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).