Stereoselective glycosylation of exo-glycals accelerated by Ferrier-type rearrangement

[GRAPHIC] Owing to the driving force of the Ferrier-type rearrangement, the exo-glycals are highly reactive with various alcohols to afford glycosides and glycoconjugates with exclusive alpha-configuration. The resulting vinyl group in these glycosylation products can be further elaborated for general applications, including the synthesis of spiro derivatives and glycosylation of 2-ketoaldonic acids.