High-purity amino acid derivative and method for preparing the same

Abstract

This invention discloses a high-purity amino acid derivative. The raw materials, by weight, include: 1-3 parts proline, 20-30 parts organic solvent, 0.5-1 part polypeptide condensing agent, 0.1-0.5 parts nucleophilic catalyst, and 1-1.5 parts amino protecting agent. This invention controls the reaction rate of the raw materials to allow the esterification reaction to occur under relatively mild conditions. Furthermore, the presence of diisopropylcarbodiimide maximizes the production of proline methyl ester, thus increasing the reaction yield. The addition of an alkylaminopyridine compound further enhances the protective effect of tert-butyloxycarbonyl ester on the proline amino group, reducing the reaction between the methyl ester intermediate and the amino group and preventing the formation of amide groups. Simultaneously, the mild reaction conditions allow the generated product to achieve high purity without complex subsequent separation, making it suitable as an intermediate in various pharmaceuticals.

Description

TECHNICAL FIELD

[0001] The present application relates to a high-purity amino acid derivative and a preparation method thereof, in particular to the field of C07D, and in particular to a heterocyclic compound. BACKGROUND

[0002] The preparation of polypeptide drugs from amino acid derivatives has become a hot spot in drug research and development. Polypeptide drugs have a wide range of indications and high safety, and are applied to the prevention, diagnosis and treatment of various diseases. Proline drugs have good permeability in the body, are often used as osmotic regulators, and can also be used as enzyme protectants and have the effect of scavenging free radicals. Hydroxyproline methyl ester, as a medical intermediate, can be used for the research and synthesis of various polypeptide drugs. It is of great significance to develop a high-purity and high-yield hydroxyproline methyl ester for the research and synthesis of medicines.

[0003] Chinese patent CN112194606A discloses a preparation method of N-BOC-cis-4-hydroxy-L-proline methyl ester. L-hydroxyproline is used as a raw material, and then BOC is protected by amino, and then methyl esterification is performed. The obtained proline methyl ester has a high yield, but the reaction time is long. Chinese patent CN201080051130 discloses a preparation method of N-Boc-cis-amino-L-proline methyl ester. Trans-hydroxyproline is used as a raw material, and sodium azide needs to be added for chiral conversion. The reaction process is violent and easy to cause the deprotection of BOC, affecting the yield. SUMMARY

[0004] In order to improve the preparation purity of proline derivatives and reduce the generation of by-products, the first aspect of the present application provides a high-purity amino acid derivative. The preparation raw material includes, by weight: proline 1-3 parts, organic solvent 20-30 parts, polypeptide condensing agent 0.5-1 part, nucleophilic catalyst 0.1-0.5 part, and amino protecting agent 1-1.5 parts.

[0005] As a preferred embodiment, the proline is selected from one or a combination of several of L-proline, D-proline and DL-proline.

[0006] As a preferred embodiment, the L-proline is selected from one or a combination of several of 4-hydroxy-L-proline, L-thioproline, L-amino proline and L-amido proline.

[0007] As a preferred embodiment, the proline is 4-hydroxy-L-proline.

[0008] As a preferred embodiment, the organic solvent is selected from one or a combination of several of hydrocarbon solvents, alcohol solvents, ester solvents, phenolic solvents, ketone solvents and furan.

[0009] As a preferred embodiment, the organic solvent used in step 1 is a combination of chloroform and methanol, the organic solvent used in step 2 is tetrahydrofuran, and the organic solvent used in step 3 is a combination of chloroform and petroleum ether.

[0010] As a preferred embodiment, the amount of the organic solvent used is 8-12 parts by weight of chloroform, 1-2 parts by weight of methanol in step 1, 10-15 parts by weight of tetrahydrofuran in step 2, and the volume ratio of chloroform to petroleum ether is (3-5):1 in step 3.

