A preparation method of cl2a-sn-38 and application thereof

Abstract

The present application relates to a preparation method of CL2A-SN-38, the preparation method comprises the following steps: (1) reaction of intermediate 3 and compound 2 to prepare intermediate 4; (2) dehydroxy protection group and then deamination protection group of intermediate 4 prepared in step (1) to prepare the CL2A-SN-38. The preparation method of CL2A-SN-38 has the advantages of few reaction steps, simple operation, low cost, high purity and yield, and is suitable for industrial production.

Description

Technical Field

[0001] This invention relates to the field of medicinal chemistry, and in particular to a method for preparing CL2A-SN-38 and its application. Background Technology

[0002] CL2A-SN-38 is a drug-linker conjugate composed of the linker CL2A and the potent DNA topoisomerase I inhibitor SN-38. It can be used to prepare antibody-drug conjugates (ADCs). CL2A is a non-cleavable linker containing a PEG8 and triazo PBC-peptide-mc structure. CL2A exhibits pH-sensitive cleavage properties, allowing it to cleave under specific conditions, releasing drug molecules and producing a bystander effect. Furthermore, CL2A can bind antibodies to cysteine ​​residues via disulfide bonds, forming stable antibody-drug conjugates. SN-38 is a potent DNA topoisomerase I inhibitor with significant antitumor activity. When CL2A-SN-38 is used as part of an ADC, SN-38 can be released within tumor cells to exert its antitumor effect.

[0003]

[0004] As a crucial component of ADCs (Advanced Drug Acquisition Methods), CL2A-SN-38 holds significant promise for applications in cancer treatment. By binding to specific antibodies, CL2A-SN-38 can target tumor cells and precisely release drug molecules, thereby achieving highly effective and low-toxicity anti-tumor therapy. Furthermore, with the continuous deepening of ADC research and technological advancements, CL2A-SN-38 is expected to become a treatment option for more cancer patients in the future. Summary of the Invention

[0005] The problem the invention aims to solve

[0006] The purpose of this invention is to provide a method for preparing CL2A-SN-38 suitable for industrial production.

[0007] Solution for solving the problem

[0008] This invention provides a method for preparing CL2A-SN-38, the method comprising the following steps:

[0009] (1) Intermediate 3 was reacted with compound 2 to prepare intermediate 4.

[0010]

[0011] (2) After removing the hydroxyl protecting group and then the amino protecting group from intermediate 4 obtained in step (1), the CL2A-SN-38 is prepared.

[0012]

[0013] Wherein, R2 is an amino protecting group and R3 is a hydroxy protecting group.

[0014] Preferably, R2 is selected from allyloxycarbonyl (ALLOC), tert-butoxycarbonyl (BOC), (4-methoxyphenyl)diphenylmethyl (MMT), 4-methyltriphenylmethyl (MTT), and 9-fluorenoxycarbonyl (Fmoc), with MMT being the most preferred;

[0015] Preferably, R3 is selected from 2-methoxyethoxymethyl (MEM), methoxymethane (MOM), tert-butyldimethylsilyl (TBDMS), tert-butyldiphenylsilyl (TBDPS), triethylsilyl (TES), trimethylsilyl (TMS), triisopropylsilyloxymethyl (TOM), triphenylmethyl (Tr), acetate group, benzoate group, benzyl, tetrahydropyranyl, preferably TBDMS;

[0016] Preferably, compound 2 in step (1) is 10-O-TBDMS-SN-38-20-O-chloroformate;

[0017] Preferably, in step (1), the mass ratio of the intermediate 3 to the compound 2 is 1 to 3:1, preferably 2.17:1;

[0018] Preferably, step (1) occurs in the presence of solvent D;

[0019] Preferably, the solvent D is selected from one or more of chloroform, dichloromethane, trichloromethane, dichloroethane, acetonitrile, benzene, toluene, and tetrahydrofuran, and is preferably dichloromethane.

