Formation of Quaternary Chiral Centers by N-Heterocyclic Carbene-Cu-Catalyzed Asymmetric Conjugate Addition Reactions with Grignard Reagents on Trisubstituted Cyclic Enones

The copper-catalyzed conjugate addition of Grignard reagents to 3-substituted cyclic enones allows the formation of all-carbon chiral quaternary centers We demonstrate in this article that N-heterocyclic carbencs act as efficient chiral ligands for this transformation High enantioselectivities (up to 96% ee) could be obtained for a variety of substrates