overcomes the shortcomings of existing technologies. Epoxides such as PO react with hydrochloric acid in THF at extremely fast rates, almost instantaneously at room temperature, completely removing both acid and chloride ions. Epoxides like PO are cheaper than pinene and limonene, resulting in lower costs (PO price: ¥169 / L; pinene price: ¥771 / kg; limonene price: ¥1129 / kg; data source: the cheapest price for each chemical on the Peking University reagent management platform). Furthermore, the products formed by PO and hydrochloric acid, 1-chloro-2-propanol or 2-chloro-1-propanol, can be easily separated and purified for sale as chemical raw materials. These characteristics determine that this method is not only inexpensive but also achieves near-zero emissions, minimizes environmental pollution, and can create some high-value-added byproducts.

[0082] Therefore, the present invention particularly provides a method for preparing an N-carboxyl intracyclic anhydride of an amino acid, comprising reacting the amino acid with a cyclizing agent to generate an N-carboxyl intracyclic anhydride of the amino acid and an acid, and using an epoxide as an acid-removing agent. The amino acid can be any kind of amino acid, such as as defined above. In this document, the acid can be a hydrogen halide, such as hydrogen chloride or hydrogen bromide. The cyclizing agent can be as defined above, including ethylene oxide, propylene oxide, 1,2-epoxybutane, dimethyl ethylene oxide, cyclohexane oxide, and their halogen-substituted derivatives. All the advantages described above can be achieved when using this method. The method may include adding the amino acid or its derivative to a container, adding a solvent, such as analytical grade tetrahydrofuran, adding an epoxide, such as propylene oxide, stirring until homogeneous (e.g., under magnetic stirring), adding the cyclizing agent, such as triphosgene, under atmospheric conditions, followed by stirring (e.g., sealing or micro-opening of the gas inlet plug).

[0083] The present invention also provides a method for preparing polyamino acid nitrogen-carboxylated anhydrides. This method includes the steps described above for preparing amino acid nitrogen-carboxylated anhydrides. The method may further include a step of reacting the obtained amino acid nitrogen-carboxylated anhydride with N,N-dimethylformamide and a benzylamine initiator. Preferably, the side chain of the amino acid contains a carboxyl group, for example, the R1 group is an optionally substituted C group. 1-6 Straight-chain or branched alkyl carboxyl groups. For example, the amino acid is glutamic acid.

[0084] For example, the method includes... L Glutamic acid was added to tetrahydrofuran and epichlorohydrin, stirred until homogeneous, and then triphosgene was added under atmospheric conditions. After reacting at room temperature, the mixture was dried and crystallized to obtain the final product. L -Glutamic acid nitrogen-carboxyl anhydride. The method may also include the determination of glutamic acid nitrogen-carboxyl anhydride. L -Glutamic acid nitrogen-carboxylic acid anhydride was added to N,N-dimethylformamide and benzylamine initiator, and reacted at room temperature to obtain the final product, poly(N-dimethylformamide). L -Glutamic acid, with a degree of polymerization N of 20, as shown in the examples. Compared to conventional methods, this method for preparing polyamino acid nitrogen-carboxylic acid anhydrides can produce polyamino acids in higher yields.

[0085] Example

[0086] The following examples illustrate certain illustrative embodiments of the compounds, compositions, and methods disclosed herein. These examples should not be considered as limiting in any way. Nor should they be considered as expressing any preferred embodiments or indicating any direction for further research. Unless otherwise specified, the experimental methods used in the following examples are conventional methods, and the materials, reagents, etc., used are commercially available.

[0087] Example 1: L Synthesis of β-glutamate benzyl ester nitrogen-carboxylic acid anhydride

[0088] Will L β-Glutamate benzyl ester (5.0 g, 21.1 mmol, 1 equivalent) was added to a thick-walled, pressure-resistant flask, followed by 60 mL of analytical grade tetrahydrofuran, propylene oxide (15.3 mL, 211 mmol, 10 equivalents), and triphosgene (3.184 g, 10.5 mmol, 0.5 equivalents). The mixture was stirred at room temperature for 1.5 hours. After washing with water and drying, the mixture was allowed to diffuse crystallize to obtain the final product. L - Glutamic acid benzyl ester nitrogen-carboxylic acid anhydride (5.159 g, yield 93%).

[0089] L The proton and carbon NMR spectra of benzyl glutamate nitrogen-carboxylic acid anhydride are as follows:

[0090] 1H NMR (400MHz, CDCl3) δ7.42–7.31(m,5H),6.70(s,1H),5.13(s,2H),4.38(ddd,J=6 .7,5.4,1.0Hz,1H),2.59(t,J=6.9Hz,1H),2.32–2.21(m,1H),2.18–2.06(m,1H).

[0091] 13 C NMR (101MHz, CDCl3) δ172.5,169.6,152.2,135.3,128.8,128.7,128.4,67.2,57.0,29.8,26.9.

[0092] Example 2: Synthesis of glycine nitrogen-carboxyl anhydride

[0093] Nitrogen-tert-butoxycarbonylglycine (1.0 g, 5.7 mmol, 1 equivalent) was added to a 100 mL round-bottom flask, followed by 20 mL of analytical grade acetonitrile, 4 mL of propylene oxide (57.1 mmol, 10 equivalents), and triphosgene (861 mg, 2.9 mmol, 0.5 equivalents). The reaction was allowed to proceed for 1.5 hours, then evaporated to dryness and crystallized. The final product, glycine nitrogen-carboxylic acid anhydride (357 mg, 62% yield), was obtained.

[0094] The proton and carbon NMR spectra of glycine nitrogen-carboxylic acid anhydride are as follows:

[0095] 1 H NMR (400MHz, DMSO-d6) δ8.83 (s, 1H), 4.18 (s, 2H).

[0096] 13 C NMR (101MHz, DMSO-d6) δ169.4, 153.0, 46.3.

[0097] Example 3: ε-N-benzyloxycarbonyl L -Lysine nitrogen-carboxylic acid anhydride

[0098] ε-nitrobenzyloxycarbonyl L ε-Lysine (1.0 g, 3.6 mmol, 1 equivalent) was added to a thick-walled, pressure-resistant flask, followed by 15 mL of analytical grade tetrahydrofuran, 2.5 mL of propylene oxide (36 mmol, 10 equivalent), and triphosgene (534 mg, 1.8 mmol, 0.5 equivalent). The mixture was stirred at room temperature for 1.5 hours. The solution was washed with water, dried, and crystallized to obtain the final product ε-nitro-benzyloxycarbonyl. L -Lysine nitrogen-carboxylic acid anhydride (929 mg, yield 85%).

[0099] ε-N-benzyloxycarbonyl L The proton and carbon NMR spectra of the lysine nitrogen-carboxylic acid anhydride are as follows:

[0100] 1 H NMR (400MHz, DMSO-d6) δ9.08 (s, 1H), 7.40–7.28 (m, 5H), 7.26 (t, J = 6.1Hz, 1H), 5.00 (s, 2H), 4 .43(dd,J=7.4,5.1Hz,1H),2.99(dt,J=6.1,6.1Hz,2H),1.80–1.58(m,1H),1.48–1.22(m,4H).

[0101] 13 C NMR (101MHz, DMSO-d6) δ171.7,156.1,152.0,137.3,128.4,127.8,127.8,124.2,65.2,57.0,30.7,28.8,21.6.

[0102] Example 4: L Synthesis of -alanine nitrogen-carboxylic acid anhydride

[0103] Will L 1-Alanine (1.0 g, 11.2 mmol, 1 equivalent) was added to a thick-walled, pressure-resistant flask, followed by 30 mL of analytical grade tetrahydrofuran, 8.0 mL of propylene oxide (112.2 mmol, 10 equivalents), and triphosgene (1.674 g, 5.6 mmol, 0.5 equivalents). The mixture was stirred at room temperature for 19.5 hours. The mixture was washed with water, dried, and crystallized to obtain the final product. L -Alanine nitrogen-carboxylic acid anhydride (821 mg, yield 64%).

[0104] L The proton and carbon NMR spectra of the alanine nitrogen-carboxylic acid anhydride are as follows:

[0105] 1 H NMR (400MHz, CDCl3) δ6.76 (br, 1H), 4.42 (qd, J = 7.0, 1.0Hz, 1H), 1.56 (d, J = 7.0Hz, 3H).