[0020] Preferably, the dehydroxyl protecting group in step (2) is deprotected using tetrabutylammonium fluoride-tetrahydrofuran;

[0021] Preferably, the deprotection occurs in the presence of solvent E;

[0022] Preferably, the solvent E is selected from one or more of dichloromethane and acetic acid, and more preferably from dichloromethane and acetic acid;

[0023] Preferably, the concentration of the tetrabutylammonium fluoride-tetrahydrofuran is 0.5-2M, more preferably 1M;

[0024] Preferably, after the deprotection is completed, washing, drying, and gradient elution are performed.

[0025] Preferably, the deamination protecting group in step (2) is deprotected using dichloroacetic acid;

[0026] Preferably, the deprotection occurs in the presence of anethole.

[0027] Preferably, the preparation of the intermediate 3 includes the following steps:

[0028] Intermediate 2 was reacted with MCC-acetylene to prepare intermediate 3.

[0029]

[0030] Preferably, the mass ratio of the intermediate 2 to the MCC-acetylene is 1 to 3:1, more preferably 1.93:1;

[0031] Preferably, the preparation of intermediate 3 takes place in the presence of solvent C and a catalyst;

[0032] Preferably, the solvent C is selected from one or more of chloroform, dichloromethane, trichloromethane, dichloroethane, acetonitrile, benzene, toluene, and tetrahydrofuran, and is preferably dichloromethane;

[0033] Preferably, the catalyst is selected from one or more of triphenylphosphine, cuprous bromide, and diisopropylethylamine, and more preferably triphenylphosphine, cuprous bromide, and diisopropylethylamine.

[0034] Preferably, the preparation of intermediate 2 includes the following steps:

[0035] Intermediate 1 was reacted with PEG-N3 to prepare intermediate 2.

[0036]

[0037] Preferably, the mass ratio of intermediate 1 to PEG-N3 is 1:0.8 to 1.2, more preferably 1:1.05;

[0038] Preferably, the preparation of intermediate 2 takes place in the presence of solvent B and an amidating agent;

[0039] Preferably, the solvent B is selected from one or more of chloroform, dichloromethane, trichloromethane, dichloroethane, acetonitrile, benzene, toluene, and tetrahydrofuran, and is preferably dichloromethane;

[0040] Preferably, the amidating agent is selected from one or more of CDI, DCC, EDCI, EEDQ, HATU, and IIDQ, with EEDQ being the most preferred.

[0041] Preferably, the preparation of intermediate 1 includes the following steps:

[0042] Intermediate 1 was prepared by reacting compound 1 with p-aminobenzyl alcohol.

[0043]

[0044] Wherein, R1 is an amino protecting group.

[0045] Preferably, R1 is selected from acetyl, trifluoroacetyl, allyloxycarbonyl (ALLOC), tert-butoxycarbonyl (BOC), benzyloxycarbonyl (CBZ) and 9-fluorenylmethoxycarbonyl (Fmoc), with Fmoc being the most preferred;

[0046] Preferably, the molar ratio of compound 1 to p-aminobenzyl alcohol is 2:1 to 1:2, and more preferably 1:1;

[0047] Preferably, the preparation of intermediate 1 takes place in the presence of solvent A, an amidating agent, and an amine compound.

[0048] Preferably, solvent A is selected from one or more of chloroform, dichloromethane, trichloromethane, dichloroethane, acetonitrile, benzene, toluene, and tetrahydrofuran, and is preferably dichloromethane;

[0049] Preferably, the amidating agent is selected from one or more of CDI, DCC, EDCI, EEDQ, HATU, and IIDQ, with EEDQ being the most preferred;

[0050] Preferably, the amine compound is selected from one or more of trimethylamine, diethylamine, diethanolamine, propylamine, methylisopropylamine, diisopropylamine, and butylamine, and is preferably diethylamine;

[0051] Preferably, the reaction is diluted with a nonpolar solvent after completion;

[0052] Preferably, the nonpolar solvent is selected from one or more of n-hexane, cyclohexane, heptane, benzene, and toluene, with heptane being the most preferred.

