A method of synthesizing a linker-mmaf

Abstract

The application relates to a method for synthesizing a linker-MMAF, comprising the following steps: S2. a condensation reaction of compound III and compound IV to obtain compound V; wherein in the step S2, the condensation reaction is carried out in the presence of a condensing agent 1-propylphosphonic anhydride. The synthesis method of the application does not need reverse preparation, is simple to operate, effectively reduces the refining cost, and when refining, the product yield is improved while high-purity products are obtained.

Description

Technical Field

[0001] This invention belongs to the field of organic chemical synthesis technology, and specifically relates to a method for synthesizing linker-MMAF. Background Technology

[0002] Antibody-drug conjugates (ADCs), as a type of targeted anticancer drug, perfectly combine monoclonal antibodies and highly effective cytotoxins. They fully utilize the advantages of monoclonal antibodies in terms of targeting and high selectivity, while also taking advantage of the high killing power of cytotoxins against tumor cells. At the same time, because the drug formed after the cytotoxin and antibody are conjugated has very low toxicity to healthy cells, it effectively solves the problem of the high toxicity of single cytotoxins to the body.

[0003] When selecting cytotoxins, MMAF, as an anti-mitotic auristatin derivative, shows high potential. Existing linker-MMAF synthesis methods commonly involve protecting the carboxylic acid terminus of MMAF with a methyl group, condensing the linker and MMAF, and then removing the methyl ester. However, during the hydrolysis of the methyl ester, some linkers are easily detached or broken, making the crude product difficult to purify and requiring HPLC preparation, which is costly. Furthermore, common condensing agents generally have poor reaction rates during the condensation of the linker and MMAF, resulting in numerous impurities. Summary of the Invention

[0004] The problem the invention aims to solve

[0005] To address the aforementioned problems in the prior art, this invention provides a method for synthesizing linker-MMAF, which results in a more thorough reaction, fewer impurities, and a higher purity product while improving product yield.

[0006] Solution for solving the problem

[0007] The first objective of this invention is to provide a method for preparing compound V, comprising the following steps:

[0008]

[0009] S2. Compound III and compound IV undergo a condensation reaction to give compound V;

[0010] In step S2, the condensation reaction is carried out in the presence of the condensing agent 1-propylphosphonic anhydride.

[0011] Preferably, step S2 is carried out in organic solvent A.

[0012] Preferably, the organic solvent A is one or more of dichloromethane, tetrahydrofuran, 2-methyltetrahydrofuran, and N,N-dimethylformamide, and is preferably dichloromethane.

[0013] Preferably, in step S2, the condensation reaction is carried out in the presence of an organic base.

[0014] Preferably, the organic base is one or more of piperidine, triethylamine, N,N-diisopropylethylamine, and pyridine, and more preferably N,N-diisopropylethylamine.

[0015] The second objective of this invention is to provide a method for synthesizing linker-MMAF, characterized by comprising the following steps:

[0016]

[0017] S2. Compound III and compound IV undergo a condensation reaction to give compound V;

[0018] S3. Compound V is deprotected to give compound VI;

[0019] S4. Compound VI and RM undergo a condensation reaction to give compound VII;

[0020] S5. Compound VII was deprotected to give compound I;

[0021] In step S2, the condensation reaction is carried out in the presence of the condensing agent 1-propylphosphonic anhydride.

[0022] R- stands for connector;

[0023] M is selected from -OH and One of them.

[0024] Preferably, R is selected from one of the following L1, L2 and L3 structures:

[0025]

[0026] Preferably, step S2 is carried out in organic solvent A.

[0027] Preferably, the organic solvent A is one or more of dichloromethane, tetrahydrofuran, 2-methyltetrahydrofuran, and N,N-dimethylformamide, and is preferably dichloromethane.

[0028] Preferably, in step S2, the condensation reaction is carried out in the presence of an organic base.

[0029] Preferably, the organic base is one or more of piperidine, triethylamine, N,N-diisopropylethylamine, and pyridine, and more preferably N,N-diisopropylethylamine.

[0030] Preferably, step S3 is carried out in organic solvent B.

[0031] Preferably, the organic solvent B is one or more of dichloromethane, tetrahydrofuran, 2-methyltetrahydrofuran, and N,N-dimethylformamide, and is preferably dichloromethane.

[0032] Preferably, step S3 is performed in the presence of an alkali.

