A green preparation process of decarboxylated carnosine

Abstract

The invention provides a green preparation process of decarboxylated carnosine, comprising: (1) placing histamine hydrochloride in solvent A, adding alkali and stirring to dissolve, then dropping chloropropionyl chloride into the solution within 30 minutes, continuing stirring for 8 hours, and separating to obtain liquid A; (2) adding an equal volume of solvent B into liquid A, then introducing ammonia gas, stirring overnight, monitoring the reaction by TLC, removing the solvent, and obtaining an oily substance; (3) adding solvent C into the oily substance until the pH value of the solution is less than 3.0, and separating to obtain liquid B; (4) adding 3 times the volume of solvent D into liquid B, precipitating decarboxylated carnosine hydrochloride, collecting and drying to obtain a white powdery solid. The obtained decarboxylated carnosine hydrochloride is tested, and the yield is ≥74% based on histamine hydrochloride; the preparation process has the advantages of simple synthesis process, easy operation, and green environmental protection; and in the synthesis process, the use of protective groups is avoided, effectively reducing the production cost.

Description

Technical Field

[0001] The invention relates to the technical field of decarboxylated carnosine preparation, and in particular to a green preparation process of decarboxylated carnosine. Background Art

[0002] Carcinine is an imidazole dipeptide that was first discovered in crustaceans and later in the hearts of mammals. It can capture hydroxyl radicals, elemental oxygen and hydrogen peroxide radicals, and inhibit lipid oxidation caused by non-metallic ions, stably protecting cell membranes and giving them good antioxidant properties. At the same time, it can bind to different target sites of collagen, and by occupying the sites, it can prevent collagen from being glycosylated, protect the elasticity of collagen and elastin, and play a role in brightening the skin and avoiding wrinkles on the skin surface.

[0003] There are currently two main routes for the synthesis of decarboxylated carnosine. One is provided in the application document with application number 201911320600.5 and patent name A method for synthesizing decarboxylated carnosine. Figure 1 ; The second is Inorganica Chimica Acta, 361 (6), 1705-1714; 2008 and New Journal of Chemistry, 24 (12), 1037-1042; 2000 provided in the synthetic route 2, see Figure 2 In both of the above two synthetic routes, toxic condensing agents are required. The condensing agents used by Inorganica Chimica Acta are HOBt and TBTU, and those used by New Journal of Chemistry are BOP and triethylamine. These condensing agents are not only toxic, but also account for a large proportion of weight in the synthesis process, which does not meet the requirements of green production. In addition, both of the above two synthetic routes have the disadvantages of many production steps and low atom economy, which leads to high production costs of decarboxylated carnosine. Therefore, providing a preparation process with a simple process, high yield, high cost and green and environmentally friendly synthesis process is of great significance for the production of decarboxylated carnosine. Summary of the invention

[0004] In view of the above-mentioned deficiencies in the prior art, the present invention provides a green preparation process for decarboxylated carnosine. In the process, chloropropionyl chloride and histamine hydrochloride are used as raw materials, and the preparation is completed by two-step synthesis to obtain decarboxylated carnosine hydrochloride, and the yield is ≥74% based on histamine hydrochloride. The preparation process has the advantages of simple synthesis process, easy operation, and green environmental protection. In addition, in the synthesis process, the use of protecting groups is avoided, thereby effectively reducing the production cost.

[0005] The technical solution of the present invention is as follows:

[0006] A green preparation process of decarboxylated carnosine, the steps are as follows:

[0007] (1) placing histamine hydrochloride in solvent A, then adding a base thereto, stirring to dissolve the base, then adding chloropropionyl chloride dropwise to the solution within 30 minutes under stirring, continuing stirring for 8 hours, performing solid-liquid separation, and obtaining liquid A; wherein the equivalent ratio of histamine hydrochloride, base and chloropropionyl chloride is 1:2.7-3.5:1; and solvent A is capable of dissolving histamine hydrochloride;

[0008] (2) adding an equal volume of solvent B to liquid A, then passing ammonia gas, stirring overnight, monitoring the completion of the reaction by TLC, removing the solvent, and obtaining an oily substance; wherein solvent B is an alkaline salt;

[0009] (3) adding solvent C to the oily substance, stirring thoroughly, and then continuing to add the mixed solution under stirring until the pH of the solution is less than 3.0, performing solid-liquid separation, and obtaining liquid B; wherein solvent C is a hydrochloric acid alcohol solution;

[0010] (4) adding 3 times the volume of solvent D to liquid B, decarboxylated carnosine hydrochloride is precipitated, and after collection and drying, a white powder solid is obtained; wherein solvent D is an ester solution.