[0053] The effects of the invention

[0054] The preparation method of CL2A-SN-38 of this invention has few reaction steps, is simple to operate, has low cost, high purity and high yield, and is suitable for industrial production. Detailed Implementation

[0055] 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.

[0056] This invention provides a method for preparing CL2A-SN-38, the method comprising the following steps:

[0057] (1) Intermediate 3 was reacted with compound 2 to prepare intermediate 4.

[0058]

[0059] (2) After removing the hydroxyl protecting group and then the amino protecting group from intermediate 4 obtained in step (1), the CL2A-SN-38 is prepared.

[0060]

[0061] Wherein, R2 is an amino protecting group and R3 is a hydroxy protecting group.

[0062] In some embodiments, R2 is selected from allyloxycarbonyl (ALLOC), tert-butoxycarbonyl (BOC), (4-methoxyphenyl)diphenylmethyl (MMT), 4-methyltriphenylmethyl (MTT), and 9-fluorenylmethoxycarbonyl (Fmoc).

[0063] In some implementations, R2 is an MMT.

[0064] In some embodiments, R3 is selected from 2-methoxyethoxymethyl (MEM), methoxymethane (MOM), tert-butyldimethylsilyl (TBDMS), tert-butyldiphenylsilyl (TBDPS), triethylsilyl (TES), trimethylsilyl (TMS), triisopropylsilyloxymethyl (TOM), triphenylmethyl (Tr), acetate group, benzoate group, benzyl, tetrahydropyranyl.

[0065] In some implementations, R3 is a TBDMS.

[0066] In some embodiments, compound 2 in step (1) is 10-O-TBDMS-SN-38-20-O-chloroformate.

[0067] In some embodiments, in step (1), the mass ratio of the intermediate 3 to the compound 2 is 1 to 3:1.

[0068] In some embodiments, in step (1), the mass ratio of the intermediate 3 to the compound 2 is 1:1, or 1.1:1, or 1.2:1, or 1.3:1, or 1.4:1, or 1.5:1, or 1.6:1, or 1.7:1, or 1.8:1, or 1.9:1, or 2:1, or 2.1:1, or 2.17:1, or 2.2:1, or 2.3:1, or 2.4:1, or 2.5:1, or 2.6:1, or 2.7:1, or 2.8:1, or 2.9:1, or 3:1.

[0069] In some embodiments, in step (1), the mass ratio of intermediate 3 to compound 2 is 2.17:1.

[0070] In some embodiments, step (1) occurs in the presence of solvent D.

[0071] In some embodiments, the solvent D is selected from one or more of chloroform, dichloromethane, trichloromethane, dichloroethane, acetonitrile, benzene, toluene, and tetrahydrofuran.

[0072] In some embodiments, the solvent D is dichloromethane.

[0073] In some embodiments, the dehydroxyl protecting group in step (2) is deprotected using tetrabutylammonium fluoride-tetrahydrofuran.

[0074] In some embodiments, the deprotection occurs in the presence of solvent E.

[0075] In some embodiments, the solvent E is selected from one or more of dichloromethane and acetic acid.

[0076] In some embodiments, the solvent E is dichloromethane and acetic acid.

[0077] In some embodiments, the concentration of the tetrabutylammonium fluoride-tetrahydrofuran is 0.5-2M.

[0078] In some embodiments, the concentration of the tetrabutylammonium fluoride-tetrahydrofuran is 0.5M, or 0.6M, or 0.7M, or 0.8M, or 0.9M, or 1M, or 1.1M, or 1.2M, or 1.3M, or 1.4M, or 1.5M, or 1.6M, or 1.7M, or 1.8M, or 1.9M, or 2M.

[0079] In some embodiments, the concentration of the tetrabutylammonium fluoride-tetrahydrofuran is 1M.

[0080] In some embodiments, after the deprotection is completed, washing, drying, and gradient elution are performed.