[0033] Preferably, the base is one or more of piperidine and diethylamine, and more preferably diethylamine.

[0034] Preferably, step S4 is carried out in an organic solvent C.

[0035] Preferably, the organic solvent C is one or more of dichloromethane, tetrahydrofuran, 2-methyltetrahydrofuran, and N,N-dimethylformamide, and more preferably N,N-dimethylformamide.

[0036] Preferably, in step S4, the condensation reaction is carried out in the presence of the condensing agent 1-hydroxybenzotriazole.

[0037] Preferably, in step S4, the condensation reaction is carried out in the presence of an organic base.

[0038] Preferably, the organic base is one or more of triethylamine, N,N-diisopropylethylamine, and pyridine, with pyridine being the most preferred.

[0039] Preferably, step S5 is carried out in organic solvent D.

[0040] Preferably, the organic solvent D is one or more of dichloromethane, tetrahydrofuran, 2-methyltetrahydrofuran, and N,N-dimethylformamide, and is preferably dichloromethane.

[0041] Preferably, step S5 is performed in the presence of an acid.

[0042] Preferably, the acid is one or more of hydrochloric acid, sulfuric acid, phosphoric acid, and trifluoroacetic acid, and trifluoroacetic acid is preferred.

[0043] Preferably, the method further includes the following steps:

[0044]

[0045] S1. Compound II was deprotected to give compound III.

[0046] Preferably, step S1 is a reaction in an organic solvent E.

[0047] Preferably, the organic solvent E is one or more of dichloromethane, tetrahydrofuran, 2-methyltetrahydrofuran, and N,N-dimethylformamide, and is preferably dichloromethane.

[0048] Preferably, step S1 is performed in the presence of an alkali.

[0049] Preferably, the base is one or more of piperidine and diethylamine, and more preferably diethylamine.

[0050] Preferably, the method further includes the following steps:

[0051] S6. Compound I from step S5 is slurried with organic solvent F and purified by silica gel column chromatography.

[0052] Preferably, in step S6, the organic solvent F is diethyl ether.

[0053] Preferably, in step S6, the eluent for the silica gel column is a mixed solvent of dichloromethane and methanol.

[0054] Preferably, the volume ratio of the mixed solvent is dichloromethane:methanol = (10-30):1, more preferably dichloromethane:methanol = (15-25):1, and even more preferably dichloromethane:methanol = 20:1.

[0055] The effects of the invention

[0056] In the synthesis steps of this invention, the condensation reaction is carried out using 1-propyl cyclic phosphate anhydride (T3P) as the condensation agent, resulting in a more complete reaction and fewer impurities. Compared to other condensation agents, 1-propyl cyclic phosphate anhydride (T3P) exhibits low toxicity and low allergenicity, is environmentally friendly, and is economically viable. The synthesis method of this invention does not require reverse-phase preparation, is simple to operate, and effectively reduces purification costs. Furthermore, during purification, it yields a high-purity product while simultaneously improving product yield. Detailed Implementation

[0057] To make the technical solution and beneficial effects of the present invention more apparent and understandable, a detailed description is provided below by listing specific embodiments. Unless otherwise defined, the technical and scientific terms used herein have the same meanings as those in the technical field to which this application pertains.

[0058] The first objective of this invention is to provide a method for preparing compound V, comprising the following steps:

[0059]

[0060] S2. Compound III and compound IV undergo a condensation reaction to give compound V;

[0061] In step S2, the condensation reaction is carried out in the presence of the condensing agent 1-propylphosphonic anhydride.

[0062] In some embodiments, step S2 is performed in organic solvent A.

[0063] In some embodiments, the organic solvent A is one or more of dichloromethane, tetrahydrofuran, 2-methyltetrahydrofuran, and N,N-dimethylformamide.

[0064] In some embodiments, the organic solvent A is dichloromethane.

[0065] In some embodiments, the condensation reaction in step S2 is carried out in the presence of an organic base.

[0066] In some embodiments, the organic base is one or more selected from piperidine, triethylamine, N,N-diisopropylethylamine, and pyridine.

[0067] In some embodiments, the organic base is N,N-diisopropylethylamine.

