NEW SYNTHESIS OF PENEMS VIA A REDUCTIVE CYCLIZATION REACTION OF OXALIMIDES WITH TRIALKYL PHOSPHITE

Abstract

Treatment of the oxalimide 5 with triethyl phosphite formed the penem 3 and the triethoxyphosphonium ylide 7, presumably via the common carbene intermediate 10. Prolonged heating of 7 afforded 3 and its C-5 epimer. Similar reaction of the oxalimide 13 with trimethyl phosphite gave only the ylide 14, which was further heated to cyclize to the penem 15.