Xue Hansong, Jiang Danfeng, Jiang Huan, Kee Choon Wee, Hirao Hajime, Nishimura Takahiro, Wong Ming Wah, Tan Choon-Hong
†Department of Chemistry and Biological Chemistry, Nanyang Technological University, 21 Nanyang Link, Singapore 637371.
§Department of Chemistry, Kyoto University, Sakyo-ku, Kyoto 6068502, Japan.
J Org Chem. 2015 Jun 5;80(11):5745-52. doi: 10.1021/acs.joc.5b00709. Epub 2015 May 22.
Chiral bicyclic guanidine can act as an efficient chiral Brønsted base catalyst in enantioselective reactions, delivering good yields with high enantioselectivities. There is interest in understanding the detailed mechanisms of these guanidine-catalyzed reactions. Herein, we performed a detailed kinetic study of three different types of chiral bicyclic guanidine-catalyzed reactions, determining the bifunctionality of our guanidine catalyst. Although these three reactions share a similar catalytic cycle, their intrinsic kinetic behaviors are significantly different from each other because of the difference in the rate-determining step. The calculated theoretical rate expression for each reaction, as a result of the mechanism elucidated with density functional theory calculations, agrees well with the respective experimentally observed rate equation.
手性双环胍可作为对映选择性反应中一种高效的手性布朗斯特碱催化剂，以高对映选择性提供良好的产率。人们对了解这些胍催化反应的详细机理很感兴趣。在此，我们对三种不同类型的手性双环胍催化反应进行了详细的动力学研究，确定了我们的胍催化剂的双功能性。尽管这三个反应共享相似的催化循环，但由于速率决定步骤的差异，它们的内在动力学行为彼此显著不同。通过密度泛函理论计算阐明机理后，计算得到的每个反应的理论速率表达式与各自实验观察到的速率方程吻合良好。