[0068] The second objective of this invention is to provide a method for synthesizing linker-MMAF, comprising the following steps:

[0069]

[0070]

[0071] S2. Compound III and compound IV undergo a condensation reaction to give compound V;

[0072] S3. Compound V is deprotected to give compound VI;

[0073] S4. Compound VI and RM undergo a condensation reaction to give compound VII;

[0074] S5. Compound VII was deprotected to give compound I;

[0075] In step S2, the condensation reaction is carried out in the presence of the condensing agent 1-propylphosphonic anhydride; R- is a linker.

[0076] M is selected from -OH and One of them.

[0077] In some embodiments, R is selected from one of the following L1, L2, and L3 structures:

[0078]

[0079]

[0080] In some embodiments, step S2 is performed in organic solvent A.

[0081] In some embodiments, the organic solvent A is one or more of dichloromethane, tetrahydrofuran, 2-methyltetrahydrofuran, and N,N-dimethylformamide.

[0082] In some embodiments, the organic solvent A is dichloromethane.

[0083] In some embodiments, the condensation reaction in step S2 is carried out in the presence of an organic base.

[0084] In some embodiments, the organic base is one or more selected from piperidine, triethylamine, N,N-diisopropylethylamine, and pyridine.

[0085] In some embodiments, the organic base is N,N-diisopropylethylamine.

[0086] In some embodiments, step S3 is performed in organic solvent B.

[0087] In some embodiments, the organic solvent B is one or more of dichloromethane, tetrahydrofuran, 2-methyltetrahydrofuran, and N,N-dimethylformamide.

[0088] In some embodiments, the organic solvent B is dichloromethane.

[0089] In some embodiments, step S3 is performed in the presence of a base.

[0090] In some embodiments, the base is one or more of piperidine and diethylamine.

[0091] In some embodiments, the base is diethylamine.

[0092] In some embodiments, step S4 is performed in an organic solvent C.

[0093] In some embodiments, the organic solvent C is one or more of dichloromethane, tetrahydrofuran, 2-methyltetrahydrofuran, and N,N-dimethylformamide.

[0094] In some embodiments, the organic solvent C is N,N-dimethylformamide.

[0095] In some embodiments, in step S4, the condensation reaction is carried out in the presence of the condensing agent 1-hydroxybenzotriazole.

[0096] In some embodiments, the condensation reaction in step S4 is carried out in the presence of an organic base.

[0097] In some embodiments, the organic base is one or more of triethylamine, N,N-diisopropylethylamine, and pyridine.

[0098] In some embodiments, the organic base is pyridine.

[0099] In some embodiments, step S5 is performed in organic solvent D.

[0100] In some embodiments, the organic solvent D is one or more of dichloromethane, tetrahydrofuran, 2-methyltetrahydrofuran, and N,N-dimethylformamide.

[0101] In some embodiments, the organic solvent D is dichloromethane.

[0102] In some embodiments, step S5 is performed in the presence of an acid.

[0103] In some embodiments, the acid is one or more of hydrochloric acid, sulfuric acid, phosphoric acid, and trifluoroacetic acid.

[0104] In some embodiments, the acid is trifluoroacetic acid.

[0105] In some embodiments, the method further includes the following steps:

[0106]

[0107] S1. Compound II was deprotected to give compound III.

[0108] In some embodiments, step S1 is a reaction in an organic solvent E.

[0109] In some embodiments, the organic solvent E is one or more of dichloromethane, tetrahydrofuran, 2-methyltetrahydrofuran, and N,N-dimethylformamide.

[0110] In some embodiments, the organic solvent E is dichloromethane.

[0111] In some embodiments, step S1 is performed in the presence of a base.

[0112] In some embodiments, the base is one or more of piperidine and diethylamine.

[0113] In some embodiments, the base is diethylamine.

[0114] In some embodiments, the method further includes the following steps:

[0115] S6. Compound I from step S5 is slurried with organic solvent F and purified by silica gel column chromatography.

[0116] In some embodiments, in step S6, the organic solvent F is diethyl ether.

[0117] In some embodiments, in step S6, the eluent for the silica gel column is a mixed solvent of dichloromethane and methanol.

[0118] In some embodiments, the volume ratio of the mixed solvent is dichloromethane:methanol = (10-30):1.

[0119] In some embodiments, the volume ratio of the mixed solvent is dichloromethane:methanol = (15-25):1.

[0120] In some embodiments, the volume ratio of the mixed solvent is dichloromethane:methanol = 20:1.

