Catalytic Non-Conventional trans-Hydroboration: A Theoretical and Experimental Perspective
作者:Jessica Cid、Jorge J. Carbó、Elena Fernández
DOI:10.1002/chem.201102729
日期:2012.1.27
four stages: 1) isomerization of the alkyne into the vinylidene, 2) oxidative addition of the borane reagent, 3) vinylidene insertion into the RhH bond, and finally 4) reductive elimination of the CB bond to yield the 1‐alkenylboronate. Calculations indicated that the vinylidene insertion is the selectivity‐determining step. This result was consistent with the observed Z selectivity when the sterically
我们已经在实验和理论上研究了炔烃的非常规反式-硼氢化反应。基于[Rh(cod)Cl} 2 ] / PCy 3(cod = 1,5-环辛二烯,Cy = cyclohexyl)的原位混合物的催化体系能够活化频哪醇硼烷和儿茶酚硼烷并转移硼烷基和氢化物基团在末端炔烃的相同的不受阻碍的碳原子上。与传统的顺式硼氢化相比,碱(Et 3 N)的存在有利于非常规的反式硼氢化。改变底物对反应有显着影响,对位观察到高达99%的转化率和94%的区域选择性甲基苯基乙炔 DFT和量子力学/分子机械的ONIOM计算都是在[RhCl(PR 3)2 ]系统上进行的。为了解释对(Z)-烯基硼酸酯的选择性,我们使用丙炔作为模型炔,探索了传统顺式氢硼化的几种替代机理。所提出的机理可分为四个阶段:1)炔烃异构化为亚乙烯基,2)氧化加入硼烷试剂,3)亚乙烯基插入RhH键,最后4)还原消除CB键产生1-烯基硼酸酯。计算表明,亚乙