Towards the rational design of palladium-N-heterocyclic carbene catalysts by a combined experimental and computational approach
作者:Christopher J. O'Brien、Eric Assen B. Kantchev、Gregory A. Chass、Niloufar Hadei、Alan C. Hopkinson、Michael G. Organ、David H. Setiadi、Ting-Hua Tang、De-Cai Fang
DOI:10.1016/j.tet.2005.07.101
日期:2005.10
approach towards the development of Pd–NHC catalysts is described. A range of benzimidazolylidinium ligands incorporating electron-rich and electron-poor substituents were prepared and evaluated in the Suzuki reaction. The most electron-rich ligand showed the highest catalytic activity. Based on this information, the first alkyl–alkyl Negishi cross-coupling reaction protocol was developed. Evaluation of
描述了开发Pd-NHC催化剂的组合实验和计算方法。制备了一系列结合了富电子取代基和贫电子取代基的苯并咪唑基铱配体,并在Suzuki反应中进行了评估。最富电子的配体表现出最高的催化活性。基于此信息,开发了第一个烷基-烷基Negishi交叉偶联反应方案。对N,N′-二芳基-(4,5-二氢)咪唑基亚胺基鎓配体的评估显示出对金属中心周围的空间形貌的强烈依赖性。Negishi反应中活性最高的配体,其Pd(0)和PdCl 2的计算研究-复合物和相关结构是在B3LYP / DZVP和HF / 3-21G的理论水平上建模的。势能超表面随着配体尺寸的增加而变平。计算出卡宾/ Pd(0)加合物的结合能(约31–40 kcal mol -1),约为PH 3的结合能(约16 kcal mol -1)。使用AIM分析发现分子内相互作用较弱。