Highly Efficient Construction of Trifluoromethylated Heterocycles; [3+2] Annulation of N,N′-Cyclic or C,N-Cyclic Azomethine Imines with Trifluoromethyl-Containing Electron-Deficient Olefins

A highly regio- and stereoselective synthesis of pyrazolidine analogues by the use of N,N'-cyclic or C,N-cyclic azomethine imines with two different trifluoromethyl-containing olefins has been developed. The method affords highly functionalized trifluoromethyl-containing pyrazolidine analogues in excellent yields with high diastereoselectivities under mild conditions.