Synthetic approach toward antibiotic ezomycins. I. Synthesis of 5-amino-5-deoxyoctofuranose-(1,4) derivatives by henry reaction and their stereochemistry

Ezomycins were discovered in a fermentation beer of Streptomyces species as antibiotics, which consisted of aminoocturonic acid, aminoglucuronic acid and base. As a part of a total synthesis of ezomycins, the title compounds have been synthesized. A KF-catalyzed Henry reaction between a nitropentose and a glyceraldehyde derivative gave a nitro alcohols mixture. Hydrogenation of the intact mixture, followed by 7V-acetylation afforded three diastereomers. The absolute configurations of the newly-introduced chiral centers were established by chemical methods and a X-ray crystal structure analysis.