Synthesis of D-hexos-5-uloses by novel in situ hydrolysis of epoxides derived from 6-deoxyhex-5-enopyranosides.

[reaction: see text] Epoxides derived from 2,3, 4-tri-O-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)C(1) conformation. The methodology has been used to prepare D-xylo-hexos-5-ulose (5-ketoglucose), a synthetic precursor to 1-deoxynojirimycin and a possible intermediate in the biosynthesis of inositols.