Reduction of α-D-Hexopyranosulosides

Abstract

Reduction of isopropyl tri-O-acetyl-α-D-arabino-hexopyranosuloside with sodium borohydride or diborane leads almost exclusively to the gluco-configuration. Catalytic reductions, on the other hand, provide an epimeric mixture with the manno-configuration predominating in ratios of about 2:1. The reduction of isopropyl tri-O-acetyl-α-D-lyxo-hexopyranosuloside with either sodium borohydride or diborane is less stereoselective than in the case of the arabino-isomer and leads to compounds of the galacto-and talo-configurations in the ratio of 3:2. The latter is formed highly stereoselectively when the lyxosuloside derivative is hydrogenated catalytically.2-O-(α-D-Mannopyranosyl)-glycerol and the gluco-isomer are synthesized.