Preparation of the 2,3-anhydro-4,6-O-benzylidene derivatives of methyl α- and β-D-talopyranoside and of methyl α-D-gulopyranoside

Abstract

Instructions are given for preparing the title compounds in reproducibly good yields from the appropriate anomer of methyl 4,6-O-benzylidene-2,3-di-O-tosyl-D-galactopyranoside. The α-anomer is converted into a mixture of the anhydro-α-taloside and anhydro-α- guloside by reaction with sodium methoxide in dimethyl sulfoxide as solvent at room temperature. The β-anomer forms the anhydro-β-taloside under similar conditions but with dioxan as solvent for the reactants.