Synthesis and characterization of a free phenylene bis(N-heterocyclic carbene) and its di-Rh complex: Catalytic activity of the di-Rh and CCC–NHC Rh pincer complexes in intermolecular hydrosilylation of alkynes
作者:Gurusamy Thangavelu Senthil Andavan、Eike B. Bauer、Christopher S. Letko、T. Keith Hollis、Fook S. Tham
DOI:10.1016/j.jorganchem.2005.07.088
日期:2005.12
regioselective, stereoselective, and chemoselective: terminal alkynes give predominantly the β-(Z) isomer and internal alkynes afford the β-(E) isomer in chloroform or benzene. One of the strongest attributes of the catalyst systems is that the results were achieved without exclusion of air and without purification of commercially available reagents.
1,3-双(3-丁基咪唑-1-基)苯二碘化物(1)与Li(2,2,6,6-四甲基哌啶)反应生成游离的双卡宾1,3-双(3-丁基咪唑) -2-亚苄基-1-基)苯(3),已通过光谱表征。将游离双卡宾与[Rh(COD)Cl] 2结合,得到相应的二Rh双(N-杂环卡宾)配合物(4),该配合物在结构上得到了表征。发现二-Rh双卡宾络合物显示出复杂的溶液13 C和1 H NMR光谱,这些光谱被指定为非对映异构体的混合物。双-Rh双卡宾化合物4的晶体结构由一对对映异构的阻转异构体组成。非对映异构的阻转异构体被指定为光谱复杂度的来源。二-Rh二卡宾络合物4和CCC-NHC Rh钳夹络合物2被用作末端炔烃和内部炔烃的硅氢加成反应的催化剂。两种催化剂都是高活性,区域选择性,立体选择性和化学选择性的:末端炔烃主要产生β-(Z)异构体,内部炔烃提供氯仿或苯中的β-(E)异构体。催化剂体系的最强属性之一是在不排除空气且未纯化市售试剂的情况下获得了结果。