[0106] 13 C NMR (101MHz, CDCl3) δ170.3, 152.6, 53.5, 17.8.

[0107] Example 5: L Synthesis of tyrosine nitrogen-carboxylic acid anhydride

[0108] Will LTyrosine (1.0 g, 6.1 mmol, 1 equivalent) was added to a thick-walled, pressure-resistant flask, followed by 15 mL of analytical grade tetrahydrofuran, 4.3 mL of propylene oxide (61 mmol, 10 equivalents), and triphosgene (897 mg, 3.0 mmol, 0.5 equivalents). The mixture was stirred at room temperature for 7 hours. The solution was washed with water, dried, and crystallized to obtain the final product. L -Tyrosine nitrogen-carboxylic acid anhydride (961 mg, yield 83%).

[0109] L The proton and carbon NMR spectra of the nitrogen-carboxylic acid anhydride of tyrosine are as follows:

[0110] 1 H NMR (400MHz, DMSO-d6) δ9.34(br,1H),9.03(br,1H),6.97(d,J=8.4Hz,2H),6.69(d,J=8.4Hz, 2H), 4.70 (td, J=5.0, 1.0Hz, 1H), 2.93 (dd, J=14.5, 5.0Hz, 1H), 2.89 (dd, J=14.5, 5.0Hz, 1H).

[0111] 13 C NMR (101MHz, DMSO-d6) δ170.9,156.5,151.7,130.7,124.6,115.2,58.5,35.5.

[0112] Example 6: Synthesis of sarcosine nitrogen-carboxylic acid anhydride

[0113] Nitrogen-tert-butoxycarbonyl sarcosine (1.0 g, 5.3 mmol, 1 equivalent) was added to a 100 mL round-bottom flask, followed by 20 mL of analytical grade acetonitrile. Propylene oxide (3.7 mL, 53 mmol, 10 equivalents) was added under ice-water bath conditions, and triphosgene (793 mg, 2.7 mmol, 0.5 equivalents) was added. The reaction was allowed to proceed for 1.5 hours. The mixture was then washed with water, dried, and crystallized to give the final product, sarcosine nitrogen-carboxylic anhydride (381 mg, 63% yield).

[0114] The 1H and 1C NMR spectra of sarcosine nitrogen-carboxylic acid anhydride are as follows:

[0115] 1 H NMR (400MHz, CDCl3) δ4.13 (s, 2H), 3.03 (s, 3H).

[0116] 13 C NMR (101MHz, CDCl3) δ165.5, 152.4, 51.0, 30.4.

[0117] Example 7:L Synthesis of hydroxyproline nitrogen-carboxylic acid anhydride

[0118] Will L -N-tert-butyloxycarbonylhydroxyproline (5.0 g, 21.6 mmol, 1 equivalent) was added to a 250 mL round-bottom flask, followed by 50 mL of analytical grade acetonitrile. Propylene oxide (15.1 mL, 216 mmol, 10 equivalents) was added under ice-water bath, and triphosgene (3.222 g, 10.8 mmol, 0.5 equivalents) was added. The reaction was allowed to proceed for 1.5 hours. The mixture was washed with water, dried, and filtered through a silica gel column to obtain the final product. L -Hydroxyproline nitrogen-carboxylic acid anhydride (2.696 g, purity: 95% by mass, yield: 75%, containing 5% EA).

[0119] L The proton and carbon NMR spectra of the hydroxyproline nitrogen-carboxylic acid anhydride are as follows:

[0120] 1 H NMR (400MHz, DMSO-d6) δ5.31(br,1H),4.72(dd,J=10.8,6.8Hz,1H),4.54(ddd,J=4.8,4.8,1.5Hz,1H),3.71(dd,J= 11.2, 4.8Hz, 1H), 3.06 (dd, J = 11.2, 1.5Hz, 1H), 2.23 (ddd, J = 12.2, 10.8, 4.8Hz, 1H), 1.95 (dd, J = 12.2, 6.8Hz, 1H).

[0121] 13 C NMR (101MHz, DMSO-d6) δ170.3,154.7,72.6,62.3,55.0,35.5.

[0122] Example 8: L -Methionine nitrogen-carboxylic acid anhydride

[0123] Will L 1-Methionine (1.0 g, 6.7 mmol, 1 equivalent) was added to a thick-walled, pressure-resistant flask, followed by 20 mL of analytical grade tetrahydrofuran, 4.7 mL of propylene oxide (67 mmol, 10 equivalents), and triphosgene (1.002 g, 3.4 mmol, 0.5 equivalents). The mixture was stirred at room temperature for 2 hours. After washing with water and drying, the solution was filtered through a silica gel column to obtain the final product. L - Methionine-carboxylic acid anhydride (700 mg, yield 60%).

[0124] L The proton and carbon NMR spectra of the methionine nitrogen-carboxylic acid anhydride are as follows:

[0125] 1 H NMR (400MHz, CDCl3) δ7.06 (br, 1H), 4.51 (ddd, J = 7.4, 5.0, 1.1Hz, 1H), 2.67 (t, J =6.6Hz,2H),2.25(dtd,J=14.6,6.6,5.0Hz,1H),2.17–2.01(m,1H),2.09(s,3H).

[0126] 13 C NMR (101MHz, CDCl3) δ169.9, 152.9, 56.7, 30.2, 29.8, 15.2.

[0127] Example 9: L -Tryptophan nitrogen-carboxylic acid anhydride

[0128] Will L Tryptophan (1.0 g, 4.9 mmol, 1 equivalent) was added to a thick-walled, pressure-resistant flask, followed by 15 mL of analytical grade tetrahydrofuran, propylene oxide (3.4 mL, 49 mmol, 10 equivalents), and triphosgene (749 mg, 2.5 mmol, 0.5 equivalents). The mixture was stirred at room temperature for 1.5 hours. The solution was washed with water, dried, and crystallized to obtain the final product. L -Tryptophan nitrogen-carboxylic acid anhydride (1.020 g, yield 90%).

[0129] L The proton and carbon NMR spectra of the -tryptophan nitrogen-carboxylic acid anhydride are as follows:

[0130] 1 H NMR (400MHz, DMSO-d6) δ11.00(d,J=2.5Hz,1H),9.09(s,1H),7.55(d,J=7.9Hz,1H),7.36(d,J=8.1Hz,1H),7.15(d,J=2.5Hz, 1H),7.13–7.05(m,1H),7.05–6.96(m,1H),4.78(t,J=5.0Hz,1H),3.22(dd,J=15.0,5.0Hz,1H),3.14(dd,J=15.0,5.0Hz,1H).

[0131] 13 C NMR (101MHz, DMSO-d6) δ171.3,151.9,136.0,127.2,124.5,121.1,118.6,118.5,111.5,107.1,58.3,26.5.

[0132] Example 10: L-proline nitrogen-carboxylic acid anhydride

[0133] Will L -N-tert-butyloxycarbonylproline (1.0 g, 4.7 mmol, 1 equivalent) was added to a 100 mL round-bottom flask, followed by 15 mL of analytical grade acetonitrile. Propylene oxide (3.7 mL, 47 mmol, 10 equivalents) was added under ice-water bath, and triphosgene (700 mg, 2.3 mmol, 0.5 equivalents) was added. The reaction was allowed to proceed for 2.5 hours. The mixture was washed with water, dried, and filtered through a silica gel column to obtain the final product. L -proline nitrogen-carboxylic acid anhydride (470 mg, yield 72%).

[0134] L The proline nitrogen-carboxylic acid anhydride's 1H and 1C NMR spectra are as follows:

[0135] 1 H NMR(400MHz, CDCl3) δ4.32(dd,J=9.1,7.4Hz,1H),3.73(dt,J=11.3,7.4Hz,1H),3.30(ddd,J=11.3,8.5,4.6Hz,1H),2.28 (dtd,J=12.4,7.4,3.7Hz,1H),2.24–2.14(m,1H),2.09(dtd,J=14.3,9.1,7.4,4.6Hz,1H),1.92(dq,J=12.4,9.1Hz,1H).

