PREPARATION PROCESS OF ALPHA-L-ASPARTYL-L-PHENYL-ALANINE METHYL ESTER OR HYDROHALIDE THEREOF

摘要

alpha -L-aspartyl-L-phenylalanine methyl ester or the hydrohalide thereof is prepared by esterifying alpha -L-aspartyl-L-phenylalanine or alpha -L-aspartyl-L-phenylalanine which has been formed in situ by treating an N-protected- alpha -L-aspartyl-L-phenylalanine in an aqueous solution of sulfuric acid or a methanol-containing aqueous solution of sulfuric acid in the presence of an alkali metal halide or alkaline earth metal halide in a medium composed of sulfuric acid, water and methanol, thereby to allow the resulting alpha -L-aspartyl-L-phenyl-alanine methyl ester to precipitate as its corresponding hydrohalide, and then isolating the hydrohalide; and when the preparation of the methyl ester is desired, neutralizing the hydrohalide.