[0121] The method of the present invention will be described below through specific embodiments. It should be understood that these embodiments are used to illustrate the basic principles, main features and advantages of the present invention, and the present invention is not limited to the scope of the following embodiments. The implementation conditions used in the embodiments can be further adjusted according to specific requirements, and the implementation conditions not specified are usually the conditions in conventional experiments.

[0122] The following abbreviations are used in this article, and they have the definitions shown below:

[0123] Cit is citrulline;

[0124] Dap stands for dolaproine;

[0125] DCM stands for dichloromethane;

[0126] DEA is diethylamine;

[0127] DIEA is N,N-diisopropylethylamine;

[0128] Dil is dolaisoleuine;

[0129] DMF is N,N-dimethylformamide;

[0130] Fmoc is N-(9-fluorenylmethoxycarbonyl);

[0131] HOBt is 1-hydroxybenzotriazole;

[0132] N-Me-Val is N-methylvaline;

[0133] PAB is p-aminobenzyl;

[0134] PNP is p-nitrophenol;

[0135] MC stands for 6-maleiminohexanoyl (maleiminohexanoyl);

[0136] Phe is phenylalanine;

[0137] TFA stands for trifluoroacetic acid;

[0138] T3P is 1-propyl phosphate cyclic anhydride;

[0139] Valine;

[0140] ODMB is a (2,4-dimethoxybenzyl) ester group;

[0141] Val-Cit is a valine-citrulline dipeptide;

[0142] MMAF stands for N-Me-Val-Val-Dil-Dap-Phe.

[0143] In the following examples, unless otherwise specified, all temperatures are in Celsius; unless otherwise specified, all starting materials and reagents are commercially available or synthesized according to known methods; commercially available materials and reagents are used directly without further purification; unless otherwise specified, commercially available manufacturers include, but are not limited to, Sinopharm Group, Bailingwei Technology Co., Ltd., TCI (Shanghai) Chemical Industry Development Co., Ltd., Shanghai Bid Pharmaceutical Technology Co., Ltd., and Shanghai Mairui Chemical Technology Co., Ltd.

[0144] Unless otherwise specified in the examples, the solution in the reaction refers to an aqueous solution.

[0145] Unless otherwise specified in the examples, the reaction temperature is room temperature, which is 20℃-30℃.

[0146] Example 1: Preparation of Compound III (Dap-Phe-ODMB)

[0147] In a 1L single-necked flask, compound II (Fmoc-Dap-Phe-ODMB) (47.00 g, 0.0665 mol, 1.0 eq) and 500.00 mL of dichloromethane (DCM) were added, and magnetic stirring was started. 94 mL of diethylamine (DEA) was added. The reaction was carried out at 30°C for 12 hours. The reaction was confirmed to be complete, indicating the reaction was finished. The solvent was removed to obtain crude compound III (Dap-Phe-ODMB).

[0148] Example 2: Preparation of compound V (Fmoc-MMAF-ODMB)

[0149] In a 1L three-necked flask, add crude compound III (Dap-Phe-ODMB) (0.0665 mol, 1.0 eq) and 500.00 mL of dichloromethane (DCM), and start magnetic stirring. Add compound IV (Fmoc-N-Me-Val-Val-Dil) (42.42 g, 0.0665 mol, 1.0 eq). Cool in an ice bath, maintaining the internal temperature between 0°C and 10°C, and add 1-propyl phosphate cycloanhydride (T3P) (25.39 g, 0.0798 mol, 1.2 eq), followed by dropwise addition of N,N-diisopropylethylamine (DIEA) (12.89 g, 0.0997 mol, 1.5 eq). After the addition is complete, stir in an ice bath for 10 minutes, then move to room temperature and react for 5 hours. The reaction is considered complete when compound IV (Fmoc-N-Me-Val-Val-Dil) has completely reacted. The reaction solution was washed with water (500.00 mL*1), 5% citric acid aqueous solution (500.00 mL*1), saturated sodium bicarbonate aqueous solution (500.00 mL*1), and saturated brine (500.00 mL*1). The organic layer was dried with anhydrous sodium sulfate, filtered, dissolved, and purified to obtain 66.10 g of compound V (Fmoc-MMAF-ODMB) (purity 95%, yield 90%).

