Method for preparing Fmoc-Gly-Pro-OH

Abstract

The invention relates to the field of organic synthesis, in particular to a method for preparing Fmoc-Gly-Pro-OH, which comprises the following steps of: 1, reacting Fmoc-Gly-OH serving as a raw material with a chlorination reagent to synthesize acyl chloride; and 2, carrying out a coupling reaction on the obtained acyl chloride and L-proline to generate a product, carrying out post-treatment on the reaction liquid to obtain a crude product of Fmoc-Gly-Pro-OH, and crystallizing the crude product to obtain the Fmoc-Gly-Pro-OH. According to the method, purification of an intermediate is avoided, the reaction process is relatively well controlled, and high-quality Fmoc-Gly-Pro-OH can be efficiently and stably prepared. The method provided by the invention provides a new choice for a commercial production process of Fmoc-Gly-Pro-OH.

Description

Technical Field

[0001] This invention relates to the field of organic chemical synthesis, and specifically to a method for preparing Fmoc-Gly-Pro-OH. Background Technology

[0002] Fmoc-Gly-Pro-OH, Chinese name: N-fluorenylmethoxycarbonyl-L-glycine-L-proline

[0003] Molecular formula C 22 H 22 N2O5, molecular weight: 394.43 g / mol.

[0004] Chemical structural formula:

[0005]

[0006] Fmoc-Gly-Pro-OH is an Fmoc-protected glycine-proline dipeptide, in which the two amino acids are glycine and proline, and the protecting group on glycine is Fmoc. Fmoc-Gly-Pro-OH is an important intermediate in the synthesis of polypeptides, especially in the solid-phase synthesis of polypeptides, and is commonly used in the synthesis of various drugs.

[0007] A method for preparing Fmoc-Gly-Pro-OH was reported in the literature (Journal of Agricultural and Food Chemistry, 2022, val. 70, #7, pp. 2160-2168). This method involves the direct condensation of Fmoc-Gly-OH with L-proline using Fmoc-Gly-OH as the starting material and HBTU as the condensing agent. However, this method requires the relatively expensive condensing reagent HBTU, and the post-processing is cumbersome, purification is difficult, and it is not conducive to industrial production.

[0008] Another method for synthesizing Fmoc-Gly-Pro-OH is described in the literature (Organic Letters, 2005, vol. 7, #13, pp. 2619-2622). This method uses glycerol-L-proline as a starting material and directly protects it with FmocCl to obtain Fmoc-Gly-Pro-OH. The reported yield of the final product can reach 96%. However, the starting material glycerol-L-proline used in this method is very expensive, which leads to high production costs and is not conducive to industrial production.

[0009] There is a significant demand for Fmoc-Gly-Pro-OH in both domestic and international markets. Currently, domestic methods for producing this compound suffer from high manufacturing costs and insufficient product purity, resulting in production capacity that cannot meet the demands of high-end drug synthesis. Therefore, optimizing the production process of Fmoc-Gly-Pro-OH to reduce costs and obtain high-purity products is an urgent problem to be solved. Summary of the Invention

[0010] To overcome the shortcomings of the prior art, the technical problem to be solved by the present invention is to provide a method for preparing Fmoc-Gly-Pro-OH.

[0011] To solve the above-mentioned technical problems, the technical solution provided by the present invention is as follows:

[0012] A method for preparing Fmoc-Gly-Pro-OH includes the following steps:

[0013] (1) Add Fmoc-Gly-OH and solvent to the reaction vessel, cool down and add acyl chloride reagent dropwise, stir the reaction after the addition is complete to obtain an acyl chloride solution of N-fluorenylmethoxycarbonyl-L-glycine;

[0014] (2) Add L-proline and solvent to the reaction vessel, cool down and add N-fluorenmethoxycarbonyl-L-glycine acyl chloride solution dropwise. After the reaction is completed, slowly add quenching reagent to quench the reaction and obtain crude Fmoc-Gly-Pro-OH. After crystallization, Fmoc-Gly-Pro-OH is obtained.

[0015] The specific reaction formula is as follows:

[0016]

[0017] Preferably, the acyl chloride reagent in step (1) is selected from thionyl chloride and oxalyl chloride.

