Palladium-Catalyzed Stereospecific S-Glycosylation by Allylic Substitution

S-Glycosides are considerably more stable toward chemical degradation and enzymatic hydrolysis than O-glycosides, and thioglyco-peptides/proteins also demonstrate critical bioactivities in the living system. However, the general and stereoselective synthetic strategies are still challenging. Herein, a versatile S-glycosylation approach was developed by palladium-catalyzed allylic substitution to form alpha- and beta-thioglycosides respectively under mild conditions. A wide range of substrates were tolerated to afford thioglycosides in a stereospecific manner with 70%-86% yields. This protocol also created the quick access to various S-linked disaccharides and glycopeptides.