Department of Chemistry , Southern University of Science and Technology (SUSTech) , 1088 Xueyuan Road , Shenzhen 518055 , China.
Academy for Advanced Interdisciplinary Studies , Southern University of Science and Technology , 1088 Xueyuan Road , Shenzhen 518055 , China.
Org Lett. 2018 Apr 20;20(8):2143-2147. doi: 10.1021/acs.orglett.8b00312. Epub 2018 Mar 30.
The incorporation of Brønsted acid, thiourea anion binding, and transition metal catalysis enables an efficient method to synthesize chiral indolines via hydrogenation of indoles. Catalyzed by a rhodium/ZhaoPhos complex, asymmetric hydrogenation of unprotected indoles is performed smoothly with excellent enantioselectivities (up to 99% ee, up to 400 TON). Brønsted acid HCl activates indoles to form iminium ion intermediates. Mechanistic studies support the assumption that anion binding plays a crucial role as a secondary interaction. DFT calculations reveal an outer-sphere mechanism in this chemical transformation.
布朗斯台德酸、硫脲阴离子结合和过渡金属催化的结合使通过吲哚加氢合成手性吲哚啉成为可能。在铑/赵磷配合物的催化下，未保护的吲哚的不对称氢化反应顺利进行，具有优异的对映选择性（高达 99%ee，高达 400TON）。布朗斯台德酸 HCl 激活吲哚形成亚胺离子中间体。机理研究支持阴离子结合作为二次相互作用发挥关键作用的假设。DFT 计算揭示了这种化学转化的外球机制。
