Synthesis of 2-exo-Methylenepenam by Reductive 1,2-Elimination and S-S Bond Fission in a PbBr₂/Al Bimetal System

Tanaka, H.; Nishioka, Y.; Kameyama, Y.; Sumida, S.-i.; Matsuura, H.; Torii, S. Chem. Lett. 1995, 709.

A convenient synthesis of 2-exo-methylenepenam was performed by reductive elimination of a 3,4-disubstituted chlorine atom(s) and/or a triflate moiety and S-S bond fission of the phenylsulfonylthio group of p-methoxybenzyl 3,4-dichloro or 4-chloro-3-(trifluoromethanesulfonyloxy)-2-[4-(phenylsulfonylthio)-2-oxoazetidin-1-yl]-2-butenoate derived from peniciline G in a lead(II) bromide/alminum bimetal redox system.