Short and efficient synthesis of (2S,3R,4R,5R) and (2S,3R,4R,5S)-tetrahydroxyazepanes via the Henry reaction

The Henry reaction with the easily available α-d-xylo-pentodialdose afforded a diastereomeric mixture of nitroaldoses with the α-d-gluco- and β-l-ido-configuration, respectively, in good yield. When n-BuLi was used as the base, the reaction afforded the α-d-gluco-nitroaldose as the only product. The reduction of the nitro group in the α-d-gluco- and β-l-ido-nitroaldoses, removal of the protecting groups and intramolecular reductive cyclo-amination afforded the corresponding (2S,3R,4R,5R) and (2S,3R,4R,5S) tetrahydroxyazepanes.