[0136] 13 C NMR (101MHz, CDCl3) δ168.9, 154.9, 63.1, 46.5, 27.6, 26.9.

[0137] Example 11: L -Phenylalanine nitrogen-carboxylic acid anhydride

[0138] Will L 1.0 g (6.1 mmol, 1 equivalent) of phenylalanine was added to a thick-walled, pressure-resistant flask, followed by 15 mL of analytical grade tetrahydrofuran, 4.3 mL (60 mmol, 10 equivalents) of propylene oxide, and triphosgene (897 mg, 4.0 mmol, 0.5 equivalents). The mixture was stirred at room temperature for 7 hours. The solution was washed with water, dried, and crystallized to obtain the final product. L -Phenylalanine nitrogen-carboxylic acid anhydride (961 mg, yield 83%).

[0139] L The proton and carbon NMR spectra of the nitrogen-carboxylic acid anhydride of phenylalanine are as follows:

[0140] 1H NMR (400MHz, CDCl3) δ7.38–7.27(m,3H),7.17(dd,J=7.7,1.8Hz,2H),6.48(br,1H),4.53 (ddd,J=7.8,4.3,1.0Hz,1H), 3.24(dd,J=14.2,4.3Hz,1H), 3.01(dd,J=14.2,7.8Hz,1H).

[0141] 13 C NMR (101MHz, CDCl3) δ168.9,152.1,134.0,129.3,128.1,59.0,37.9.

[0142] Example 12: L -Serine nitrogen-carboxylic acid anhydride synthesis

[0143] Will L 1-Serine (1.0 g, 9.5 mmol, 1 equivalent) was added to a thick-walled, pressure-resistant flask, followed by 30 mL of analytical grade dioxane, 6.7 mL of propylene oxide (95.2 mmol, 10 equivalents), and triphosgene (1.415 g, 4.8 mmol, 0.5 equivalents). The mixture was stirred at room temperature for 4 hours. The solution was then filtered through a silica gel column to crystallize, yielding the final product. L -Serine nitrogen-carboxylic acid anhydride (890 mg, yield 71%).

[0144] L The proton and carbon NMR spectra of the serine nitrogen-carboxylate anhydride are as follows:

[0145] 1 H NMR (400MHz, THF-d8) δ7.89 (brs, 1H), 4.69 (brs, 1H), 4.35–4.32 (m, 1H), 3.81 (dd, J = 11.6, 3.4Hz, 1H), 3.71 (dd, J = 11.6, 2.7Hz, 1H).

[0146] 13 C NMR (101MHz, THF-d8) δ170.6, 153.6, 61.6, 61.5.

[0147] Example 13: L Synthesis of threonine nitrogen-carboxylic acid anhydride

[0148] Will LThreonine (2.0 g, 8.4 mmol, 1 equivalent) was added to a thick-walled, pressure-resistant flask, followed by 30 mL of analytical grade tetrahydrofuran, 12 mL of propylene oxide (95.2 mmol, 10 equivalent), and triphosgene (2.5 g, 4.8 mmol, 0.5 equivalent). The mixture was stirred at room temperature for 12 hours. The solution was washed with water, dried, and crystallized to obtain the final product. L -Threonine nitrogen-carboxylic acid anhydride (1.186 g, yield 48%).

[0149] L The proton and carbon NMR spectra of the -threonine nitrogen-carboxylic acid anhydride are as follows:

[0150] 1 H NMR (400MHz, DMSO-d6) δ9.05(brs,1H),5.17(brs,1H),4.32(dd,J=2.3,1.1Hz,1H),3.98(qd,J=6.6,2.3Hz,1H),1.14(d,J=6.6Hz,3H).

[0151] 13 C NMR (101MHz, DMSO-d6) δ170.5,152.7,65.4,63.7,19.9.

[0152] Example 14: γ-(2-(2-(2-(2-methoxyethoxy)ethoxy) L Synthesis of -glutamate nitrogen-carboxylic acid anhydride

[0153] γ-(2-(2-(2-(2-methoxyethoxy)ethoxy) L γ-Glutamic acid (2.82 g, 9.6 mmol, 1 equivalent) was added to a thick-walled, pressure-resistant flask, followed by 50 mL of analytical grade tetrahydrofuran, 6.7 mL of propylene oxide (96.1 mmol, 10 equivalents), and triphosgene (1.475 g, 4.8 mmol, 0.5 equivalents). The mixture was stirred at room temperature for 2 hours. The solution was then filtered through a silica gel column to obtain the final product γ-(2-(2-(2-methoxyethoxy)ethoxy) L -Glutamic acid nitrogen-carboxylic acid anhydride (2.206 mg, yield 72%).

[0154] γ-(2-(2-(2-(2-methoxyethoxy)ethoxy) L The proton and carbon NMR spectra of the -glutamate nitrogen-carboxylic acid anhydride are as follows:

[0155] 1H NMR(400MHz, DMSO-d6)δ9.09(br,1H),4.46(ddd,J=7.9,5.4,1.2Hz,1H),4.20–4.07(m,2H),3.60(dd,J=5.3,4.2Hz, 2H),3.57–3.47(m,5H),3.46–3.39(m,2H),3.24(s,3H),2.47(t,J=7.6Hz,2H),2.10–1.96(m,1H),1.99–1.83(m,1H).

[0156] 13 C NMR (101MHz, DMSO-d6) δ171.8,171.4,151.9,71.3,69.8,69.7,69.6,68.2,63.5,58.1,56.2,29.1,26.5.

[0157] Example 15: (S)-2-amino-4-((3-(benzylamino)-3-oxopropyl)selenoyl)butyric acid nitrogen-carboxylic acid anhydride

[0158] (S)-2-amino-4-((3-(benzylamino)-3-oxypropyl)selenoyl)butyrate (1.0 g, 2.7 mmol, 1 equivalent) was added to a thick-walled, pressure-resistant flask, followed by 15 mL of analytical grade tetrahydrofuran, 2.0 mL of propylene oxide (27 mmol, 10 equivalent), and triphosgene (397 mg, 1.3 mmol, 0.5 equivalent). The mixture was stirred at room temperature for 1.5 hours. After washing with water and drying, the solution was filtered through a silica gel column to obtain the final product (S)-2-amino-4-((3-(benzylamino)-3-oxypropyl)selenoyl)butyrate N-carboxylic anhydride (570 mg, 58% yield).

[0159] The proton and carbon NMR spectra of (S)-2-amino-4-((3-(benzylamino)-3-oxopropyl)seleno)butyric acid N-carboxyl anhydride are shown below:

[0160] 1 H NMR(400MHz, DMSO-d6)δ9.11(br,1H),8.40(t,J=5.9Hz,1H),7.36–7.19(m,5H),4.52(ddd,J=7.8,5.2,1.2Hz, 1H), 4.28 (d, J = 5.9Hz, 2H), 2.75 (t, J = 7.3Hz, 2H), 2.69–2.58 (m, 2H), 2.55 (t, J = 7.3Hz, 2H), 2.12–2.00 (m, 2H).

[0161] 13C NMR (101MHz, DMSO-d6) δ171.4,170.8,152.0,139.4,128.3,127.2,126.7,56.9,42.1,36.5,31.9,18.4,18.3.

[0162] Example 16: L -Cysteine ​​nitrogen-Carboxylic acid anhydride

[0163] Will L Cysteine ​​(10.0 g, 82.5 mmol, 1 equivalent) was added to a thick-walled, pressure-resistant flask, followed by 120 mL of analytical grade tetrahydrofuran, 23 mL of propylene oxide (330.2 mmol, 4 equivalents), and triphosgene (12.313 g, 41.3 mmol, 0.5 equivalents). The mixture was stirred at room temperature for 5 hours, evaporated to dryness, and crystallized to obtain the final product. L -Cysteine ​​nitrogen-carboxylic acid anhydride (9.443 g, yield 78%).

[0164] L The 1H and 1C NMR spectra of cysteine ​​nitrogen-carboxylic acid anhydride are shown below (a small amount of DMSO-d6 was added to THF-d8):

[0165] 1 H NMR (400MHz, THF-d8) δ13.36–12.30(br,1H),8.27(br,1H),4.35(ddd,J=8.5,3.9,1.4Hz,1H),3.69(dd,J=11.2,8.5Hz,1H),3.47(dd,J=11.2,3.9Hz,1H).

