Hansen Jørn, Autschbach Jochen, Davies Huw M L
Department of Chemistry, Emory University, 440 Atwood Hall, 1515 Dickey Drive, Atlanta, Georgia 30322, USA.
J Org Chem. 2009 Sep 4;74(17):6555-63. doi: 10.1021/jo9009968.
The mechanism of rhodium-catalyzed cyclopropanation and C-H functionalization reactions with methyl phenyldiazoacetate and methyl diazoacetate has been studied computationally with DFT. In accordance with experimental data, it has been demonstrated that donor/acceptor rhodium carbenoids display potential energy activation barriers consistent with the much higher selectivity in cyclopropanation and C-H insertion chemistry compared to the traditionally used acceptor carbenoids derived from unsubstituted diazo esters. Significantly higher potential energy barriers were found for transformations of donor/acceptor carbenoids than for those of acceptor systems, primarily due to the inherent stability of the former. Analyses of transition state geometries have led to the development of a rational model for the prediction of the stereochemical outcome of intermolecular C-H insertions with donor/acceptor rhodium carbenoids.
已使用密度泛函理论（DFT）对铑催化的苯乙酸甲酯和重氮乙酸甲酯进行环丙烷化反应及C-H官能化反应的机理进行了计算研究。根据实验数据表明，与传统使用的由未取代重氮酯衍生的受体型卡宾相比，供体/受体型铑卡宾在环丙烷化和C-H插入化学中表现出与更高选择性相一致的势能活化能垒。供体/受体型卡宾转化的势能垒明显高于受体体系，这主要是由于前者固有的稳定性。对过渡态几何结构的分析已形成了一个合理模型，用于预测供体/受体型铑卡宾分子间C-H插入的立体化学结果。
