The fragmentation patterns of anhydro sugars 1—6 in electron impact mass spectrometry have been proposed, and verified by means of metastable ions scanning method.
A series of compounds had been synthesised from 1.6-anhydro-2,4-di-O-benzyl-β-D-glucopyranose with good yields.The The effects of C-3 protecting groups on ring-opening reaction and the glycosidation of α-D-glucopyra...A series of compounds had been synthesised from 1.6-anhydro-2,4-di-O-benzyl-β-D-glucopyranose with good yields.The The effects of C-3 protecting groups on ring-opening reaction and the glycosidation of α-D-glucopyranosyl bromides were studied.展开更多
The title compound △14,15-anhydro-24-thiocarbonylbufalin （1） was prepared by the reaction of natural product bufalin with Lawesson reagent. The crystal structure of 1, C24H3002S＇C24H3002S, was determined by single...The title compound △14,15-anhydro-24-thiocarbonylbufalin （1） was prepared by the reaction of natural product bufalin with Lawesson reagent. The crystal structure of 1, C24H3002S＇C24H3002S, was determined by single-crystal X-ray diffraction analysis. It belongs to monoclinic, space group C2, with a = 30.9845（2）, b = 6.8036（3）, c = 22.5791（15）/k, V= 4241.7（4） A3, Mr = 384.21, Z = 4, Dc= 1.204 g/cm3,μ = 1.463 mm4, F（000） = 1664, S = 1.064, R = 0.0487 and wR = 0.0645 for 4683 unique reflections, of which 3757 were observed （I 〉 2σ（/））. The asymmetric unit contains two independent molecules （ⅠandⅡ）, which are closely similar to each other except for the orientation of the lactone ring. Both conformations of I and II are in good agreement with the solution structure in methanol as indicated by 1H-NMR analysis. Due to the presence of heavy atom sulfur in the molecules, the final refinement resulted in a small Flack parameter 0.02（3）, permitting the assignments of the absolute configuration. In the solid state, intermolecular hydrogen bonds involving thiocarbonyl group in the lactone moiety and the hydroxyl groups in the steroid moiety ester linked adjacent molecules into a three-dimensional network. Compound 1 showed weak inhibition on Na＋/K＋-ATPase in contrast to the strong inhibitory activity of the parent compound bufalin, suggesting that the carbonyl group in lactone moiety and the hydroxyl group atC-14 play important roles for the inhibition of Na＋/K＊-ATPase.展开更多
New highly stereoregular 2, 3 -di- O-(p-azidobenzyl )-(1 →5 ) - α-D -ribofuranan was synthesized byselective ring-opening polymerization of 1, 4-anhydro-2, 3 - di-O -(p-azidobenzyl )-α-D -ribopyranose(ADABR) using ...New highly stereoregular 2, 3 -di- O-(p-azidobenzyl )-(1 →5 ) - α-D -ribofuranan was synthesized byselective ring-opening polymerization of 1, 4-anhydro-2, 3 - di-O -(p-azidobenzyl )-α-D -ribopyranose(ADABR) using phosphorus pentafluoride or tin tetrachloride as catalyst at low temperature indichloromethane. The monomer was obtained by the reaction of p - bromomethyl -phenyleneazide with 1, 4 -anhydro-α-D-ribose in DMF. The structure of poly(ADANR) was identified by specific rotation and ^(13)C-NMR spectroscopy. Acid chloride-AgCl_4 complex catalyst such as CH_2=C(CH_3)C^+OClO_4^- used in thepolymerization resulted in polymers with mixed structures, i.e. (1→5)-α-D-ribofuranosidic and (1→4)-β-D-ribopyranosidic units. However, with C_6H_5C^+OClO_4^- as catalyst, pure (1→5)-α-D-ribofuranan was obtained.The effects of catalyst, polymerization temperature and time on polymer stereoregularity were examined, andthe mechanism of the ring-opening polymerization was discussed.展开更多
Complex formation of 1,6-anhydro-β-maltose and sodium ions was characterized using single-crystal X-ray crystallography and solution- and solid-state NMR spectroscopy. The 7-coordination structure, comprising two 1,6...Complex formation of 1,6-anhydro-β-maltose and sodium ions was characterized using single-crystal X-ray crystallography and solution- and solid-state NMR spectroscopy. The 7-coordination structure, comprising two 1,6-anhydro-β-maltoses, a thiocyanate ion and a sodium ion, was identified in the crystal of the complex, where a sodium ion was positioned in the center of the pentagon. In the NMR study, the line broadening of 23Na signals and the decrease of the spin-lattice relaxation times (T1) of 23Na were observed in CD3OD in the presence of 1,6-anhydro-β-maltose, indicating complex formation.展开更多
Reductive debromination of anhydro-6-(R)-hydroxycthyl-6-(R) 7 by zinc in ammonium acetate gave 9 in 81% yield with high stcreosclectivity of 6-(α):6-(β)= 13: 1
文摘The fragmentation patterns of anhydro sugars 1—6 in electron impact mass spectrometry have been proposed, and verified by means of metastable ions scanning method.
