Showing papers on "Pyranose published in 1995"
TL;DR: This work reports the first example of specific enzyme inhibition by a spirohydantoin at the anomeric position of a sugar in the presence of glycogen phosphorylase.
129 citations
TL;DR: The determination of the structure of this protein provides fundamental knowledge for understanding its mode of action and the nature of allosteric conformational changes that regulate its function.
77 citations
TL;DR: In this article, the synthesis of O-isopropylidene derivatives was performed by reaction with acetone using the zeolite HY as catalyst, achieving moderate to good yields.
56 citations
TL;DR: The two major radiation-induced decomposition products of 2'-deoxyadenosine in oxygen-free aqueous solution have been isolated by reverse-phase HPLC and the expected furanose form of the initially generated formamidopyrimidine derivative was made to characterize.
Abstract: The two major radiation-induced decomposition products of 2'-deoxyadenosine in oxygen-free aqueous solution have been isolated by reverse-phase HPLC. The 1H and 13C NMR features of the two modified nucleosides obtained in DMSO-d6 are indicative of a similar formamidopyrimidine structure for the base residue (the ring-opened form of a C-8 hydroxylated purine). Interestingly, the sugar moiety exhibits a pyranose configuration, the two nucleosides being a pair of alpha and beta anomers. One-bond and long-range 1H-13C 2D NMR experiments have allowed the complete assignment of the carbon atoms. Confirmation of the base structure was obtained by 1H-15N scalar-correlated 2D NMR experiments. Attempts were made to characterize the expected furanose form of the initially generated formamidopyrimidine derivative. In this respect, isomerization reaction of the sugar moiety of the latter compound takes place rapidly after gamma-irradiation as inferred from 1H NMR analysis. The conformational study of the sugar moiety of the two pyranose anomers was inferred from detailed 600.13 MHz 1H NMR analysis in D2O. The alpha anomer exhibits a predominant 1C4 conformation whereas the beta anomer adopts preferentially a 4C1 conformation. In addition, the dynamic study of the restricted rotation of the formamido bond has revealed a 1/5 ratio in favor of the s-cis rotamer for both nucleosides. The energy barrier at coalescence was determined to be delta G# = 75.5 kJ.mol-1 (Tc = 370 K).
50 citations
TL;DR: The precise atomic coordinates obtained in this study can be directly transposed to give an improved structure for cellulose II where, in particular, only the gt conformation would be present at the primary hydroxyl groups of both polysaccharide chains.
45 citations
37 citations
TL;DR: In this article, cyclomaltoheptaose-ethylenediaminetetraacetate (CD-EDTA) was synthesized using NMR and MS techniques and its properties were discussed.
37 citations
Patent•
06 Mar 1995
TL;DR: In this paper, the derivates of formula (I) are new, with the exception of sialyl Lewis-X and -A, and derivs. of formulas (I, A, B, Cpds.
Abstract: Cpds. of formula (I) are new, with the exception of sialyl Lewis-X and -A, and derivs. of these which contain a N3, NH2 or OH substit. in place of a N-acetyl gp., or contain glycerin in place of fucose: R , R = H, CH2X or CH2O(CH2)mX ; or R +R = a six-membered substd. carbo- or hetero-cycle; R = O, S, H or CH2OX ; R , R = O- alpha -NANA (where NANA is N-acetylneuraminic acid), O- beta -NANA, OSO3H, or another monobasic acid; R = H, OH or 1-25C alkyl; or R +R = a six-membered substd. carbo- or heterocycle; Y = O- alpha -NANA, O- beta -NANA, OSO3H, or another monobasic acid; Z = a pyranose, a furanose or an open-chain polyalcohol; m, n, p, q = 1-20; X, X , X = H, NH2, COOH, OH, CH2OH, CH2NH, aryl, 1-25C alkyl or CH2O(CH2)qX; X = H, 1-25C alkyl or aryl; or X +X = O or S.
31 citations
TL;DR: In this article, the white rot fungus Oudemansiella mucida with d-glucose resulted in transient accumulation of d- arabino -hexos-2-ulose ( 1, 2-keto-d -glucoses) which was subsequently quantitatively converted into a new tricarbonyl sugar metabolite.
29 citations
TL;DR: Gradient-enhanced, two-dimensional, homonuclear correlation techniques (GCOSY) of carbohydrates provide numerous correlations based on 4J and 5J long-range interactions that are especially useful for spectral assignments in the envelope of pyranosyl ring protons located in the typically very crowded 3 to 4 ppm region.
