291. M. Tissot, A. Pérez Hernández, D. Müller, M. Mauduit, A. Alexakis,
     “Highly Enantioselective and Regioselective Copper-Catalyzed 1,4 Addition of Grignard Reagents to Cyclic Enynones”
     Org. Lett. 2011, 13, 1524-1527.
     [ Correction dans Org. Lett. 2011, 13, 2798]

In this letter we describe an unusual result in terms of regioselectivity with respect to copper-catalyzed conjugate additions of various Grignard reagents to cyclic enynones. The use of Cu(OTf)₂ and NHC ligand L1 as the catalyst combination in CH₂Cl₂ led to the unique formation of the 1,4 adduct. This selectivity does not follow the general trend previously observed in the literature using extended Michael acceptors. Moreover these reactions allowed for the creation of a quarternary stereogenic center with enantioselectivities up to 97% ee.

DOI : 10.1021/ol200219m 

archive ouverte unige:14606