Toward the Syntesis of New Dideoxy δ-Dicarbonyl Heptoses

he preparation of a delta-dicarbonyl sugar thorough ring-opening, by a methoxymercuration-demercuration procedure, of a 5-spirocyclopropanated D-galactose derivative, is reported. This method constitutes a new route for the transformation of a hexose into new and interesting delta-dicarbonyl sugars, synthetic precursors of cyclitols, carba- and azasugars. Moreover this is, to our best knowledge, the first reported example of an elongation to a higher sugar starting from a spirocyclopropanated saccharide.