A NEW METHOD OF ORTHOESTERIFICATION, UNDER KINETIC CONTROL, AT NONANOMERIC POSITIONS - APPLICATION TO THE D-GLUCOSE AND D-MANNOSE SERIES AND SELECTIVE HYDROLYSIS OF THE CORRESPONDING ORTHOESTERS

The reaction of ketene acetals with D-glucose, D-mannose, and their methyl glycosides is described as a new route to unusual cyclic orthoesters (at non anomeric positions). The reaction proceeds by preferential attack of the reagent on the primary hydroxyl group. The synthesis of strained rings (2,3-diequatorial orthoester) is possible. The resulting methoxyethylidene derivatives are very sensitive to hydrolysis, and mild conditions lead to hydroxyacetates that are potentially useful intermediates for carbohydrates synthesis.