Enantioselective Michael Additions to α,β-Unsaturated Imides Catalyzed by a Salen−Al Complex

(Salen)aluminum complex 1b is an efficient catalyst for the conjugate addition of di- and trisubstituted nitriles to a wide range of acyclic alkyl- and aryl-substituted alpha,beta-unsaturated imides. This new methodology provides access to multifunctional compounds that previously have not been readily accessible in enantioenriched form. Synthetic applications of these products include the preparation of enantiomerically enriched piperidines, as exemplified by an expedient asymmetric catalytic synthesis of (-)-paroxetine.