Showing papers on "Pyranose published in 1982"
TL;DR: This chapter discusses the structural analysis of complex carbohydrates using high-performance liquid Chromatography, gas chromatography, and mass spectrometry to identify the identity, points of attachment, and stereochemistry of any noncarbohydrate moieties.
Abstract: Publisher Summary This chapter discusses the structural analysis of complex carbohydrates using high-performance liquid chromatography, gas chromatography, and mass spectrometry. The primary structure of a complex carbohydrate is known only when all of the following characteristics have been elucidated: (1) the glycosyl residue composition—that is, the identity and the ratio of the monosaccharides that are glycosidically linked to each other within the complex carbohydrate, (2) the absolute configuration, D or L, of each glycosyl residue, (3) the glycosyl linkage composition—that is, the carbon atoms of each glycosyl residue to which other glycosyl residues are glycosidically linked, (4) the ring form, pyranose or furanose, of each glycosyl residue, (5) the sequence of the glycosyl residues, (3) the anomeric configuration of the glycosidic linkage of each glycosyl residue, and (7) the identity, points of attachment, and stereochemistry, if appropriate, of any noncarbohydrate moieties.
94 citations
58 citations
TL;DR: In this article, a new procedure was described for the synthesis of glycosyl cyanides by reaction of 1-O-acyl sugars with trimethyl-silyl cyanide in a polar aprotic solvent and in the presence of a Lewis acid as catalyst.
Abstract: A new procedure is described for the synthesis of glycosyl cyanides by reaction of 1-O-acyl sugars with trimethyl-silyl cyanide in a polar aprotic solvent and in the presence of a Lewis acid as catalyst. A variety of ribosyl and arabinosyl cyanides have been made in this way from sugar derivatives having acyl, chloro, or methoxy leaving groups at the anomeric position, furanose or pyranose rings, and acyl or benzyl protecting groups. The 1,2-Trans-glycosyl cyanide was formed when the starting sugar had a participating 2-O-acyl substituent. A mixture of cyanide anomers was obtained when the starting sugar was protected with non-participating benzyl groups.
50 citations
TL;DR: In this paper, it was shown that pyrolysis of (1→3)-glycans can lead to a peeling reaction of the same type as that already known for alkaline degradation.
43 citations
TL;DR: In this article, the structure of the protected 1-deoxy-l-nitroaldoses was determined by an X-ray analysis, and the configurations of the bromonitro compounds 14, 18, 18 and 22 were deduced from their molecular rotations.
Abstract: Synthesis of Protected 1-Deoxy-1-nitroaldoses
The direct oxidation of the oxime 1 with t-butyl hydroperoxide and vanadyl acetylacetonate yielding the nitro derivative 2 (54%, Scheme 1) could not be applied to other oximes. Diastereoselective bromination of the aldonolactone oxims 7 and 10–12 according to known procedures gave the corresponding bromonitroso compounds which were oxidized to the bromonitro compounds 9, 14, 18 and 22, respectively. Oxidation of the bromonitroso compound in the D-mannopyranose series proved difficult, but the corresponding chloronitro derivative 23 was easily obtained according to Corey & Estreicher (Scheme 2 and 3). The structure of the bromonitro compound 9 was determined by an X-ray analysis, and the configurations of the bromonitro compounds 14, 18 and 22 were deduced from their molecular rotations. Reduction of the bromonitro compounds gave the protected 1-deoxy-l-nitroaldoses 2, 15/16, 19/20, and 24/25, respectively, in good overall yields. The ribose derivatives 15 and 16 were detritylated to give the nitro compound 4, and the mannose derivative 2 was partially deprotected to give the monoisopropylidene compound 26. The nitro group shows a normal anomeric effect which is reflected in the IR. spectra of the pyranose derivatives 19 and 20, and 24 and 25.
31 citations
TL;DR: In this paper, the chemical shift assignments and tautomeric distribution of three fructose-containing disaccharides, lactulose, cellobiulose and maltulose have been established with the 13C deuterium-induced, differential isotope-shift (d.i.s.) technique.
29 citations
TL;DR: 1H and 13C nuclear magnetic resonance studies show that 5KF exists in different forms in anhydrous dimethyl-d6 sulfoxide and D2O, and both the beta-pyranose and beta-furanose forms of 5Kf are proposed to be substrates for yeast hexokinase.
Abstract: 5-Keto-D-fructose (5KF) is isolated from cultures of Gluconobacter cerinus growing on D-fructose as the sole carbon source. 5KF is a substrate for hexokinase, fructokinase, and several polyol dehydrogenases. 1H and 13C nuclear magnetic resonance studies show that 5KF exists in different forms in anhydrous dimethyl-d6 sulfoxide and D2O. In dimethyl-d6 sulfoxide, 5KF exists as a spirane dimer with linked furanose and pyranose rings, similar to the structure reported for crystalline 5KF [Hassen, L., Hordvik, A., & Hove, R. (1976) J. Chem. Soc., Chem. Commun., 572-. In D2O, 5KF exists predominantly (greater than 95%) in a beta-pyranose form with the 5-keto group hydrated to form a gem-diol. 13C--1H coupling patterns, 13C relaxation measurements, and 13C deuterium-induced differential isotope shifts confirm this structure of 5KF. The phosphorylation of 5KF by fructokinase can be accounted for by an approximately 2% proportion of the beta-furanose form in solution at 25 degrees C. Both the beta-pyranose and beta-furanose forms of 5KF are proposed to be substrates for yeast hexokinase.
