Deoxygenation of sugar derivatives by the Wolff–Kishner reaction

Abstract

The Wolff–Kishner reaction converts 1,5-anhydro-4,6-O-benzylidene-2-deoxy-D-erythro-hex-3-ulose (1) into its 3-deoxygenated analogue (2) in high yield. In contrast, methyl 4,6-O-benzylidene-3-deoxy-β-D-erythro-hexopyranosid-2-ulose (3) and methyl 4,6-O-benzylidene-2-deoxy-α-D-erythro-hexopyranosid-3-ulose (10) afford complex mixtures of products, most of which appear to arise through elimination processes; the expected deoxygenated glycosides (5) and (11) were isolated in only moderate and low yields, respectively. A slightly modified procedure in the reaction with (10) provided the pyrazole derivative (14) as the only product in high yield.