Murai反应中芳香酮邻位C–H键活化的区域选择性的理论研究  

A theoretical research on the regioselectivity for ortho C-H activation of aromatic ketone in Murai reaction

作　　者：唐艳辉[1] 李慧[2,3] 李龙飞[3] 

机构地区：[1]北京服装学院材料科学与工程学院,北京100029 [2]北方民族大学化学与化学工程学院,银川750021 [3]北京化工大学化工资源有效利用国家重点实验室,北京100029

出　　处：《中国科学：化学》2017年第6期787-793,共7页SCIENTIA SINICA Chimica

基　　金：国家自然科学基金(编号:21672018);北京服装学院重点项目(编号:2014A-01)资助

摘　　要：钌催化剂RuH_2(CO)(PPh_3)_3使Murai反应中芳香酮β位C–H键的催化活化反应具有极高的产率与选择性.本文采用密度泛函(DFT)方法研究了钌配合物催化芳香酮邻位C–H键活化的反应机理,剖析了芳香酮C–H键活化反应中产生区域选择性的原因.计算结果表明,C–H键的活化位垒为1.1 kcal/mol,从反应动态学角度很好地解释了该反应的区域选择性.通过路径a与路径b的比较,发现C=C双键更容易插入到Ru–H键而不是Ru–C键中.另外,无论C–C键形成(C–C活化过程)出现在路径a的烯烃插入基元反应,还是出现在路径b的还原消除基元反应,C–C键形成步骤都是整个催化反应的决速步骤.与路径a和b比较,反应路径c中C–C键形成过程的空间位阻较大,能垒也更高.RuH2（CO）（PPh3） is an important catalyst for Murai reaction, which brings a very high regioselectivity in ortho C-H activation of aromatic ketone. In this work, we studied the mechanism of ruthenium complexes catalyzed aromatic ketone ortho C-H activation reaction by density functional method （DFT） method, and explained the regioselectivity by designing three different reaction processes, path a, path b and path c. Calculated results show that the barrier for C-H activation is 1.1 kcal/mol, which explains well the regioselectivity. In the comparison of path a and path b, it is found that the C=Cdouble bond is easier to insert to the Ru-H bond than the Ru-C bond. In addition, the process of C-C bond formation （C^C activation） is the rate determining step in the reaction cycle no matter it appears in the olefin insertion step in path a or in the reductive elimination step in path b. The comparison of the path c with path a and path b suggests that the steric hindrance in the formation of C-C bond in path c is much bigger than that in path a and path b, which results in a higher energy barrier in this step.

关 键 词：C–H活化 Murai反应 区域选择性 密度泛函理论 钌催化剂 

分 类 号：O621.251[理学—有机化学]