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

Abstract From the Canadian patent

32 -, ABSTRACT OF THE DISCLOSURE, a-L-aspartyl-L-phenylalanine methyl ester or the hydrohalide thereof is prepared by esterifying a-L-aspartyl-L-phenylalanine or a-L-aspartyl-Lphenylalanine which has been formed in situ by treating an N-protected-a-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 a-L-aspartyl-L-phenyl-alanine methyl ester to precipitate as its corresponding hydrohalide, and then isolating the hydrohalide; and when the preparation of the …