[0150] Example 3: Preparation of compound VI (MMAF-ODMB)

[0151] In a 1L single-necked flask, compound V (Fmoc-MMAF-ODMB) (41.00 g, 0.0371 mol, 1.0 eq) and 400.00 mL of dichloromethane (DCM) were added, and magnetic stirring was started. 82 mL of diethylamine (DEA) was added. The reaction was carried out at 30°C for 12 hours. The reaction was confirmed to be complete, and the reaction was considered finished. The solvent was removed to obtain crude compound VI (MMAF-ODMB). The crude compound VI (MMAF-ODMB) was added to 500.00 mL of petroleum ether and stirred for 2 hours. The mixture was filtered, and the solid was washed with 500.00 mL of petroleum ether to obtain 31.50 g of compound VI (MMAF-ODMB) (purity 95%, yield 96%).

[0152] Example 4: Preparation of MC-MMAF-ODMB

[0153] In a 250 mL three-necked flask, compound VI (MMAF-ODMB) (9.00 g, 0.0102 mol, 1.0 eq) and 90.00 mL of N,N-dimethylformamide (DMF) were added, and magnetic stirring was started. 1-Hydroxybenzotriazole (HOBt) (0.28 g, 0.0020 mol, 0.2 eq) and 6-maleimide hexanoic acid (2.15 g, 0.0102 mol, 1.0 eq) were added. The mixture was cooled in an ice bath, maintaining the internal temperature between 0°C and 10°C, and pyridine (1.21 g, 0.0153 mol, 1.5 eq) was added dropwise. After the addition was complete, the mixture was transferred to an oil bath and reacted at an external temperature of 35°C for 12 hours. The reaction was confirmed to be complete, and the reaction was considered finished. The crude compound MC-MMAF-ODMB was obtained by solvent removal. The crude compound MC-MMAF-ODMB was added to 90.00 mL of diethyl ether and stirred for 2 hours. The mixture was then filtered, and the solid was washed with 90.00 mL of diethyl ether to obtain 11.00 g of crude compound MC-MMAF-ODMB.

[0154] Example 5: Preparation of MC-MMAF

[0155] In a 500 mL single-necked flask, 11.00 g of crude MC-MMAF-ODMB and 110.00 mL of dichloromethane (DCM) were added, and a magnetic stirrer was started. 11.00 mL of trifluoroacetic acid (TFA) was added dropwise. After the addition was complete, the mixture was allowed to react at room temperature for 10 minutes. The reaction was then checked, and the compound MC-MMAF-ODMB was found to be completely reacted, indicating the reaction was finished. The crude compound MC-MMAF was obtained by solvent extraction. The crude compound MC-MMAF was added to 110.00 mL of diethyl ether and stirred for 2 hours. The mixture was filtered, and the solid was washed with 90.00 mL of diethyl ether. The solid was then purified by silica gel column chromatography using a mixed solvent of dichloromethane and methanol (volume ratio: dichloromethane:methanol = 20:1) to yield 7.55 g of compound MC-MMAF (purity 95%, yield 80%).

[0156] Example 6: Preparation of MC-Val-Cit-PAB-MMAF-ODMB

[0157] In a 250 mL three-necked flask, compound VI (MMAF-ODMB) (9.00 g, 0.0102 mol, 1.0 eq) and 90.00 mL of N,N-dimethylformamide (DMF) were added, and magnetic stirring was started. 1-hydroxybenzotriazole (HOBt) (0.28 g, 0.0020 mol, 0.2 eq) and MC-Val-Cit-PAB-PNP (7.53 g, 0.0102 mol, 1.0 eq) were added. The mixture was cooled in an ice bath, maintaining the internal temperature between 0°C and 10°C, and pyridine (1.21 g, 0.0153 mol, 1.5 eq) was added dropwise. After the addition was complete, the mixture was transferred to an oil bath and reacted at an external temperature of 35°C for 12 hours. The reaction was confirmed to be complete, indicating the reaction was finished. The crude product MC-Val-Cit-PAB-MMAF-ODMB was obtained by solvent removal. The crude compound MC-Val-Cit-PAB-MMAF-ODMB was added to 90.00 mL of diethyl ether and stirred for 2 hours. The mixture was then filtered, and the solid was washed with 90.00 mL of diethyl ether to obtain 15.65 g of the crude compound MC-Val-Cit-PAB-MMAF-ODMB.