[0081] In some embodiments, the deamination protecting group in step (2) is deprotected using dichloroacetic acid.

[0082] In some embodiments, the deprotection occurs in the presence of anethole.

[0083] In some embodiments, the preparation of the intermediate 3 includes the following steps:

[0084] Intermediate 2 was reacted with MCC-acetylene to prepare intermediate 3.

[0085]

[0086] In some embodiments, the mass ratio of the intermediate 2 to the MCC-acetylene is 1 to 3:1.

[0087] In some embodiments, the mass ratio of the intermediate 2 to the MCC-acetylene is 1:1, or 1.1:1, or 1.2:1, or 1.3:1, or 1.4:1, or 1.5:1, or 1.6:1, or 1.7:1, or 1.8:1, or 1.9:1, or 1.93:1, or 2:1, or 2.1:1, or 2.2:1, or 2.3:1, or 2.4:1, or 2.5:1, or 2.6:1, or 2.7:1, or 2.8:1, or 2.9:1, or 3:1.

[0088] In some embodiments, the mass ratio of the intermediate 2 to the MCC-acetylene is 1.93:1.

[0089] In some embodiments, the preparation of intermediate 3 occurs in the presence of solvent C and a catalyst.

[0090] In some embodiments, the solvent C is selected from one or more of chloroform, dichloromethane, trichloromethane, dichloroethane, acetonitrile, benzene, toluene, and tetrahydrofuran.

[0091] In some embodiments, the solvent C is dichloromethane.

[0092] In some embodiments, the catalyst is selected from one or more of triphenylphosphine, cuprous bromide, and diisopropylethylamine.

[0093] In some embodiments, the catalyst is triphenylphosphine, cuprous bromide, and diisopropylethylamine.

[0094] In some embodiments, the preparation of intermediate 2 includes the following steps:

[0095] Intermediate 1 was reacted with PEG-N3 to prepare intermediate 2.

[0096]

[0097] In some embodiments, the mass ratio of intermediate 1 to PEG-N3 is 1:0.8 to 1.2.

[0098] In some embodiments, the mass ratio of the intermediate 1 to the PEG-N3 is 1:0.8, or 1:0.85, or 1:0.9, or 1:0.95, or 1:1, or 1:1.05, or 1:1.1, or 1:1.15, or 1:1.2.

[0099] In some embodiments, the mass ratio of intermediate 1 to PEG-N3 is 1:1.05.

[0100] In some embodiments, the preparation of intermediate 2 occurs in the presence of solvent B and an amidating agent.

[0101] In some embodiments, solvent B is selected from one or more of chloroform, dichloromethane, trichloromethane, dichloroethane, acetonitrile, benzene, toluene, and tetrahydrofuran.

[0102] In some embodiments, solvent B is dichloromethane.

[0103] In some embodiments, the amidating agent is selected from one or more of carbonyl diimidazole (CDI), dicyclohexyl carbodiimide (DCC), 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDCI), 2-ethoxy-1-ethoxycarbonyl-1,2-dihydroquinoline (EEDQ), 2-(7-azabenzotriazole)-N,N,N',N'-tetramethylurea hexafluorophosphate (HATU), and 1-ethoxycarbonyl-2-isobutyrooxy-1,2-dihydroxyquinoline (IIDQ).

[0104] In some embodiments, the amidating agent is EEDQ.

[0105] In some embodiments, the preparation of intermediate 1 includes the following steps:

[0106] Intermediate 1 was prepared by reacting compound 1 with p-aminobenzyl alcohol.

[0107]

[0108] Wherein, R1 is an amino protecting group.

[0109] In some embodiments, R1 is selected from acetyl, trifluoroacetyl, allyloxycarbonyl (ALLOC), tert-butoxycarbonyl (BOC), benzyloxycarbonyl (CBZ), and 9-fluorenylmethoxycarbonyl (Fmoc).

[0110] In some implementations, R1 is Fmoc.

[0111] In some embodiments, compound 1 is Fmoc-Lys(MMT)-OH.

