CN103193712B - A kind of preparation method of N-BETA-Alanyl-L-histidine - Google Patents

Abstract

The present invention relates to a kind of preparation method of N-BETA-Alanyl-L-histidine, comprise by phthalyl-N-BETA-Alanyl-L-histidine and organic amine in a solvent reacting by heating slough protecting group, after separating out product, filter, solvent wash, drying, obtain N-BETA-Alanyl-L-histidine product; Or through concentrated, crystallization, filtration and drying, obtain without hydrazine N-BETA-Alanyl-L-histidine product.Its advantage is that method is easy, and cost is low, workable, does not have toxic compounds hydrazine in gained carnosine product, the quality of product is fully ensured and embodies the security of product to health.

Description

A kind of preparation method of L-carnosine

technical field

The invention belongs to the technical field of organic compound preparation, and in particular relates to a preparation method of L-carnosine.

Background technique

L-carnosine (English name: L-Carnosine, CAS No.: 305-84-0) was first detected in beef by Russian scientists Gulewitsh and Amiradzibi in 1900. It is found in mammalian brain, muscle and other tissues with nerve distribution. It exists widely in animals, and its concentration in animals is about 1-20mmol.L ^-1 , especially in chicken breast meat. In organisms, it is synthesized by carnosine synthase using β-alanine and L-histidine. The chemical name is β-alanyl-L-histidine, and its chemical structure is as follows:

L-carnosine can participate in and regulate various physiological activities of the human body. It has excellent natural anti-oxidation, scavenging free radicals, chelating with transition metals, neuroprotection, promoting wound healing and anti-aging, and has effects on hypertension, heart disease, etc. Disease, senile cataract, ulcer healing, etc. have therapeutic effects, so it has broad application prospects in the fields of medicine, health care, and hygiene.

At present, the chemical synthesis method of L-carnosine is mainly to first protect the amino group in β-alanine with phthalic anhydride, react to obtain phthalyl β-alanine, and then condense with L-histidine The intermediate phthaloyl-L-carnosine is obtained, and the protective group of the intermediate is removed through hydrazinolysis reaction with hydrazine hydrate, and then the product L-carnosine is obtained through decolorization, concentration, crystallization, filtration and drying. Typical bibliographical reports are the patents of CN101117334A (new method for synthesizing L-carnosine) and CN101284862A (synthetic method for L-carnosine) as publication number, and non-patent literature (synthetic research of L-carnosine, Chen Jianhui, Wu Zhigang, Jian Qing, Amino Acids and Biological Resources, 2008, 30, 50-52) and so on.

The above-mentioned method has the advantages that raw materials are easy to get, the processing route is shorter, and the total yield is higher. However, due to the use of hydrazine hydrate in the production process, certain hydrazine residues (about 20 ppm) are arranged in the L-carnosine product.

As is well known in the industry, hydrazine is a highly toxic chemical that is harmful to human health. It can enter the human body through inhalation, ingestion, and skin absorption, causing dizziness, nausea, and excitement to the central nervous system. and other symptoms of poisoning. In addition, hydrazine is considered a suspected carcinogen. Therefore, how to effectively reduce or even completely remove the residue of hydrazine in L-carnosine products has always been a technical problem that the industry has been paying attention to for a long time and is eager to solve. However, so far, there is no corresponding technical suggestion in the published Chinese and foreign patents and non-patent literature to prepare hydrazine-free carnosine. For this reason, the applicant has found a solution to the problem after many explorations. On the basis of technology, by using other non-hydrazine deprotection reagents to remove phthaloyl group, remove the source of hydrazine from the source, and prove this method by detecting the finished L-carnosine product obtained by using this technology It is completely effective and completely solves the problem of hydrazine residue in the product of L-carnosine prepared by the current mainstream hydrazinolysis method. The technical solution to be introduced below is produced under this background.

Contents of the invention

The problem to be solved in the present invention is to provide a method for preparing hydrazine-free L-carnosine without hydrazine residues at all, so as to ensure product quality and reflect the safety of L-carnosine products on human health.

The invention provides a preparation method of L-carnosine as follows: phthalyl-L-carnosine and organic amine are heated and reacted in a solvent to remove the protective group and react to obtain L-carnosine. The method may further include: the L-carnosine product obtained after the reaction is precipitated, filtered, washed with an organic solvent, and dried to obtain the L-carnosine product. Or the method may further include: the L-carnosine product obtained after the reaction is concentrated, crystallized, filtered and dried to obtain the L-carnosine product.

The L-carnosine obtained by the above preparation method of the present invention is hydrazine-free L-carnosine.

