Diastereoselective cycloadditions of new trifluoromethyl azomethine ylides derived from trifluorothioacetamides

Two methods of generation of new trifluoromethyl azomethine ylides are described: by heating N,N-dimethyl-bis(methylthio)-orthotrifluoroacetamide 2 or by deprotonation of trifluoromethyl thioamidium salts. Trapping by dipolarophiles leads to 2-trifluoromethyl pyrrolidines and pyrrolizidines with high diastereoselectivity. Copyright (C) 1996 Published by Elsevier Science Lt