RING-CLOSURE METHOD FOR 1-CARBACEPHALOSPORIN SIX-MEMBERED RING

摘要

X-83276 The invention provides a process for preparing 7-protected amino4-protected carboxy-1-carbacephalosporins which includes subjecting a 3protected-amino-4-(1-propylene oxide)-methyl(protected carboxy)-azetidin-2-one to a strong base to form a 2-hydroxycepham and thereafter dehydrating the 2-hydroxycepham to form the desired 1-carbacephalosporin. Also included in the invention are novel intermediates.