27 citations
TL;DR: In this paper, all six isomeric mono-O-sulfates of β-d-Galp-(1 → 4)-β-d−GlcpNAc-O-(CH2)8COOMe (LacNAc)-MCO have been chemically synthesized and characterized by high-resolution 1H NMR spectroscopy.
TL;DR: Data collected on this compound suggests that, in solution, it is largely a glycosylamine in the beta pyranose form, which exists in two different conformational forms.
TL;DR: The first crystal structure data on an Amadori compound, N-(1-deoxy-beta-D-fructopyranos-1-yl)-glycine, are reported, which forms a three-dimensional network of two infinite chains that have an ammonium group as a common segment.
TL;DR: In this paper, the antiherpes agent 2'-deoxy-5-ethyl-4'-thiouridine was obtained via in situ pyranoside rearrangement of the sugar and subsequent coupling.
Abstract: Methyl 2-deoxy-3,4-0-thiocarbonyl-beta-D-ribopyranoside was converted into the thione carbonate by reaction with thiophosgene. Bromide ion-catalyzed 0-S rearrangement produced methyl 2-deoxy-3-0,4-S-carbonyl-4-thio-beta-D-ribopyranoside (3a) and the 3-0,4-S isomer 3b. The carbonates were cleaved with ammonia and the 3-0,4-S pyranoside sugar coupled with bis(trimethylsilyl)-5-ethyluracil using trimethylsilyl triflate to provide the antiherpes agent 2'-deoxy-5-ethyl-4'-thiouridine 9. The reaction proceeded via in, situ pyranoside rearrangement-of the sugar and subsequent coupling. The pyranoside sugar could also be converted to the furanoside form with Dowex H+ acid resin and coupled in conventional fashion to give the nucleoside. Coupling of methyl 4-0-carbamoyl-2-deoxy-3-thio-beta-D-ribopyranoside (4b) with the bis(trimethylsilyl)-5-ethyluracil gave 1-[2-[2-(hydroxymethyl)thiiran-1-yl]-1-methoxyethyl]-5-ethyluracil.
TL;DR: In this article, a new synthetic method providing both enantiomers by heteroconjugate addition strategy was described for stereocontrolled synthesis of optically active compounds from sugar chirons.
TL;DR: An eight-step synthetic sequence led from the known D-xylo-pentodialdose 8 to imidazole compound 12 by a van Leusen methodology and the intramolecular SN2 ring closure of the O-triflated benzylidene derivative 13 as mentioned in this paper.
Abstract: An eight-step synthetic sequence led from the known D-xylo-pentodialdose 8 to imidazo-L-xylo-piperidinose 15, the key steps being the build-up of imidazole compound 12 by a van Leusen methodology and the intramolecular SN2 ring closure of the O-triflated benzylidene derivative 13. xylo-Piperidinose 15 appears in a half-chair conformation like the oxocarbonium ions which are the postulated intermediates in the glycoprocessing of the pyranose polysaccharides. This bicyclic azasugar should be a glycosidase inhibitor.
TL;DR: An N-acylated bicyclic amino [ 2.2.2] lactone provides access to a new class of glycopeptide analogues of pyranoses and determines the anomeric configuration of the spirodiketopiperazine, which may be equilibrated to the more stable furanose form.
TL;DR: In this paper, the reaction of methyl 2,3-anhydro-4,6-O-benzylidene-α-d -allopyranoside (3 ) with Ph n MLi [M = As or P, n = 2; M = Sn, n= 3] gives methyl 4,6O-bene-2,deoxy-2-M-α -d -altropyraniumide (4 ; M = Ph 2 As, Ph 2 P or Ph 3 Sn).
TL;DR: In this article, two synthetic approaches to 2,6-dideoxy-4-S-methyl-4thio-D-ribo pyranose, a component of the oligosaccharide of esperamicins, are described.
TL;DR: In this paper, it was shown that the Amadori rearrangement of glucosamine may be reversible and possibly stereospecific in particular diastereoisomers, in which the coordination sphere actually contains one bidentate ethane-1,2-diamine chelate and a multidentate ligand which is an N-(2′-aminoethyl)amino-substituted glycosylamine derived from glucosamines, fructosamine or mannosamine.