[0166] 13 C NMR(101MHz,THF-d8)δ173.4,173.2,56.8,32.7.

[0167] Example 17: L -Phenylonoxy-Carboxylic Acid Anhydride

[0168] Will L 1.0 g (6.0 mmol, 1 equivalent) of phenyllactic acid was added to a thick-walled, pressure-resistant flask, followed by 15 mL of analytical grade tetrahydrofuran, 4.2 mL (60 mmol, 10 equivalents) of propylene oxide, and 3.0 mmol (893 mg, 0.5 equivalents) of triphosgene. The mixture was stirred at room temperature for 24 hours, washed with water, dried, and crystallized to obtain the final product. L -Phenylonoxy-carboxylic acid anhydride (750 mg, yield 65%).

[0169] LThe proton and carbon NMR spectra of -phenyllactic acid oxy-carboxylic acid anhydride are as follows:

[0170] 1 H NMR (400MHz, CDCl3) δ7.41–7.29(m,3H),7.26–7.19(m,2H),5.30(t,J=4.9Hz,1H),3.38(dd,J=14.9,4.9Hz,1H),3.25(dd,J=14.9,4.9Hz,1H).

[0171] 13 C NMR (101MHz, CDCl3) δ166.5,147.9,131.6,129.8,129.3,128.5,80.0,36.5.

[0172] Example 18: L Synthesis of -mandelic acid oxy-carboxylic acid anhydride

[0173] Will L Mandelic acid (1.0 g, 6.6 mmol, 1 equivalent) was added to a thick-walled, pressure-resistant flask, followed by 20 mL of analytical grade tetrahydrofuran, 4.6 mL of propylene oxide (66 mmol, 10 equivalents), and triphosgene (976 mg, 3.3 mmol, 0.5 equivalents). The mixture was stirred at room temperature for 24 hours, washed with water, dried, and crystallized to obtain the final product. L -Mandelic acid oxy-carboxylic acid anhydride (575 mg, yield 49%).

[0174] L The proton and carbon NMR spectra of mandelic acid oxy-carboxylic acid anhydride are as follows:

[0175] 1 H NMR (400MHz, DMSO-d6) δ7.47–7.40(m,2H),7.39–7.24(m,3H),5.04(s,1H).

[0176] 13 C NMR (101MHz, DMSO-d6) δ174.2,140.3,128.2,127.8,126.7,72.5.

[0177] Example 19: Synthesis of D-Penicillamine N-Carboxylic Anhydride

[0178] Will DPenicillamine (1.0 g, 6.7 mmol, 1 equivalent) was added to a thick-walled, pressure-resistant flask, followed by 15 mL of analytical grade tetrahydrofuran, 5.8 mL of propylene oxide (82.5 mmol, 10 equivalents), and triphosgene (1.22 g, 4.1 mmol, 0.5 equivalents). The mixture was stirred at room temperature for 1.5 hours, evaporated to dryness, and crystallized to obtain the final product. D - Penicillamine nitrogen-carboxylic acid anhydride (771 mg, yield 53%).

[0179] D The proton and carbon NMR spectra of penicillamine nitrogen-carboxylic acid anhydride are as follows:

[0180] 1 H NMR (400MHz, DMSO-d6) δ 13.18 (s, 1H), 8.24 (s, 1H), 4.12 (d, J = 1.0Hz, 1H), 1.62 (s, 3H), 1.41 (s, 3H).

[0181] 13 C NMR (101MHz, DMSO-d6) δ171.6,170.2,66.5,52.9,29.8,25.9.

[0182] Example 20: Oxy-tert-butyl L -Serine nitrogen-carboxylic acid anhydride synthesis

[0183] oxygen-tert-butyl L 1-Serine (1.0 g, 6.2 mmol, 1 equivalent) was added to a thick-walled, pressure-resistant flask, followed by 15 mL of analytical grade tetrahydrofuran, 4.3 mL of propylene oxide (62.0 mmol, 10 equivalents), and triphosgene (930.1 mg, 3.1 mmol, 0.5 equivalents). The mixture was stirred for 1.5 hours, and the solution was filtered through a silica gel column to obtain the final product, oxy-tert-butyl. L -Serine nitrogen-carboxylic acid anhydride (1.0081 g, yield 87%).

[0184] Oxy-tert-butyl L The proton and carbon NMR spectra of the serine nitrogen-carboxylate anhydride are as follows:

[0185] 1 H NMR (400MHz, DMSO-d6) δ 8.95 (br, 1H), 4.57 (dt, J = 2.8, 1.5Hz, 1H), 3.62 (dd, J = 10.3, 2.8Hz, 1H), 3.50 (dd, J = 10.3, 2.8Hz, 1H), 1.10 (s, 9H).

[0186] 13C NMR (101MHz, DMSO-d6) δ170.2, 152.3, 73.2, 59.9, 58.6, 27.1.

[0187] Example 21: L Synthesis of -N-tert-butoxycarbonyl aspartic acid-1-methyl ester N-carboxylic acid anhydride

[0188] Will L 1-N-tert-Butoxycarbonyl aspartic acid-1-methyl ester (1.0 g, 4.0 mmol, 1 equivalent) was added to a 50 mL round-bottom flask, followed by 15 mL of analytical grade acetonitrile. Under magnetic stirring, propylene oxide (2.8 mL, 40.0 mmol, 10 equivalents) was added, and the mixture was stirred until homogeneous. Then, triphosgene (613.2 mg, 2.0 mmol, 0.5 equivalents) was added under atmospheric conditions. The reaction was carried out at 0°C for two hours, and the mixture was directly dried under vacuum to obtain the final product. L -N-tert-Butoxycarbonylaspartic acid-1-methyl ester N-Carboxylic acid anhydride (500 mg, yield 71%).

[0189] L The proton and carbon NMR spectra of 1-N-N-tert-butoxycarbonyl aspartic acid-1-methyl ester are as follows:

[0190] 1 H NMR (400MHz, DMSO-d6) δ8.96 (d, J=4.4Hz, 1H), 4.32 (ddd, J=7.2, 4.4, 3.0Hz, 1H) ,3.70(s,3H),3.23(dd,J=16.8,7.2Hz,1H),2.91(ddd,J=16.8,3.0,1.1Hz,1H).

[0191] 13 C NMR (101MHz, DMSO-d6) δ170.9,165.1,148.9,52.9,48.4,30.7.

[0192] Example 22: Nitrogen ε-(tert-Butoxycarbonyl)- L Synthesis of -Lysine nitrogen-carboxylic acid anhydride

[0193] Nitrogen ε-(tert-butoxycarbonyl)- L Lysine (1.0 g, 4.1 mmol, 1 equivalent) was added to a thick-walled, pressure-resistant flask, followed by 15 mL of analytical grade tetrahydrofuran. Under magnetic stirring, propylene oxide (2.8 mL, 41.0 mmol, 10 equivalents) was added, and the mixture was stirred thoroughly. Then, triphosgene (620.2 mg, 2.0 mmol, 0.5 equivalents) was added under atmospheric conditions. The mixture was reacted at room temperature for two hours, washed with water, dried, and crystallized to obtain the final product, ε-(tert-butyloxycarbonyl)-.L -Lysine nitrogen-carboxylic acid anhydride (888 mg, yield 80%).

[0194] Nitrogen ε-(tert-Butoxycarbonyl)- L The proton and carbon NMR spectra of the lysine nitrogen-carboxylic acid anhydride are as follows:

[0195] 1 H NMR(400MHz,DMSO-d6)δ9.07(br,1H),6.79(t,J=6.0Hz,1H),4.42(dd,J=7.3,5.2 Hz, 1H), 2.89 (q, J = 6.0Hz, 2H), 1.78–1.57 (m, 2H), 1.37 (s, 9H), 1.43–1.19 (m, 4H).

[0196] 13 C NMR (101MHz, DMSO-d6) δ171.7,155.6,152.0,77.4,57.0,30.6,28.9,28.3,21.6.

