Stereoselective Synthesis of 3,3-Disubstituted Oxindoles and Spirooxindoles via Allylic Alkylation of Morita–Baylis–Hillman Carbonates of Isatins with Cyclic Sulfamidate Imines Catalyzed by DABCO

An efficient, organocatalytic, and ecofriendly method has been developed for the quick construction of a wide array of 3,3-disubstituted oxindoles in good to excellent yields and diastereomeric ratio (up to ≤96:4) with excellent functional group tolerance via an allylic alkylation reaction of cyclic sulfamidate imines with a number of MBH carbonates of isatins in 2-MeTHF as an environmentally benign solvent at room temperature using 5 mol % of DABCO. Furthermore, a metal-free-based one-shot synthesis of a medicinally promising polycyclic spirooxindole with an all-carbon spirocenter has been achieved with outstanding dr value (up to ≤99:1).