The pH-independent, acid-catalyzed and base-catalyzed hydrolyses of N- acyloxymethylazetidin-2-ones all occur at the ester function. The pH-independent hydrolysis involves rate-limiting alkyl CO fission and formation of an exocyclic β-lactam iminum ion. This iminium ion is then trapped by water at the exocyclic iminium carbon atom, rather than at the β-lactam carbonyl carbon atom, to form the corresponding N-hydroxymethylazetidin- ...