[0197] Example 23: Nitrogen ε-trifluoroacetyl- L Synthesis of -Lysine nitrogen-carboxylic acid anhydride

[0198] Nitrogen ε-trifluoroacetyl- L Lysine (1.0 g, 4.1 mmol, 1 equivalent) was added to a thick-walled, pressure-resistant flask, followed by 15 mL of analytical grade tetrahydrofuran. Under magnetic stirring, propylene oxide (2.8 mL, 41.0 mmol, 10 equivalents) was added, and the mixture was stirred thoroughly. Then, triphosgene (620.2 mg, 2.0 mmol, 0.5 equivalents) was added under atmospheric conditions. The mixture was reacted at room temperature for two hours, washed with water, dried, and crystallized to obtain the final product, N-ε-trifluoroacetyl- L -Lysine nitrogen-carboxylic acid anhydride (900 mg, yield 81%).

[0199] Nitrogen ε-trifluoroacetyl- L The 1H NMR spectrum of the -lysine nitrogen-carboxylic acid anhydride is as follows: 1 H NMR(400MHz, DMSO-d6,δ)9.40(t,1H),9.09(s,1H),4.43(t,1H),3.17(q,2H),1.86–1.58(m,2H),1.50(p,2H),1.44–1.21(m,2H).

[0200] Example 24: L Synthesis of -glutamate nitrogen-carboxylic acid anhydride

[0201] Will L1.0 g (6.8 mmol, 1 equivalent) of glutamic acid was added to a thick-walled, pressure-resistant flask, followed by 15 mL of analytical grade tetrahydrofuran. Under magnetic stirring, epichlorohydrin (2.1 mL, 68.0 mmol, 10 equivalents) was added, and the mixture was stirred until homogeneous. Then, triphosgene (1.01 g, 3.4 mmol, 0.5 equivalents) was added under atmospheric conditions. The mixture was reacted at room temperature for 20 hours, dried, and crystallized to obtain the final product. L -Glutamic acid nitrogen-carboxylic acid anhydride (1.0 g, yield 89%).

[0202] L The proton and carbon NMR spectra of the -glutamate nitrogen-carboxylic acid anhydride are as follows:

[0203] 1 H NMR(400MHz,DMSO-d6)δ12.27(br,1H),9.09(br,1H),4.46(ddd,J=7.5,5.5,1.2Hz,1H), 2.37(t,J=7.5Hz,2H), 2.00(dtd,J=14.0,7.5,5.5Hz,1H), 1.87(dq,J=14.7,7.5Hz,1H).

[0204] 13 C NMR (101MHz, DMSO-d6) δ173.4,171.5,152.0,56.3,29.1,26.6.

[0205] Example 25: Comparative Experiment of Absorbents

[0206] Taking the synthesis of (S)-2-amino-4-((3-(benzylamino)-3-oxypropyl)selenoyl)butyric acid nitrogen-carboxyl anhydride as an example, the effects of different absorbents on the separation yield are compared.

[0207] (S)-2-amino-4-((3-(benzylamino)-3-oxypropyl)selenoyl)butyrate (1.0 g, 2.7 mmol, 1 equivalent) was added to a thick-walled, pressure-resistant flask, followed by 15 mL of analytical grade tetrahydrofuran, 2.0 mL of propylene oxide (27 mmol, 10 equivalent), and triphosgene (397 mg, 1.3 mmol, 0.5 equivalent). The mixture was stirred at room temperature for 1.5 hours. After quenching, the solution was purified by column chromatography to obtain the final product (S)-2-amino-4-((3-(benzylamino)-3-oxypropyl)selenoyl)butyrate N-carboxylic anhydride (570 mg, 58% yield).

[0208] (S)-2-amino-4-((3-(benzylamino)-3-oxopropyl)selenoyl)butyrate (1.0 g, 2.7 mmol, 1 equivalent) was added to a reaction flask, followed by 15 mL of analytical grade tetrahydrofuran, α-pinene (0.6 mL, 3.8 mmol, 1.4 equivalent), and triphosgene (346 mg, 1.2 mmol, 0.4 equivalent). The mixture was stirred at 50°C for 5 hours. The amino acid could not be dissolved, and column chromatography failed to yield the corresponding product, with a separation yield of 0%. It is speculated that pinene, acting as an absorbent, only produces a small amount of reaction after prolonged heating and stirring, and column chromatography also resulted in rapid decomposition of the product on the column.

[0209] Example 26: Experimental Study on the Effects of Different Epoxy Compounds

[0210] To synthesize L Taking benzyl glutamate nitrogen-carboxylic acid anhydride as an example, the specific experimental procedure is the same as in Example 1, except that ethylene oxide, dimethyl ethylene oxide or cyclohexyl epoxide are used as absorbents respectively.

[0211] 1. Ethylene oxide absorbent

[0212] Will L L-Glutamic acid benzyl ester (1.0 g, 4.2 mmol, 1 equivalent) was added to a thick-walled, pressure-resistant flask, followed by 9 mL of analytical grade tetrahydrofuran, 8 mL of ethylene oxide in THF solution (3 M in THF, 6 equivalents), and triphosgene (637.3 mg, 2.1 mmol, 0.5 equivalents). The mixture was stirred at room temperature for 1.5 hours. After washing with water and crystallization, the final product, L-glutamic acid benzyl ester N-carboxylic acid anhydride (1.0 g, 93% yield), was obtained.

[0213] 2. Gem-dimethyl ethylene oxide absorbent

[0214] Will L L-Glutamic acid benzyl ester (1.0 g, 4.2 mmol, 1 equivalent) was added to a thick-walled, pressure-resistant flask, followed by 15 mL of analytical grade tetrahydrofuran, gem-dimethyl ethylene oxide (1.47 g, 20 mmol, 4.8 equivalent), and triphosgene (642.5 mg, 2.1 mmol, 0.5 equivalent). The mixture was stirred at room temperature for 1.5 hours. The solution was then evaporated to dryness and filtered through a silica gel column to obtain the final product, L-glutamate benzyl ester N-carboxylic acid anhydride (272.2 mg, 25% yield).

[0215] 3. Use cyclohexyl epoxy absorbent

[0216] L-Glutamic acid benzyl ester (1.0 g, 4.2 mmol, 1 equivalent) was added to a thick-walled, pressure-resistant flask, followed by 15 mL of analytical grade tetrahydrofuran, cyclohexylethylene oxide (2.5 g, 25 mmol, 6.0 equivalent), and triphosgene (626.4 mg, 2.1 mmol, 0.5 equivalent). The mixture was stirred at room temperature for 1.5 hours. The solution was then evaporated to dryness and filtered through a silica gel column to obtain the final product, L-glutamic acid benzyl ester N-carboxylic acid anhydride (546.3 mg, 49% yield).

[0217] 4. Use epichlorohydrin absorbent

[0218] L-Glutamic acid benzyl ester (1.0 g, 4.2 mmol, 1 equivalent) was added to a thick-walled, pressure-resistant flask, followed by 15 mL of analytical grade tetrahydrofuran, epichlorohydrin (1.3 mL, 16.8 mmol, 4 equivalents), and triphosgene (632.5 mg, 2.1 mmol, 0.5 equivalents). The mixture was stirred at room temperature for 1.5 hours. After washing with water and crystallization, the final product, L-glutamic acid benzyl ester N-carboxylic acid anhydride (959 mg, yield 86%), was obtained.

[0219] The experimental results are summarized in Table 1.

[0220] Table 1: Effects of epichlorohydrin absorbent

[0221]

[0222]

[0223] Example 27: Synthesis of β-alanine N-carboxylic acid anhydride

[0224]

[0225] β-Alanine (1.0 g, 11.2 mmol, 1 equivalent) was added to a thick-walled, pressure-resistant flask, followed by 40 mL of analytical grade tetrahydrofuran. Under magnetic stirring, epichlorohydrin (3.5 mL, 44.9 mmol, 4 equivalents) was added, and the mixture was stirred until homogeneous. Then, triphosgene (1.67 g, 5.6 mmol, 0.5 equivalents) was added under atmospheric conditions. The reaction was allowed to proceed at room temperature for 14 hours. The mixture was then evaporated to dryness and crystallized to give the final product, β-alanine N-carboxylic anhydride (879 mg, 68% yield).