Phthaloyl-L-carnosine of the present invention has following structural formula:

The organic amines are recommended to be linear or branched organic amines with 1 to 4 carbon atoms, such as primary amines (primary amines) such as methylamine, ethylamine, propylamine, and butylamine.

The amount of the organic amine is equivalent or excessive, for example, the molar ratio of phthaloyl-L-carnosine to the organic amine is 1: (1-4).

The recommended reaction time for removing the protecting group is 1-3 hours.

The solvent is at least one of water or an organic solvent selected from C ₁ -C ₆ alcohols, C ₂ -C ₆ ketones, acetonitrile, tetrahydrofuran (THF) or dioxane, etc. At least one of or their mixed solvents, such as at least one of methanol, ethanol, propanol, butanol, acetone, isopropanol, acetonitrile, tetrahydrofuran or dioxane, etc.

The reaction temperature of the heating reaction to remove the protecting group is from 30° C. to reflux, and the reflux temperature refers to the solvent reflux temperature. Further recommended reaction temperature is 30-80°C.

The washing solvent is at least one of C ₁ -C ₆ alcohol, C ₂ -C ₆ ketone, C ₂ -C ₆ ether, C ₂ -C ₆ ester or C ₁ -C ₆ haloalkane species, such as at least one of methanol, ethanol, propanol, acetone, isopropanol, ether, ethyl acetate, or dichloromethane.

The recommended concentration and crystallization is to remove the reaction solvent by distillation under reduced pressure or normal pressure, then add the solvent for crystallization and heat to reflux until the product is precipitated. The solvent for crystallization is a C ₁ -C ₆ alcohol, such as methanol, ethanol or isopropanol.

Since the present invention does not use hydrazine hydrate to remove the protecting group of L-carnosine, the introduction of hydrazine is avoided from the source, and the possibility of hydrazine residue in the product is completely eliminated, so that the quality of L-carnosine products can be fully guaranteed and reflected The safety of products to human health.

Detailed ways

Content of the present invention is further described in conjunction with the following examples, but content of the present invention is not limited to the content involved in the examples:

Example 1:

Add 7.12 grams (2 mmol) of phthaloyl-L-carnosine and 80 mL of monomethylamine aqueous solution (30%, mass ratio) to a 250 mL reaction flask, and stir the mixed system at 80 ° C for 2 hours to stop the reaction and remove the solvent , adding 200 mL of absolute ethanol, stirring and heating to reflux, a white powdery solid was precipitated, filtered, washed with 20 mL of ether, and dried to obtain 3.87 g of carnosine product, yield: 88%. Hydrazine was not detected in the product.

Example 2:

Add 14.2 g (4 mmol) of phthaloyl-L-carnosine, 14 mL of methylamine ethanol solution (27-30%, mass ratio) and 350 mL of absolute ethanol into a 500 mL reaction flask, and heat to reflux for 1 hour. Filtrate hot, wash with 2×80 mL of absolute ethanol, wash with 2×80 mL of ether, and dry to obtain 8.02 g of carnosine product with a yield of 89%. Hydrazine was not detected in the product.

Example 3:

Add 3.56 g (1 mmol) of phthaloyl-L-carnosine, 30 mL of isopropanol and 4 mL of methylamine aqueous solution (30%, mass ratio) to a 100 mL reaction flask, heat to reflux for 1.5 h, and heat filter, 2×80 mL Wash with absolute ethanol, wash with 2×80 mL ether, and dry to obtain 1.68 g of carnosine product, with a yield of 74%.

Example 4:

Add 3.56 g (1 mmol) of phthaloyl-L-carnosine, 30 mL of isopropanol and 4 mL of methylamine-ethanol solution (27-30%, mass ratio) into a 100 mL reaction flask, heat to reflux for 1 hour, and filter while hot. Wash with 2×60 mL of absolute ethanol, 2×40 mL of ether, and dry to obtain 1.8 g of carnosine product with a yield of 80%.

Example 5:

In a 100mL reaction flask, add 3.56 grams (1 mmol) of phthaloyl-L-carnosine, 30 mL of THF and 4 mL of methylamine aqueous solution (30%, mass ratio), heat to reflux for 2 hours, remove the solvent, and add 100 mL of ethanol to the obtained solid Reflux, filter, wash with 2×60 mL of anhydrous methanol, and dry to obtain 1.51 g of carnosine product with a yield of 69%.

Embodiment 6:

Add 3.56 g (1 mmol) of phthaloyl-L-carnosine, 30 mL of tetrahydrofuran and 4 mL of methylamine ethanol solution (27-30%, mass ratio) into a 100 mL reaction flask, reflux for 3 hours, filter while hot, 2× Wash with 60 mL of absolute ethanol, 2×30 mL of ethyl acetate, and dry to obtain 1.60 g of carnosine product with a yield of 71%.

