Monodentate transient directing group promoted Pd-catalyzed direct ortho-C‒H arylation and chlorination of α-ketoesters for three-step synthesis of Cloidogrel racemate
作者:Jian Wang、Yongdi Wu、Wengang Xu、Xuelian Lu、Yunfang Wang、Guangyuan Liu、Bing Sun、Yirong Zhou、Fang-Lin Zhang
DOI:10.1016/j.tet.2022.132980
日期:2022.9
An unprecedented direct ortho C–H arylation and chlorination of α-ketoesters were successfully accomplished by using a combination of monodentate transient directing group strategy and palladium catalysis. The in situ formed imine changed the bidentate coordination model of α-ketoesters to monodentate, so as to fulfill the ortho C–H activation. Importantly, the key binuclear cyclopalladium intermediate
通过使用单齿瞬时导向基团策略和钯催化的组合,成功地实现了 α-酮酯的前所未有的直接邻位C-H 芳基化和氯化。原位形成的亚胺将α-酮酯的双齿配位模式改变为单齿配位,从而实现邻位C-H活化。重要的是,由乙酸根阴离子桥接的关键双核环钯中间体通过 X 射线衍射得到了明确的特征,这有力地支持了所提出的机制。实用性进一步描述为通过随后的两步衍生化轻松获得口服抗血小板药物氯吡格雷消旋体。