[0018] Preferably, the solvent in step (1) is selected from dichloromethane, toluene, benzene, and chloroform; the amount of the solvent used is 3 to 10 times the mass of Fmoc-Gly-OH.

[0019] Preferably, the molar ratio of Fmoc-Gly-OH to acyl chloride reagent in step (1) is 1:1.5 to 2.5, and the cooling temperature in step (1) is 0-10℃.

[0020] Preferably, the solvent in step (2) is selected from dichloromethane, toluene, benzene, tetrahydrofuran, DMF, and chloroform; the amount of the solvent used is 3 to 10 times the mass of L-proline.

[0021] Preferably, the molar ratio of L-proline in step (2) to Fmoc-Gly-OH in step (1) is 1:1.0 to 3.0, and the cooling temperature in step (2) is 5-15℃.

[0022] Preferably, the quenching agent in step (2) is water; the crystallization specifically involves: the crude Fmoc-Gly-Pro-OH is purified by recrystallization, and the solvent used for recrystallization purification is one or more of ethanol, methanol, isopropanol, tetrahydrofuran, ethyl acetate, diethyl ether, isopropyl ether, methyl tert-butyl ether or petroleum ether.

[0023] In this invention, if there is a conflict between the Chinese name and the structural formula of a compound, the structural formula shall prevail, unless the structural formula is obviously incorrect.

[0024] The beneficial effects of this invention are as follows:

[0025] The method for preparing Fmoc-Gly-Pro-OH provided by this invention can efficiently and stably synthesize high-quality Fmoc-Gly-Pro-OH with a purity greater than 99.5%, a single impurity of less than 0.3%, and an ee value greater than 99%. It avoids the need for intermediate purification, and the reaction process is relatively easy to control, making it suitable for large-scale industrial production. Attached Figure Description

[0026] Figure 1 The image shows the HNMR spectrum of Fmoc-Gly-Pro-OH obtained in specific embodiment 1 of the present invention. Detailed Implementation

[0027] The present invention is illustrated below with reference to examples, but is not intended to limit the invention. Any simple substitutions or modifications made to the present invention by those skilled in the art are within the scope of the technical solutions protected by this invention.

[0028] Example 1

[0029] 1. Synthesis of N-fluorenylmethoxycarbonyl-L-glycine acyl chloride

[0030] Add 600 g of dichloromethane to a clean, dry 1000 mL reaction flask, then add 100 g of N-fluorenylmethoxycarbonyl-L-glycine (molecular weight 297.3 g / mol, molar weight 336.3 mmol), stir, and cool to 0-10 °C in an ice-water bath. Add 60.1 g of thionyl chloride (molecular weight 118.97 g / mol, molar weight 504.4 mmol) dropwise over 0.5 hours. After the addition is complete, raise the temperature to room temperature and stir for 4 hours until the solid is completely dissolved. Monitor the reaction with HPLC. After the reaction is complete, cool the reaction solution to 0-10 °C and maintain a nitrogen atmosphere for later use.

[0031] 2. Synthesis of Fmoc-Gly-Pro-OH

[0032] Add 96.6 g of L-proline (molecular weight 115.13 g / mol, molar number 841.75 mmol) and 600 g of dichloromethane to a clean, dry 2000 mL reaction flask. Cool to 5-15 °C, and add dropwise the N-fluorenemethoxycarbonyl-L-glycine acyl chloride solution obtained in the first step, controlling the temperature not to exceed 20 °C. Add the solution over 2 hours, then bring the temperature to room temperature and stir for 16 hours. Monitor the reaction with HPLC. After the reaction is complete, quench the reaction with water, stir for 30 minutes, allow to stand and separate the layers, wash once with 600 g of saturated brine, dry with 100 g of anhydrous sodium sulfate, filter, and evaporate the filtrate under reduced pressure to obtain the crude product. Recrystallize the crude product with 500 g of ethyl acetate, filter to obtain the wet product. Dry the wet product under vacuum at 50 °C to obtain 66.42 g of dry product. The two-step yield is 50.1%, HPLC ≥ 99.5%, maximum single impurity ≤ 0.3%, and ee value > 99%.

