Convenient, in situ generation of anhydrous hydrogen iodide for the preparation of alpha-glycosyl iodides and vicinal iodohydrins and for the catalysis of Ferrier glycosylation.

[reaction: see text] Anhydrous hydrogen iodide is generated in situ by the reaction of solid iodine and a thiol. The HI thus generated has been employed for the efficient preparation of alpha-glycosyl iodides and vicinal iodohydrins from the corresponding glycosyl acetates and epoxides, respectively, and for Ferrier glycosylation of alcohols and thiols.