PREPARATION OF ANTIBIOTICS

摘要

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