Chemical synthesis method of ergothioneine

Abstract

The invention provides a chemical synthesis method of ergothioneine, and aims to realize efficient and high-purity synthesis of ergothioneine by optimizing reaction conditions and step design. The method comprises the following main steps: firstly, preparing dimethyl aspartate hydrochloride, then carrying out dimethylation on amino, then preparing chloroketone, and closing an imidazole ring with S-benzyl thiourea. And finally, hydrolyzing methyl ester, methylating dimethyl sulfate into quaternary ammonium salt, removing benzyl protection, and passing through ion exchange resin to obtain purified ergothioneine. The method is mild in reaction condition, simple and convenient to operate, high in reaction yield and purity, suitable for large-scale industrial production and wide in application prospect.

Description

Technical Field

[0001] The present invention relates to the field of chemical synthesis, and more specifically to a chemical synthesis method of ergothioneine. Background Art

[0002] Ergothioneine is a naturally occurring sulfur-containing amino acid derivative with a variety of biological activities, such as antioxidant, anti-inflammatory, anti-radiation and cytoprotective functions. Due to its unique chemical properties and potential biomedical applications, ergothioneine has attracted increasing attention in the fields of medicine, food and cosmetics.

[0003] At present, the extraction of ergothioneine mainly relies on natural sources, such as mushrooms, beans and some microorganisms. However, this extraction method is limited by the supply of natural resources and has high costs. Therefore, the development of efficient chemical synthesis methods has become a hot topic in scientific research.

[0004] Traditional ergothioneine synthesis methods generally involve multi-step reactions, and due to the problems of harsh reaction conditions, low yield, and low product purity, existing synthesis methods still have many challenges in industrial production. Therefore, there is an urgent need for a novel synthesis method that can improve synthesis efficiency and simplify process steps. Summary of the invention

[0005] In order to overcome the deficiencies in the prior art, a chemical synthesis method of thioneine is provided, which specifically comprises the following scheme:

[0006] A chemical synthesis method of ergothioneine, wherein the synthesis method comprises the following steps:

[0007] S1, preparing dimethyl aspartate hydrochloride;

[0008] S2. Introducing a protecting group: adding aspartic acid dimethyl ester hydrochloride and sodium carbonate to dichloromethane and stirring evenly; slowly adding benzyl mercaptan dropwise and continuing stirring for 6 hours; after the reaction is completed, washing the reaction solution with water, drying the organic phase with anhydrous sodium sulfate, and removing the solvent by rotary evaporation; introducing a protecting group can avoid unnecessary side reactions in subsequent reactions, improve the stability of the intermediate, and thus ensure the quality of the final product.

[0009] S3. Synthesis of chloroketone: dissolve dimethyl N,N-dimethylaspartate in anhydrous tetrahydrofuran, add tert-butylmagnesium chloride, then add anhydrous sodium chloroacetate, stir to react, extract with dichloromethane after the reaction is completed, wash with water, dry and concentrate to obtain chloroketone.

[0010] S4, cyclization reaction: dissolve the intermediate chloroketone in acetonitrile, add S-benzylthiourea hydrochloride, add potassium carbonate in batches under stirring, release carbon dioxide gas, heat and stir; after the reaction is completed, cool to room temperature, add water and diethyl ether to separate; dry the organic layer, and remove the solvent by rotary evaporation to obtain an intermediate with an imidazole ring;

[0011] S5. Hydrolysis reaction: dissolve the intermediate with imidazole ring in methanol, slowly add sodium hydroxide; stir at 25°C for 12 hours, monitor the reaction completion, add hydrochloric acid to neutralize the reaction solution and adjust the pH to weak acidity, filter out the solid, extract the organic layer with ether, remove the solvent by rotary evaporation, dissolve the residue in acetone, add dimethyl sulfate dropwise, heat under reflux until the reaction is complete, and then concentrate the solvent to obtain methyl sulfate.

[0012] S6, deprotection reaction: the methyl sulfate is added to ethanol, 5% palladium carbon is added, and the mixture is placed in an autoclave, and 10 kg of hydrogen pressure is replaced, and the benzyl group is removed by heating and stirring. The palladium carbon catalyst is removed by filtration, and the ethanol is concentrated. The residue is purified by ion exchange resin to obtain the finished product ergothioneine.

