Liquid-phase synthesis process of cyclotripeptide-5

Abstract

The invention discloses a liquid phase synthesis process of cyclotripeptide-5. Specifically, the invention provides a synthesis method of a compound as shown in a formula I-5, which comprises the following steps: in an organic solvent, in the presence of organic tertiary amine alkali and a condensing agent, carrying out intramolecular cyclization reaction on a compound as shown in a formula I-4 to obtain the compound I-5. According to the synthesis process provided by the invention, the yield of the intermediate is high, the cyclotripeptide-5 with the purity higher than 99% can be obtained under the condition that further purification is not needed, and high-performance liquid-phase synthesis of the cyclotripeptide-5 is realized.

Description

Technical Field

[0001] This invention relates to a liquid-phase synthesis process for cyclic tripeptide-5. Background Technology

[0002] Cyclic peptides, as an important source of marine drugs, are receiving increasing attention. Cyclic modification of peptides can enhance their spatial structure complexity and increase their specific surface area, thus providing more opportunities for interaction with targets. This helps to obtain more diverse active molecules and improve the utilization rate of peptide raw materials. This strategy further expands the application prospects of this class of anti-wrinkle peptides in the field of cosmetic skincare. Cyclic peptides typically have a larger specific surface area, higher affinity for targets, stronger recognition specificity, and better stability. They are not easily degraded by enzymes and exhibit strong skin penetration properties. Compared with linear structures, cyclic peptides have significant advantages in stability and affinity, thus showing greater application potential in cosmetic skincare and medical anti-aging. Because cyclization avoids degradation from the ends by exopeptidases, the stability of cyclic peptides is significantly improved. They also often exhibit higher target binding affinity than linear analogs, and their overall performance is generally superior to linear peptides.

[0003] Tripeptide-5 is a synthetic peptide composed of three amino acids and is now widely used in skincare products. Its main functions include stimulating collagen production, anti-wrinkle and anti-aging effects, promoting skin repair, and regulating inflammatory responses. This peptide improves skin elasticity and barrier function through signal transduction mechanisms, making it suitable for anti-aging and repair products.

[0004] Cyclic tripeptide-5 is a cyclic structure formed by cyclization modification of tripeptide-5. Studies have shown that when used in combination with other cyclic peptides, cyclic tripeptide-5 exhibits significant synergistic effects in promoting the expression of type I, III, and IV collagen genes, inhibiting acetylcholine secretion, improving skin elasticity, and reducing wrinkles. However, current literature reports on liquid-phase synthesis methods for cyclic tripeptide-5 are still relatively limited. Summary of the Invention

[0005] The technical problem to be solved by the present invention is that the existing methods for synthesizing polypeptide compounds have many steps, long cycles, and many side reactions and impurities. The present invention provides a liquid-phase synthesis process for cyclic tripeptide-5.

[0006] The present invention solves the above-mentioned technical problems through the following technical solutions.

[0007] This invention provides a method for synthesizing compounds of formula I-5, comprising the following steps: In an organic solvent, in the presence of an activator, an organic tertiary amine base, and a condensing agent, compound I-4 undergoes an intramolecular cyclization reaction to yield compound I-5; .

[0008] In some embodiments, the organic solvent is a conventional organic solvent in the art, preferably a halogenated hydrocarbon solvent and / or an ether solvent, more preferably an ether solvent. The halogenated hydrocarbon solvent may be a chloromethane solvent, such as dichloromethane. The ether solvent may be a cyclic ether solvent, more preferably a five-membered ring ether solvent and / or a six-membered ring ether solvent, such as tetrahydrofuran and / or 1,4-dioxane.

[0009] In some embodiments, the molar volume ratio of the compound of formula I-4 to the organic solvent is (0.10-1.5) mol / L, preferably (0.10-0.5) mol / L, for example (0.20-0.25) mol / L.

[0010] In some embodiments, the activator is a triazole activator, preferably a hydroxybenzotriazole activator, and more preferably 1-hydroxy-7-azabenzotriazole (HOAT) or 1-hydroxybenzotriazole (HOBT), for example 1-hydroxybenzotriazole (HOBT).

[0011] In some embodiments, the molar ratio of the compound of formula I-4 to the activator is 1:(1-6), preferably 1:(2-5), for example 1:3.

[0012] In some embodiments, the organic tertiary amine base is an aliphatic tertiary amine base, preferably a non-nucleophilic aliphatic tertiary amine base, such as N,N-diisopropylethylamine (DIEA).

[0013] In some embodiments, the molar ratio of the compound of formula I-4 to the organic tertiary amine base is 1:(3-10), preferably 1:(4-7), for example 1:6.

[0014] In some embodiments, the condensing agent is a carbodiimide condensing agent, such as 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride.

[0015] In some embodiments, the molar ratio of the compound of formula I-4 to the condensing agent is 1:(1-6), preferably 1:(2-5), for example 1:3.

