Synthesis Of Several New-Type Amino Acids And Its Derivatives For Medical Purposes

Amino acids and its derivatives are significant medical materials, pharmaceutical intermediates and medical ingredients, which have been widely used in pharmaceutical fields. So it is valuable to prepare the new-type pharmeceutical amino acids with basic amino acids and these compounds have broad market-prospects.In this paper, it is reported that five amino acids'compounds which are S-carboxymethyl-L-Cysteine, Erdosteine, L–Citrulline, L-Homocitrulline and Ornithine respectively. All products are confirmed by IR, melting point, elements'analysis, HPLC and so on. The former four compounds are pure samples.S-carboxymethyl-L-Cysteine is obtained by the reaction of L-Cysteine and chloroactic acid in alkaline solution on the low-temperature. The influences of temperature, crystal manner and other conditions are studied. After recrystallization the purity of the final product is over 99.66%Erdosteine is synthesized by two steps. First, DL-homocysteine thiolactone hydrochloride is reacted with chloroacetyl chloride at 10℃for 3 hours with yield of 81.9%. Second, the prior product is reacted with thiolacetic acid at 0~5℃for 2 hours and Erdosteine is obtained with yield of 78% after recrystallization in ethanol. We still seek after the method of further purification with column chromatogram. The purity of the final product is over 99.88%.L-Citrulline and L-Homocitrulline are prepared by the same process. The materials are respectively L-ornithine monohydrochloride and L-lysine monohydrochloride. After a series of reactions such as reacting with copper, N-acylating and removing copper the products are obtained. The reaction reagents are alkaline copper carbonate and urea. The copper(Ⅱ) compounds are treated with hydrogen sulfide. Then the products are obtained with yield of over 60%. The mechanism is simply discussed.Ornithine is prepared by the hydrolyzation of L-arginine. First, L-arginine is hydrolyzed in the aqueous solution of sodium carbonate. Second, the worked reaction solution is treated using 732 cation-exchange resin. The best condition is determined. Till now the final product is partially racemized L-ornithine. The experiment is still under way.