Reduction of Isopropyl Tri-O-acetyl-2-oximino-α-D-hexopyranosides

Hydrogénation of 2-oximino-α-D-arabino-hexopyranosides in the presence of palladium and hydrazine provided high stereoselectivity for the formation of 2-amino-2-deoxy-α-D-glucopyranosides including disaccharide structures. Similar yields of gluco-isomer were normally obtained on reduction by borane of 2-acetoximino-tri-O-acetyl-α-D-arabino-hexopyranosides in tetrahydrofuran. However, reduction of 2-O-(2-acetoximino-tri-O-acetyl-α-D-arabino-hexopyranosyl)-1,3-dibenzoylglycerol provided a ratio of about 3:2 of the gluco-to manno-isomers. Reductions with lithium aluminum hydride were not appreciably stereoselective. Treatment of isopropyl 2-oximino-α-D-arabino-hexopyranoside with hydrazine in the presence of palladium catalyst gave isopropyl 2-deoxy-α-D-arabino-hexopyranoside in a novel room-temperature Wolff–Kishner type reaction.Reduction of isopropyl tri-O-acetyl 2-oximino-α-D-lyxo-hexopyranoside both with borane and lithium aluminum hydride proceeded with slight stereoselectivity for the galacto-isomer.