Structure and reactivity of anhydro-sugars. Part VII. Syntheses of 5-deoxy-D-xylo-hexose

Several routes for the synthesis of 5-deoxy-D-xylo-hexose have been investigated. Hydrogen in the presence of Raney nickel which had been stirred with an acidic ion-exchange resin converted 5,6-anhydro-1,2-O-isopropyl-idene-α-D-glucofuranose into a mixture of 6-deoxy-1,2-O-isopropylidene-α-D-glucofuranose and 5-deoxy-1,2-O-isopropylidene-α-D-xylo-hexofuranose. Contrary to a previous report, it has been shown that the action of lithium aluminium hydride on 6-O-benzoyl-1,2-O-isopropylidene-5-O-tosyl-α-D-glucofuranose gives mainly crystalline 5-deoxy-1,2-O-isopropylidene-α-D-xylo-hexofuranose, although it was shown chromatographically that some 6-deoxy-1,2-O-isopropylidene-β-L-idofuranose is also formed. Treatment of 6-O-benzoyl-1,2-O-isopropylidene-5-O-tosyl-α-D-glucofuranose with sodium α-toluenethiolate gave 6-S-benzyl-1,2-O-isopropylidene-6-thio-β-L-idofuranose, from which 6-deoxy-1,2-O-isopropylidene-β-L-idofuranose was derivable by nickel desulphurisation.