Synthesis of New Oxapenams and Carbapenams

Abstract

Diazoketones derived from 4-thioazetldinon-1-ylacetic acids, on metal-catalysed decomposition, gave either carbapenams andlor oxapenams depending upon the nature o f the substituent present on the thia function.Synthesis o f a novel axapenam carboxylic acid 16 which exhlblted potent 8-lactamase mhibitory properties comparable t o clavulanlc acid is described.Copper-catalysed decompositiw, of some monocyclic azetidmone diazoketones possessing a t h e r an arylthlo group or an slkylthio group a t posltian-4 was recently reported by Oida, Yoshtda and Dhkl1.They observed the formation o f 2-arylthiomethylene oxapenam 3 i n the former case and an oxocephanl !!i n the l a t t e r 2 instance.Recently we reported the formation of a m i x t u r e o f carbapenams 6 and 1 and an oxapenam 8 i n R : p -n i t r a b e n z y l the decomposltim of d~azoketone 1.We would now like to present some of the results w i t h monocyclic azetidinone d~azoketones possessmg different mercaptan substituents a t posttion-4.