Triflic Imide‐Catalyzed Glycosylation of Disarmed Glycosyl ortho‐Isopropenylphenylacetates and ortho‐Isopropenylbenzyl Thioglycosides

Abstract Glycosylation reaction involving the coupling of a glycosyl donor with a glycosyl acceptor is one of the cornerstones of chemical preparation of pure glycans and glycoconjugates of biological relevance. Catalytic glycosylation of glycosyl ester donors and thioglycosides is an attractive but underexplored topic in carbohydrate chemistry. Herein, triflic imide (Tf 2 NH)‐catalyzed glycosylation of various O ‐, S ‐, and C ‐nucleophiles has been achieved using disarmed glycosyl ortho ‐isopropenylphenylacetates (GIPPAs) and ortho ‐isopropenylbenzyl thioglycosides as glycosylating agents. The reactions proceed under mild conditions to give the desired glycosides in good‐to‐excellent yields. Of particular note, the comparable reactivity for the α ‐isomers and the β ‐ones of GIPPAs is observed. The mechanistic investigation demonstrates that the isopropenyl group is essential for the reaction and its preferential protonation triggers the reaction. This work provides another member to the arsenals of glycosyl ester and thioglycoside donors suitable for acid‐catalyzed glycosylation to create various glycosidic bonds.