Enantioselective Michael addition catalyzed by an optically active 1-chlorovinyl cobalt(III) complex

Abstract The optically active 1-chlorovinyl cobalt(III) complex was prepared from the ketoiminatocobalt(II) complex upon treatment with sodium borohydride in the presence of 1,1,1-trichloroethane. The obtained complex was found to catalyze the enantioselective Michael addition of various malonates on cyclic or acyclic enones to afford the corresponding adduct. In this reaction, the use of sodium alkoxide as a base with 1-chlorovinyl cobalt(III) complex catalyst was crucial to improving both the reactivity and enantioselectivity.