Metal-catalyzed C - H glycosylation reactions with glycosyl chloride donors have emerged as a useful strategy for the synthesis of C -glycosides. Previously, palladium and nickel complexes were reported to catalyze C - H glycosylation reactions using amide-linked bidentate auxiliaries. Herein, a ruthenium-catalyzed ortho C - H glycosylation reaction of arenes with various glycosyl chloride donors using a monodentate pyridine directing group is developed. Preliminary mechanistic studies indicated that two-electron oxidative addition and reductive elimination of ruthenocycle intermediate led to the glycosylation products.