[0226] The 1H and 1C NMR spectra of β-alanine N-carboxylic acid anhydride are as follows:

[0227] 1 H NMR (400MHz, DMSO-d6) δ8.38 (s, 1H), 3.26 (td, J = 6.7, 2.8 Hz, 2H), 2.75 (t, J = 6.7 Hz, 2H).

[0228] 13 C NMR (101MHz, DMSO-d6) δ167.0, 149.6, 34.3, 28.3.

[0229] Example 28: Synthesis of 3-amino-3-(4-methylphenyl)propionic acid nitrogen-carboxylic acid anhydride

[0230]

[0231] 1.0 g (5.6 mmol, 1 equivalent) of 3-amino-3-(4-methylphenyl)propionic acid was added to a thick-walled, pressure-resistant flask, followed by 30 mL of analytical grade tetrahydrofuran. Under magnetic stirring, 1.8 mL (22.3 mmol, 4 equivalents) of epichlorohydrin was added, and the mixture was stirred until homogeneous. Then, triphosgene (826.6 mg, 2.8 mmol, 0.5 equivalents) was added under atmospheric conditions. The mixture was reacted at room temperature for 4 hours, evaporated to dryness, and crystallized to give the final product, 1.017 g (89% yield), of 3-amino-3-(4-methylphenyl)propionic acid N-carboxylic anhydride.

[0232] The 1H and 1C NMR spectra of 3-amino-3-(4-methylphenyl)propionic acid nitrogen-carboxylic acid anhydride are shown below:

[0233] 1 H NMR(400MHz, DMSO-d6)δ8.90(d,J=3.0Hz,1H),7.21(s,4H),4.76(td,J=6.2,3.0 Hz, 1H), 3.13 (dd, J=16.1, 6.2Hz, 1H), 2.94 (dd, J=16.1, 6.2Hz, 1H), 2.29 (s, 3H).

[0234] 13 C NMR (101MHz, DMSO) δ166.1,149.3,137.5,136.7,129.4,126.0,49.0,36.3,20.7.

[0235] Example 29: Synthesis of 3-amino-3-(4-chlorophenyl)propionic acid nitrogen-carboxylic acid anhydride

[0236]

[0237] 1.0 g (5.0 mmol, 1 equivalent) of 3-amino-3-(4-chlorophenyl)propionic acid was added to a thick-walled, pressure-resistant flask. 30 mL of analytical grade tetrahydrofuran was added, followed by epichlorohydrin (1.6 mL, 20.0 mmol, 4 equivalents) under magnetic stirring. After thorough mixing, triphosgene (755.6 mg, 2.5 mmol, 0.5 equivalents) was added under atmospheric conditions. The reaction was allowed to proceed at room temperature for 3 hours. The mixture was then evaporated to dryness and crystallized to give the final product, 3-amino-3-(4-chlorophenyl)propionic acid N-carboxylic anhydride (953 mg, 84% yield).

[0238] The 1H and 1C NMR spectra of the nitrogen-carboxylic acid anhydride of 3-amino-3-(4-chlorophenyl)propionic acid are as follows:

[0239] 1 H NMR (400MHz, DMSO-d6) δ8.95(d,J=2.8Hz,1H),7.48(d,J=8.1Hz,2H),7.37(d,J=8.1H z,2H),4.86–4.80(m,1H),3.15(dd,J=16.1,5.5Hz,1H),2.98(dd,J=16.1,7.2Hz,1H).

[0240] 13 C NMR (101MHz, DMSO) δ165.8,149.2,138.6,132.8,128.8,128.2,48.8,36.0.

[0241] Example 30: Synthesis of ε-nitro-trifluoroacetyl-L-lysine nitrogen-carboxyl anhydride

[0242]

[0243] ε-N-trifluoroacetyl-L-lysine (1.0 g, 4.1 mmol, 1 equivalent) was added to a thick-walled, pressure-resistant flask, followed by 20 mL of analytical grade tetrahydrofuran. Under magnetic stirring, propylene oxide (1.2 mL, 16.4 mmol, 4 equivalents) was added, and the mixture was stirred until homogeneous. Then, triphosgene (624.3 mg, 2.0 mmol, 0.5 equivalents) was added under atmospheric conditions. The reaction was allowed to proceed at room temperature for 3 hours, followed by rotary evaporation to dryness and crystallization to obtain the final product, ε-N-trifluoroacetyl-L-lysine N-carboxylic anhydride (953 mg, 84% yield).

[0244] The 1H and 1C NMR spectra of ε-nitro-trifluoroacetyl-L-lysine nitrogen-carboxyl anhydride are shown below:

[0245] 1H NMR (400MHz, DMSO-d6) δ9.42(t,J=6.5Hz,1H),9.10(s,1H),4.43(t,J=6.5Hz,1H),3.17(q,J=6.5Hz,2H),1.75( ddt,J=15.5,10.6,5.2Hz,1H),1.69–1.59(m,1H),1.49(p,J=7.4Hz,2H),1.43–1.34(m,1H),1.34–1.21(m,1H).

[0246] 13 C NMR (101MHz, DMSO) δ171.7,156.8,156.4,156.0,155.7,152.0,120.3,117.4,114.6,111.7,57.0,30.6,27.7,21.6.

[0247] Example 31: Synthesis of L-valine N-Carboxylic Anhydride

[0248]

[0249] L-valine (1.0 g, 8.5 mmol, 1 equivalent) was added to a thick-walled, pressure-resistant flask, followed by 20 mL of analytical grade tetrahydrofuran. Under magnetic stirring, propylene oxide (2.4 mL, 34.0 mmol, 4 equivalents) was added, and the mixture was stirred until homogeneous. Then, triphosgene (1.29 g, 4.3 mmol, 0.5 equivalents) was added under atmospheric conditions. The mixture was reacted at room temperature for 4 hours, washed with water, dried, and crystallized to obtain the final product, L-valine N-carboxylic anhydride (890 mg, 72% yield).

[0250] The proton and carbon NMR spectra of L-valine nitrogen-carboxylic acid anhydride are as follows:

[0251] 1 H NMR (400MHz, Chloroform-d) δ 6.85 (br, 1H), 4.22 (dd, J = 4.2, 1.0 Hz, 1H), 2.25 (heptd, J = 6.9, 4.2 Hz, 1H), 1.08 (d, J = 6.9 Hz, 3H), 1.03 (d, J = 6.9 Hz, 3H).

[0252] 13 C NMR (101MHz, Chloroform-d) δ169.1, 153.7, 63.2, 30.9, 18.3, 16.7.

[0253] Example 32: Synthesis of L-Leucine N-Carboxylic Anhydride

[0254]

[0255] L-Leucine (2.0 g, 15.2 mmol, 1 equivalent) was added to a thick-walled, pressure-resistant flask, followed by 40 mL of analytical grade tetrahydrofuran. Under magnetic stirring, propylene oxide (6.0 mL, 91.0 mmol, 6 equivalents) was added, and the mixture was stirred until homogeneous. Then, triphosgene (2.30 g, 7.6 mmol, 0.5 equivalents) was added under atmospheric conditions. The mixture was reacted at room temperature for 3 hours, washed with water, dried, and crystallized to obtain the final product, L-leucine N-carboxylic anhydride (1.70 g, 70% yield).

[0256] The proton and carbon NMR spectra of L-leucine nitrogen-carboxylic acid anhydride are as follows:

[0257] 1H NMR (400MHz, DMSO-d6) δ9.13 (br, 1H), 4.45 (dd, J = 8.7, 5.5Hz, 1H), 1.81–1.65 (m, 1H), 1.65–1.49 (m, 2H), 0.92–0.85 (m, 6H).

[0258] 13 C NMR (101MHz, DMSO-d6) δ172.1,152.0,55.6,40.1,24.2,22.8,21.2.

[0259] Example 33: Synthesis of poly-β-alanine

[0260]

[0261] β-alanine N-carboxylic acid anhydride (150 mg, 1.3 mmol, 50 equivalents) was added to a glass vial, followed by 4 mL of chromatographically pure N,N-dimethylformamide and 26 μL of benzylamine initiator (1 M N,N-dimethylformamide solution). The mixture was reacted at room temperature for 30 hours, precipitated with diethyl ether, and dried under vacuum to obtain the final product, poly-β-alanine (91 mg, 99% yield). Degree of polymerization: 50.

