A new synthesis of pyrrolidines via imino-aldol reaction of (2-trimethylsilylmethyl)cyclopropyl ketones with imines

A new synthesis of 2,3,5-trisubstituted pyrrolidines from the imino-aldols formed from Lewis acid-mediated reactions of (2-trimethylsilylmethyl)cyclopropyl ketones with benzylimines is described. The ring closure of the imino-aldols formed from the benzylimines of 2-chloro-, 2-fluoro-, and 2-trifluoromethylbenzaldehydes proceeds with predominantly 2,5-anti selectivity to generate the corresponding pyrrolidines in moderate yields.