An Organocatalytic Michael–Michael Cascade for the Enantioselective Construction of Spirocyclopentane Bioxindoles: Control of Four Contiguous Stereocenters

An organocatalytic Michael-Michael cascade for the enantioselective construction of spirocyclopentane bioxindoles was developed in moderate to good yield with good diastereoselectivities and excellent enantioselectivities. The straightforward process, catalyzed by a bifunctional chiral squaramide catalyst, serves as a powerful tool for the enantioselective construction of potentially biological bioxindoles with four contiguous chiral centers, of which two are spiro all-carbon quaternary centers on a single cyclopentane ring.