Abstract
In order to prepare ampicillin prodrugs conveniently for practical use, a new synthetic method for 6β-aminopenicillanic acid (6-APA) esters as key intermediates of various ampicillin prodrugs has been developed. Acylation of 6-APA esters to ampicillin esters was achieved in good yields by using phenylglycyl chloride hydrochloride in dichloromethane in the presence of sodium bicarbonate and amide, or ammonium bicarbonate alone. KBT-1585, bacampicillin, talampicillin and pivampicillin have been obtained in good yields by this procedure.
