Potential hexokinase inhibitors. Synthesis and properties of 2,3-anhydro-D-allose, 2,3-anhydro-D-ribose, and 2-O-methylsulphonyl-D-mannose

Hydrogenolysis of benzyl 2,3-anhydro-a-D-allopyranoside (4) in tetrahydrofuran over palladium-charcoal afforded crystalline 2,3-anhydro-a-D-allopyranose (6a). When dissolved in water this sugar underwent rapid mutarotation to give an equilibrium mixture containing mainly the a-pyranose (6a) (41%) and the ß-furanose (6d) (42%), together with the ß-pyranose (6b) and the a-furanose (6c) (5 and 12%, not individually assigned). 2,3-Anhydro-D-ribose, as an equilibrium mixture (13), has been prepared by hydrogenolysis of benzyl 2,3-anhydro-a-D- ribopyranoside (12). 2-O-Methylsulphonyl-a-D-mannopyranose (18) has been prepared and shown to give 1,6-anhydro-ß-D-glucopyranose (20) with base.