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.