Stereoselectivity of Reactions at the Glycoside Center of Carbohydrates: VII. Synthesis of Aryl α- and -β-D-Glucopyranosides by Helferich, Catalyzed by Boron Trifluoride Etherate

Abstract

13C NMR spectroscopy was used to study the stereoselectivity of glycosylation of phenols with the α and β anomers of penta-O-acetyl-D-glucopyranose, penta-O-trifluoroacetyl-D-glucopyranose, and 2,3,4,6-tetra-O-acetyl-1-O-trifluoroacetyl-D-glucopyranose in the presence of boron trifluoride etherate at varied temperature, time, and catalyst amount. The boron trifluoride etherate-catalyzed reaction of penta-O-acetyl-β-D-glucopyranose and 2,3,4,6-tetra-O-acetyl-1-O-trifluoroacetyl-β-D-glucopyranose with phenols occurs with a high stereocontrol to give, depending on conditions, predominantly 1,2-cis- or 1,2-trans-arylglycosides. This reaction can be used for preparative synthesis of the α- and β-anomeric forms of glycosides of a wide range of phenols.