Abstract: Reaction between cis- or trans-[Co(en)2CI2]+(en = ethane-1,2-diamine) and D-glucosamine (2-amino-2-deoxy-D-glucopyranose) in neutral aqueous solution results in a very complicated product mixture including as a major component several isomeric complex ions in which the co-ordination sphere is formally made up of two ethane-1,2-diamine units and one sugar unit. Separation of these complexes by ion-exchange chromatography, and subsequent spectroscopic and structural studies have shown that they are diastereomeric forms in which the co-ordination sphere actually contains one bidentate ethane-1,2-diamine chelate and a multidentate ligand which is an N-(2′-aminoethyl)amino-substituted glycosylamine derived from glucosamine, fructosamine or mannosamine. The presence of the fructosamine moiety reveals that the complex formation reaction is accompanied by the Amadori rearrangement of glucosamine, while the presence of the mannosamine moiety indicates that this rearrangement may be reversible and possibly stereospecific in particular diastereoisomers. Crystal structure determinations have definitively characterised eight of the reaction products as: 1 a complex of the 1-N-(2′-aminoethyl)amino-substituted glucosamine in which the sugar, although chelated to the metal as part of a tridentate ligand, is in its open-chain form and in which the four nitrogen atoms derived from the original two ethane-1,2-diamine units are essentially coplanar; 2 a complex of tridentate 1-N-(2′-aminoethyl)amino-substituted glucosamine in which the sugar has its pyranose form and the chelate edges spanned by the original ethane-1,2-diamine units are in the Δ configuration; 3 a complex of 1-N-(2′-aminoethyl)amino-substituted glucosamine in which the sugar is in its open-chain form and the ligand is bound in a quadridentate manner, with the chelate edges spanned by the original ethane-1,2-diamine units in the Δ configuration; 4 a complex of 1-N-(2′-aminoethyl)amino-substituted mannosamine in which the sugar has a furanose form and is part of a quadridentate ligand, and the chelate edges spanned by the original ethane-1,2-diamine units are in the Δ configuration; 5 a complex of quadridentate 1-(2′-aminoethylamino)-1-deoxy-fructopyranosylamine in which the chelate edges spanned by the original ethane-1,2-diamine units are in the Δ configuration; 6 a complex of quadridentate 1-(2′-aminoethylamino)-1-deoxy-fructopyranosylamine in which the chelate edges spanned by the original ethane-1,2-diamine units are in the Δ configuration; 7 the same complex as 6 but in the form where its co-ordinated sugar hydroxyl group is deprotonated; and 8 a complex of 1-(2′-aminoethylamino)-1-deoxyfructopyranosylamine in which the chelate edges spanned by the original ethane-1,2-diamine units are in the Δ configuration.
TL;DR: In this article, the preparation and evaluation of potent small molecule inhibitors of FKBP-12 rotamase activity is described, and the versatility of these ligands is demonstrated with respect to effector domain exploration.
TL;DR: In this article, a new strategy for the regio-and stereoselective synthesis of chiral tetrahydrofurans fused to the pyranose skeleton was proposed.
Abstract: A New Synthetic Strategy for the Synthesis of Chiral Polysubstituted Tetrahydrofurans Annulated to Pyranoses
An efficient strategy for the regio- and stereoselective synthesis of the chiral tetrahydrofurans 2, 3, 5, 6, 10–16, fused to the pyranose skeleton, from the anhydro sugars 1 and 4 and 1,3-dicarbonyl compounds via 5-enol-exo-exo-tet ring closure is described. Furthermore, the syntheses of the regioisomeric tetrahydrofuran 9, the γ-hydroxy-tetrahydrofulan 19 and the branched-chain sugar 20 were successfully achieved.
TL;DR: In this article, the Felkin model was used to assign the 6 R, 7 R absolute configuration of a mixture of nitroaldols obtained from the mixture of 1,2:3,4- di -O- isopropylidene-α-d -galacto- hexodialdo-1,5-pyranose.
TL;DR: In this article, a trifluoromethylated pyranose was synthesized and their mesomorphic properties were investigated, showing a chiral smectic C phase and very large spontaneous polarization over 700 nC·cm−2.
Abstract: Novel ferroelectric liquid crystals with a trifluoromethylated pyranose were synthesized and their mesomorphic properties were investigated. These compounds exhibited a chiral smectic C phase and showed very large spontaneous polarization over 700 nC·cm−2. Relationships between molecular structures and physical properties were discussed.