[0013] Further, the step of preparing dimethyl aspartate hydrochloride in S1 is to dissolve L-aspartic acid in methanol and stir to react; slowly add concentrated hydrochloric acid to the reaction solution and continue stirring for 4 hours; after the reaction is completed, the reaction solution is rotary evaporated to remove the solvent to obtain dimethyl aspartate hydrochloride;

[0014] Furthermore, in S2, formaldehyde is used in 5 equivalents of 37% aqueous solution, and formic acid is used in 10 equivalents of 88% aqueous solution.

[0015] Furthermore, tert-butylmagnesium chloride is used as the base in S3.

[0016] Furthermore, the temperature of the stirring reaction in S4 is 70°C.

[0017] Furthermore, the stirring reaction time in S5 is 8 to 10 hours.

[0018] Furthermore, the temperature of the stirring reaction in S6 is 60°C.

[0019] Furthermore, the deprotection solvent in S6 is methanol or ethanol.

[0020] Beneficial effects:

[0021] The present invention provides a chemical synthesis method of thioneine, specifically comprising the following steps: first preparing dimethyl aspartate hydrochloride, then by introducing a protecting group, carrying out cyclization reaction, deprotection and other steps, finally obtaining highly purified thioneine. The method of the present invention achieves efficient synthesis of thioneine by accurately controlling reaction conditions, such as temperature, time and reagent concentration, with few by-products, high product purity, and good repeatability and stability. Meanwhile, the method reaction conditions are mild, easy to operate, suitable for large-scale industrial production, and has high cost-effectiveness and environmental friendliness. The whole synthesis process is economical and efficient, and is suitable for a wide range of industrial applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a roadmap for the chemical synthesis of ergothioneine. DETAILED DESCRIPTION

[0023] In order to deepen the understanding of the present invention, the present invention will be further described in detail below in conjunction with examples. The examples are only used to explain the present invention and do not constitute a limitation on the protection scope of the present invention.

[0024] Figure 1 is a chemical synthesis route of ergothioneine, such as Figure 1 As shown, the synthetic method step includes first, preparing dimethyl aspartate hydrochloride, then introducing a protecting group, reacting with benzyl mercaptan in dichloromethane to generate an intermediate. Then, by cyclization, a ring intermediate is obtained under the conditions of ethanol and methylsulfonic acid. Finally, a deprotection reaction is carried out to obtain purified thioneine. Specific embodiments are as follows:

[0025] Embodiment 1:

[0026] S1. Preparation of dimethyl aspartate hydrochloride:

[0027] Dissolve L-aspartic acid (10 g, 75 mmol) in 100 mL of methanol and stir at 40°C. Slowly drop concentrated hydrochloric acid (20 mL, 240 mmol) into the reaction solution and keep stirring for 4 hours. After the reaction is completed, remove the solvent by rotary evaporation to obtain white solid aspartic acid dimethyl ester hydrochloride.

[0028] S2, amino dimethylation:

[0029] Add the above-prepared dimethyl aspartate hydrochloride (10g, 50mmol) to a 250mL reaction bottle, then add 37% formaldehyde (20g, 250mmol) and 88% formic acid (26g, 500mmol), and stir evenly. Heat and reflux and stir for 6 hours. After the reaction is completed, concentrate to remove excess formaldehyde and formic acid, add 100mL water and 200mL dichloromethane to separate the layers, extract the aqueous phase with 100mL dichloromethane, combine the organic phases, wash with water, dry with anhydrous sodium sulfate, and remove the solvent by rotary evaporation to obtain N,N-dimethylamino aspartic acid dimethyl ester.

[0030] S3, Chloroketone Synthesis:

[0031] Dissolve N,N-dimethylaspartic acid dimethyl ester (9 g, 50 mmol) in anhydrous tetrahydrofuran, add tert-butylmagnesium chloride (200 ml, 200 mmol), then add anhydrous sodium chloroacetate (8.74 g, 75 mmol) and triethylamine (7.6 g, 75 mmol), stir and react for 16 hours. After the reaction is completed, cool to 0 degrees, add hydrochloric acid and dichloromethane to separate the layers, wash the organic phase with water, dry and concentrate to obtain chloroketone.

