Exceptionally<i>E</i>- and β-Selective NHC-Cu-Catalyzed Proto-Silyl Additions to Terminal Alkynes and Site- and Enantioselective Proto-Boryl Additions to the Resulting Vinylsilanes: Synthesis of Enantiomerically Enriched Vicinal and Geminal Borosilanes
作者:Fanke Meng、Hwanjong Jang、Amir H. Hoveyda
DOI:10.1002/chem.201203803
日期:2013.2.25
N‐heterocyclic carbene (NHC) copper complexes. Specifically, a commercially available imidazolinium salt, cheap CuCl (1.0 mol %) and Me2PhSi–B(pin), readily and inexpensively prepared in one vessel, are used to convert terminal alkynes to (E)‐β‐vinylsilanes efficiently (79–98 % yield) and in >98 % E and >98 % β‐selectivity. Vinylsilanes are converted to borosilanes with 5.0 mol % of a chiral NHC–Cu complex in
提出了一种特殊的位和E选择性催化方法,用于通过末端炔烃的甲硅烷基化制备含硅烯烃。此外,所得的乙烯基硅烷被用作底物,以通过另一种催化方法产生邻位或双键的硼硅烷。此类产物源自Si取代烯烃的对映选择性原硼酸。N-杂环卡宾(NHC)铜络合物催化所有转化。具体地说,使用一种在一个容器中容易且廉价地制备的市售咪唑啉盐,便宜的CuCl(1.0 mol%)和Me 2 PhSi–B(pin),可将末端炔烃有效地转化为(E)-β-乙烯基硅烷(79 –98%的产率)和> 98%的E和> 98%的β选择性。乙烯基硅烷以5.0 mol%的手性NHC-Cu络合物转化为硼硅烷,产率为33-94%,对映体比率高达98.5:1.5(er)。烷基取代的底物专门提供邻位的硼硅烷。芳基和杂芳基取代的烯烃优先提供双键异构体。在两类转化中,不同类别的手性NHC引起较高的对映选择性:C 1对称的单齿Cu络合物最适合于含烷基的乙烯基硅烷