17 citations
TL;DR: In this paper, Melezitose [O-α-d-glucopyranosyl-(1→3)-β-d -fructofuranosyl α- d -glucophyranoside] monohydrate was crystallized in two polymorphic forms (I and II) and the structure of form II, studied by X-ray crystallography, showed an orthorhombic cell having a 7.135 (4), b 15.362 (8), c 19.134 (8) A, space group P212121,
17 citations
TL;DR: The reaction of benzyl exo -3,4-O-benzylidene-β- l -arabinopyranoside 1 with α-acetobromo-d -glucose 3 resulted in a mixture of two disaccharides, 5 and 6, in which the configuration of the acetal ring was different.
15 citations
TL;DR: In this article, the proton and solvent catalyzed rate constants of furanose formation are 2 to 3 times greater than those of pyranose, and activation and thermodynamic parameters are calculated.
13 citations
TL;DR: Triflation of methyl 3-azido-3,4-dideoxy-α or β-DL-threo-pentopyranoside with triethylamine as acid acceptor in dichloromethane, gave the two isomers of a 1:2′, 2:1′ dianhydride Benzoate displacement of the α triflate occured with a pyranose to furanose contraction reaction at C-2 as discussed by the authors.
TL;DR: The crystal structure of the title compound, a model for the glycosyl linkage between the asparagine side chain and N‐acetyl glucosamine in glycoproteins, has been determined and compared to other model structures.
Abstract: The crystal structure of the title compound, a model for the glycosyl linkage between the asparagine side chain and N-acetyl glucosamine in glycoproteins, has been determined and compared to other model structures. The pyranose ring in the crystal is in the 4C1 chair conformation and the amide functions at C1 and at C2 are both oriented such that the amide protons are nearly trans to their respective sugar-ring protons. Coupling constants determined from the fully assigned proton nmr spectrum in aqueous solution are consistent with the conformation in the crystal.
TL;DR: In this article, the pyranose ring of 2.3,4-tri-O -acetyl N -(diacetylamino)-β-d -glucopyranurono-1,6,1-lactam derivative was examined by 1 H- and 13 C-n.r.
TL;DR: In this paper, the crystal structure of 1,6-anhydro-β-d -mannopyranose, C 6 H 10 O 5, is solved by MULTAN and refined to R(F) = 0.043 for 2355 reflections.
TL;DR: In this article, the Cremer-Pople puckering parameters are, 0 = 6.69 o, Q = 0.068 for 1603 reflections, Z = 2, U = 833.0 A 3, d m = 2.08 Mg m -3, F(000) = 516.7o.
Abstract: C6H11o9P2-.Ba2+.7H2o, M, = 521.5, is monoclinic, space group P21, a = 11.881 (4), b = 8.616 (5), c = 8.350 (4) A,B = 102.95 (3)0, Z = 2, U = 833.0 A 3, d m = 2.09, d c = 2.08 Mg m -3, F(000) = 516. Mo Ka (u = 0.034 mm -1) intensity data. R is 0.068 for 1603 reflections. Of the two endocyclic C-O bonds in the glucose ring, C(5)-O(5) [1.463 (23)] is longer than C(1)-O(5) [1.395 (23)A]. The pyranose sugar ring takes a 4C1 chair conformation. The Cremer-Pople puckering parameters are, 0 = 6.69 o, Q = 0.619 A and
0 = 263.7o. The conformation about the exocyclic C(5)-C(6) bond is gauche-gauche, in contrast to gauche-trans observed in the structure of glucose 1-phosphate. The phosphate ester bond, P-O(6), is 1.61 (1)A. It is similar in length to the 'high-energy' P~O bond in phosphoenolpyruvate. The Ba 2÷ ion is surrounded by nine O atoms within a distance of 2.95 A, of which seven are from water molecules. There is an intramolecular hydrogen bond between the sugar hydroxyl 0(4) and phosphate oxygen O(12).
TL;DR: The reaction of a 2,3-Anhydro sugar with an 6-Amino sugar with NH4Cl in boiling dimethylformamide preponderantly yielded the trans-diequatorial product with gluco-configuration of the pyranose.
TL;DR: Properties of a PII-D type α-glucosidase in the labellar homogenate of the blowfly, Phormia regina were investigated and compared with those of the pyrasnose site on the sugar receptor, indicating that P II-T was converted, at least partially, into PII -D by the treatment with DOC and DTT.
TL;DR: The 13C spectra of the glucomannans from Eremurus lactiflorus and E. luteus were analyzed in comparison with the spectrum of low-molecular-weight model compounds.
Abstract: The13C spectra of the glucomannans fromEremurus lactiflorus andE. luteus are analyzed in comparison with the spectra of low-molecular-weight model compounds. It has been shown that the linear polymer chain consists of 1 → 4-bound glycosidic residues in the pyranose form, which confirms the results of earlier chemical investigations of these polysaccharides.