[0016] In some embodiments, the compound of formula I-4 is added after being suspended in a sulfoxide solvent. The sulfoxide solvent is preferably selected from one or more of dimethyl sulfoxide, tetrahydrofuran, thionyl chloride, and diphenyl sulfoxide, for example, a mixture of dimethyl sulfoxide and tetrahydrofuran. In the mixture of dimethyl sulfoxide and tetrahydrofuran, the volume ratio of dimethyl sulfoxide to tetrahydrofuran is preferably (1-3):1, for example, 2:1. The molar volume ratio of the compound of formula I-4 to the sulfoxide solvent is preferably (0.1-1.0) mol / L, more preferably (0.1-0.3) mol / L, for example, 0.25 mol / L.

[0017] In some embodiments, the reaction temperature of the intramolecular cyclization reaction is 10-50°C, preferably 20-40°C, for example 20-30°C.

[0018] In some embodiments, the progress of the intramolecular cyclization reaction can be detected using conventional monitoring methods in the art (e.g., TLC, HPLC, or NMR), with the reaction endpoint generally defined as the disappearance of the starting material or the cessation of the reaction.

[0019] In some embodiments, the reactants for the intramolecular cyclization reaction consist of the following substances: the organic solvent, the organic tertiary amine base, the condensing agent, the compound of formula I-4, and the sulfoxide solvent.

[0020] In some embodiments, the method for synthesizing the compound of formula I-5 includes the following steps: adding a sulfoxide solution of the compound of formula I-4 to a mixture of an organic solvent, an activator, a condensing agent and an organic tertiary amine base at 10-50°C to carry out an intramolecular cyclization reaction to obtain the compound of formula I-5.

[0021] In some embodiments, the intramolecular cyclization reaction further includes a post-treatment, which includes alkaline washing.

[0022] In some embodiments, the alkaline washing agent is a metal bicarbonate, such as sodium bicarbonate.

[0023] In some embodiments, the method for synthesizing the compound of formula I-5 further includes a method for synthesizing the compound of formula I-4, which includes the following steps: In a solvent, in the presence of an inorganic base, compound I-3 undergoes a deprotection reaction to give compound I-4; .

[0024] In some embodiments, the solvent is a mixture of water and an alcohol solvent. The volume ratio of the water to the alcohol solvent in the mixture may be (1.0-3.0):1, preferably (1.5-2.5):1, for example, 2.2:1.

[0025] In some embodiments, the alcohol solvent is selected from one or more of methanol, ethanol and isopropanol, preferably methanol.

[0026] In some embodiments, the molar volume ratio of the compound of formula I-3 to the solvent is (0.1-0.8) mol / L, preferably (0.1-0.2) mol / L, for example 0.16 mol / L.

[0027] In some embodiments, the inorganic base is a metal hydroxide base, preferably selected from one or more of sodium hydroxide, potassium hydroxide, calcium hydroxide and lithium hydroxide, and more preferably lithium hydroxide, such as lithium hydroxide monohydrate.

[0028] In some embodiments, the molar ratio of the compound of formula I-3 to the inorganic base is 1:(2-10), preferably 1:(3-6), for example 1:4.5.

[0029] In some embodiments, the deprotection reaction is carried out at a temperature of 10-50°C, preferably 20-35°C.

[0030] In some embodiments, the progress of the deprotection reaction can be monitored using conventional monitoring methods in the art (e.g., TLC, HPLC, or NMR), with the reaction endpoint generally defined as the disappearance of the starting material or the cessation of the reaction. The reaction time for the deprotection reaction is preferably 2-10 hours, more preferably 3-7 hours, for example, 4 hours.

[0031] In some embodiments, the reactants for the deprotection reaction consist of the solvent, the inorganic base, and the compound of formula I-3.

[0032] In some embodiments, the method for synthesizing the compound of formula I-5 further includes a method for synthesizing the compound of formula I-3, which includes the following steps: In an organic solvent, in the presence of an activator, an organic tertiary amine base and a condensing agent, compounds of formula I-1 and I-2 undergo a condensation reaction to obtain compound I-3. .

[0033] In some embodiments, the organic solvent is a conventional organic solvent in the art, preferably an ether solvent and / or a halogenated hydrocarbon solvent, more preferably an ether solvent. The halogenated hydrocarbon solvent may be a chloromethane solvent, such as dichloromethane. The ether solvent may be a cyclic ether solvent, more preferably a five-membered ring ether solvent and / or a six-membered ring ether solvent, such as tetrahydrofuran and / or 1,4-dioxane.

[0034] In some embodiments, the molar volume ratio of the compound of formula I-1 to the organic solvent is (0.3-1.5) mol / L, preferably (0.3-0.7) mol / L, for example (0.50-0.52) mol / L.

