Conjugate addition of organocuprates to chiral bicyclic delta-lactams. Enantioselective synthesis of cis-3,4-disubstituted and 3,4,5-trisubstituted piperidines

[GRAPHICS] Chiral nonracemic bicyclic lactam 3, easily accessible by cyclodehydration of (R)-phenylglycinol and racemic methyl 4-formylhexanoate, was converted t o the unsaturated lactams 5, which undergo the stereoselective conjugate ad dition of lower order cyanocuprates to ultimately lead to enantiopure cis-3 ,4-disubstituted and 3,4,5-trisubstituted piperidines.