Ferric Chloride Promoted Glycosidation of Alkyl Thioglycosides

Reported herein is a new reaction for glycosylation with thioglycosides in the presence of iron(III) chloride. Previously, FeCl₃ was used for the activation of thioglycosides as a Lewis acid co-promoter paired with NIS. In the reported process, although 5.0 equiv of FeCl₃ are needed to activate thioglycosides most efficiently, no additives were used, and the reactions with reactive glycosyl donors smoothly proceeded to completion in 1 h at 0 °C. This work showcases a new direction in developing glycosylation methods using greener and earth-abundant activators.