Ruthenium‐Catalyzed Stereo‐ and Site‐Selective ortho‐ and meta‐C−H Glycosylation and Mechanistic Studies

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.