[0112] In some embodiments, the molar ratio of compound 1 to p-aminobenzyl alcohol is 2:1 to 1:2.

[0113] In some embodiments, the molar ratio of compound 1 to p-aminobenzyl alcohol is 2:1, or 1.9:1, or 1.8:1, or 1.7:1, or 1.6:1, or 1.5:1, or 1.4:1, or 1.3:1, or 1.2:1, or 1.1:1, or 1:1, or 1:1.1, or 1:1.2, or 1:1.3, or 1:1.4, or 1:1.5, or 1:1.6, or 1:1.7, or 1:1.8, or 1:1.9, or 1:2.

[0114] In some embodiments, the molar ratio of compound 1 to p-aminobenzyl alcohol is 1:1.

[0115] In some embodiments, the preparation of intermediate 1 occurs in the presence of solvent A, an amidating agent, and an amine compound.

[0116] In some embodiments, solvent A is selected from one or more of chloroform, dichloromethane, trichloromethane, dichloroethane, acetonitrile, benzene, toluene, and tetrahydrofuran.

[0117] In some embodiments, solvent A is dichloromethane.

[0118] In some embodiments, the amidating agent is selected from one or more of carbonyl diimidazole (CDI), dicyclohexyl carbodiimide (DCC), 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDCI), 2-ethoxy-1-ethoxycarbonyl-1,2-dihydroquinoline (EEDQ), 2-(7-azabenzotriazole)-N,N,N',N'-tetramethylurea hexafluorophosphate (HATU), and 1-ethoxycarbonyl-2-isobutyrooxy-1,2-dihydroxyquinoline (IIDQ).

[0119] In some embodiments, the amidating agent is EEDQ.

[0120] In some embodiments, the amine compound is selected from one or more of trimethylamine, diethylamine, diethanolamine, propylamine, methylisopropylamine, diisopropylamine, and butylamine.

[0121] In some embodiments, the amine compound is diethylamine.

[0122] In some embodiments, the reaction is diluted with a nonpolar solvent after completion.

[0123] In some embodiments, the nonpolar solvent is selected from one or more of n-hexane, cyclohexane, heptane, benzene, and toluene.

[0124] In some embodiments, the nonpolar solvent is heptane.

[0125] Example 1: Preparation of Intermediate 1

[0126]

[0127] In a 1000 mL three-necked flask, 32 g of Fmoc-Lys(MMT)-OH, 6.52 g of p-aminobenzyl alcohol, and 13.04 g of EEDQ were added, followed by 150 mL of anhydrous dichloromethane. After stirring overnight, 50 mL of diethylamine was added, and the mixture was stirred for 6 hours. The reaction mixture was concentrated to approximately 100 mL. Heptane was then added to dilute the mixture, and the solution was concentrated back to 100 mL. This process of adding heptane was repeated twice (100 mL each time) to obtain a two-phase mixture containing a colloidal substance. 50 mL of dichloromethane was added to the colloidal substance, and the mixture was stirred. Then, 160 mL of heptane was slowly added. The mixture was stirred for 1 hour, and the slurry was filtered to give Lys(MMT)-PABOH (intermediate 1), 26.05 g (99.6% yield).

[0128] Example 2: Preparation of Intermediate 2

[0129]

[0130] 23.02 g of Lys(MMT)-PABOH (intermediate 1) and 24.21 g of O-(2-azidoethyl)-O'-(N-dihydroxyacetyl-2-aminoethyl)heptaethylene glycol (PEG-N3) were added to 180 mL of anhydrous dichloromethane. While stirring, 11.08 g of EEDQ was added to the reaction solution. After stirring for approximately 18 hours, the reaction mixture was concentrated and purified by silica gel column chromatography. The product was obtained by elution with ethyl acetate-methanol and concentration.