[0011] Furthermore, in step (1), the solvent A is one of dichloromethane, chloroform, acetonitrile, isopropyl ether or methyl tert-butyl ether.

[0012] Furthermore, in step (1), the base is one of sodium hydroxide, sodium carbonate, potassium hydroxide, potassium carbonate, triethylamine, diisopropylethylamine or trimethylamine.

[0013] Furthermore, in step (1), the equivalent ratio of histamine hydrochloride, base and chloropropionyl chloride is 1:3.1:1.

[0014] Furthermore, in step (2), the solvent B is one of methanol, ethanol, water or isopropanol.

[0015] Furthermore, in step (2), the solvent is removed by rotary evaporation to obtain an oily substance.

[0016] Furthermore, in step (3), the solvent C is one of a 1N hydrochloric acid methanol solution or a 1N hydrochloric acid ethanol solution.

[0017] Furthermore, in step (1) and step (3), solid-liquid separation is performed by suction filtration.

[0018] Furthermore, in step (4), the solvent D is one of ethyl acetate, methyl acetate, isopropyl acetate, propyl acetate or butyl acetate.

[0019] Compared with the prior art, the beneficial effects of the present invention are:

[0020] 1. In the present invention, chloropropionyl chloride and histamine hydrochloride are used as raw materials, and a one-pot continuous operation is adopted to complete the synthesis reaction to obtain decarboxylated carnosine hydrochloride. The process has the advantages of simple synthesis process and easy operation; and in the synthesis process, the use of protecting groups is avoided, thereby effectively reducing production costs.

[0021] 2. The preparation process provided by the present invention can obtain decarboxylated carnosine hydrochloride by crystallization, which reduces the difficulty of post-processing, making the preparation process simple, easy to control, and green and environmentally friendly.

[0022] 3. Using the preparation process provided by the present invention, the yield of decarboxylated carnosine hydrochloride obtained is ≥73% based on histamine hydrochloride. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0024] Figure 1 This is the preparation process flow chart provided in the application document with application number 201911320600.5.

[0025] Figure 2 The preparation process flow chart provided by Inorganica Chimica Acta, 361(6), 1705-1714; 2008 and New Journal of Chemistry, 24(12), 1037-1042; 2000.

[0026] Figure 3 The present invention provides a flow chart of the preparation process.

[0027] Figure 4 This is a sample diagram of Example 1 with an injection volume of 4 μl.

[0028] Figure 5 This is a sample diagram of Example 1 with an injection volume of 6 μl.

[0029] Figure 6 This is a sample diagram of Example 1 with an injection volume of 8 μl. DETAILED DESCRIPTION

[0030] In order to enable those skilled in the art to better understand the technical solutions in the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in combination with the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0031] Example 1

[0032] A green preparation process of decarboxylated carnosine, the steps are as follows:

[0033] (1) 36 g of histamine hydrochloride was placed in 450 mL of dichloromethane, and then 24.6 g (3.1 equivalents) of sodium hydroxide was added thereto. After stirring for 1 hour, the sodium hydroxide dissolved. Then, 25.4 g (1 equivalent) of chloropropionyl chloride was added dropwise to the solution under stirring for 30 minutes. Stirring was continued for 8 hours, and the solid was removed by suction filtration to obtain Liquid A;

[0034] (2) Add an equal volume of methanol to liquid A, then continue to introduce ammonia gas for 4 hours (consuming about 40 liters of ammonia gas), stir overnight, monitor the completion of the reaction by TLC, and remove the solvent by rotary evaporation to obtain an oily substance;

[0035] (3) adding a 1N methanol solution of hydrochloric acid to the oily substance under sufficient stirring until the pH of the solution reaches 2.8, performing solid-liquid separation, removing the solid, and obtaining liquid B;

[0036] (4) 3 volumes of ethyl acetate were added to Liquid B to precipitate decarboxylated carnosine hydrochloride. After collection and drying, 37.8 g of a white powdery solid was obtained. The yield was 75.7% based on histamine hydrochloride.

