Benzyne-Promoted, 1,2- cis -Selective O -Glycosylation with Benzylchalcogenoglycoside Donors.

Here, we show that the reaction of benzylchalcogenoglycosides with benzyne in the presence of alcohols results in highly 1,2- cis -selective O -glycosylation in a solvent-dependent manner. Thioglycosides, selenoglycosides, and alcohols with a range of nucleophilicities lead to a productive reaction, and unusual protecting groups, auxiliary groups, and additives are avoided.