[0032] S4, cyclization reaction:

[0033] The intermediate chloroketone (10.4 g, 50 mmol) was dissolved in acetonitrile, S-benzylthiourea hydrochloride (12.2 g, 60 mmol) was added, potassium carbonate (16.56 g, 120 mmol) was added in batches under stirring, carbon dioxide gas was released, and the mixture was heated and stirred; after the reaction was completed, the mixture was cooled to room temperature, solid matter was first filtered out, and water and ether were added to the concentrated filtrate to separate the layers; the organic layer was dried, and the solvent was removed by rotary evaporation to obtain an intermediate with an imidazole ring;

[0034] S5. Hydrolysis reaction:

[0035] Dissolve the intermediate with imidazole ring (16 g, 50 mmol) in 100 ml methanol, slowly add 10% sodium hydroxide aqueous solution (24 g, 60 mmol); stir at 25 ° C for 12 hours, monitor the reaction completion, add hydrochloric acid to neutralize the reaction solution to adjust the pH to 3-5, filter out the solid, extract the organic layer with ether, remove the solvent by rotary evaporation, dissolve the residue in 200 ml acetone, add dimethyl sulfate (6.3 g, 50 mmol) dropwise, heat reflux until the reaction is complete, and then concentrate the solvent to obtain methyl sulfate.

[0036] S6, deprotection reaction:

[0037] The above methyl sulfate (20.8 g, 50 mmol) was added to 120 ml of ethanol, 2 g of 5% palladium carbon was added, and the mixture was placed in an autoclave, 10 kg of hydrogen pressure was replaced, and the mixture was heated and stirred for 10 hours. The reaction was monitored to be complete, the palladium carbon catalyst was filtered out, the ethanol was concentrated, and the residue was purified by ion exchange resin to obtain the finished product ergothioneine.

[0038] As a further improvement, the above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A chemical synthesis method for ergothioneine, characterized in that, The synthetic method comprises the following steps: S1, preparing dimethyl aspartate hydrochloride; S2, aminodimethylation: add excess formaldehyde and formic acid to dimethyl aspartate hydrochloride, heat and reflux, and stir for 6 hours; after the reaction is completed, remove excess formaldehyde and formic acid by rotary evaporation, add dichloromethane and water, neutralize with sodium bicarbonate, wash the dichloromethane phase with water, dry and concentrate to obtain N,N-dimethylaspartic acid dimethyl ester; S3. Synthesis of chloroketone: Add tert-butylmagnesium chloride and sodium chloroacetate to dimethyl N,N-dimethylaspartate. After the reaction is completed, extract with dichloromethane, wash with water, dry and concentrate to obtain chloroketone. S4, cyclization reaction: dissolve the intermediate chloroketone in acetonitrile, add S-benzylthiourea hydrochloride, add potassium carbonate in batches under stirring, heat and stir; after the reaction is completed, cool to room temperature, extract the organic layer with ether; dry the organic layer, and remove the solvent by rotary evaporation to obtain an intermediate with an imidazole ring; S5. Hydrolysis reaction: dissolve the intermediate with imidazole ring in methanol, slowly add sodium hydroxide; stir at 25°C for 12 hours until the reaction is complete; after the reaction is complete, add hydrochloric acid to neutralize, filter out the solid, extract the organic layer with ether, remove the solvent by rotary evaporation, dissolve the residue in acetone, add dimethyl sulfate dropwise, and concentrate to obtain methyl sulfate after the reaction is complete. S6, deprotection reaction: the above salt is added to ethanol, 5% palladium carbon is added, and the mixture is placed in an autoclave, and the benzyl group is removed under 10 kg of hydrogen pressure, and the palladium carbon catalyst is filtered out, and the ethanol is concentrated. The residue is purified by ion exchange resin to obtain the finished product ergothioneine.

2. a chemical synthesis method of thioneine according to claim 1, is characterized in that, S1 The steps of preparing dimethyl aspartate hydrochloride are as follows: dissolving L-aspartic acid in methanol and stirring for reaction; slowly adding concentrated hydrochloric acid to the reaction solution and continuing stirring for 4 hours; after the reaction is completed, rotary evaporating the reaction solution to remove the solvent to obtain dimethyl aspartate hydrochloride.

3. a kind of chemical synthesis method of ergothioneine according to claim 1, is characterized in that, S2 contains 5 equivalents of formaldehyde and 10 equivalents of formic acid.

4. a chemical synthesis method of thioneine according to claim 1, is characterized in that, Tert-butyl magnesium chloride is used as the base in S3.

5. a chemical synthesis method of thioneine according to claim 1, is characterized in that, The temperature of the stirring reaction in S4 is 70°C.

6. a chemical synthesis method of thioneine according to claim 1, is characterized in that, The stirring reaction time in S5 is 8 to 10 hours.

7. a chemical synthesis method of thioneine according to claim 1, is characterized in that, The reaction temperature in S6 is 60 degrees.

8. a chemical synthesis method of thioneine according to claim 1, is characterized in that, The deprotection solvent in S6 is ethanol or methanol.

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