Chiral diselenides from benzylamines: Catalysts in the diethylzinc addition to aldehydes

A series of new chiral diselenides with a N-atom in the side chain was prepared by a short synthetic sequence (Scheme I). Only 1 mol-% of these diselenides catalyzed very effectively the diethylzinc addition to various aromatic and alpha,beta-unsaturated aldehydes yielding the secondary alcohols in up to 98% ee (Scheme 2 and Tables I and 2). An asymmetric amplification was observed with these catalysts. Detailed NMR studies were performed to characterize the catalytically active species.