Lee Kang-sang, Brown M Kevin, Hird Alexander W, Hoveyda Amir H
Department of Chemistry, Merkert Chemistry Center, Boston College, Chestnut Hill, Massachusetts 02467, USA.
J Am Chem Soc. 2006 Jun 7;128(22):7182-4. doi: 10.1021/ja062061o.
We present the first examples of Cu-catalyzed enantioselective conjugate additions of alkyl- and arylzinc reagents to unactivated cyclic beta-substituted enones. Transformations are promoted in the presence of 2.5-15 mol % of a readily available chiral NHC-based Cu complex, affording the desired products bearing all-carbon quaternary stereogenic centers in 67-->98% yield and in up to 97% ee. Catalytic enantioselective reactions can be carried out on a benchtop, with undistilled solvent and commercially available (not further purified) Cu salts. Mechanistic models, accounting for the observed levels and trends in enantioselectivity are provided.
我们展示了首例铜催化的烷基锌试剂和芳基锌试剂对未活化的环状β-取代烯酮的对映选择性共轭加成反应。在2.5 - 15 mol%易于获得的手性NHC基铜配合物存在下，反应得以顺利进行，以67%至98%的产率和高达97%的对映体过量（ee）得到带有全碳季碳立体中心的所需产物。催化对映选择性反应可以在实验台上进行，使用未蒸馏的溶剂和市售（无需进一步纯化）的铜盐。文中还提供了能够解释所观察到的对映选择性水平和趋势的机理模型。
