Lewis Acid Promoted Diastereoselective Addition of TMSCN and TMSCF3 to Isatin-Derived N‑Sulfinyl Ketimines: Synthesis of Optically Active Tetrasubstituted 3‑Aminooxindoles

A practical and efficient method for preparation of highly enantio­merically enriched 3-cyano-3-amino­oxindoles and 3-tri­fluoro­methyl-3-amino­oxindoles with up to 99% optical purity by a Lewis acid promoted diastereo­selective Strecker reaction and trifluoro­methylation of isatin-derived N-tert-butane­sulfinyl ketimines has been developed. This protocol allows direct use of N-free isatin substrates under mild conditions.