[0037] Example 2

[0038] A green preparation process of decarboxylated carnosine, the steps are as follows:

[0039] (1) 1 equivalent of histamine hydrochloride is placed in dichloromethane, and then 2.7 equivalents of sodium hydroxide are added thereto. After stirring for 1 hour, the sodium hydroxide is dissolved. Then, 1 equivalent of chloropropionyl chloride is added dropwise to the solution under stirring conditions within 30 minutes. Stirring is continued for 8 hours, and suction filtration is performed to obtain Liquid A;

[0040] (2) Add an equal volume of methanol to liquid A, then continue to introduce ammonia gas for 4 hours (consuming about 40 liters of ammonia gas), stir overnight, monitor the completion of the reaction by TLC, and remove the solvent by rotary evaporation to obtain an oily substance;

[0041] (3) adding a 1N methanol solution of hydrochloric acid to the oily substance under sufficient stirring until the pH of the solution reaches 2.5, and performing solid-liquid separation to obtain Liquid B;

[0042] (4) 3 volumes of ethyl acetate were added to liquid B to precipitate decarboxylated carnosine hydrochloride. After collection and drying, a white powdery solid was obtained. The yield was 74.5% based on histamine hydrochloride.

[0043] Example 3

[0044] A green preparation process of decarboxylated carnosine, the steps are as follows:

[0045] (1) 1 equivalent of histamine hydrochloride is placed in dichloromethane, and then 3.5 equivalents of sodium hydroxide are added thereto. After stirring for 1 hour, the sodium hydroxide is dissolved. Then, 1 equivalent of chloropropionyl chloride is added dropwise to the solution under stirring for 30 minutes. Stirring is continued for 8 hours, and suction filtration is performed to obtain Liquid A;

[0046] (2) Add an equal volume of methanol to liquid A, then continue to introduce ammonia gas for 4 hours (consuming about 40 liters of ammonia gas), stir overnight, monitor the completion of the reaction by TLC, and remove the solvent by rotary evaporation to obtain an oily substance;

[0047] (3) adding a 1N hydrochloric acid methanol solution to the oily substance under sufficient stirring until the pH of the solution reaches 2.0, and performing solid-liquid separation to obtain Liquid B;

[0048] (4) 3 volumes of ethyl acetate were added to liquid B to precipitate decarboxylated carnosine hydrochloride. After collection and drying, a white powdery solid was obtained. The yield was 74.3% based on histamine hydrochloride.

[0049] Example 4

[0050] The difference between this embodiment and embodiment 1 is:

[0051] In step (1), acetonitrile is used to replace dichloromethane, and potassium hydroxide is used to replace sodium hydroxide;

[0052] The yield was 75.2% based on histamine hydrochloride.

[0053] Example 5

[0054] The difference between this embodiment and embodiment 1 is:

[0055] In step (1), chloroform is used to replace dichloromethane, and sodium carbonate is used to replace sodium hydroxide;

[0056] The yield was 75.0% based on histamine hydrochloride.

[0057] Example 6

[0058] The difference between this embodiment and embodiment 1 is:

[0059] In step (1), triethylamine is used instead of sodium hydroxide;

[0060] The yield was 74.9% based on histamine hydrochloride.

[0061] Example 7

[0062] The difference between this embodiment and embodiment 1 is:

[0063] In step (2), ethanol is used instead of methanol;

[0064] The yield was 74.8% based on histamine hydrochloride.

[0065] Example 8

[0066] The difference between this embodiment and embodiment 1 is:

[0067] In step (3), the methanolic hydrochloric acid solution is replaced with a 1N ethanolic hydrochloric acid solution;

[0068] The yield was 75.1% based on histamine hydrochloride.

[0069] Example 9

[0070] The difference between this embodiment and embodiment 1 is:

[0071] In step (4), methyl acetate is used instead of ethyl acetate;

[0072] The yield was 75.2% based on histamine hydrochloride.

