Asymmetric Synthesis of α-Trifluoromethyl Pyrrolidines through Organocatalyzed 1,3-Dipolar Cycloaddition Reaction.

The optically active α-trifluoromethyl pyrrolidines have been achieved through organocatalyzed 1,3-dipolar cycloaddition reaction first. With diphenylprolinol trimethylsilyl ether as catalyst and in the presence of 3,5-dinitrobenzoic acid, the reaction of trifluoroethylamine-derived ketimine with 2-enals gave α-trifluoromethyl pyrrolidines bearing three contiguous stereogenic centers in excellent diastereoselectivies, stereoselectivities, and yields.