Thiosugars. XII. Studies on unsaturated sugars derived from glucosyl N,N-dimethyldithiocarbamate.

Abstract

2-O-Mesyl-3, 4, 6-tri-O-acetyl-β-D-glucopyranosyl N, N-dialkyldithiocarbamate (VI or VII, VI : methyl, VII : ethyl) was prepared starting from the corresponding bromide by treatment with sodium N, N-dialkyldithiocarbamate (III or IV, III : methyl, IV : ethyl). Reflux of a mixture of VI or VII and potassium thiolacetate in acetone-ethanol afforded 2-S-acetyl-2-thio-3, 4, 6-tri-O-acetyl-β-D-mannopyranosyl N, N-dialkyldithiocarbamate (VIII or IX, VIII : methyl, IX : ethyl) in 30 to 40% yield. The structure was confirmed by UV, IR, NMR and the formation of 3, 4, 6-tri-O-acetyl-D-hydroglucal. When a mixture of VI and potassium acetate in acetone-ethanol was refluxed for one hour, crystals (XI), m.p. 104°, [α]20D+185.8° were obtained in 93% yield. The product was also obtainable by acetylation of 1, 2-dideoxy-1, 2-(N, N-dimethylammonium)-dithiocarbonyl-β-D-mannopyranose methanesulfonate (XIII) which was prerared starting from VI, by deacetylation and successive evaporation of an aqueous solution of the deacetylated product. The structure of XI was assigned to be 2-N, N-dimethyldithiocarbamoyl-2-deoxy-3, 4, 6-tri-O-acetyl-D-arabino-hexopyranose-1-ene, and the reaction mechanism of the formation was discussed. Deacetylation of XI afforded 2-N, N-dimethyldithiocarbamoyl-2-deoxy-D-arabino-hexopyranose-1-ene (XIV), m.p. 157°, [α]20D+131.9° which is a new type of unsaturated sugars. The nuclear magnetic resonance spectroscopy helped greatly in the determination of the structures of compounds in this series.