Organocatalytic Asymmetric Michael Addition of Oxindoles to Nitroolefins for the Synthesis of 2,2-Disubstituted Oxindoles Bearing Adjacent Quaternary and Tertiary Stereocenters

A bifunctional thiourea-catalyzed Michael addition of
activated
indolin-3-ones to nitroolefins has been developed. The synthetically
useful 2,2-disubstituted indolin-3-one derivatives with vicinal chiral
quaternary–tertiary stereocenters were obtained in high yields
with excellent stereoselectivities. The adduct can be readily transformed
into a structurally interesting heterocyclic architecture by means
of further synthetic elaboration.