A novel approach to dihydropyrrolones from iron-substituted alpha,beta-unsaturated imines and organolithium and Grignard reagents: Developments, mechanisms and stereoselective syntheses

Reactions of N-sulfonylimines, derived from Cp(CO)(2)Fe-substituted (Z)-ena ls and benzenesulfonamide, with Grignard or organolithium reagents furnish N-sulfonyldihydropyrrolones. When N-sulfinylimines and organometallic reage nts are used, unprotected alpha,beta -unsaturated gamma -lactams are formed exclusively. Recent mechanistic studies and diastereoselective variations for the synthesis of chiral 5-substituted dihydropyrrolones from iron-subst ituted azadienes are discussed here.