[0073] Detection:

[0074] The product obtained in Example 1 was tested by HPLC under the following chromatographic conditions:

[0075] Instrument: Agilent LC1260;

[0076] Chromatographic column: caprisil C18 5μm 100A 250×4.6mm;

[0077] Mobile phase A: 0.05 mol / L sodium dihydrogen phosphate solution;

[0078] Mobile phase B: acetonitrile;

[0079] Mobile phase A:mobile phase B=7:3;

[0080] Flow rate: 1 mL / min;

[0081] Collection time: 30min;

[0082] Sample preparation:

[0083] Weigh 3 portions of the white powdered solid of Example 1, dissolve them in the mobile phase, filter them with a 0.45 μm organic membrane, and then place the 3 samples in 3 injection bottles, marked as sample 1, sample 2 and sample 3; inject 4 μl into sample 1, 6 μl into sample 2, and 8 μl into sample 3; see the spectrum Figure 4 , Figure 5 and Figure 6 ;

[0084] The purity of sample 1, sample 2 and sample 3 was statistically analyzed by area normalization method; the purity of sample 1 was 95.6559%, the purity of sample 2 was 97.5438%, and the purity of sample 3 was 96.0015%; it can be seen that the purity of the samples obtained by the present invention can reach more than 95%.

[0085] Comparative Example 1

[0086] The difference from Example 1 is that in step (1), the dripping of chloropropionyl chloride is controlled to be completed over 31 minutes, specifically the dripping time is controlled to be 36 minutes; the yield is 55.4% based on histamine hydrochloride.

[0087] Comparative Example 2

[0088] The difference from Example 1 is that in step (3), 1N hydrochloric acid methanol solution is added to the oily substance until the pH of the solution is 3.3; the yield is 50.3% based on histamine hydrochloride.

[0089] Although the present invention has been described in detail by reference to the preferred embodiments, the present invention is not limited thereto. Without departing from the spirit and essence of the present invention, a person of ordinary skill in the art may make various equivalent modifications or substitutions to the embodiments of the present invention, and these modifications or substitutions shall be within the scope of the present invention. Any person of ordinary skill in the art may easily think of changes or substitutions within the technical scope disclosed by the present invention, and these shall be within the scope of protection of the present invention. Therefore, the scope of protection of the present invention shall be subject to the scope of protection of the claims.

Claims

1. A green preparation process for decarboxylated carnosine, characterized in that: Here are the steps: (1) placing histamine hydrochloride in solvent A, then adding a base thereto, stirring to dissolve the base, then adding chloropropionyl chloride dropwise to the solution within 30 minutes under stirring, continuing stirring for 8 hours, and performing solid-liquid separation to obtain liquid A; wherein the equivalent ratio of histamine hydrochloride, the base and the chloropropionyl chloride is 1:2.7-3.5:1; and wherein solvent A is capable of dissolving histamine hydrochloride; (2) Add an equal volume of solvent B to liquid A, then introduce ammonia gas, stir overnight, monitor the completion of the reaction by TLC, remove the solvent, and obtain an oily substance; Wherein, solvent B is ethanol or methanol; (3) adding solvent C to the oily substance under sufficient stirring until the pH of the solution is less than 3.0, performing solid-liquid separation, and obtaining liquid B; wherein solvent C is a hydrochloric acid alcohol solution; (4) adding 3 times the volume of solvent D to liquid B, decarboxylated carnosine hydrochloride precipitates, and after collection and drying, a white powdery solid is obtained; wherein solvent D is an ester solution; Solvent A is one of dichloromethane, chloroform, acetonitrile, isopropyl ether or methyl tert-butyl ether; Solvent C is one of 1N hydrochloric acid methanol solution or 1N hydrochloric acid ethanol solution; The solvent D is one of ethyl acetate, methyl acetate, isopropyl acetate, propyl acetate or butyl acetate.

2. the green preparation process of decarboxylated carnosine as claimed in claim 1, is characterized in that, In step (1), the base is one of sodium hydroxide, sodium carbonate, potassium hydroxide, potassium carbonate, triethylamine, diisopropylethylamine or trimethylamine.

3. the green preparation process of decarboxylated carnosine as claimed in claim 1, is characterized in that, In step (1), the equivalent ratio of histamine hydrochloride, base and chloropropionyl chloride is 1:3.1:

1.

4. the green preparation process of decarboxylated carnosine as claimed in claim 1, is characterized in that, In step (2), the solvent is removed by rotary evaporation to obtain an oily substance.

5. the green preparation process of decarboxylated carnosine as claimed in claim 1, is characterized in that, In step (1) and step (3), solid-liquid separation is performed by suction filtration.

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