Stereospecific synthesis of β-d-allopyranosides by dihydroxylation of β-d-erythro-2,3-dideoxyhex-2-enopyranosides

The synthesis of 4,6-O-benzylidene-β-d-erythro-2-3-dideoxyhex-2-enopyranosides and their osmium and ruthenium catalysed dihydroxylation reactions have been investigated. These reactions have been shown, for a range of monosaccharides and a disaccharide, to proceed stereospecifically to give β-d-allopyranosides in moderate to excellent yield.