文摘A series of compounds had been synthesised from 1.6-anhydro-2,4-di-O-benzyl-β-D-glucopyranose with good yields.The The effects of C-3 protecting groups on ring-opening reaction and the glycosidation of α-D-glucopyranosyl bromides were studied.
基金supported by the National Natural Science Foundation of China(81102518)
文摘The title compound △14,15-anhydro-24-thiocarbonylbufalin （1） was prepared by the reaction of natural product bufalin with Lawesson reagent. The crystal structure of 1, C24H3002S＇C24H3002S, was determined by single-crystal X-ray diffraction analysis. It belongs to monoclinic, space group C2, with a = 30.9845（2）, b = 6.8036（3）, c = 22.5791（15）/k, V= 4241.7（4） A3, Mr = 384.21, Z = 4, Dc= 1.204 g/cm3,μ = 1.463 mm4, F（000） = 1664, S = 1.064, R = 0.0487 and wR = 0.0645 for 4683 unique reflections, of which 3757 were observed （I 〉 2σ（/））. The asymmetric unit contains two independent molecules （ⅠandⅡ）, which are closely similar to each other except for the orientation of the lactone ring. Both conformations of I and II are in good agreement with the solution structure in methanol as indicated by 1H-NMR analysis. Due to the presence of heavy atom sulfur in the molecules, the final refinement resulted in a small Flack parameter 0.02（3）, permitting the assignments of the absolute configuration. In the solid state, intermolecular hydrogen bonds involving thiocarbonyl group in the lactone moiety and the hydroxyl groups in the steroid moiety ester linked adjacent molecules into a three-dimensional network. Compound 1 showed weak inhibition on Na＋/K＋-ATPase in contrast to the strong inhibitory activity of the parent compound bufalin, suggesting that the carbonyl group in lactone moiety and the hydroxyl group atC-14 play important roles for the inhibition of Na＋/K＊-ATPase.
文摘New highly stereoregular 2, 3 -di- O-(p-azidobenzyl )-(1 →5 ) - α-D -ribofuranan was synthesized byselective ring-opening polymerization of 1, 4-anhydro-2, 3 - di-O -(p-azidobenzyl )-α-D -ribopyranose(ADABR) using phosphorus pentafluoride or tin tetrachloride as catalyst at low temperature indichloromethane. The monomer was obtained by the reaction of p - bromomethyl -phenyleneazide with 1, 4 -anhydro-α-D-ribose in DMF. The structure of poly(ADANR) was identified by specific rotation and ^(13)C-NMR spectroscopy. Acid chloride-AgCl_4 complex catalyst such as CH_2=C(CH_3)C^+OClO_4^- used in thepolymerization resulted in polymers with mixed structures, i.e. (1→5)-α-D-ribofuranosidic and (1→4)-β-D-ribopyranosidic units. However, with C_6H_5C^+OClO_4^- as catalyst, pure (1→5)-α-D-ribofuranan was obtained.The effects of catalyst, polymerization temperature and time on polymer stereoregularity were examined, andthe mechanism of the ring-opening polymerization was discussed.
文摘Complex formation of 1,6-anhydro-β-maltose and sodium ions was characterized using single-crystal X-ray crystallography and solution- and solid-state NMR spectroscopy. The 7-coordination structure, comprising two 1,6-anhydro-β-maltoses, a thiocyanate ion and a sodium ion, was identified in the crystal of the complex, where a sodium ion was positioned in the center of the pentagon. In the NMR study, the line broadening of 23Na signals and the decrease of the spin-lattice relaxation times (T1) of 23Na were observed in CD3OD in the presence of 1,6-anhydro-β-maltose, indicating complex formation.
文摘Reductive debromination of anhydro-6-(R)-hydroxycthyl-6-(R) 7 by zinc in ammonium acetate gave 9 in 81% yield with high stcreosclectivity of 6-(α):6-(β)= 13: 1
