Asymmetric Cycloaddition of N-2,2,2-Trifluoroethylisatin Ketimines and Unsymmetrical Dicarbonyl-Activated Alkenes: Construction of 5′-Trifluoromethylated 3,2′-Pyrrolidinyl Spirooxindoles with Three Carbonyl Groups

Abstract

The asymmetric cycloaddition between N-2,2,2-trifluoroethylisatin ketimines and unsymmetrical dicarbonyl-activated alkenes catalyzed by a bifunctional squaramide has been discovered. The present study demonstrates an efficient approach for the regio-, diastereo-, and enantioselective synthesis of densely functionalized 5′trifluoromethylated 3,2′-pyrrolidinyl spirooxindoles featuring three different types of carbonyl groups.