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

A copper-catalyzed umpolung of N -2,2,2-trifluoroethylisatin ketimines for the enantioselective 1,3-dipolar cycloaddition with benzo[ b ]thiophene sulfones was developed. Using a catalyst system consisting of an ( S , S p )- t Bu-Phosferrox ligand, Cu(OTf) 2 , and Cs 2 CO 3 , a range of pentacyclic spirooxindoles containing pyrrolidine and benzo[ b ]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.