Synthesis of 3-hydroxycephems from penicillin G through cyclization of chlorinated 4-(phenylsulfonylthio)-2-azetidinones promoted by a BiCl3/Sn or TiCl4/Sn bimetal redox system

Article abstract of DOI:10.1246/bcsj.68.1385

A novel access to 3-hydroxycephems was attained from penicillin G via the C=C bond cleavage of 1-(1-alkoxycarbonyl-2-chloromethyl-2-propenyl)-4-(phenylsulfonylthio)- 2-azetidinones by successive treatment with RuCl₃/HIO₄ and HIO₄/CuSO₄ and reductive cyclization of I-(I-alkoxycarbonyl-3-chloro-2-hydroxy-1-propenyl)-4-(phenylsulfonylth io)-2-azetidinones on treatment with a newly devised BiCl₃/Sn or TiCl₄/Sn bimetal redox couple in DMF containing pyridine.