[0262] The 1H NMR spectrum of poly-β-alanine is as follows:

[0263] 1H NMR (400MHz, Chloroform-d) δ3.78–3.62(m,2H),2.86–2.72(m,2H).

[0264] Example 34: Polymer L - Comparative experiment on the synthesis of glutamate

[0265] 1. Previous synthetic routes

[0266]

[0267] In an Erlenmeyer flask, 10 g of L-glutamic acid was weighed and added to 50 mL of benzyl alcohol. 6 mL of concentrated sulfuric acid was added dropwise at 0°C, and the reaction was continued at 0°C for 16 h. The mixture was then neutralized and washed with isopropanol and triethylamine, precipitated with diethyl ether, and dried. 10 g of L-glutamic acid benzyl ester was obtained, with a yield of 42%.

[0268] Will L 5.0 g (21.1 mmol, 1 equivalent) of benzyl glutamate was added to a thick-walled, pressure-resistant flask, followed by 60 mL of analytical grade tetrahydrofuran. Under magnetic stirring, 15.3 mL (211 mmol, 10 equivalent) of propylene oxide was added, and the mixture was stirred until homogeneous. Then, under atmospheric conditions, 3.184 g (10.5 mmol, 0.5 equivalent) of triphosgene was added, and the mixture was stirred at room temperature for 1.5 hours. The mixture was washed with water, extracted with ethyl acetate, dried, and subjected to diffusion crystallization to obtain the final product. L - Glutamic acid benzyl ester nitrogen-carboxylic acid anhydride (5.159 g, yield 93%).

[0269] Will L 201 mg, 0.8 mmol, 50 equivalents of benzyl glutamate N-carboxylic acid anhydride were added to a glass vial, followed by 4 mL of chromatographically pure N,N-dimethylformamide and 15 μL of benzylamine initiator (1 M N,N-dimethylformamide solution). The mixture was reacted at room temperature for 30 hours, precipitated with diethyl ether, and dried under vacuum to obtain the final product, polybenzyl glutamate. L -Glutamic acid (100mg, yield 60%).

[0270] polybenzyl L 100 mg of L-glutamic acid was dissolved in 5 mL of tetrahydrofuran, and 1 mL of hydrobromic acid-acetic acid solution was added. The mixture was sealed and reacted at room temperature for 3 days to precipitate, yielding 40 mg of poly-L-glutamic acid with a yield of 68%.

[0271] The total yield of the four steps is 16%.

[0272] 2. Gather L Direct two-step synthesis of glutamate

[0273]

[0274] Will L 1.0 g (6.8 mmol, 1 equivalent) of glutamic acid was added to a thick-walled, pressure-resistant flask, followed by 15 mL of analytical grade tetrahydrofuran. Under magnetic stirring, epichlorohydrin (2.1 mL, 68.0 mmol, 10 equivalents) was added, and the mixture was stirred until homogeneous. Then, triphosgene (1.01 g, 3.4 mmol, 0.5 equivalents) was added under atmospheric conditions. The mixture was reacted at room temperature for 20 hours, dried, and crystallized to obtain the final product. L -Glutamic acid nitrogen-carboxylic acid anhydride (1.0 g, yield 89%).

[0275] Will L Glutamic acid nitrogen-carboxylic acid anhydride (200 mg, 1.2 mmol, 20 equivalents) was added to a glass bottle, followed by 4 mL of chromatographically pure N,N-dimethylformamide and 58 μL of benzylamine initiator (1 M N,N-dimethylformamide solution). The mixture was reacted at room temperature for 30 hours, precipitated with diethyl ether, and dried under vacuum to obtain the final product, poly(N,N-dimethylformamide). L -Glutamic acid (120 mg, yield 80%). Degree of polymerization N is 20.

[0276] The total yield for both steps is 72%.

[0277] Gather L The 1H NMR spectrum of -glutamate is as follows:

[0278] 1 H NMR (400MHz, DMSO-d6) δ4.40–3.92(m,1H),3.89–3.11(m,2H),2.41–2.16(m,1H),2.04–1.67(m,1H).

[0279] SEC characterization Figure 2 .

[0280] It should be understood that although the invention has been described in conjunction with its detailed description, the foregoing description is intended to illustrate, and not limit, the scope of the invention as defined by the appended claims. Other aspects, advantages, and modifications are within the scope of the appended claims.

[0281] The structural formulas and names of different amino acids and products in the examples are as follows:

[0282] Amino acids:

[0283]

[0284] product:

[0285]

Claims

1. A method for preparing a compound of formula (II), the method comprising reacting a compound of formula (I) with a cyclizing agent to generate a compound of formula (II) and an acid, and using an epoxide as an acid scavenger. ， ， in: R1 is -R4-R5-R6, where R4 is H, an unsubstituted C, or a C that is substituted with a hydroxyl or thiol group. 1-6 Straight-chain or branched alkyl, unsubstituted or halogenated, C 1-6 C-substituted with alkyl, hydroxyl, mercapto, carboxyl, or aryl groups 1-6 Alkoxy, carboxyl, amino, carbonylamino or aminocarbonyl, guanidinyl, unsubstituted or hydroxylated phenyl, unsubstituted or hydroxylated benzyl, indolyl, imidazolyl, guanidinyl or carbonyl-C 1-6 Alkoxy or C 1-6 alkoxycarbonyl; R5 is absent, oxygen, selenyl, thio, carbonyl, ester, ester imino or imino ester, imino, amino, carbonyl amino, carbonyl imino or imino carbonyl, benzyl ester, unsubstituted or hydroxylated phenyl, unsubstituted or hydroxylated benzyl, indole, imidazolyl, guanidinyl, carbonyl-C 1-6 Alkoxy or C 1-6 Alkoxy carbonyl, hydroxyl, thiol, or carboxyl groups; R6 is absent, H, unsubstituted or substituted with hydroxyl, thiol or halogen C. 1-6 Straight-chain or branched alkyl groups; unsubstituted or halogenated, C 1-6 C-substituted with alkyl, hydroxyl, mercapto, carboxyl, or aryl groups 1-6 Alkoxy, hydroxyl, carboxyl, thiol, amino, carbonylamino, guanidinyl, unsubstituted or hydroxyl-substituted phenyl, Boc or Cbz, unsubstituted or hydroxyl-substituted phenyl-C 1-6 Alkyl, indolyl, imidazolyl, guanidinyl, carbonyl-C 1-6 Alkoxy or C 1-6 Alkoxycarbonyl, benzyl ester, benzyl iminocarbonyl-C 1-6 Alkyl, trifluoroacetyl, tert-butoxycarbonyl, or -[O(CH2)] m1 ] m2 -O-R7; Where R7 is H, or C that is unsubstituted or substituted with a hydroxyl or thiol group. 1-6 Straight-chain or branched alkyl, unsubstituted or halogenated, C 1-6 C-substituted with alkyl, hydroxyl, mercapto, carboxyl, or aryl groups 1-6 Alkoxy, carbonyl-C 1-6 Alkyl or imino-C 1-6 Alkyl group; m1 and m2 are each independent integers from 1 to 6; Alternatively, R1 is unsubstituted or replaced by halogen, hydroxyl, or C. 1-6 Alkyl, mercapto, carboxyl mono, di, or trisubstituted aryl groups, R2 is N, O or S, or R1 and R2 together with the carbon atoms attached to them form a 3-7 membered ring, wherein the 3-7 membered ring is optionally substituted with a halogen, mercapto or hydroxyl group, wherein the 3-7 membered ring is indolyl, imidazolyl, pyrrolidinyl, mercaptopyrrolidinyl or hydroxypyrrolidinyl. R3 indicates the absence of H, halogen, or C that is unsubstituted or substituted with a hydroxyl or thiol group. 1-6 Straight-chain or branched alkyl, unsubstituted or halogenated, C 1-6 C-substituted with alkyl, hydroxyl, mercapto, carboxyl, or aryl groups 2-6 Straight-chain or branched alkenyl or ynyl, C 1-6 Alkyl or aryl, wherein one or more hydrogen atoms are optionally substituted with halogens, or R3 is Boc or Cbz. The aryl group is phenyl, biphenyl, or naphthyl, and the phenyl, biphenyl, or naphthyl group is unsubstituted or converted by halogen, hydroxyl, or C. 1-6 Alkyl, mercapto, and carboxyl groups are mono, di, or trisubstituted. The epoxy compound is selected from one or more of the following: ethylene oxide, propylene oxide, 1,2-epoxybutane, dimethyl ethylene oxide, cyclohexane oxide, and their halogen-substituted derivatives. The cyclizing agent is selected from one or more of the following: phosgene, diphosgene, and triphosgene.

