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).