Formation of Vinyl-, Vinylhalide- or Acyl-Substituted Quaternary Carbon Stereogenic Centers through NHC−Cu-Catalyzed Enantioselective Conjugate Additions of Si-Containing Vinylaluminums to β-Substituted Cyclic Enones
作者:Tricia L. May、Jennifer A. Dabrowski、Amir H. Hoveyda
DOI:10.1021/ja110054q
日期:2011.2.2
generated efficiently by a site-selective hydroalumination of an alkyne with dibal-H. The desired products, containing a quaternary carbon stereogenic center, are obtained in 48-95% yield after purification and in 89:11 to >98:2 enantiomer ratio (er). The vinylsilane moiety within the products can be functionalized to afford acyl, vinyliodide, or desilylated alkenes in 67% to >98% yield and with >90% retention
描述了含硅乙烯基铝试剂对 β 取代的环戊烯酮和环己烯酮的对映选择性共轭加成 (ECA) 的催化方法。反应由 1.0-5.0 mol% 的双齿 NHC-Cu 复合物促进,该复合物由空气稳定的 CuCl(2)•2H(2)O 制备并原位使用,通常在 15-20 分钟内完成。必需的乙烯基金属是通过用 dibal-H 对炔烃进行位点选择性氢铝化来有效生成的。在纯化后以 48-95% 的产率和 89:11 至 >98:2 的对映异构体比 (er) 获得所需产物,其中包含一个季碳立体中心。产物中的乙烯基硅烷部分可以被官能化,以 67% 至 >98% 的产率提供酰基、乙烯基碘或脱甲硅烷基化烯烃,并且烯烃的立体化学特性保留 >90%。