2. The preparation method according to claim 1, wherein the halogen-substituted derivative is epichlorohydrin.

3. The preparation method according to claim 1, wherein R1 is H, or C that is unsubstituted or substituted with hydroxyl or thiol groups. 1-6 Straight-chain or branched alkyl groups, or BnNHCOCH2CH2SeCH2CH2.

4. The preparation method according to claim 1, wherein R1 is a linear or branched C 1-6 Alkyl, C 1-6 Alkyl hydroxyl, C 1-6 Alkyl mercapto, C 1-6 Alkylamino, C 1-6 Alkyl carbonyl amino, C 1-6 Alkylphenyl, C 1-6 Alkylguanidine, C 1-6 Alkyl thio C 1-6 Alkyl, C 1-6 Alkyloxy C 1-6 alkyl.

5. The preparation method according to claim 1, wherein the aryl group is substituted with a hydroxyl or a thiol group.

6. The preparation method according to claim 1, wherein the amino, hydroxyl, or carboxyl group is protected.

7. The preparation method according to claim 1, wherein R1 is H, CH3, CH(CH3)2, CH2CH(CH3)2, CH(CH3)CH2CH3, CH2-C6H5, methylindole, CH2-C6H4-OH, CH2-COOH, CH2-CONH2, (CH2)2-COOH, (CH2)4-NH2, (CH2)2-CONH2, (CH2)2-S-CH3, CH2-OH, CH(CH3)-OH, CH2-SH, methylimidazolyl, BnCO2NH(CH2)4, BnCO2(CH2)2, CH2-CH2-CH2-CN3H4, BnNHCOCH2CH2SeCH2CH2, CH3O(CH2CH2O)3COCH2CH2, SHC(CH3)2, C6H5, C(CH3)3OCH3, or trifluoroacetyliminobutyl.

8. The preparation method according to claim 1, wherein R2 is N or O.

9. The preparation method according to claim 8, wherein R3 is absent, H or methyl, or wherein R1 and R2 together with the carbon atoms attached thereto form a pyrrolidinyl or hydroxypyrrolidinyl group.

10. The preparation method according to claim 9, wherein the imino group is protected.

11. The preparation method according to claim 1, wherein the compound of formula (I) is an amino acid or a Boc or Cbz-protected derivative of the amino acid, wherein the amino acid is selected from the group consisting of glycine, alanine, valine, leucine, isoleucine, methionine, proline, tryptophan, serine, tyrosine, cysteine, phenylalanine, asparagine, glutamine, threonine, aspartic acid, glutamic acid, lysine, arginine, histidine, ε-nitrobenzyloxycarbonyllysine, benzyl glutamate, sarcosine, hydroxyproline, (S)-2-amino-4-((3-(benzylamino)-3-oxypropyl)selenoyl)butyric acid, γ-(2-(2-(2-(2-methoxyethoxy)ethoxy)glutamic acid, penicillamine, L-phenyllactic acid, L-mandelic acid, or oxy-tert-butyl-serine, or ε-nitro-trifluoroacetyl-L-lysine, and The compound of formula (II) is a carboxyl ring anhydride of the corresponding amino acid or a Boc or Cbz protected derivative of the amino acid.

12. The preparation method according to claim 11, wherein the carboxyl ring anhydride is an N- or O-carboxyl ring anhydride.

13. The preparation method according to any one of claims 1-12, wherein the method is carried out under atmospheric conditions, and / or the method is carried out at room temperature or under conditions without heating.

14. The preparation method according to any one of claims 1-12, further comprising the steps of crystallization and / or column chromatography.

15. A method for preparing a compound of formula (V), said method comprising reacting a compound of formula (IV) with a cyclizing agent to generate a compound of formula (V) and an acid, and using an epoxide as an acid scavenger. ， ， Where R is N, O, or S; R1 indicates the absence of H, halogen, or C that is unsubstituted or substituted with a hydroxyl or thiol group. 1-6 Straight-chain or branched alkyl groups, C 2-6 Straight-chain or branched alkenyl or alkynyl or C 1-6 Alkoxy, wherein one or more hydrogen atoms are optionally substituted with halogens, or R1 represents Boc or Cbz; R2 is H, or C that is unsubstituted or substituted with a hydroxyl or thiol group. 1-6 Straight-chain or branched alkyl groups, carbonyloxy groups -C 1-6 Alkyl, or unsubstituted or halogenated, C 1-6 C-substituted with alkyl, hydroxyl, mercapto, carboxyl, or aryl groups 1-6 alkoxy or aryl, wherein the aryl group is phenyl, biphenyl, or naphthyl, and wherein the phenyl, biphenyl, or naphthyl group is unsubstituted or converted by halogen, hydroxyl, or C. 1-6 Alkyl, mercapto, and carboxyl groups are mono, di, or trisubstituted. The epoxy compound is selected from one or more of the following: ethylene oxide, propylene oxide, 1,2-epoxybutane, dimethyl ethylene oxide, cyclohexane oxide, and their halogen-substituted derivatives. The cyclizing agent is selected from one or more of the following: phosgene, diphosgene, and triphosgene.

16. The preparation method according to claim 15, wherein, R2 is a halogenated or C 1-6 A straight-chain or branched alkyl, hydroxyl, or thiol-substituted phenyl group.

17. The preparation method according to claim 15, wherein R2 is methylphenyl or methyl ester, ethyl ester, or propyl ester.

18. The preparation method according to claim 15, wherein the method is carried out under atmospheric conditions, and / or the method is carried out at room temperature or under conditions without heating.

19. The preparation method according to claim 15 further includes the steps of crystallization and / or column chromatography.

20. The preparation method according to claim 15, wherein the compound of formula (IV) is β-alanine, 3-amino-3-(4-methylphenyl)propionic acid or 3-amino-3-(4-chlorophenyl)propionic acid, and the compound of formula (V) is β-alanine nitrogen-carboxylic acid anhydride, 3-amino-3-(4-chlorophenyl)propionic acid nitrogen-carboxylic acid anhydride or 3-amino-3-(4-methylphenyl)propionic acid nitrogen-carboxylic acid anhydride.

21. A method for forming a copolymer, comprising the steps of the preparation method of any one of claims 15-20, and further comprising the step of forming a copolymer from a compound of formula (V).

22. A method for synthesizing a polymer, comprising preparing a compound of formula (II) using the method of any one of claims 1-14 and / or preparing a compound of formula (V) using the method of any one of claims 15-20, and polymerizing one or more compounds of the same or different formula (II) and / or one or more compounds of the same or different formula (V) to form a polymer.

23. The method of claim 22, wherein the polymer is a polyamino acid.

24. A method for preparing L-alanine-L-glutamic acid-L-lysine-L-tyrosine polypeptide polymers, comprising: L-alanine, L-glutamic acid or L-glutamic acid benzyl ester, and N-ε-trifluoroacetyl- L -Lysine or L-tyrosine reacts with a cyclizing agent to generate the corresponding amino acid N-carboxyl ring anhydride and acid, wherein an epoxide is used as an acid remover in the preparation of one or more corresponding amino acid N-carboxyl ring anhydrides. Then, the corresponding amino acid N-carboxyl ring anhydride is polymerized to form an L-alanine-L-glutamic acid-L-lysine-L-tyrosine polypeptide polymer. The cyclizing agent is selected from one or more of the following: phosgene, diphosgene, and triphosgene; The epoxy compound is selected from one or more of the following: ethylene oxide, propylene oxide, 1,2-epoxybutane, dimethyl ethylene oxide, cyclohexane oxide, and their halogen-substituted derivatives.

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