TL;DR: The molecular and crystal structures of 2,3,4,6,1′,3′,4′,6′-octa-O-acetyl-β-sophorose (β-Sophoroses octaacetate), methyl 2, 3, 4, 6, 3′, 4′, 6′ 6′-hepta, O-deoxy-β -sophoroside heptaacetate, and methyl 6′ deoxy-α-sphoroside hexaacetates were determined by X-ray diffraction
TL;DR: In this paper, the pyrolysis of trimethylsilyl derivatives of saccharides was investigated by DTA-TG, MS, GC/MS and TG-GC/MS.
Abstract: The pyrolysis of trimethylsilyl derivatives of saccharides (1) was investigated by DTA-TG, MS, GC/MS and TG-GC/MS. The DTA-TG/DTG curves showed that the pyrolysis of 1 occurred in one stage. The exothermic peaks were due to sublimation or thermal decomposition by vaporization. The cleavage mechanism by electron impact of 1 was classified into four categories: 1) stepwise elimination of the side-chain, 2) cleavage of the side-chain, 3) cleavage of the pyranose ring, and 4) cleavage of the pyranose ring and side-chain at the same time. The mass-spectrum for 1 revealed the main common four fragment ions, such asm/z 73, 191, 204 and 217, with cleavage of the pyranose ring. These fragment ions were detected with a similar retention time in the gas cromatogram by GC/MS or TG-GC/MS. The retention time for 1 increased in the sequence aldopentose
TL;DR: The low-temperature X-ray structure of α,α-allo-trehalose trihydrate (α-D-allopyranosyl α-D allopyranoide trihydrates, C 12 H 22 O 11.3H 2 O) is reported in this paper.
Abstract: The low-temperature X-ray structure of α,α-allo-trehalose trihydrate (α-D-allopyranosyl α-D-allopyranoside trihydrate, C 12 H 22 O 11 .3H 2 O) is reported. There are two conformationally similar, but symmetry-independent sugar molecules plus six water molecules in the asymmetric unit. The sugar molecules lack internal crystallographic symmetry because of the relative conformations of the hydroxymethyl substituents and the torsion angles about the glycosidic linkage. The pyranose rings have slightly distorted 4 C 1 conformations. The sugar and water molecules are linked by many hydrogen bonds to form a complex three-dimensional network. The intramolecular O...O contact distances are larger than those reported in a calcium complex of α,α-allotrehalose
TL;DR: The recent synthesis of a variety of bromoglycosyl imines2 from glycosyl azides contitutes a new example of the synthetic value of radical-mediated halogenation, so that substrates containing an activated C—H bond can be converted under mild conditions and in high yield into halogenated polyfunctional products which are not accessible by other routes.
TL;DR: The first crystal structure data on an Amadori compound, N-(1-deoxy-β-d-fructopyranos-1-yl)-glycine, are reported in this paper.
Abstract: The first crystal structure data on an Amadori compound, N-(1-deoxy-β-d-fructopyranos-1-yl)-glycine, are reported. The space group is P21 with Z = 2 and cell parameters a = 7.246(1), b = 10.009(1), c = 7.060(1) A, and β = 101.085(6)°. The structure was solved by direct methods and refined to a final R of 2.9% and Rw of 3.8% for 1385 reflections to give esd's of 0.002 A in bond lengths and 0.2° in angles. The conformation of the carbohydrate is the normal 2C5 pyranose chair. Bond lengths and valence angles compare well with average values from a number of pyranose structures. The molecule of the Amadori compound exists in the zwitterion form and has the C-6-O-6-C-2-C-1-N-C-2'-C-1'-O-1' chain in a zig-zag conformation, that is (together with O-2') substantionally planar. All hydroxyl, carboxyl, and ring oxygen atoms, and the secondary ammonuim group are involved in hydrogen bonding, which forms a three-dimensional network of two infinite chains that have an ammonium group as a common segment. The shortest intra- and inter-molecular hydrogen bonds involve donors of the pyranosyl moiety and acceptors of the amino acid portion, and vice versa.
Patent•
07 Jul 1995
TL;DR: An external preparation for skin comprising at least one member selected from the group consisting of escinol and its salts represented by the following constitutional formula (1): ##STR1## (wherein R 1 is hydrogen atom or hydroxyl group and R 2 is pyranose residue) is described in this article.
Abstract: An external preparation for skin comprising at least one member selected from the group consisting of escinol and its salts represented by the following constitutional formula (1): ##STR1## (wherein R 1 is hydrogen atom or hydroxyl group and R 2 is pyranose residue.) Due to the effect of escinol which characterizes the present invention, the external preparation in accordance with the present invention is excellent in whitening effect and has a high safety.