Studies on Structures of Degradation Products of Aspoxicillin. II. Polymerization Products of Aspoxicillin in Aqueous Solution

Abstract

Intermolecular condensation of a novel semisynthetic penicillin, aspoxicillin (ASPC) was studied. Several products with small amounts on standing in an aqueous solution at room temperature were detected by the amide-bond formation between a primary amine at the side chain and a lactam carbonyl of another molecule. Their structures were estimated to be a dimer, epi-isomer of dimer, a trimer, and their analogues of the β-lactam ring opening. This polymerization reaction is known to occur in penicillins such as ampicillin and amoxicillin with the primary amine group at the benzylic position.