Ruthenium‐Catalyzed Stereo‐ and Site‐Selective <i>ortho‐</i> and <i>meta</i>‐C−H Glycosylation and Mechanistic Studies
Xue‐Ya Gou, Yuke Li, Wei‐Yu Shi, Yu‐Yong Luan, Yanan Ding, Yang An, Yan‐Chong Huang, Bo‐Sheng Zhang, Xue‐Yuan Liu, Yong‐Min Liang
Abstract
Abstract C‐aryl glycosides are popular basic skeletons in biochemistry and pharmaceutical chemistry. Herein, ruthenium‐catalyzed highly stereo‐ and site‐selective ortho ‐ and meta ‐C Ar −H glycosylation is described. A series of C‐aryl pyranosides and furanosides were synthesized by this method. The strategy showed good substrate scope, and various N ‐heterocyclic directing groups were compatible with the reaction system. A mechanistic study suggested that the key pathway of ortho ‐C Ar −H glycosylation might involve oxidative addition/reduction elimination, whereas aryl meta ‐C−H glycosylation was mediated by σ ‐activation. Density functional theory calculations also showed that the high stereoselectivity of meta ‐C Ar −H glycosylation was due to steric hindrance.