[0035] In some embodiments, the molar ratio of the compound of formula I-1 to the compound of formula I-2 is 1:(0.5-2.0), preferably 1:(0.8-1.2), for example 1:(1.0-1.1).

[0036] In some embodiments, the organic tertiary amine base is an aliphatic tertiary amine base, preferably a non-nucleophilic aliphatic tertiary amine base, such as N,N-diisopropylethylamine (DIEA).

[0037] In some embodiments, the molar ratio of the compound of formula I-1 to the organic tertiary amine base is 1:(0.5-5), preferably 1:(1-3), for example 1:2.

[0038] In some embodiments, the condensing agent is a carbodiimide condensing agent, such as 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride.

[0039] In some embodiments, the molar ratio of the compound of formula I-1 to the condensing agent is 1:(0.5-3.0), preferably 1:(1.0-1.5), for example 1:1.2.

[0040] In some embodiments, the activator is a triazole activator, preferably a hydroxybenzotriazole activator, and more preferably 1-hydroxy-7-azabenzotriazole (HOAT) or 1-hydroxybenzotriazole (HOBT), for example 1-hydroxybenzotriazole (HOBT).

[0041] In some embodiments, the molar ratio of the compound of formula I-1 to the activator is 1:(0.5-3.0), preferably 1:(1.0-1.5), for example 1:1.2.

[0042] In some embodiments, the reaction temperature of the condensation reaction is 10-50°C, preferably 20-40°C, for example 20-30°C.

[0043] In some embodiments, the progress of the condensation reaction can be detected using conventional monitoring methods in the art (e.g., TLC, HPLC, or NMR), generally with the disappearance of the starting material or the cessation of the reaction as the endpoint. The reaction time of the condensation reaction is preferably 1-8 hours, more preferably 2-5 hours, for example, 3 hours.

[0044] In some embodiments, the reactants for the condensation reaction consist of the following substances: the organic solvent, the activator, the organic tertiary amine base, the condensing agent, the compound of formula I-1, and the compound of formula I-2.

[0045] The present invention also provides a method for synthesizing compounds of formula I-6, which includes the following steps: (1) Compound I-5 was prepared by the synthetic method described above; (2) In an acidic alcoholic solution, compound I-5 undergoes a deprotection reaction to give compound I-6; .

[0046] In some embodiments, the acid in the alcoholic solution is an inorganic acid, preferably selected from one or more of hydrochloric acid, hydrofluoric acid, hydrobromic acid, and phosphoric acid, with hydrochloric acid being the most preferred.

[0047] In some embodiments, the concentration of the acid in the alcoholic solution of the acid is (2.0-4.0) mol / L, for example, 2.0 mol / L.

[0048] In some embodiments, the alcoholic solution of the acid is an ethanolic solution of the acid.

[0049] In some embodiments, the alcoholic solution of the acid is a hydrochloric acid-ethanol solution.

[0050] In some embodiments, the molar mass ratio of the compound of formula I-5 to the alcoholic solution of the acid is (0.1-1.0) mol / kg, preferably (0.1-0.5) mol / kg, for example 0.3 mol / kg.

[0051] In some embodiments, the deprotection reaction is carried out at a temperature of 10-50°C, preferably 20-40°C, for example 20-30°C.

[0052] In some embodiments, the progress of the deprotection reaction can be detected using conventional monitoring methods in the art (e.g., TLC, HPLC, or NMR), generally with the disappearance of the starting material or the cessation of the reaction as the endpoint. The reaction time of the deprotection reaction is 0.5-5 h, more preferably 0.5-2 h, for example, 1 h.

[0053] In some embodiments, the reaction raw materials for the synthesis of the compound of formula I-6 consist of an alcoholic solution of the acid and the compound of formula I-5.

[0054] In some embodiments, the deprotection reaction further includes a post-treatment, which includes crystallization.

[0055] The crystallization preferably occurs in a nitrile solvent and water, and more preferably in acetonitrile and water. The volume ratio of the nitrile solvent to water is preferably (1-3):1, for example, 2:1.

[0056] The present invention also provides a method for synthesizing a compound of formula I, comprising the following steps: (1) Compound I-6 was prepared by the synthetic method described above; (2) In a solvent, in the presence of a catalyst and a hydrogen source, compounds of formula I-6 undergo a reduction reaction to obtain compound I; .

[0057] In some embodiments, the solvent is water and / or an ether solvent, preferably a mixture of water and an ether solvent.

[0058] In some embodiments, the volume ratio of water to ether solvent in the mixed solvent is (1-8):1, preferably (3-5):1, for example 4:1.

[0059] In some embodiments, the molar volume ratio of the compound of formula I-6 to the solvent is (0.05-0.5) mol / L, preferably (0.05-0.15) mol / L, for example (0.08-0.1) mol / L.

