Process for preparing aminohydroxycephamcarboxylates

摘要

A useful synthetic intermediate, 7-amino-3-acyloxycepham-4-carboxylic acid aralkyl ester, is prepared by reducing 7-amido-3-oxocepham-4-carboxylic acid aralkyl ester with alkali metal borohydride in a dry organic solvent at temperature lower than -20 DEG C. and then acylating the resulting 3-hydroxycepham compound with an acylating reagent to give 3-acyloxycepham compound, and then subjecting the 3-acyloxycepham compound to amide cleavage consisting of treatments (1) with a mixture of phosphorus pentachloride and aromatic base giving imino-chloride and (2) with alcohol for converting the latter into imino-ether and for subjecting the product to alcoholysis giving the objective compound.