Alkenylborane-Derived Frustrated Lewis Pairs: Metal-Free Catalytic Hydrogenation Reactions of Electron-Deficient Alkenes
作者:J. Sreedhar Reddy、Bao-Hua Xu、Tayseer Mahdi、Roland Fröhlich、Gerald Kehr、Douglas W. Stephan、Gerhard Erker
DOI:10.1021/om3006068
日期:2012.8.13
these alkenylboranes undergo FLP reactions acting as catalysts for the hydrogenation of imines. Perhaps most remarkably, some of these alkenylboranes retain the C═C double bonds under FLP/H2 reaction conditions and heterolytically split dihydrogen in the presence of the Lewis base DABCO and catalyze the hydrogenation of the electron-poor C═C double bonds of diaryl-substituted enones.
通过1,1-碳链化路线制备了一系列烯基硼烷,并将其用作路易斯酸组分,用于产生沮丧的路易斯对(FLP)。1-炔烃与B(C 6 F 5)3的反应得到RCH═C(C 6 F 5)B(C 6 F 5)2系统4a(R = n -C 3 H 7),4b(R = n -C 4 H 9),4c(R = Ph)和4d(R = t -C 4 H 9), 分别。在环境温度下,衍生自化合物4a – d的烯基硼烷/ t Bu 3 P FLP与二氢(2.5 bar)迅速反应。笨重的系统4D离开alkenylborane不饱和的C = C双键和,得到二氢裂解产物[吨卜3 PH] [吨BuCH═C(C 6 ˚F 5)BH(C 6 ˚F 5)2 ](10D) 。相比之下,体积较小的系统4a / t, Bu 3 P和4b / t在这些条件下,Bu 3 P分解成二氢,并干净地还原了它们的C═C双键,生成了相应的1-五氟苯基烷基氢硼酸盐[