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Showing papers on "Pyranose published in 2003"


Journal ArticleDOI
TL;DR: It is established that the 2-O-Me Fuc-containing nonasaccharide side chain of wine RG-II has the structure (Api [triple bond] apiose): [see structure].

73 citations


Journal ArticleDOI
TL;DR: In this paper, the authors studied the thermolysis of sucrose at 185°C in a closed glassware and presence of air, with the help of GC/MS after acetylation of reaction products.

64 citations


Journal ArticleDOI
TL;DR: In developing MM4 to reproduce these data, it was necessary to have good energies for simple alcohols and ethers, together with an adequate treatment of hydrogen bonding, and then to include the anomeric effect, and the ethylene glycol type system, as was previously recognized.
Abstract: Ab initio calculations [B3LYP/6-311++G(2d,2p)] have been carried out on 84 conformations of 12 different sugars (hexoses), in both pyranose and furanose forms, with the idea of generating a data base for carbohydrate structural energies that may be used for developing the predictive value of molecular mechanics calculations for carbohydrates. The average value for the apparent gas phase anomeric effect for a series of 31 pairs of pyranose conformations was found to be 1.83 kcal/mol (vs. 2.67 kcal/mol with a smaller basis set used in earlier calculations). In developing MM4 to reproduce these data, it was necessary first to have good energies for simple alcohols and ethers, together with an adequate treatment of hydrogen bonding, and then to include the anomeric effect, and the ethylene glycol type system, as was previously recognized. It was also found that the so-called delta-2 effect, long recognized in carbohydrates, must be explicitly included, in order to obtain acceptable results. When a force field that included all of these items as developed from the small molecules based on the MM4 hydrocarbon force field was applied without any parameter adjustment to the set of hexopyranose and furanose conformations mentioned earlier, the Eβ − Eα was found to have an average value of 1.88 kcal/mol, versus 1.74 for the quantum calculations. The signed average and RMS deviations of the MM4 from the QM results were +0.15 and 0.87 kcal/mol. © 2003 Wiley Periodicals, Inc. J Comput Chem 24: 1504–1513, 2003

61 citations


Journal ArticleDOI
TL;DR: The first report on characterization of the covalent flavinylation site in flavoprotein pyranose 2-oxidase revealed that the flavin is covalently bound to histidine residue in the peptide STHW, consistent with the results of N-terminal amino acid sequencing by Edman degradation.

59 citations


Journal ArticleDOI
TL;DR: In this paper, the composition of various 2-keto aldoses, including 1-deoxy-D-erythro-hexos-3-ulose and 3-keto-aldoses in aqueous solution has been determined by NMR spectroscopy.
Abstract: Keto aldoses usually form complex mixtures of equilibrating isomers in solution. This is due to the two different positions that may be used for ring closure in dicarbonyl sugars. The composition of various 2-keto aldoses 1–5 and 8, the 3-keto aldose 2-deoxy-D-erythro-hexos-3-ulose (9), and the ketose 1-deoxy-D-ribulose (10) in aqueous solution has been determined by NMR spectroscopy. The investigated keto aldoses form equilibria containing three to fifteen isomers. Among various furanose and pyranose ring structures stemming from 1,4-, 1,5-, 2,5-, and 2,6-cyclization, bicyclic forms were also found in several cases. The 2-keto aldoses mainly exist as hydrated isomers in H2O. Therefore, these forms and their proportions were compared to forms found in two homomorphous aldoses and one homomorphous ketose as model compounds. Besides the NMR data, also the composition of the 2-keto aldoses agreed with the average of forms found in the model compounds, a finding that might eventually be useful for deducing the composition of other keto aldoses.

51 citations


Patent
05 Sep 2003
TL;DR: A method of inhibiting or effecting the activity of protein kinase activity is discussed in this paper, which comprises contacting a protein Kinase with a compound of formula (I) being a derivative of a furanose or pyranose form of a monosaccharide, or a pharmaceutically acceptable salt thereof.
Abstract: A method of inhibiting or effecting the activity of protein kinase activity which comprises contacting a protein kinase with a compound of formula (I) being a derivative of a furanose or pyranose form of a monosaccharide, or a pharmaceutically acceptable salt thereof.

