Liu Tao, Han Shu-Min, Han Ling-Li, Wang Lu, Cui Xiang-Yang, Du Chong-Yang, Bi Siwei
Department of Chemistry and Chemical Engineering, Key Lab of Inorganic Chemistry, Shandong Provincial Education Department, Jining University, Qufu 273155, Shandong, China.
Org Biomol Chem. 2015 Mar 28;13(12):3654-61. doi: 10.1039/c4ob02064b.
A density functional theory study was performed to understand the detailed mechanisms of the cross-benzoin reactions catalyzed by N-heterocyclic carbene (NHC) species. Our theoretical study predicted that the first H-transfer operates with water in solution as a mediator, and the second H-transfer undergoes a concerted mechanism rather than a stepwise one. In addition, the chemoselectivity of the reactions studied in this work has been explored. P1 was obtained as a major product mainly due to the more stable intermediate formed by reaction of NHC with reactant R1. Different steric effects resulting from the fused six-membered ring in transition state TS7 and the fused five-membered ring in transition state TS13 are the origin leading to the chemoselectivity.
进行了密度泛函理论研究，以了解由N-杂环卡宾（NHC）物种催化的交叉安息香反应的详细机制。我们的理论研究预测，第一次氢转移以溶液中的水作为介质进行，第二次氢转移经历协同机制而非分步机制。此外，还探索了本工作中所研究反应的化学选择性。P1作为主要产物得到，主要是由于NHC与反应物R1反应形成的中间体更稳定。过渡态TS7中的稠合六元环和过渡态TS13中的稠合五元环产生的不同空间效应是导致化学选择性的根源。
