Organocatalytic Enantioselective Michael-Michael-Michael-Aldol Condensation Reactions: Control of Six Stereocenters in a Quadruple-Cascade Asymmetric Synthesis of Polysubstituted Spirocyclic Oxindoles.

An organocatalyzed enantioselective Michael-Michael-Michael-aldol cascade reaction for the construction of cyclopentane fused spirooxindoles was achieved. The domino reaction provided the spirooxindoles with six contiguous stereocenters including a quaternary center in good yields (55-64%) with excellent enantioselectivities (up to >99% ee). Enantioselective Michael-Michael-Michael-aldol condensation-aromatization reactions of an isomeric product were observed.