[0131] Example 3: Preparation of Intermediate 3

[0132]

[0133]

[0134] In a 1000 mL three-necked flask, 130 mL of anhydrous dichloromethane, 10.6 g of O-(2-azidoethyl)-O'-[(N-dihydroxyacetyl-2-aminoethyl)-Lys(MMT)-PABOH]heptaethylene glycol (intermediate 2) and 5.49 g of 4-(N-maleimidemethyl)-N-(2-propynyl)cyclohexane-1-carboxamide (MCC-yne) were added, followed by 0.52 g of triphenylphosphine, 0.34 g of cuprous bromide, and 0.5 mL of diisopropylethylamine. The reaction mixture was stirred at room temperature for 14 hours. The mixture was concentrated and purified by chromatography. The pure product solution was collected and washed with EDTA, water, and brine, and concentrated to give intermediate 3 (11.88 g, 89% yield).

[0135] Example 4: Preparation of Intermediate 4

[0136]

[0137] In a 1000 mL three-necked flask, add 6.15 g of 10-O-TBDMS-SN-38-20-O-chloroformate and 200 mL of anhydrous dichloromethane. Then, slowly add dropwise a solution of 13.35 g of intermediate 3 with 66 mL of anhydrous dichloromethane. React at room temperature for 1.5 h. The reaction mixture is washed successively with 50 mM sodium acetate buffer (pH 5.3), water, and brine, dried over anhydrous sodium sulfate, filtered, and the resulting solution is used directly in the next reaction step.

[0138] Example 5: Preparation of CL2A-SN38

[0139]

[0140] 1. Remove TBDMS:

[0141] Add 15 mL of 1 M tetrabutylammonium fluoride-tetrahydrofuran solution, 20 mL of anhydrous dichloromethane, and 1.5 mL of acetic acid to the previous step solution. Stir the mixture for 2 hours. Wash the reaction mixture sequentially with 0.25 M citrate buffer (pH 6), water, and brine, and dry over anhydrous sodium sulfate. Perform silica gel column chromatography with a methanol-dichloromethane gradient elution, and concentrate to obtain 7.7 g.

[0142] 2. MMT removal:

[0143] The dichloromethane solution of the above product was mixed with 1.67 g of anisole, cooled to <5°C, and 3.47 g of dichloroacetic acid was added. The reaction was carried out for 2 hours. Tert-butyl methyl ether was added, and the mixture was filtered to obtain product CL2A-SN-38 (5.5 g, yield 90%).

[0144] 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 CL2A-SN-38, characterized in that, The preparation method includes the following steps: (1) Intermediate 3 was reacted with compound 2 to prepare intermediate 4. (2) After removing the hydroxyl protecting group and then the amino protecting group from intermediate 4 obtained in step (1), the CL2A-SN-38 is prepared. Wherein, R2 is an amino protecting group and R3 is a hydroxy protecting group.

2. The preparation method according to claim 1, characterized in that, The R2 is selected from allyloxycarbonyl (ALLOC), tert-butoxycarbonyl (BOC), (4-methoxyphenyl)diphenylmethyl (MMT), 4-methyltriphenylmethyl (MTT), and 9-fluorenoxycarbonyl (Fmoc), preferably MMT; Preferably, R3 is selected from 2-methoxyethoxymethyl (MEM), methoxymethane (MOM), tert-butyldimethylsilyl (TBDMS), tert-butyldiphenylsilyl (TBDPS), triethylsilyl (TES), trimethylsilyl (TMS), triisopropylsilyloxymethyl (TOM), triphenylmethyl (Tr), acetate group, benzoate group, benzyl, tetrahydropyranyl, preferably TBDMS; Preferably, compound 2 in step (1) is 10-O-TBDMS-SN-38-20-O-chloroformate; Preferably, in step (1), the mass ratio of the intermediate 3 to the compound 2 is 1 to 3:1, preferably 2.17:1; Preferably, step (1) occurs in the presence of solvent D; Preferably, the solvent D is selected from one or more of chloroform, dichloromethane, trichloromethane, dichloroethane, acetonitrile, benzene, toluene, and tetrahydrofuran, and is preferably dichloromethane.