[0011] As a preferred embodiment, the amount of the organic solvent used is 9-11 parts by weight of chloroform, 1.2-1.8 parts by weight of methanol in step 1, 11-14 parts by weight of tetrahydrofuran in step 2, and the volume ratio of chloroform to petroleum ether is (4-5):1 in step 3.

[0012] As a preferred embodiment, the amount of the organic solvent used is 10 parts by weight of chloroform, 1.5 parts by weight of methanol in step 1, 13 parts by weight of tetrahydrofuran in step 2, and the volume ratio of chloroform to petroleum ether is 4.5:1 in step 3.

[0013] As a preferred embodiment, the polypeptide condensing agent is selected from one or a combination of carbodiimide condensing agents, phosphonium condensing agents, and urea condensing agents.

[0014] As a preferred embodiment, the carbodiimide condensing agent is selected from one of diisopropyl carbodiimide, 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride, and dicyclohexyl carbodiimide.

[0015] As a preferred embodiment, the polypeptide condensing agent is diisopropyl carbodiimide.

[0016] As a preferred embodiment, the nucleophilic catalyst is selected from one or a combination of alkylamino pyridine compounds or allyl amino pyridines.

[0017] As a preferred embodiment, the alkylamino pyridine compound is N-methyl-N-(oxetanyl)aminopyridine.

[0018] As a preferred embodiment, the preparation method of the N-methyl-N-(oxetanyl) aminopyridine comprises the following steps: mixing bipyridine hydrochloride and methylamine hydrochloride with a weight ratio of 2:1, adding ethyl acetate to stir and reflux for 5h, adding triethylamine with a mass concentration of 40%, controlling the pH value to be 11-12, vacuum filtering, mixing the filter cake with triethylamine with a mass concentration of 50%, adding epichlorohydrin dropwise, stirring and refluxing for 4h, vacuum distilling, and drying to obtain solid N-methyl-N-(oxetanyl) aminopyridine.

[0019] As a preferred embodiment, the amino protecting agent is selected from one or a combination of carbonyl ester, phthalimide, phthalamide, p-toluenesulfonamide, and trifluoroacetamide.

[0020] As a preferred embodiment, the carbonyl ester is selected from one or a combination of tert-butyloxycarbonyl ester, benzyloxycarbonyl ester, and diphenyl-2-propyloxycarbonyl ester.

[0021] As a preferred embodiment, the amino protecting agent is tert-butyloxycarbonyl ester.

[0022] The applicant found in the experiment that the carboxyl methyl esterification reaction can be fully carried out by using 4-hydroxy-L-proline and methanol under the action of a catalyst diisopropyl carbodiimide, and the reaction condition is relatively mild by adding methanol dropwise. The protection effect of tert-butyloxycarbonyl ester on amino acid can be further increased by adding an alkylamino pyridine compound, so that the tert-butyloxycarbonyl ester is connected to the heterocycle of proline, and the reaction intensity is reduced by adding tert-butyloxycarbonyl ester dropwise, so as to control the reaction of the methyl ester intermediate with the amino group on the amino acid, thereby avoiding the generation of amide groups. The pH value of the system is controlled during the reaction to prevent the inversion of the chirality of the amino acid.

[0023] The second aspect of the present application provides a preparation method of an amino acid derivative with high purity, comprising the following steps:

[0024] (1) adding proline and a polypeptide condensing agent to an organic solvent, stirring at room temperature for 6-8h, vacuum filtering after the reaction is completed, and obtaining white solid;

[0025] (2) mixing the white solid obtained in step 1 and a nucleophilic catalyst in an organic solvent, stirring, controlling the reaction temperature to be 25-40℃, reacting for 1-2h, and adding an amino protecting agent dropwise, and reacting for 6-8h;

[0026] (3) washing the solid product with an organic solvent by vacuum filtering, repeating the washing for 3 times, taking the white solid, and drying to obtain the product.

[0027] As a preferred embodiment, step 1 is to add proline and polypeptide condensing agent into chloroform, react at room temperature for 1-2 h, then drop methanol, drop completely within 40-50 min, react under constant stirring for 5-6 h, filter under reduced pressure after the reaction is completed, and obtain white solid.

