A Facile and Direct Glycosidation Method for the Synthesis of 2‐Deoxy α‐Rhamnosides Catalyzed by Ferric Chloride

A facile and highly efficient O ‐glycosylation method for stereoselective synthesis of 2,6‐dideoxy‐ O ‐glycosides has been described promoted by FeCl 3 , an eco‐friendly, easily available and non‐toxic catalyst. Acetylated 2‐deoxy rhamnoside was chosen as the glycosyl donor for its convenient preparation and great stability at room temperature. The glycosylation was amenable to a wide range of acceptors including primary, secondary, tertiary alcohols, sterols, amino acid derivatives and sugar derivatives. Thus, 2,6‐dideoxyglycosides and oligosaccharides were obtained in short reaction time (<40 min) at room temperature in good to excellent yields (70‐97 %) with preponderant α‐selectivity (α/β=4:1 to >19:1).