Copper-Catalyzed Umpolung of -2,2,2-Trifluoroethylisatin Ketimines for the Enantioselective 1,3-Dipolar Cycloaddition with Benzo[]thiophene Sulfones.

A copper-catalyzed umpolung of -2,2,2-trifluoroethylisatin ketimines for the enantioselective 1,3-dipolar cycloaddition with benzo[]thiophene sulfones was developed. Using a catalyst system consisting of an (,)-Bu-Phosferrox ligand, Cu(OTf), and CsCO, a range of pentacyclic spirooxindoles containing pyrrolidine and benzo[]sulfolane subunits were obtained in high efficiency with excellent regio-, diastereo-, and enantioselectivites under mild conditions. The practicality and versatility of the reaction were also demonstrated.