A NEW SYNTHESIS OF O-GLYCOSIDES FROM TOTALLY O-UNPROTECTED GLYCOSYL DONORS

摘要

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 beta-D-fructopyranosides 7. Conversely alpha-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.OEt(2) under ultrasonication. [References: 24]