L-Proline/CeCl·7HO-NaI mediated stereoselective synthesis of α-2-deoxy glycosides from glucal.

Glucal with different alcohols can be converted into the corresponding 2-deoxy glycosides without Ferrier rearrangement in high yield by treatment with eco friendly transition metal based catalysts [CuCl·2HO-NaI (A) or CeCl·7HO-NaI (B)] and chiral amine ligand L-proline at various reaction conditions which were optimized for stereoselectivity. The catalyst CeCl·7HO-NaI (B) and ligand L-proline in toluene, was found to be much more efficient and high atom economic for the stereoselective glycosidation of propargyl alcohol with glucal, afforded exclusively α-2-deoxy propargyl glycoside in 98% optimized yield. The ligand L-proline was used for the first time in stereoselective glycosidation of α-2-deoxy glycosides involving glucal and alcohols.