Embodiment 7:

In a 100mL reaction flask, add 3.56 grams (1 mmol) of phthaloyl-L-carnosine, 30 mL of dioxane and 4 mL of methylamine aqueous solution (30%, mass ratio), heat to reflux for 2 hours, and filter while hot, 2 ×30mL dichloromethane washed, dried to obtain carnosine product 2.04g, yield 90%.

Embodiment 8:

Add 3.56 g (1 mmol) of phthaloyl-L-carnosine, 30 mL of dioxane and 5 mL of methylamine ethanol solution (27-30%, mass ratio) into a 100 mL reaction flask, heat to reflux for 2.5 h, and remove the solvent , adding absolute ethanol 100mL, stirring and heating to reflux, a white powder solid was precipitated, filtered, washed with 20mL of ethanol, and dried to obtain 2.2 grams of carnosine product with a yield of 97%.

Embodiment 9:

Add 3.56 grams (1 mmol) of phthaloyl-L-carnosine, 30 ml of ethanol and 3.8 mL of n-propylamine to a 100 mL reaction flask, heat to reflux for 2 hours, filter, wash with 20 mL of isopropanol, and dry to obtain 2.04 grams of carnosine. Yield 90%.

Example 10:

Add 3.56 grams (1 mmol) of phthaloyl-L-carnosine, 30 mL of ethanol and 3.7 mL of n-butylamine to a 100 mL reaction flask, heat to reflux for 2 hours, filter, wash with 20 mL of absolute ethanol, and dry to obtain 2.14 grams of carnosine product , 95% yield.

Example 11:

Add 3.56 g (1 mmol) of phthaloyl-L-carnosine, 30 ml of water and 4 mL of ethylamine aqueous solution (65-70%, mass ratio) to a 100 mL reaction flask, heat to reflux for 1 hour, remove the solvent, and add 30 mL of ethanol Reflux, cool, filter, wash with 20 mL of ethanol, and dry to obtain 1.37 g of carnosine product with a yield of 61%.

Example 12:

Add 3.56 g (1 mmol) of phthaloyl-L-carnosine, 30 mL of acetone and 4 mL of methylamine aqueous solution (30%, mass ratio) into a 100 mL reaction flask, heat to reflux for 2 hours, remove the solvent, add 30 mL of ethanol to reflux , cooled, filtered, washed with 20 mL of ethanol, and dried to obtain 1.54 grams of carnosine product, with a yield of 68%.

Example 13:

Add 3.56 g (1 mmol) of phthaloyl-L-carnosine, 30 mL of ethanol and 3.0 mL of isopropylamine to a 100 mL reaction flask, heat to reflux for 2.5 hours, remove the solvent, add 30 mL of ethanol to reflux, cool, filter, and 20 mL of ethanol Wash and dry to obtain carnosine product: 1.4 g, yield 62%.

Claims (8)

1. a preparation method for N-BETA-Alanyl-L-histidine, is characterized in that in a solvent with 30 DEG C under reflux temperature, and the organic primary amine of phthalyl-N-BETA-Alanyl-L-histidine and 1 to 2 carbon atom obtains N-BETA-Alanyl-L-histidine after reacting and sloughing protecting group in 1 ~ 3 hour; The mol ratio of described phenyl-diformyl-N-BETA-Alanyl-L-histidine and the organic primary amine of 1 to 2 carbon atom is 1:(1 ~ 4).

2. preparation method according to claim 1, is characterized in that described reaction to be sloughed after protecting group through separating out product, filtration, organic solvent washing and drying, obtaining N-BETA-Alanyl-L-histidine product.

3. preparation method according to claim 1, is characterized in that described reaction to be sloughed after protecting group through concentrated, crystallization, filtration and drying, obtains N-BETA-Alanyl-L-histidine product.

4. the preparation method according to claim 1,2 or 3, is characterized in that described N-BETA-Alanyl-L-histidine product is without hydrazine N-BETA-Alanyl-L-histidine product.

5. preparation method according to claim 1, is characterized in that described solvent is selected from water, C ₁~ C ₆alcohol, C ₂~ C ₆ketone, acetonitrile, tetrahydrofuran (THF), dioxane or their mixed solvent.

6. preparation method according to claim 2, is characterized in that described washing organic solvent is C ₁~ C ₆alcohol, C ₂~ C ₆ketone, C ₂~ C ₆ether, C ₂~ C ₆ester or C ₁~ C ₆haloalkane at least one.

7. preparation method according to claim 3, is characterized in that described crystallization solvent is C ₁~ C ₆alcohol.

8. preparation method according to claim 1, is characterized in that described temperature of reaction is 30 ~ 80 DEG C.