[0028] Compared with the prior art, the present application has the following beneficial effects:

[0029] (1) The proline derivative of the present application controls the reaction speed of raw materials, so that the esterification reaction occurs under a relatively mild condition, and under the action of diisopropyl carbodiimide, proline methyl ester is generated as much as possible, thereby improving the yield of the reaction.

[0030] (2) The proline derivative of the present application further increases the protection of the tert-butoxycarbonyl ester on the amino group of proline by adding an alkylaminopyridine compound, reduces the reaction of the methyl ester intermediate with the amino group, and avoids the generation of amide groups.

[0031] (3) The proline derivative of the present application has a mild reaction condition, and the generated product can achieve high purity without complex subsequent separation, and can be used as an intermediate of various medicines. DETAILED DESCRIPTION

[0032] The present application will be specifically described below through examples. It is necessary to point out here that the following examples are only used to further illustrate the present application and cannot be understood as limiting the protection scope of the present application. Some non-essential improvements and adjustments made by the person skilled in the art based on the content of the present application still belong to the protection scope of the present application.

[0033] In addition, if not otherwise specified, the raw materials used are commercially available.

[0034] Example 1

[0035] A high-purity amino acid derivative is prepared from raw materials including, by weight: proline 3 parts, organic solvent 28 parts, polypeptide condensing agent 0.75 parts, nucleophilic catalyst 0.35 parts, and amino protecting agent 1.3 parts.

[0036] The proline is 4-hydroxy-L-proline, which is purchased from TCI (Shanghai) Chemicals Co., Ltd.

[0037] The polypeptide condensing agent is diisopropyl carbodiimide.

[0038] The nucleophilic catalyst is N-methyl-N-(oxetanyl)aminopyridine, and the preparation method comprises the following steps: 2 parts by weight of 4,4-bipyridine dihydrochloride (CAS: 27926-72-3) is mixed with 1 part by weight of methylamine hydrochloride (CAS: 593-51-1), ethyl acetate is added, stirring is carried out under reflux for 5 h, 40% by mass of triethylamine is added, the pH value is controlled to be 12, filtration is carried out under reduced pressure, the whole filter cake is mixed with 50% by mass of triethylamine, the pH value is controlled to be 12, epichlorohydrin is added dropwise, the weight ratio of epichlorohydrin to 4,4-bipyridine dihydrochloride is 2:1, stirring is carried out under reflux for 4 h, distillation is carried out under reduced pressure, and then drying is carried out to obtain solid N-methyl-N-(oxetanyl)aminopyridine.

[0039] The amino protecting agent is tert-butyloxycarbonyl ester.

[0040] A preparation method of an amino acid derivative with high purity, comprising the following steps:

[0041] (1) proline, a polypeptide condensing agent is added to chloroform, and reaction is carried out at room temperature for 1.5 h, then methanol is added dropwise, and the addition is completed within 40 min, and reaction is carried out under constant stirring for 5 h, then filtration is carried out under reduced pressure, and white solid is obtained;

[0042] (2) the white solid obtained in step 1 and a nucleophilic catalyst are added to an organic solvent, stirring is carried out, the reaction temperature is controlled to be 30 ℃, reaction is carried out for 2 h, an amino protecting agent is added dropwise, and reaction is carried out for 8 h;

[0043] (3) filtration is carried out under reduced pressure, the solid product is washed with an organic solvent, the washing is repeated for 3 times, the white solid is taken, and drying is carried out, and then the amino acid derivative with high purity is obtained.

[0044] The organic solvent used in step 1 is chloroform 10 parts by weight and methanol 1.5 parts, the organic solvent used in step 2 is tetrahydrofuran 13 parts, and the organic solvent used in step 3 is a combination of chloroform and petroleum ether, and the volume ratio is 4.5:1.