[0158] Example 7: Preparation of MC-Val-Cit-PAB-MMAF

[0159] In a 500 mL single-necked flask, 15.65 g of crude compound MC-Val-Cit-PAB-MMAF-ODMB and 150.00 mL of dichloromethane (DCM) were added, and magnetic stirring was started. 15.00 mL of trifluoroacetic acid (TFA) was added dropwise. After the addition was complete, the mixture was allowed to react at room temperature for 10 minutes. The reaction was then checked, and the compound MC-Val-Cit-PAB-MMAF-ODMB was found to have reacted completely, indicating the reaction was finished. The solution was removed to obtain crude compound MC-Val-Cit-PAB-MMAF. The crude compound MC-Val-Cit-PAB-MMAF was added to 150.00 mL of diethyl ether and stirred for 2 hours. After filtration, the solid was washed with 90.00 mL of diethyl ether and then purified by silica gel column chromatography. The eluent for the silica gel column chromatography was a mixed solvent of dichloromethane and methanol in a volume ratio of dichloromethane:methanol = 20:1, yielding 11.00 g of compound MC-Val-Cit-PAB-MMAF (purity 95%, yield 81%).

[0160] Example 8: Preparation of MC-Val-Ala-PAB-MMAF-ODMB

[0161] In a 250 mL three-necked flask, compound VI (MMAF-ODMB) (9.00 g, 0.0102 mol, 1.0 eq) and 90.00 mL of N,N-dimethylformamide (DMF) were added, and magnetic stirring was started. 1-hydroxybenzotriazole (HOBt) (0.28 g, 0.0020 mol, 0.2 eq) and MC-Val-Ala-PAB-PNP (6.65 g, 0.0102 mol, 1.0 eq) were added. The mixture was cooled in an ice bath, maintaining the internal temperature between 0°C and 10°C, and pyridine (1.21 g, 0.0153 mol, 1.5 eq) was added dropwise. After the addition was complete, the mixture was transferred to an oil bath and reacted at an external temperature of 35°C for 12 hours. The reaction was confirmed to be complete, indicating the reaction was finished. The crude product MC-Val-Ala-PAB-MMAF-ODMB was obtained by solvent removal. The crude compound MC-Val-Ala-PAB-MMAF-ODMB was added to 90.00 mL of diethyl ether and stirred for 2 hours. The mixture was then filtered, and the solid was washed with 90.00 mL of diethyl ether to obtain 15.50 g of the crude compound MC-Val-Ala-PAB-MMAF-ODMB.

[0162] Example 9: Preparation of MC-Val-Ala-PAB-MMAF

[0163] In a 500 mL single-necked flask, 15.50 g of crude compound MC-Val-Ala-PAB-MMAF-ODMB and 150.00 mL of dichloromethane (DCM) were added, and magnetic stirring was started. 15.00 mL of trifluoroacetic acid (TFA) was added dropwise. After the addition was complete, the mixture was allowed to react at room temperature for 10 minutes. The reaction was then checked, and the compound MC-Val-Ala-PAB-MMAF-ODMB was found to have completely reacted, indicating the reaction was finished. The solution was removed to obtain crude compound MC-Val-Ala-PAB-MMAF. The crude compound MC-Val-Ala-PAB-MMAF was added to 150.00 mL of diethyl ether and stirred for 2 hours. After filtration, the solid was washed with 90.00 mL of diethyl ether and then purified by silica gel column chromatography. The eluent for the silica gel column chromatography was a mixed solvent of dichloromethane and methanol in a volume ratio of 20:1, yielding 10.41 g of compound MC-Val-Ala-PAB-MMAF (purity 95%, yield 82%).

[0164] It should be understood that the above embodiments are exemplary and are not intended to encompass all possible implementations included in the claims. Various modifications and changes can be made to the above embodiments without departing from the scope of this disclosure. Similarly, the various technical features of the above embodiments can be arbitrarily combined to form other embodiments of the present invention that may not be explicitly described. Therefore, the above embodiments only illustrate several implementations of the present invention and do not limit the scope of protection of this patent.

Claims

1. A method for preparing compound V, characterized in that, Includes the following steps: ； S2. Compound III and compound IV undergo a condensation reaction to give compound V; In step S2, the condensation reaction is carried out in the presence of the condensing agent 1-propylphosphonic anhydride. Step S2 involves a reaction in organic solvent A; The organic solvent A is dichloromethane; In step S2, the condensation reaction is carried out in the presence of an organic base; The organic base is N,N-diisopropylethylamine.

