Process for the conversion of threo-(2R,3R)-2-hydroxy-3-(2- aminophenylthio)-3-(4-methoxyphenyl)propionic acid derivatives

摘要

A process for the conversion of threo-(2R,3R)-2-hydroxy-3- (2-aminophenylthio)-3-(4-methoxyphenyl)propionic acid derivatives into threo-2-hydroxy-3-(2-aminophenylthio)-3-(4- methoxyphenyl)propionic acid esters, which are intermediates for the synthesis of diltiazem. The invention relates to a method for the recycle of a waste product of diltiazem synthesis.