The use of 1- O-sulfonyl- d-mannopyranose derivatives in β- d-mannopyranoside synthesis

Abstract

Several 1- O-sulfonyl derivatives of d-mannopyranose having a nonparticipating benzyl ether group at C-2 and ester functions at C-6 and C-4 were synthesized from the corresponding d-mannopyranosyl chloride derivatives with silver sulfonates in acetonitrile. The reaction of 1- O-sulfonyl- d-mannopyranose compounds with methanol in various solvents at room temperature gave high yields of glycosides with low degrees of stercoselectivity. On the other hand, 1- O-suffonyl- d-mannopyranose derivatives having an acyl participating-group at O-2 and benzyl ethers at C-3, C-4, and C-6 gave high yields and high stereoselectivity of α- d-mannopyranosides with primary and secondary alcohols in several solvents. Model studies were carried out to determine the best combination of 2- O-acyl group, solvent, time, temperature, and 1- O-sufonyl group to give high yields with high stereoselectivity. The method has been used to prepare in good yields more complex glycosides, including perbenzylated methy 2- O-(α- d-mannopyranosyl)-α- d-mannopyranoside.