[0060] In some embodiments, the catalyst is a metal catalyst, preferably a palladium catalyst, and more preferably a zero-valent palladium catalyst, such as palladium on carbon.

[0061] In some embodiments, the molar ratio of the compound of formula I-6 to the catalyst is 1:(0.2-2.0), preferably 1:(0.2-0.7), for example 1:(0.4-0.5).

[0062] In some implementations, the hydrogen source is hydrogen gas.

[0063] In some embodiments, when the hydrogen source is hydrogen gas, the pressure of the hydrogen gas is 0.3-1.5 MPa, preferably 0.3-0.8 MPa, for example 0.5 MPa.

[0064] In some embodiments, the reduction reaction is carried out at a temperature of 10-50°C, preferably 20-40°C, for example 20-30°C.

[0065] In some embodiments, the progress of the reduction reaction can be detected using conventional monitoring methods in the art (e.g., TLC, HPLC, or NMR), with the reaction endpoint generally defined as the disappearance of the starting material or the cessation of the reaction.

[0066] In some embodiments, the reaction raw materials for the reduction reaction consist of the solvent, the catalyst, the hydrogen source, and the compound of formula I-6.

[0067] In some embodiments, the synthesis method of the compound of formula I further includes post-processing, which includes purification; the solvent used for purification is a mixture of alcohol solvents and ester solvents.

[0068] In some embodiments, the alcohol solvent is methanol and / or ethanol, preferably methanol.

[0069] In some embodiments, the ester solvent is ethyl acetate.

[0070] In some embodiments, the mass ratio of the alcohol solvent to the ester solvent in the mixed solvent is (5-20):1, preferably (8-12):1, for example 10:1.

[0071] The present invention also provides a compound as shown in Formula I-4: .

[0072] The present invention also provides a compound as shown in Formulas I-5: .

[0073] The present invention also provides a compound as shown in Formula I-6: .

[0074] Based on common knowledge in the field, the above-mentioned preferred conditions can be combined arbitrarily to obtain various preferred embodiments of the present invention.

[0075] The reagents and raw materials used in this invention are all commercially available.

[0076] The positive and progressive effects of this invention are as follows: the synthetic process provided by this invention has a high yield of intermediates, and cyclic tripeptide-5 with a purity of over 99% can be obtained without further purification, thus realizing the high-efficiency liquid-phase synthesis of cyclic tripeptide-5. Detailed Implementation

[0077] The present invention is further illustrated below by way of embodiments, but the invention is not limited to the scope of the embodiments described herein. Experimental methods in the following embodiments that do not specify specific conditions were performed according to conventional methods and conditions, or as selected according to the product instructions.

[0078] Example 1

[0079] Step 1: Synthesis of Boc-Lys(Tfa)-OH

[0080] Start the reactor stirring, open the reactor feed port, and add 17.50 kg of deionized water, 3.50 kg of trifluoroacetyl lysine, 3.06 kg of sodium carbonate, and 12.42 kg of tetrahydrofuran in sequence, followed by dropwise addition of 3.78 kg of di-tert-butyl dicarbonate. After the dropwise addition is complete, control the temperature of the solution at 25°C for the reaction. Adjust the pH of the solution to 6.5 with 6.55 kg of concentrated hydrochloric acid. Concentrate the solution under reduced pressure at 45°C in a water bath until there are almost no droplets flowing out, then stop the concentration. Extract the concentrated solution with 10.15 kg of isopropyl ether, and keep the aqueous phase at a constant temperature with stirring for 3 hours to crystallize. Filter the solution, wash the filter cake with deionized water, discard the filtrate, collect the filter cake, and obtain the wet product. Dry the wet product at 50°C to obtain the product, with a yield of 97.98%.

[0081] Step 2: Synthesize Lys(Cbz)-OMe

[0082] Start the reactor stirring, open the reactor feed port, and add 12.65 kg of methanol and 4.00 kg of Lys(Cbz)-OH sequentially, followed by 4.65 kg of trimethylchlorosilane dropwise. After the addition is complete, control the temperature of the liquid at 24°C and stop the reaction. Add 0.5 kg of anhydrous sodium acetate to the reactor. Concentrate the liquid under reduced pressure at 50°C in a water bath until there are basically no more droplets flowing out, and stop the concentration. Dissolve the concentrated liquid. Add industrial salt to the reactor, stir for 30 min, then spread 2.00 kg of diatomaceous earth and filter. Wash the filter cake with ethyl acetate, discard the filter cake, separate the filtrate, and retain the organic phase. Dry the organic phase with 0.92 kg of anhydrous magnesium sulfate, stir for 15 min, filter, wash the filter cake with ethyl acetate, discard the filter cake, and concentrate the filtrate under reduced pressure at 45°C in a water bath until there are basically no more droplets flowing out, and stop the concentration to obtain the product with a yield of 91.90%.

