PROCEDE POUR LA PREPARATION DU CEPHALEXINE ET DU CEPHRADINE

摘要

1473090 Cephalosporins LILLY INDUSTRIES Ltd 18 July 1974 [19 July 1973] 34337/73 Heading C2C A 7 -α- aminoacetamido - cephalosporin - 4- carboxylic acid is made by reacting a 7-aminocephalosporin-4-carboxylic acid ester with a reactive derivative of anα-aminoacetic acid, in which the amino group is protected by forming an enamine with a #-dicarbonyl compound; removing the amino protecting group from the product; adding sufficient hydrazine or its derivative (e.g. semicarbazide) to prevent reaction of the liberated dicarbonyl compound; and, if desired de-esterifying the resulting 7-α- aminoacetamido compound.