Synthesis of d-Hexos-5-uloses by Novel in Situ Hydrolysis of Epoxides Derived from 6-Deoxyhex-5-enopyranosides

Epoxides derived from 2,3,4-tri-<i>O</i>-protected-6-deoxyhex-5-enopyranosides are hydrolyzed in situ to ultimately give novel protected-d-hexos-5-ulose derivatives (sugar 1,5-dicarbonyls, 5-ketohexoses) in moderate to high yields. The products adopt a bicyclic structure (1,6-anhydropyranos-5-ulose) in solution with the pyranose ring in ⁴<i>C</i>₁ conformation. The methodology has been used to prepare d-<i>xylo</i>-hexos-5-ulose (5-ketoglucose), a synthetic precursor to 1-deoxynojirimycin and a possible intermediate in the biosynthesis of inositols.