[0083] Step 3: Synthesize Boc-Val-Lys(Cbz)-OMe

[0084] Start the reactor stirring, open the reactor feed port, and sequentially add 10.75 kg of 2-methyltetrahydrofuran, 2.50 kg of Boc-Val-OH, 3.66 kg of Lys(Cbz)-OMe, and 1.87 kg of 1-hydroxybenzotriazole. Add 2.65 kg of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride in batches, and then add 2.23 kg of N,N-diisopropylethylamine dropwise. Control the reaction temperature at 25±3℃, then stop the reaction. Add water to the reactor for extraction, separate the liquids, retain the organic phase, and discard the aqueous phase. Add water and 2.50 kg of sodium bicarbonate to the reactor, stir until the solid dissolves, extract, separate the liquids, retain the organic phase, and discard the aqueous phase. The organic phase was discarded; water and 6.10 kg of sodium chloride were added to the reactor and stirred until the solid dissolved. The mixture was extracted, separated, and the organic phase was retained while the aqueous phase was discarded. The mixture was stirred at 25±5℃ for 30 min, separated, and the organic phase was retained while the aqueous phase was discarded. Water and sodium chloride were added to the reactor and stirred until the solid dissolved. The mixture was extracted, separated, and the organic phase was retained while the aqueous phase was discarded. The organic phase was concentrated under reduced pressure at 45℃ in a water bath until almost no droplets flowed out. The concentration was stopped to obtain the crude product. The crude product was added to the reactor, slurried, and stirred at 30±5℃ for 15 h. The liquid was filtered, washed, and the filtrate was discarded. The filter cake was collected to obtain the wet material. The wet material was dried at 50℃ to obtain the product with a yield of 87.15%.

[0085] Step 4: Synthesis of H-Val-Lys(Cbz)-OMe

[0086] Start the stirring in the reactor, open the feed port of the reactor, and add 6.49 kg of dichloromethane and 4.90 kg (10 mol) of Boc-Val-Lys(Cbz)-OMe in sequence, followed by 10.94 kg of trifluoroacetic acid. After the addition is complete, keep the temperature warm for 30 min; control the temperature of the liquid at 25±3℃ and react for 2 h, then stop the reaction; control the water bath at 45℃ and concentrate the liquid under reduced pressure until there are basically no liquid droplets flowing out, then stop the concentration to obtain crude product; dissolve the crude product in 17.39 kg (19.5 L) of tetrahydrofuran, and add 7.00 kg (54.2 mol) of N,N-diisopropylethylamine dropwise until pH=5±0.5 to obtain H-Val-Lys(Cbz)-OMe liquid; Step 5: Synthesize Boc-Lys(Tfa)-Val-Lys(Cbz)-OMe Start the reactor stirring, open the reactor feed port, and sequentially add 34.71 kg (10 mol) of H-Val-Lys(Cbz)-OMe solution, 3.73 kg (10.9 mol) of Boc-Lys(Tfa)-OH, and 1.61 kg (11.9 mol) of 1-hydroxybenzotriazole. Add 2.28 kg (11.9 mol) of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride in portions, and dropwise add 2.56 kg (19.8 mol) of N,N-diisopropylethylamine. Control the solution temperature at 25±3℃ and react for 3 hours, then stop the reaction. Add water to the reactor, control the solution temperature at 25±3℃ and stir for 20 minutes. Concentrate the solution under reduced pressure at 45℃ in a water bath until the solution reaches the required concentration. No liquid droplets flowed out, so concentration was stopped, and crude material was obtained. Water, 1.2 kg of isopropyl ether, 10.55 kg of ethyl acetate, and 0.39 kg of sodium bicarbonate were added to the reactor and stirred. The solution was filtered, the filter cake was washed with water, the filtrate was discarded, and the filter cake was collected to obtain wet material. 42.9 kg of water, 15.50 kg (19.6 L) of methanol, and wet material were added to the reactor, and the solution temperature was controlled at 25±3℃ and stirred for 20 min to obtain Boc-Lys(Tfa)-Val-Lys(Cbz)-OMe solution. Step Six: Synthesis of Boc-Lys-Val-Lys(Cbz)-OH Start the reactor and stir. Add 43.32 kg (10 mol) of Boc-Lys(Tfa)-Val-Lys(Cbz)-Ome solution to the reactor. Add 1.88 kg (44.8 mol) of lithium hydroxide monohydrate in batches at a controlled temperature of 20±5℃. Control the temperature of the solution at 30±3℃ and react for 4 hours. Stop the reaction. Control the temperature of the solution at 45℃ and concentrate the solution under reduced pressure until there are basically no more droplets flowing out. Stop the concentration. Filter the solution. Wash the filter cake with water. Discard the filtrate and collect the filter cake to obtain the crude product. Add water to the reactor and adjust the pH to 7 with 5.41 kg of hydrochloric acid. Stir to crystallize. Filter the solution. Wash the filter cake with water. Discard the filtrate and collect the filter cake to obtain the wet product. Dry the wet product at 50℃ to obtain the product with a yield of 83.9%.

