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 À 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 À H glycosylation might involve oxidative addition/reduction elimination, whereas aryl meta-CÀ H glycosylation was mediated by σ-activation. Density functional theory calculations also showed that the high stereoselectivity of meta-C Ar À H glycosylation was due to steric hindrance.