2. A method for synthesizing linker-MMAF, characterized in that, Includes the following steps: ； S2. Compound III and compound IV undergo a condensation reaction to give compound V; S3. Compound V is deprotected to give compound VI; S4. Compound VI and RM undergo a condensation reaction to give compound VII; S5. Compound VII was deprotected to give compound I; In step S2, the condensation reaction is carried out in the presence of the condensing agent 1-propylphosphonic anhydride. R- stands for connector; M is selected from -OH and One of them; Step S2 involves a reaction in organic solvent A; The organic solvent A is dichloromethane; In step S2, the condensation reaction is carried out in the presence of an organic base; The organic base is N,N-diisopropylethylamine.

3. The method as described in claim 2, characterized in that, The R is selected from one of the following L1, L2, and L3 structures: ； ； 。 4. The method as described in claim 2, characterized in that, Step S3 involves a reaction in organic solvent B.

5. The method as described in claim 4, characterized in that, The organic solvent B is one or more of dichloromethane, tetrahydrofuran, 2-methyltetrahydrofuran, and N,N-dimethylformamide.

6. The method as described in claim 5, characterized in that, The organic solvent B is dichloromethane.

7. The method as described in claim 2, characterized in that, Step S3 is performed in the presence of an alkali.

8. The method as described in claim 7, characterized in that, The base is one or more of piperidine and diethylamine.

9. The method as described in claim 8, characterized in that, The base is diethylamine.

10. The method as described in claim 2, characterized in that, Step S4 involves a reaction in organic solvent C.

11. The method as described in claim 10, characterized in that, The organic solvent C is one or more of dichloromethane, tetrahydrofuran, 2-methyltetrahydrofuran, and N,N-dimethylformamide.

12. The method as described in claim 11, characterized in that, The organic solvent C is N,N-dimethylformamide.

13. The method as described in claim 2, characterized in that, In step S4, the condensation reaction is carried out in the presence of the condensing agent 1-hydroxybenzotriazole.

14. The method as described in claim 2, characterized in that, In step S4, the condensation reaction is carried out in the presence of an organic base.

15. The method as described in claim 14, characterized in that, The organic base is one or more of triethylamine, N,N-diisopropylethylamine, and pyridine.

16. The method as described in claim 15, characterized in that, The organic base is pyridine.

17. The method as described in claim 2, characterized in that, Step S5 involves a reaction in organic solvent D.

18. The method as described in claim 17, characterized in that, The organic solvent D is one or more of dichloromethane, tetrahydrofuran, 2-methyltetrahydrofuran, and N,N-dimethylformamide.

19. The method as described in claim 18, characterized in that, The organic solvent D is dichloromethane.

20. The method as described in claim 2, characterized in that, Step S5 is performed in the presence of acid.

21. The method as described in claim 20, characterized in that, The acid is one or more of hydrochloric acid, sulfuric acid, phosphoric acid, and trifluoroacetic acid.

22. The method as described in claim 21, characterized in that, The acid is trifluoroacetic acid.

23. The method as described in claim 2, characterized in that, The method further includes the following steps: ； S1. Compound II was deprotected to give compound III.

24. The method as described in claim 23, characterized in that, Step S1 involves a reaction in an organic solvent E.

25. The method as described in claim 24, characterized in that, The organic solvent E is one or more of dichloromethane, tetrahydrofuran, 2-methyltetrahydrofuran, and N,N-dimethylformamide.

26. The method as described in claim 25, characterized in that, The organic solvent E is dichloromethane.

27. The method as described in claim 23, characterized in that, Step S1 is performed in the presence of an alkali.

28. The method as described in claim 27, characterized in that, The base is one or more of piperidine and diethylamine.

29. The method as described in claim 28, characterized in that, The base is diethylamine.

30. The method according to any one of claims 2-29, characterized in that, The method further includes the following steps: S6. Compound I from step S5 is slurried with organic solvent F and purified by silica gel column chromatography.

31. The method as described in claim 30, characterized in that, In step S6, the organic solvent F is diethyl ether.

32. The method as described in claim 30, characterized in that, In step S6, the eluent for the silica gel column is a mixed solvent of dichloromethane and methanol.

33. The method as described in claim 32, characterized in that, The volume ratio of the mixed solvent is dichloromethane:methanol = (10-30):

1.

34. The method as described in claim 33, characterized in that, The volume ratio of the mixed solvent is dichloromethane:methanol = (15-25):

1.

35. The method as described in claim 34, characterized in that, The volume ratio of the mixed solvent is dichloromethane:methanol = 20:1.

Images