Diastereo- and Enantioselective Conjugate Addition of 3-Substituted Oxindoles to Nitroolefins Catalyzed by a Chiral Ni(OAc)₂-Diamine Complex under Mild Conditions

A simple catalyst system assembled from an enantiomerically pure diamine ligand and Ni(OAc)₂ efficiently generates chiral metal enolates derived from 3-substituted oxindoles bearing an N-1 carbonyl group. The enolates smoothly undergo diastereo- and enantioselective conjugate addition to a wide range of nitroolefins under mild reaction conditions, furnishing 3,3-disubstituted oxindole products bearing two vicinal quaternary/tertiary stereocenters in 74–95% yields and 60:40 to 99:1 dr, 71–97% ee.