Synthesis of bicyclic pyridone and dihydropyridone analogues of β-lactam antibiotics

Abstract

Condensation of the vinylogous urethanes 2, 26, 28 and 29 with acrylates, haloacrylates and propiolic acid has afforded easy access to bicyclic dihydropyridone and pyridone analogues of cephalosporins, carbapenams, penicillins and bisnorpenicillins. Synthesis of the pyridone is accompanied, in one instance, by an interesting cyclisation to the glutaconic anhydride 23 and significant differences in tautomeric behaviour have been found between the five-membered vinylogous urethanes 28 and 29 and their six-membered counterparts 2.