37 citations


Reference EntryDOI
TL;DR: In this article, the authors described 1.1, 2.4, 5, and 6 pyranose as the precursors of D-Fructose and Perchloric acid, respectively.
Abstract: 1, 2:4,5-Di-O-isopropylidene-beta-D-fructopyranose D-Fructose 1,2:4,5-Di-O-isopropylidene-D-erythro-2, 3-hexadiulo-2, 6-pyranose Perchloric acid Pyridinium chlorochromate Keywords: enantioselective ketones; catalysts; epoxidation; waste disposal; dioxiranes; asymmetric synthesis; fructose; perchloric acid; pyranose

36 citations


Journal ArticleDOI
TL;DR: In this paper, the 10β-bromide derivatives of DHA with activated aromatic compounds, including naphthalenes, were shown to possess a chair pyranose ring with equatorial aryl group.

33 citations


Journal ArticleDOI
TL;DR: The Group B meningococcal polysaccharide is a random coil chain in solution, and therefore, does not have antigenic epitopes dependent upon a rigid, ordered conformation.
Abstract: To elucidate the role of secondary structure in the immune response against alpha(2-->8)-linked polysialic acid, the capsular polysaccharide of Group B meningococci, we have investigated its solution dynamics by using specific models of molecular motion and hydrodynamic modeling to interpret experimental NMR data. (13)C-[(1)H] NMR relaxation times and steady-state NOE enhancements were measured for two aqueous solutions of alpha(2-->8)-linked sialic acid polysaccharides. Each contained a unique distribution of polysaccharide chain lengths, with average lengths estimated at 40 or 400 residues. Models for rigid molecule tumbling, including two based on helical conformations proposed for the polysaccharide,(31) could not explain the NMR measurements. In general for these helices, the correlation times for their overall tumbling that best account for the NMR data correspond to polysaccharide chains between 9 and 18 residues in length, far short of the average lengths estimated for either solution. The effects of internal motions incorporated into these helices was modeled with an effective correlation time representing helix tumbling as well as internal motion. This modeling demonstrated that even with extreme amounts of internal motion, "flexible helices" of 25 residues or more still could not produce the NMR measurements. All data are consistent with internal and segmental motions dominating the nuclear magnetic relaxation of the polysaccharide and not molecular tumbling. Statistical distributions of correlation times have been found specifically for the pyranose rings, linkage groups, and methoxy groups that can account for the measured relaxation times and NOE enhancements. The distributions suggest that considerable flexibility attends the polysaccharide in solution, and the ranges of motional frequencies for the linkage groups and pyranose rings are comparable. We conclude that the Group B meningococcal polysaccharide is a random coil chain in solution, and therefore, does not have antigenic epitopes dependent upon a rigid, ordered conformation.

30 citations


Journal ArticleDOI
TL;DR: The anomeric radical deuteration reactions with the conformationally restricted 1-phenylseleno-d-glucose derivatives, restricted in a (4)C(1)-conformation by an O-cyclic diketal moiety, and 4g, 5g, 6g, 7g, and 8g, restrictions by bulky O-silyl protecting groups are reported.
Abstract: We previously theorized that, since the stereoselectivity of anomeric radical reactions is significantly influenced by the kinetic anomeric effect, which can be controlled by restricting the conformation of the radical intermediate, the proper conformational restriction of the pyranose ring of the substrates would therefore make highly α- and β-stereoselective anomeric radical reactions possible. This theory was based on our previous results of the anomeric radical reactions with d-xylose derivatives as the substrates. We herein report the anomeric radical deuteration reactions with the conformationally restricted 1-phenylseleno-d-glucose derivatives, 2g and 3g, restricted in a 4C1-conformation by an O-cyclic diketal moiety, and 4g, 5g, 6g, 7g, and 8g, restricted in a 1C4-conformation by bulky O-silyl protecting groups. The radical deuterations with Bu3SnD, using the 4C1-restricted substrates 2g and 3g, afforded the corresponding α-products (α/β = 98:2) highly stereoselectively, whereas the 1C4-restricted...

30 citations


Journal ArticleDOI
TL;DR: The results show that fluorescence labeling can be chemically tuned to find optimal probes for individual galectin but also probes interacting well with many galectins, and that conjugates based on 5-carboxyfluorescein gave significantly better results than the ones based on 6-car boxyfluorscein.

Journal ArticleDOI
TL;DR: The N-protonation-induced shifts of the anomeric equilibrium in a series of N-(tetra-O-methylglucopyranosyl)anilines have been measured with high precision through an NMR titration method that compares basicities of alpha and beta anomers in a mixture of the two.
Abstract: The so-called reverse anomeric effect is the preference of cationic substituents for the equatorial position on a pyranose ring, but it is not consistent with current theories of molecular structur...

