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% <i>ee</i>). Enantioselective Michael–Michael–Michael–aldol condensation–aromatization reactions of an isomeric product were observed