Chiral copper(II) complexes as Lewis acids for catalyzed cycloaddition, carbonyl addition, and conjugate addition reactions

Bis(oxazoline) copper(II) complexes 1-3 function as enantioselective Lewis acid catalysts for carbocyclic and hetero Diels-Alder, aldol, Michael, ene, and amination reactions with substrates capable of chelation. X-ray crysta llography of the catalyst reveals a propensity for the formation of distort ed square planar or square pyramidal complexes. The sense of asymmetric ind uction is identical for all the processes catalyzed by [Cu((S,S)-t-Bu-box)] (X)(2) complexes 1 and 2 resulting from the intervention of a distorted sq uare planar catalyst-substrate binary complex.