280. S. Kehrli, D. Martin, D. Rix, M. Mauduit, A. Alexakis,
     “Formation of Quaternary Chiral Centers by N-Heterocyclic Carbene–Cu-Catalyzed Asymmetric Conjugate Addition Reactions with Grignard Reagents on Trisubstituted Cyclic Enones”
     Chem. Eur. J. 2010, 16, 9890-9904.

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 carbenes act as efficient chiral ligands for this transformation. High enantioselectivities (up to 96 % ee) could be obtained for a variety of substrates.

DOI : 10.1002/chem.201000471 

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