Lanthanum Trifluoromethane-sulfonate??Catalyzed Facile Synthesis of Per??O??acetylated Sugars and Their One??Pot Conversion to S??Aryl and O??Alkyl/Aryl Glycosides …
Lanthanum trifluoromethanesulfonate??catalyzed solvent??free per??O??acetylation with stoichiometric acetic anhydride proceeds in high yield (95%–99%) to afford exclusively pyranose products as anomeric mixtures. Subsequent anomeric substitution employing borontrifluoride etherate and thiols or alcohols furnished the corresponding 1, 2??trans?? linked thioglycosides and O??glycosides, respectively, in good to excellent overall yield (75 ...