Journal ArticleDOI
TL;DR: The N and S sites of glycosylation were determined from the 1H, 13C heteronuclear multiple-quantum coherence (HMQC) experiments and all the deprotected nucleosides were tested for their potential antitumor activity.
Abstract: A modified nitrogen and sulfur glycosylation reaction involving benzothiazole benzoxazole and pyridine nucleoside bases with furanose and pyranose sugars are described. Conformational analysis has been studied by homo- and heteronuclear two-dimensional NMR methods (2D DFQ-COSY, HMQC and HMBC). The N and S sites of glycosylation were determined from the 1H, 13C heteronuclear multiple-quantum coherence (HMQC) experiments. All the deprotected nucleosides were tested for their potential antitumor activity.

Journal ArticleDOI
TL;DR: The crystal structure of the title compound was determined by X-ray crystallography and depicts unique network of C-H...pi interactions, very closely resembling the pattern of O-H…O interactions in free sugars.

Journal ArticleDOI
TL;DR: Pyranose oxidase purified from mycelia of the basidiomycete fungi Trametes versicolor and Oudemansiella mucida catalyzed oxidation of d‐galactose successively at C‐2 and C‐3 to d‐threo‐hexos‐2,3‐diulose in the yields up to 80%.

Patent
08 Aug 2003
TL;DR: In this article, new compounds and methods for the preparation of combinatorial libraries of potentially biologically active compounds are based on monosaccharides of formula (I) being a derivative of a furanose or pyranose form of a monosACcharide.
Abstract: New compounds and methods for the preparation of combinatorial libraries of potentially biologically active compounds are based on monosaccharides of formula (I) being a derivative of a furanose or pyranose form of a monosaccharide.

Journal ArticleDOI
TL;DR: In this article, the 13C-13C coupling constants for all aldopyranoses of the D-series were calculated in terms of the self-consistent finite perturbation theory.
Abstract: 13C-13C coupling constants for all aldopyranoses of the D-series were calculated in terms of the self-consistent finite perturbation theory. General relations holding in the stereochemical behavior of the 13C-13C coupling constants for the pyranose ring were found. The results obtained make it possible to perform conformational analysis and assign configuration of the anomeric center in molecules of carbohydrates and products of their metabolism, containing a pyranose fragment.

Journal ArticleDOI
TL;DR: The molecular mass, as well as the structures of both the saccharide and acylamide side chain involved in related substances, can be determined by applying the results obtained.
Abstract: Fragmentation mechanisms of electron ionization (EI) mass spectrometry of the title compounds have been elucidated by high-resolution (HR) mass spectrometric measurements of the elemental composition and measurements of the metastable transitions (B2/E, CID). The experimental results were interpreted with the help of Mass Frontier 3.0 software, which aided the elucidation of fragmentation mechanisms and helped to deduce structures of the ions formed. Characteristic under the conditions of EI-MS measurement was the production of protonated adducts. Three distinct pathways observed include the formation of oxonium type ions, the conjugated transfer of electrons in the pyranose ring, and cleavage of the acylamide side chains. By applying the results obtained, the molecular mass, as well as the structures of both the saccharide and acylamide side chain involved in related substances, can be determined. Copyright © 2003 John Wiley & Sons, Ltd.

Journal ArticleDOI
TL;DR: In this paper, the 10β-bromide derivatives of DHA with activated aromatic compounds, including naphthalenes, were shown to possess a chair pyranose ring with equatorial aryl group.
Abstract: Lewis acid-catalysed arylation of the 10β-benzoate and, less effectively, the 10α-benzoate of dihydroartemisinin [DHA] with activated aromatic compounds, including naphthalenes, stereoselectively, provides 10α-aryl derivatives including disubstituted naphthalene derivatives. 2-Methoxynaphthalene provides the 1-, rather than the 3-substituted derivative. In contrast, 10β-aryl derivatives are obtained stereoselectively from the 10β-bromide, generated in situ from trimethylsilyl bromide and the TMS ether of 10α-DHA, and the corresponding aryl Grignard reagents. The 10α-aryl compounds are shown by NMR spectroscopy and X-ray crystallographic analysis to possess a chair pyranose ring with equatorial aryl group, whereas the 10β-aryl derivatives have a twist-boat pyranose ring with equatorial aryl group. The stereochemistry of the Lewis acid-catalysed arylations, which is common to that observed for the Lewis acid-catalysed arylation of pyranosyl glycosides with axial anomeric leaving groups in general, may be rationalized in terms of axial attack from the α or si face of the half-chair oxonium ion intermediate. On the other hand, the Grignard reagents activate the axial bromide to elimination through complexation, and thereby the aryl nucleophile attacks the incipient oxonium ion from the β or re face. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)