[0033] Example 2:

[0034] 1. Synthesis of N-fluorenylmethoxycarbonyl-L-glycine acyl chloride

[0035] Add 1200 g of dichloromethane to a clean, dry 2000 mL reaction flask, then add 200 g of N-fluorenylmethoxycarbonyl-L-glycine (molecular weight 297.3 g / mol, molar weight 673.4 mmol), stir, and cool to 0-10 °C in an ice-water bath. Add 120.2 g of thionyl chloride (molecular weight 118.97 g / mol, molar weight 1010.1 mmol) dropwise over 45 minutes. After the addition is complete, raise the temperature to room temperature and stir for 4 hours until the solid is completely dissolved. Monitor the reaction with HPLC. After the reaction is complete, cool the reaction solution to 0-10 °C and maintain a nitrogen atmosphere for later use.

[0036] 2. Synthesis of Fmoc-Gly-Pro-OH

[0037] Add 193.2 g of L-proline (molecular weight 115.13 g / mol, molar number 1680 mmol) and 1200 g of dichloromethane to a clean, dry 3000 mL reaction flask. Cool to 5-15 °C, and add the N-fluorenemethoxycarbonyl-L-glycine acyl chloride solution obtained in the first step dropwise, controlling the temperature not to exceed 20 °C. The addition should be completed over 3 hours. After the addition is complete, bring the mixture to room temperature and stir for 16 hours. Monitor the reaction with HPLC. After the reaction is complete, quench the reaction with water, stir for 30 minutes, allow to stand for phase separation, wash the organic phase once with 1200 g of saturated brine, dry with 200 g of anhydrous sodium sulfate, filter, and evaporate the filtrate under reduced pressure to obtain the crude product. Recrystallize the crude product with 1000 g of ethyl acetate, filter to obtain the wet product. Dry the wet product under vacuum at 50 °C to obtain a dry product: 153.1 g, two-step yield 57%, HPLC ≥ 99.5%, maximum single impurity ≤ 0.3%, ee value > 99%.

[0038] The above description is only a preferred embodiment of the present invention. It should be noted that those skilled in the art can make several modifications and improvements without departing from the inventive concept of the present invention, and these all fall within the protection scope of the present invention.

Claims

1. A process for the preparation of Fmoc-Gly-Pro-OH, characterized in that, The method comprises the following steps: (1) adding Fmoc-Gly-OH, a solvent into a reaction container, adding an acyl chloride reagent dropwise under cooling, stirring the reaction after the addition, and obtaining an acyl chloride solution of N-fluorenylmethoxycarbonyl-L-glycine; (2) adding L-proline, a solvent into a reaction container, adding the acyl chloride solution of N-fluorenylmethoxycarbonyl-L-glycine dropwise under cooling, slowly adding a quenching reagent for quenching after the reaction, and obtaining a crude product of Fmoc-Gly-Pro-OH, and obtaining Fmoc-Gly-Pro-OH after crystallization of the crude product; The specific reaction formula is as follows:

2. The method of claim 1, wherein, The acyl chloride reagent in the step (1) is selected from thionyl chloride and oxalyl chloride.

3. The method of claim 1, wherein, The solvent in the step (1) is selected from dichloromethane, toluene, benzene and chloroform, and the amount of the solvent is 3-10 times the mass of Fmoc-Gly-OH.

4. The method of claim 1, wherein, The molar ratio of Fmoc-Gly-OH to the acyl chloride reagent in the step (1) is 1:1.5-2.5, and the cooling temperature in the step (1) is 0-10℃.

5. The method of claim 1, wherein, The solvent in the step (2) is selected from dichloromethane, toluene, benzene, tetrahydrofuran, DMF and chloroform, and the amount of the solvent is 3-10 times the mass of L-proline.

6. The method of claim 1, wherein, The molar ratio of L-proline to Fmoc-Gly-OH in the step (2) is 1:1.0-3.0, and the cooling temperature in the step (2) is 5-15℃.

7. The method of claim 1, wherein, The quenching reagent in the step (2) is water, and the crystallization specifically comprises: purifying the crude product of Fmoc-Gly-Pro-OH by recrystallization, and using one or more of ethanol, methanol, isopropyl alcohol, tetrahydrofuran, ethyl acetate, diethyl ether, isopropyl ether, methyl tert-butyl ether or petroleum ether as the solvent for the recrystallization.

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