Asymmetric Synthesis of Cyclopentane-Substituted Oxindoles via Organocatalytic Desymmetrization of Cyclopent-4-ene-1,3-diones

The highly enantioselective desymmetrization of prochiral cyclopent-4-ene-1,3-diones has been developed via an organocatalytic Michael reaction. This desymmetrization protocol is efficiently catalyzed by 10 mol% of a bifunctional squaramide, offering a short entry into a series of cyclopentane-substituted oxindoles bearing two quaternary and one tertiary stereocenters in good yields and high stereoselectivities.