[0087] Step 7: Synthesize Cyclo(Boc-Lys-Val-Lys(Cbz))

[0088] Start the stirring in the reactor, open the feed port, and add 31.2 kg (35 L) of tetrahydrofuran, 3.48 kg (25.8 mol) of 1-hydroxybenzotriazole, 4.94 kg (25.8 mol) of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride, and 6.66 kg (51.5 mol) of N,N-diisopropylethylamine in sequence; Boc-Lys-Val-Lys(Cbz)-OH 5.20 kg (8.56 mol) of a solution was suspended in a mixed solvent of 25.40 kg (23 L) of dimethyl sulfoxide and 10.40 kg (11.7 L) of tetrahydrofuran, and added dropwise to a reaction vessel. The reaction was carried out at a controlled temperature of 25 ± 3 °C, and then stopped. The solution was concentrated under reduced pressure at a controlled temperature of 45 °C until almost no droplets flowed out, and the concentration was stopped to obtain a crude solution. Water, 15.60 kg of sodium bicarbonate, and the crude solution were added to the reaction vessel and stirred. The solution was filtered, the filter cake was washed with water, the filtrate was discarded, and the filter cake was collected to obtain a wet product. The wet product was dried, and after passing the drying test, it was packaged to obtain 5.01 kg (8.5 mol) of product, with a yield of 99.29%.

[0089] Step 8: Synthesize Cyclo(H-Lys-Val-Lys(Cbz))

[0090] 29.10 kg of hydrogen chloride ethanol solution was added to the reactor, followed by 5.00 kg (8.5 mol) of Cyclo(Boc-Lys-Val-Lys(Cbz)) in portions. After the addition was complete, the solution was heated to 25 °C and kept at that temperature for 1 h. The solution was then concentrated under reduced pressure until almost no droplets flowed out, and the concentration was stopped to obtain the crude product. 40 kg (50.9 L) of acetonitrile and 25 kg of water were added to the reactor, followed by the crude product. The solution temperature was controlled at 25 ± 3 °C and stirred to crystallize. The solution was filtered, and the filter cake was washed with acetonitrile. The filtrate was discarded, and the filter cake was collected to obtain the wet product. The wet product was dried at 50 °C to obtain the product, with a yield of 82.51%.

[0091] Step 9: Synthesize cyclic tripeptide-5

[0092] 73.60 kg of deionized water, 3.68 kg (7.5 mol) of Cyclo(H-Lys-Val-Lys(Cbz)), 0.37 kg (3.5 mol) of palladium on carbon, and 16.32 kg (18.3 L) of tetrahydrofuran were added sequentially to the reactor. After purging with nitrogen three times, hydrogen gas was introduced until the pressure reached 0.5 MPa. The reaction was stopped at a controlled temperature of 20°C. The reaction solution was filtered, the filter cake was washed with water and discarded, and the filtrate was collected. The concentrated solution was filtered, the filtrate was collected, and the filtrate was concentrated under reduced pressure at a controlled temperature of 55°C to obtain cyclic tripeptide-5 solution. 5.75 kg of methanol and 0.575 kg of ethyl acetate solution were added. The solution was concentrated under reduced pressure at a controlled temperature of 55°C, and the concentration was stopped to obtain cyclic tripeptide-5 solution. The product was freeze-dried to obtain the product with a yield of 30.33% and a purity of 99.94%.

Claims

1. A method for synthesizing a compound of formula I-5, comprising the following steps: In an organic solvent, in the presence of an activator, an organic tertiary amine base, and a condensing agent, compound I-4 undergoes an intramolecular cyclization reaction to yield compound I-5; 。 2. The synthesis method according to claim 1, characterized in that, It meets one or more of the following conditions: (1) The organic solvent is a halogenated hydrocarbon solvent and / or an ether solvent, more preferably an ether solvent; The halogenated hydrocarbon solvent may be a chloromethane solvent, such as dichloromethane; The ether solvent may be a cyclic ether solvent, preferably a five-membered ring ether solvent and / or a six-membered ring ether solvent, such as tetrahydrofuran and / or 1,4-dioxane; (2) The molar volume ratio of the compound of formula I-4 to the organic solvent is (0.10-1.5) mol / L, preferably (0.10-0.5) mol / L, for example (0.20-0.25) mol / L; (3) The activator is a triazole activator, preferably a hydroxybenzotriazole activator, and more preferably 1-hydroxy-7-azabenzotriazole or 1-hydroxybenzotriazole, for example 1-hydroxybenzotriazole; (4) The molar ratio of the compound of formula I-4 to the activator is 1:(1-6), preferably 1:(2-5), for example 1:3; (5) The organic tertiary amine base is an aliphatic tertiary amine base, preferably a non-nucleophilic aliphatic tertiary amine base, such as N,N-diisopropylethylamine; (6) The molar ratio of the compound of formula I-4 to the organic tertiary amine base is 1:(3-10), preferably 1:(4-7), for example 1:6; (7) The condensing agent is a carbodiimide condensing agent, such as 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride; (8) The molar ratio of the compound of formula I-4 to the condensing agent is 1:(1-6), preferably 1:(2-5), for example 1:3; (9) The compound of formula I-4 is added after being suspended in a sulfoxide solvent; the sulfoxide solvent is preferably selected from one or more of dimethyl sulfoxide, tetrahydrofuran, thionyl chloride and diphenyl sulfoxide, for example, a mixed solvent of dimethyl sulfoxide and tetrahydrofuran; (10) The reaction temperature of the intramolecular cyclization reaction is 10-50℃, preferably 20-40℃, for example 20-30℃; (11) The intramolecular cyclization reaction further includes post-treatment, which includes alkaline washing; Preferably, the alkaline washing reagent is a metal bicarbonate, such as sodium bicarbonate.

