Enantioselective Conjugate Silyl Additions to Cyclic and Acyclic Unsaturated Carbonyls Catalyzed by Cu Complexes of Chiral N-Heterocyclic Carbenes
作者:Kang-sang Lee、Amir H. Hoveyda
DOI:10.1021/ja910989n
日期:2010.3.10
Cu-catalyzed enantioselective conjugate additions proceed to completion within only 2 h to afford the desired silanes in 87-97% yield and 90:10-99:1 enantiomeric ratio (er). Use of a proton source (e.g., MeOH) is not required; accordingly, synthetically versatile alpha-silyl boron enolates can be obtained. The special utility of the present protocol, in comparison with the related catalytic enantioselective
公开了一种有效的铜催化方案,用于将二甲基苯基硅烷基对映选择性加成到范围广泛的环状和非环状不饱和酮、酯、丙烯腈和 α、β、γ、δ-二烯酮。反应在 1-2 mol% 的市售且廉价的 CuCl、一种易于获得的单齿咪唑啉盐和市售的(二甲基苯基甲硅烷基)频哪醇硼存在下进行。铜催化的对映选择性共轭添加仅在 2 小时内完成,以 87-97% 的产率和 90:10-99:1 的对映体比率 (er) 提供所需的硅烷。不需要使用质子源(例如,MeOH);因此,可以获得合成通用的α-甲硅烷基硼烯醇化物。本协议的特殊用途,