Journal ArticleDOI
TL;DR: The Zn(II) complexes of 4,6-O-butylidene/ethylidene-N-(α-hydroxynaphthylIDene/o-hydroxybenzylidenes)-β- d -glucopyranosylamine have been synthesized and characterized using spectral and analytical methods and structure for one of the products was established.

Journal ArticleDOI
TL;DR: The presence of an isopropylidene ketal protection of an internal diol in 3,4-O-isopropolidene-D-arabino-1-C-phenyl hexanone locks it in a conformation that prevents its cyclization to a pyranose ring.

Journal Article
TL;DR: In this paper, the authors studied the thermal stability of primary sugar allyltin derivatives: Sug-CH=CH-CH 2 SnBu 3 and found that they are stable up to at least 214°C (boiling trichlorobenzene), while those with a furanosering undergo already at 180°C a controlled decomposition with elimination of the tributylstannyl moiety and opening of the five-membered ring.
Abstract: Thermal stability of primary sugar allyltin derivatives: Sug-CH=CH-CH 2 SnBu 3 was studied. These organometallics with a pyranose ring are stable up to at least 214°C (boiling trichlorobenzene), while those with a furanosering undergo already at 180°C a controlled decomposition with elimination of the tributylstannyl moiety and opening of the five-membered ring. The mechanism of this process is discussed.

Journal ArticleDOI
TL;DR: In this paper, the structure of methyl-4-O-acetyl-2,3-anhydro-β-L-lyxopyranoside was characterized by X-ray diffraction and its structure indicates that the epoxide was opened by the hydroxyl group of the reduced acetyl; the structure was solved by direct methods and refined by full-matrix least-square methods to a final reliability index of 0.04 for the observed 1031 reflections.
Abstract: The acid-catalyzed ethylidenation of several methyl pentopyranosides has been studied and syntheses of many cyclic alkyl orthoacetates from pentopyranosides have been reported. In a study of the scope and limitation of the reduction of sugar epoxides with diborane/sodium borohydride, methyl-4-O-acetyl-2,3-anhydro-β-L-lyxopyranoside was reduced, yielding two products: methyl-2,3-anhydro-β-L-lyxopyranoside and methyl-3,4-O-ethylidene-β-L-arabinopyranoside. The latter product was characterized by X-ray diffraction and its structure indicates that the epoxide was not reduced as expected; rather, the epoxide was opened by the hydroxyl group of the reduced acetyl. Crystals of the title compound are monoclinic, space group P21 with the following cell dimensions: a = 5.818(l) A, b = 10.842(2) A, c =7.251(1) A, β = 91.47(1)°, Z = 2. Complete three-dimensional data (2θmax = 150° for Cu Kα) were collected on a CAD-4 diffractometer by the ω−2θ scan method. The structure was solved by the application of direct methods and refined by full-matrix least-square methods to a final reliability index of 0.04 for the observed 1031 reflections (I ≥ 3σ). The ethylidene ring has a twist conformation with a torsion angle of −42.8° about the C4–O bond. The pyranose ring is in a flattened chair conformation with the C2–C3–C4–C5 torsion angle of 33.5°. Of the acetal bond lengths, the C5–O5 length, (1.423 A) is shorter than the values found in other methyl pyranosides. O2–H is involved in a bifurcated hydrogen bond intramolecularly to O1 and intermolecularly to O4.

Journal ArticleDOI
TL;DR: In this paper, the authors studied the thermal stability of primary sugar allyltin derivatives: Sug-CH=CH-CH 2 SnBu 3 and found that they are stable up to at least 214°C (boiling trichlorobenzene), while those with a furanosering undergo already at 180°C a controlled decomposition with elimination of the tributylstannyl moiety and opening of the five-membered ring.
Abstract: Thermal stability of primary sugar allyltin derivatives: Sug-CH=CH-CH 2 SnBu 3 was studied. These organometallics with a pyranose ring are stable up to at least 214°C (boiling trichlorobenzene), while those with a furanosering undergo already at 180°C a controlled decomposition with elimination of the tributylstannyl moiety and opening of the five-membered ring. The mechanism of this process is discussed.