3. The synthesis method as described in claim 2, characterized in that, It meets one or more of the following conditions: (1) In the mixed solvent of dimethyl sulfoxide and tetrahydrofuran, the volume ratio of dimethyl sulfoxide to tetrahydrofuran is (1-3):1, for example, 2:1; (2) The molar volume ratio of the compound of formula I-4 to the sulfoxide solvent is (0.1-1.0) mol / L, preferably (0.1-0.3) mol / L, for example 0.25 mol / L; (3) The reaction raw materials for the intramolecular cyclization reaction consist of the following substances: the organic solvent, the organic tertiary amine base, the condensing agent, the compound of formula I-4, and the sulfoxide solvent; (4) The method for synthesizing the compound of formula I-5 includes the following steps: at 10-50°C, a sulfoxide solution of the compound of formula I-4 is added to a mixture of organic solvent, activator, condensing agent and organic tertiary amine base to carry out an intramolecular cyclization reaction to obtain the compound of formula I-5.

4. The synthesis method according to any one of claims 1-3, characterized in that, It includes a method for synthesizing compounds of formula I-4, the method comprising the following steps: In a solvent, in the presence of an inorganic base, compound I-3 undergoes a deprotection reaction to give compound I-4; ； Preferably, the method for synthesizing the compound of formula I-4 satisfies one or more of the following conditions: (1) The solvent is a mixed solution of water and alcohol solvent; In the mixed solution, the volume ratio of water to alcohol solvent can be (1.0-3.0):1, preferably (1.5-2.5):1, for example 2.2:1; The alcohol solvent may be selected from one or more of methanol, ethanol and isopropanol, preferably methanol; (2) The molar volume ratio of the compound of formula I-3 to the solvent is (0.1-0.8) mol / L, preferably (0.1-0.2) mol / L, for example 0.16 mol / L; (3) The inorganic base is a metal hydroxide base, preferably selected from one or more of sodium hydroxide, potassium hydroxide, calcium hydroxide and lithium hydroxide, and more preferably lithium hydroxide, such as lithium hydroxide monohydrate; (4) The molar ratio of the compound of formula I-3 to the inorganic base is 1:(2-10), preferably 1:(3-6), for example 1:4.5; (5) The reaction temperature of the deprotection reaction is 10-50℃, preferably 20-35℃; (6) The reaction time of the deprotection reaction is 2-10h, more preferably 3-7h, for example 4h; (7) The reaction raw materials for the deprotection reaction consist of the following substances: the solvent, the inorganic base and the compound of formula I-3.

