???-Halogeno diethyl carbonates and their use in the preparation of antibiotics

摘要

???-Halogeno diethylcarbonate is used to prepare ethylcarbonyloxy- ethyl esters of penicillins and cephalo- sporins. The amino group in ampicillin can first be protected by reaction with an acetoacetate derivative and the protecting group removed after the esterification step. The new compound ???-bromo diethylcarbonate can be used without an esterification catalyst. The new compound is obtained by reacting acetaldehyde with carbonyl bromide followed by reaction with ethanol or by a halogen exchange reaction with the corresponding ???-chloro compound.