Method for producing D-tryptophan

Abstract

The invention discloses a method for producing D-tryptophan. The method comprises the following steps: 1) L-tryptophan is stirred in methanol and cooled to 10 DEG C, thionyl chloride is added dropwise; after the adding, the temperature rises to 20 DEG C, heat insulation is performed for 5 h, methanol is concentrated, water is added, the pH is adjusted to 7-8 with ammonia water, L-tryptophan methyl ester is crystallized and filtered and dried for standby application; 2) L-tryptophan methyl ester is dissolved in the methanol, D-tartaric acid and 3% of trimethylacetaldehyde are added at room temperature, the temperature rises to 70 DEG C, backflow is performed for 5 h, cooling is performed, and double salt is obtained; 3) the double salt is dissolved in water, the pH is adjusted to 7-8 with ammonia water, and D-tryptophan methyl ester is obtained through crystallization and filtration; 4) D-tryptophan methyl ester is dissolved in water at room temperature, the pH is adjusted to over 12 with 20% of sodium hydroxide, heat insulation is performed for 4 h, crude D-tryptophan is obtained through crystallization and filtration and stirred and washed for 1 h with water, and the product D-tryptophan is obtained through centrifugation. The method belongs to asymmetric conversion and is simple to operate, high in yield and low in cost.

Description

technical field [0001] The invention relates to the technical field of chemical synthesis, in particular to a method for producing D-tryptophan. Background technique [0002] As a non-protein optically active amino acid, D-tryptophan has special physiological properties and has certain value in food, feed industry and agriculture. It can be used as non-nutritive sweetener, feed additive and plant growth agent. Especially in the pharmaceutical industry, D-tryptophan is an important synthetic precursor for anticancer agents and immunosuppressants. [0003] In the prior art, there are mainly the following defects about the preparation method of D-tryptophan: [0004] 1) Use L-tryptophan to synthesize N-acetyl-DL-tryptophan, hydrolyze it with L-aminoacylase to obtain D-acetyl tryptophan and hydrolyze it in hydrochloric acid. Because this method is 50% split conversion, and then In addition, hydrochloric acid is used for hydrolysis at the end, so the yield is relatively low. In...

AI Technical Summary

Problems solved by technology

[0004] 1) Use L-tryptophan to synthesize N-acetyl-DL-tryptophan, hydrolyze it with L-aminoacylase to obtain D-acetyl tryptophan and hydrolyze it in hydrochloric acid. Because this method is 50% split conversion, and then In addition, hydrochloric acid is used for hydrolysis at the end, so the yield is relatively low. In addition, hydrochloric acid is used for hydrolysis at the end, and the indole ring is easily decomposed in acid, and the yield of the final product is lower. Therefore, the relative cost of the process is relatively high, so that the market higher price;

[0005] 2) Using DL-tryptophan to resolve with camphorsulfonic acid, this resolution can only be 50% resolution, and cannot achieve 100% conversion, so the chirality of this method cannot be resolved above 99 , so there is no way to industrialize;

[0006] 3) Splitting by the Heine method, because two kinds of enzymes are needed, so the cost is relatively high, and the market price will also be high, making it difficult to realize industrialization