5. The synthesis method according to any one of claims 1-3, characterized in that, It includes a method for synthesizing compounds of formula I-3, the method comprising the following steps: In an organic solvent, in the presence of an activator, an organic tertiary amine base and a condensing agent, compounds of formula I-1 and I-2 undergo a condensation reaction to obtain compound I-3. ； Preferably, the method for synthesizing the compound of formula I-3 satisfies one or more of the following conditions: (1) The organic solvent is an ether solvent and / or a halogenated hydrocarbon solvent, more preferably an ether solvent; The halogenated hydrocarbon solvent may be a chloromethane solvent, such as dichloromethane; The ether solvent may be a cyclic ether solvent, more preferably a five-membered ring ether solvent and / or a six-membered ring ether solvent, such as tetrahydrofuran and / or 1,4-dioxane; (2) The molar volume ratio of the compound of formula I-1 to the organic solvent is (0.3-1.5) mol / L, preferably (0.3-0.7) mol / L, for example (0.50-0.52) mol / L; (3) The molar ratio of the compound of formula I-1 to the compound of formula I-2 is 1:(0.5-2.0), preferably 1:(0.8-1.2), for example 1:(1.0-1.1); (4) The organic tertiary amine base is an aliphatic tertiary amine base, preferably a non-nucleophilic aliphatic tertiary amine base, such as N,N-diisopropylethylamine; (5) The molar ratio of the compound of formula I-1 to the organic tertiary amine base is 1:(0.5-5), preferably 1:(1-3), for example 1:2; (6) The condensing agent is a carbodiimide condensing agent, such as 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride; (7) The molar ratio of the compound of formula I-1 to the condensing agent is 1:(0.5-3.0), preferably 1:(1.0-1.5), for example 1:1.2; (8) The activator is a triazole activator, preferably a hydroxybenzotriazole activator, and more preferably 1-hydroxy-7-azabenzotriazole or 1-hydroxybenzotriazole, for example 1-hydroxybenzotriazole; (9) The molar ratio of the compound of formula I-1 to the activator is 1:(0.5-3.0), preferably 1:(1.0-1.5), for example 1:1.2; (10) The reaction temperature of the condensation reaction is 10-50℃, preferably 20-40℃, for example 20-30℃; (11) The reaction time of the condensation reaction is 1-8h, more preferably 2-5h, for example 3h; (12) The reaction raw materials for the condensation reaction consist of the following substances: the organic solvent, the activator, the organic tertiary amine base, the condensing agent, the compound of formula I-1 and the compound of formula I-2.

6. A method for synthesizing a compound of formula I-6, comprising the following steps: (1) Compounds of formula I-5 are prepared by the synthetic method according to any one of claims 1-5; (2) In an acidic alcoholic solution, compound I-5 undergoes a deprotection reaction to give compound I-6; 。 7. The synthesis method according to claim 6, characterized in that, It meets one or more of the following conditions: (1) In the alcoholic solution of the acid, the acid is an inorganic acid, preferably selected from one or more of hydrochloric acid, hydrofluoric acid, hydrobromic acid and phosphoric acid, preferably hydrochloric acid; (2) In the alcoholic solution of the acid, the concentration of the acid is (2.0-4.0) mol / L, for example, 2.0 mol / L; (3) The alcoholic solution of the acid is an ethanolic solution of the acid; (4) The molar mass ratio of the compound of formula I-5 to the alcoholic solution of the acid is (0.1-1.0) mol / kg, preferably (0.1-0.5) mol / kg, for example 0.3 mol / kg; (5) The reaction temperature of the deprotection reaction is 10-50℃, preferably 20-40℃, for example 20-30℃; (6) The reaction time of the deprotection reaction is preferably 0.5-5h, more preferably 0.5-2h, for example 1h; (7) The reaction raw materials for the synthesis method of the compound of formula I-6 consist of the following substances: an alcoholic solution of the acid and the compound of formula I-5.

8. A method for synthesizing a compound of formula I, comprising the following steps: (1) Compounds of formula I-6 are prepared by the synthetic method described in claim 6 or 7; (2) In a solvent, in the presence of a catalyst and a hydrogen source, compounds of formula I-6 undergo a reduction reaction to obtain compound I; 。 9. The synthesis method as described in claim 8, characterized in that, It meets one or more of the following conditions: (1) The solvent is water and / or an ether solvent, preferably a mixture of water and an ether solvent; Preferably, in the mixed solvent of water and ether solvent, the volume ratio of water to ether solvent is (1-8):1, more preferably (3-5):1, for example 4:1; (2) The molar volume ratio of the compound of formula I-6 to the solvent is (0.05-0.5) mol / L, preferably (0.05-0.15) mol / L, for example (0.08-0.1) mol / L; (3) The catalyst is a metal catalyst, preferably a palladium catalyst, and more preferably a zero-valent palladium catalyst, such as palladium on carbon; (4) The molar ratio of the compound of formula I-6 to the catalyst is 1:(0.2-2.0), preferably 1:(0.2-0.7), for example 1:(0.4-0.5); (5) The hydrogen source is hydrogen gas; preferably, the pressure of the hydrogen gas is 0.3-1.5 MPa, more preferably 0.3-0.8 MPa, for example 0.5 MPa; (6) The reaction temperature of the reduction reaction is 10-50℃, preferably 20-40℃, for example 20-30℃; (7) The reaction raw materials for the reduction reaction consist of the following substances: the solvent, the catalyst, the hydrogen source, and the compound of formula I-6; (8) The synthesis method of the compound of formula I includes post-processing, the post-processing including purification; the solvent used for purification may be a mixture of alcohol solvent and ester solvent; Preferred, The alcohol solvent is methanol and / or ethanol, preferably methanol; The ester solvent is ethyl acetate; In the mixed solvent of alcohol and ester solvent, the mass ratio of alcohol solvent to ester solvent is (5-20):1, preferably (8-12):1, for example 10:

1.

10. A compound as shown in Formula I-4, Formula I-5 or Formula I-6: 、 、 。

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