Journal ArticleDOI
TL;DR: The X-ray structures of 1,3,4,6-tetra-O-acetyl-2-deoxy-alpha-D-galactopyranoside derivatives with four different 2-(acylamino) substituents have been determined with Mo K(alpha) radiation at 123 K.

Journal ArticleDOI
TL;DR: Pyranose oxidase from mycelia of the basidiomycete fungi Trametes versicolor and Oudemansiella mucida catalyzed oxidation of d−galactose successively at C −2 and C −3 to d−threo−hexos−2,3−diulose (2, 3−dehydro−d−xylose, 2,keto−d‐xyloses) in the yields up to 80% as mentioned in this paper.
Abstract: Pyranose oxidase (pyranose:O2 2‐oxidoreductase, EC 1.1.3.10) purified from mycelia of the basidiomycete fungi Trametes versicolor and Oudemansiella mucida catalyzed oxidation of d‐galactose successively at C‐2 and C‐3 to d‐threo‐hexos‐2,3‐diulose (2,3‐dehydro‐d‐galactose, 2,3‐diketo‐d‐galactose) in the yields up to 80%. The sites of oxidation were deduced from structures of the N,N‐diphenylhydrazone derivatives of the reaction products. Under the reaction conditions used, the diulose was susceptible to non‐enzymatic oxidative decarboxylation to d‐threo‐pentos‐2‐ulose (2‐dehydro‐d‐xylose, 2‐keto‐d‐xylose) in yields of 5–10%.

Journal ArticleDOI
TL;DR: The crystal structure and solution 1H and 13C NMR spectra of ethyl 1,2,3,4-tetra-O-acetyl-β-D-glucopyranuronate (8) have been determined in this article.
Abstract: The crystal structure, at 120 K, and solution 1H and 13C NMR spectra of ethyl 1,2,3,4-tetra-O-acetyl-β-D-glucopyranuronate, (8) have been determined. Compound 8 crystallizes in the triclinic space group, P1 (Z = 1) with a = 6.0209(3) A, b = 8.9698(5) A, c = 9.9818(8) A, α = 104.965(2)°, β = 98.522(3)°, γ = 106.790(5)°. The Cremer and Pople puckering parameters [Q = 0.602(4) A, θ = 7.1(4)°, φ = 325(3)°] for the pyranose ring in the solid state indicate a near ideal 4C1 chair conformation with a slight distortion in the direction towards 0H5. A number of weak, soft intermolecular C–H ⋅ ⋅ ⋅ O hydrogen bonds set up a 3D array. NMR spectra and FAB and EIMS data have been obtained. Solution NMR parameters suggest that the solid state conformation is maintained in solution in chloroform.

Journal ArticleDOI
TL;DR: In this article, the normal vibrations of two sugar epoxides (methyl 2,3-anhydro-4-deoxy-α-D-ribohexopyranoside and methyl 3,4-anhedro-α,D-talohexopyruside) have been carried out by the molecular mechanics method and a good agreement between the experimentally observed and calculated frequencies has been obtained.
Abstract: Normal vibrations of two sugar epoxides — methyl 2,3-anhydro-4-deoxy-α-D-ribohexopyranoside and methyl 3,4-anhydro-α-D-talohexopyranoside — have been carried out by the molecular mechanics method. Parametrization of the force field used has been performed and the parameters of the oxirane ring for sugar epoxides have been determined. A good agreement between the experimentally observed and calculated frequencies has been obtained. The IR spectral absorption bands of the molecules under investigation in the 1500–400-cm−1 range have been assigned on the basis of the potential energy distribution function of normal vibrations. The investigation of the potential energy surface of these molecules has shown that their pyranose ring can take conformations close to half-chair, boat, skew boat, and twist forms. Comparative analysis of the normal vibrations of various conformers has revealed that the form of the pyranose ring influences the vibrational spectra of sugar epoxides.


Journal ArticleDOI
TL;DR: In this article, the pyranose rings in both molecules take chair conformations and the nitrosourea moieties are planar, and there is an extensive hydrogen network in the crystal.
Abstract: The crystal belongs to space group P212121, and the cell dimensions are a = 8.5300(5), b = 11.4516(9) and c = 23.893(1)A. The final R value is 0.047. There are two crystallographically independent molecules in an asymmetric unit. The pyranose rings in both molecules take chair conformations. The nitrosourea moieties are planar. There is an extensive hydrogen network in the crystal.