Department of Chemistry, Merkert Chemistry Center, Boston College, Chestnut Hill, Massachusetts 02467, USA.
J Am Chem Soc. 2009 Mar 11;131(9):3160-1. doi: 10.1021/ja809382c.
A Cu-catalyzed method for efficient boron-copper addition processes involving acyclic and cyclic disubstituted aryl olefins are reported. Reactions are promoted with 0.5-5 mol % of a readily available N-heterocyclic carbene (NHC) complex; the presence of MeOH promotes in situ protonation of the C-Cu bond and leads to efficient catalyst turnover, constituting a net Cu-catalyzed hydroboration process. Reactions proceed in >98:<2 site selectivity and furnish secondary organoborane isomers that complement those obtained through reactions of boron-hydride reagents or by Rh- or Ir-catalyzed hydroborations (benzylic secondary C-B bonds). Initial observations regarding processes catalyzed by chiral NHC complexes, delivering products in up to 99:1 enantiomeric ratio, are disclosed.
报道了一种涉及非环和环取代的芳基烯烃的硼铜加成过程的高效铜催化方法。反应在 0.5-5 mol%的易得的 N-杂环卡宾（NHC）配合物的促进下进行；甲醇的存在促进了 C-Cu 键的原位质子化，并导致有效的催化剂周转，构成了净铜催化的硼氢化过程。反应具有>98:<2 的位选择性，并提供了补充通过硼氢化物试剂或 Rh 或 Ir 催化的硼氢化反应获得的那些的次级有机硼烷异构体（苄基次级 C-B 键）。披露了关于手性 NHC 配合物催化的过程的初步观察结果，这些过程以高达 99:1 的对映体比例提供产物。
