Room temperature catalytic carbon-hydrogen bond alumination of unactivated arenes: mechanism and selectivity
Room temperature catalytic carbon-hydrogen bond alumination of unactivated arenes: mechanism and selectivity
复制标题
DOI：
10.1039/c8sc02072h
复制
发表时间：
2018-06-28
期刊：
影响因子：
8.4
通讯作者：
Crimmin, Mark R.
中科院分区：
文献类型：
--
作者：
Hooper, Thomas N.;Garcon, Marti;Crimmin, Mark R.
本文首次报道了未活化芳烃的C-H键转化为C-Al键的催化方法。催化反应发生在25摄氏度（苯，甲苯和二甲苯）与钯负载低至0.1摩尔%。值得注意的是，甲苯和二甲苯的C-H活化以邻位和间位选择性进行。这种选择性是非常不寻常的，并且与Friedel-Crafts和大多数C-H硼基化方法互补。通过详细的机理分析（Eyring分析，KIE，DFT，QTAIM），我们表明，不寻常的Pd-Al金属间化合物的催化循环和选择性是由弱的吸引力分散力的过渡态C-H键断裂。
We report the first catalytic methods for the transformation of C-H bonds of unactivated arenes into C-Al bonds. The catalytic reactions occur at 25 degrees C (benzene, toluene and xylenes) with palladium loadings as low as 0.1 mol%. Remarkably, the C-H activation of toluene and xylenes proceeds with ortho- and meta-selectivity. This selectivity is highly unusual and complementary to both Friedel-Crafts and the majority of C-H borylation methods. Through a detailed mechanistic analysis (Eyring analysis, KIE, DFT, QTAIM) we show that unusual Pd-Al intermetallic complexes are on the catalytic cycle and that the selectivity is determined by weak attractive dispersion forces in the transition state for C-H bond breaking.