UBC Theses and Dissertations
Application of oxo reaction to two carbohydrate derivatives nucleoside synthesis Kan, Gordon Ying Pui
Hydroformylation of 5,6-anhydro-1,2-0-isopropylidene-α-D-glucofuranose (XXIV) with carbon monoxide (70 atm.) and hydrogen (70 atm.) at a temperature of 100-105° C. gave 6-deoxy-1,2-0-i sopropylidene-α-D-gluco-heptodialdo-1,4-furanose-3,7-pyranose (XXV) in 78% yield. Minor quantities of the rearrangement product, 6-deoxy-5-keto-1 ,2-0- i sopropyl i dene-α-D-gl ucofuranose (XXVI), and the hydro-hydroxymethyl at i on product, 6-deoxy-1 ,2-0- isopropyl idene-α-D-gl uco-hepto-1 , 4-furanose (XXVI I), were isolated in 9% and 4% yields, respectively. Acetylation of crude (XXV) afforded two anomeric derivatives (XXIX, XXVII I). Under identical experimental conditions, 5 ,6-dideoxy-1 , 2-0-isopropyl idene-α-D-xylo-hex-5-enofuranose (XXXIII) gave 5,6-dideoxy-α-D-xylo-heptodialdo-1 ,4-furanose-3,7-pyranose (XXXIV) in 51% yield. A minor amount of 5,6-dideoxy-α-D-xy1ohepto-1,4-furanose (XXXV) in about 5% yield was also detected by thin layer chromatography (T.L.C.) Fusion of 5 ,7-di-0-acetyl-6-deoxy-1,2-0-isopropylidene-α-D-gluco-heptodialdo-1,4-furanose-3,7-pyranose (XXVIII) with 5,6-dimethyl-benzimidazole using chloroacetic acid as a catalyst at 170-175°C. gave two anomeric nucleosides 1-(3'-0-acetyl-2'-deoxy-6’,7'-0-isopropylidene heptodialdo-4’,7'-pyrariose-α(and β-)-L-gulopyranosyl) -5,6-dimethyl -benzimidazole (XXXVII, XXXVIII) in 42% yield. These nucleosides were separated by multiple ascending development on preparative T.L.C. plates of silica gel G. impregnated with 2% G.E.Phosphor. Assignment of structures of the nucleosides was based on an analysis of their N.M.R. spectra.
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