3. The preparation method according to claim 1, characterized in that, The deprotection of the hydroxyl group in step (2) is performed using tetrabutylammonium fluoride-tetrahydrofuran; Preferably, the deprotection occurs in the presence of solvent E; Preferably, the solvent E is selected from one or more of dichloromethane and acetic acid, and more preferably from dichloromethane and acetic acid; Preferably, the concentration of the tetrabutylammonium fluoride-tetrahydrofuran is 0.5-2M, more preferably 1M; Preferably, after the deprotection is completed, washing, drying, and gradient elution are performed.

4. The preparation method according to claim 1, characterized in that, The deamination protecting group in step (2) is deprotected using dichloroacetic acid; Preferably, the deprotection occurs in the presence of anethole.

5. The preparation method according to any one of claims 1-4, characterized in that, The preparation of intermediate 3 includes the following steps: Intermediate 2 was reacted with MCC-acetylene to prepare intermediate 3.

6. The preparation method according to claim 5, characterized in that, The mass ratio of intermediate 2 to MCC-acetylene is 1 to 3:1, preferably 1.93:1; Preferably, the preparation of intermediate 3 takes place in the presence of solvent C and a catalyst; Preferably, the solvent C is selected from one or more of chloroform, dichloromethane, trichloromethane, dichloroethane, acetonitrile, benzene, toluene, and tetrahydrofuran, and is preferably dichloromethane; Preferably, the catalyst is selected from one or more of triphenylphosphine, cuprous bromide, and diisopropylethylamine, and more preferably triphenylphosphine, cuprous bromide, and diisopropylethylamine.

7. The preparation method according to claim 5, characterized in that, The preparation of intermediate 2 includes the following steps: Intermediate 1 was reacted with PEG-N3 to prepare intermediate 2.

8. The preparation method according to claim 7, characterized in that, The mass ratio of intermediate 1 to PEG-N3 is 1:0.8 to 1.2, preferably 1:1.05; Preferably, the preparation of intermediate 2 takes place in the presence of solvent B and an amidating agent; Preferably, the solvent B is selected from one or more of chloroform, dichloromethane, trichloromethane, dichloroethane, acetonitrile, benzene, toluene, and tetrahydrofuran, and is preferably dichloromethane; Preferably, the amidating agent is selected from one or more of CDI, DCC, EDCI, EEDQ, HATU, and IIDQ, with EEDQ being the most preferred.

9. The preparation method according to claim 7, characterized in that, The preparation of intermediate 1 includes the following steps: Intermediate 1 was prepared by reacting compound 1 with p-aminobenzyl alcohol. Wherein, R1 is an amino protecting group.

10. The preparation method according to claim 9, characterized in that, The R1 is selected from acetyl, trifluoroacetyl, allyloxycarbonyl (ALLOC), tert-butoxycarbonyl (BOC), benzyloxycarbonyl (CBZ) and 9-fluorenylmethoxycarbonyl (Fmoc), preferably Fmoc; Preferably, the molar ratio of compound 1 to p-aminobenzyl alcohol is 2:1 to 1:2, and more preferably 1:1; Preferably, the preparation of intermediate 1 takes place in the presence of solvent A, an amidating agent, and an amine compound. Preferably, solvent A is selected from one or more of chloroform, dichloromethane, trichloromethane, dichloroethane, acetonitrile, benzene, toluene, and tetrahydrofuran, and is preferably dichloromethane; Preferably, the amidating agent is selected from one or more of CDI, DCC, EDCI, EEDQ, HATU, and IIDQ, with EEDQ being the most preferred; Preferably, the amine compound is selected from one or more of trimethylamine, diethylamine, diethanolamine, propylamine, methylisopropylamine, diisopropylamine, and butylamine, and is preferably diethylamine; Preferably, the reaction is diluted with a nonpolar solvent after completion; Preferably, the nonpolar solvent is selected from one or more of n-hexane, cyclohexane, heptane, benzene, and toluene, with heptane being the most preferred.

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