Synthesis of reactive γ-lactams related to penicillins and cephalosporins

gamma-Lactams with structures analogous to both penicillin (1) and cephalosporin (2) antibiotics have been synthesised. These compounds show high reactivity towards modest nucleophiles in keeping with their design as potential inhibitors of bacterial cell wall biosynthesis. Reactive gamma-lactam analogues 27 and 29 of beta-lactamase inhibitors such as 22 have also been prepared. An X-ray crystal structure of the cephalosporin analogue 8 has allowed structural comparisons to be made with the classical beta-lactam antibiotic cephaloridine (30).