Chemical Reactivity of oxo- and aza-gamma-lactam Rings

Abstract

[eng] Different mechanisms for the alkaline hydrolysis of oxo and aza-g-lactam rings have been studied by ab initio calculations at the MP2/6-31¿G*//MP2/6-31¿G* and B3LYP/6-31¿G*//B3LYP/6-31¿G* levels. The tetrahedral intermediate can undergo two different reactions, the cleavage of the C2ÿN2 bond (the classical mechanism) and the cleavage of the C2-X6 bond (X=O, N). Both compounds present similar energy barriers for the classical fragmentation, and show considerably lower barriers for the alternative mechanism. Because of this reactivity, the compounds studied are expected to be beta-lactamase inhibitors.