Molecular modeling of γ-lactam analogues of β-lactam antibacterial agents: synthesis and biological evaluation of selected penem and carbapenem analoques

Abstract

Computational chemistry made possible the prediction of the three-dimensional structures of γ-lactam analogues of penems and carbapenems before the analogues were made. Molecular superpositioning showed that these novel structures with a 7β-acylamino side-chain present the pharmacophoric groups in close spatial similarity to the groups in biologically active cephalosporin and penicillin antibiotics. This suggests that 8-oxo-7-acylamino-1-azabicyclo[3.3.0]-oct-2-ene-2-carboxylates and the 4-thia-analogues can be accommodated in the same active sites of essential bacterial penicillin-binding proteins where cephalosporins and penicillins are recognized. The syntheses of these compounds are reported. The γ-lactams exhibit low, but detectable levels of antibacterial activity and suggest promise that substantial activity can be achieved with other γ-lactams.