A new synthesis of O-glycosides from totally O-unprotected glycosyl donors

Article abstract of DOI:10.1016/0040-4039(95)00356-H

O-Glycosidation of the totally O-unprotected aldoses (D-glucose, D-galactose and D-mannose) and D-fructose in THF or 1,4-dioxane using anhydrous FeCl₃ as promoter afforded either aldofuranosides 1, 3, 4 in good overall yields or exclusively β-D-fructopyranosides 7. Conversely α-D-aldopyranosides 2, 5 and 6 were obtained respectively from D-glucose, D-mannose and N-acetyl-D-glucosamine when the reactions were performed in the presence of BF₃.OEt₂ under ultrasonication.