3,4-Dipyranosyl-1,2,5-oxadiazole 2-oxides: synthesis and X-ray structure

3,4-Di(2,3,4,6-tetra-O-acetyl-β-d-mannopyranosyl)-1,2,5-oxadiazole 2-oxide () has been synthesised from d-mannose by a route involving as the key step dimerisation of mannopyranosyl nitrile oxide . Three methods were used for the generation of the nitrile oxide: isocyanate-mediated dehydration of nitromethylmannose derivative , treatment of aldoxime with aq. hypochlorite, and base-induced dehydrochlorination of hydroximoyl chloride . d-Gluco, d-galacto, d-xylo, and l-fucopyranosyl analogues were prepared similarly. The structure of d-mannose-derived 1,2,5-oxadiazole 2-oxide was established by X-ray crystallography.