[0045] Example 2

[0046] An amino acid derivative with high purity and a preparation method thereof, and the specific steps are the same as those in example 1, and the difference lies in that the polypeptide condensing agent is dicyclohexyl carbodiimide.

[0047] Example 3

[0048] An amino acid derivative with high purity and a preparation method thereof, and the specific steps are the same as those in example 1, and the difference lies in that the nucleophilic catalyst is dimethylaminopyridine.

[0049] Example 4

[0050] A high purity amino acid derivative and a method for preparing the same, the specific steps being the same as in Example 1, except that the volume ratio of chloroform and petroleum ether in step 3 is 3:1.

[0051] Performance test

[0052] 1. Purity: the sample is added into HPLC-MS instrument, and the concentration of proline derivative corresponding to the total peak area on the standard curve is found, and the purity = c proline derivative / c white solid * 100%

[0053] 2. Yield = m 白色固体 / (m 脯氨酸 +m 多肽缩合剂 +m 氨基保护剂 )*100%

[0054] Examples 1-4 are tested according to the above standard, and the test results are shown in Table 1.

[0055] Table 1

[0056] Purity / % Yield / % Example 1 98.52 90.31 Example 2 95.33 86.02 Example 3 90.01 91.32 Example 4 95.89 85.42

Claims

1. An amino acid derivative having high purity, characterized by comprising: The raw materials are prepared by weight parts: proline 1-3 parts, organic solvent 20-30 parts, polypeptide condensing agent 0.5-1 part, nucleophilic catalyst 0.1-0.5 part, amino protecting agent 1-1.5 parts; The proline is 4-hydroxy-L-proline; the polypeptide condensing agent is diisopropyl carbodiimide; and the catalyst is N-methyl-N-(oxetanyl) aminopyridine; The preparation method of the N-methyl-N-(oxetanyl) aminopyridine comprises the following steps: mixing bipyridine hydrochloride and methylamine hydrochloride in a weight ratio of 2:1, adding ethyl acetate to stir and reflux for 5 h, adding triethylamine with a mass concentration of 40%, controlling the pH value to be 11-12, reducing pressure filtration, mixing the filter cake with triethylamine with a mass concentration of 50%, dropwise adding epichlorohydrin, stirring and refluxing for 4 h, reducing pressure distillation, and drying to obtain solid N-methyl-N-(oxetanyl) aminopyridine; The amino protecting agent is tert-butyloxycarbonyl ester BOC; The preparation method of the amino acid derivative with high purity comprises the following steps: (1) adding proline and a polypeptide condensing agent to an organic solvent, stirring at room temperature for 6-8 h, completing the reaction, reducing pressure filtration, and obtaining white solid; (2) adding the white solid obtained in step 1 and a nucleophilic catalyst to an organic solvent, mixing and stirring, controlling the reaction temperature to be 25-40 °C, reacting for 1-2 h, dropwise adding an amino protecting agent, and reacting for 6-8 h; (3) reducing pressure filtration, washing the solid product with an organic solvent, repeating the washing for 3 times, taking white solid, and drying to obtain the product.

2. The amino acid derivative of claim 1, wherein, The organic solvent is selected from one or a combination of several of a hydrocarbon solvent, an alcohol solvent, an ester solvent, a phenolic solvent, a ketone solvent, and a furan.

3. A method for producing the amino acid derivative of high purity according to any one of claims 1 to 2, characterized by, The preparation method comprises the following steps: (1) adding proline and a polypeptide condensing agent to an organic solvent, stirring at room temperature for 6-8 h, completing the reaction, reducing pressure filtration, and obtaining white solid; (2) adding the white solid obtained in step 1 and a nucleophilic catalyst to an organic solvent, mixing and stirring, controlling the reaction temperature to be 25-40 °C, reacting for 1-2 h, dropwise adding an amino protecting agent, and reacting for 6-8 h; (3) reducing pressure filtration, washing the solid product with an organic solvent, repeating the washing for 3 times, taking white solid, and drying to obtain the product.