Chotana Ghayoor A, Rak Michael A, Smith Milton R
Department of Chemistry, Michigan State University, East Lansing, Michigan 48824, USA.
J Am Chem Soc. 2005 Aug 3;127(30):10539-44. doi: 10.1021/ja0428309.
Ir-catalyzed borylations of 4-substituted benzonitriles are described. In contrast to electrophilic aromatic substitutions and directed ortho metalations, C-H activation/borylation enables functionalization at the 2-position, adjacent to the cyano group, when the 4-subsitutent is larger than cyano. When an excess of borane reagent is used, diborylation can be achieved with a single regioisomer being formed in certain cases. Extension of sterically directed borylation to cyano-substituted, five- and six-membered ring heterocycles is also reported.
描述了铱催化的4-取代苯甲腈的硼化反应。与亲电芳香取代反应和导向邻位金属化反应不同，当4-取代基大于氰基时，碳氢键活化/硼化反应能够在氰基相邻的2-位进行官能团化。当使用过量的硼烷试剂时，在某些情况下可以实现双硼化反应，且只形成单一的区域异构体。还报道了将空间导向硼化反应扩展到氰基取代的五元及六元环杂环化合物。
