Regioselective Mono-oxidation of Non-protected Carbohydrates by Brominolysis of the Tin Intermediates

Abstract

Most of the glycosides examined were smoothly oxidized by the bis-tributyltin oxide-bromine method without protection of the other hydroxyl groups to the mono-oxo derivatives in high yield and with high regioselectivity. The regioselectivity (position of oxidation) can be predicted from two independent rules : anomeric control (the oxidation takes place at C-3 for the glycosides which have an equatorial glycosidic linkage and at C-4 for those which have an axial glycosidic linkage) and axial oxidation for cis-1, 2 glycols.