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  • 1
    Electronic Resource
    Electronic Resource
    Glycosylimidate, 18. Regioselektive Reaktionen partiell geschützter Zucker Einfache Synthese von 3,4-Diazido-3,4-didesoxy-L-arabinose aus D-Arabinose (1985)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1985 (1985), S. 1546-1556 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Glycosyl Imidates, 18.- Regioselective Reactions of Partially Protected Sugars Convenient Synthesis of 3,4-Diazido-3,4-dideoxy-L-arabinose from D-ArabinoseBenzyl β-D-arabinopyranoside (1) gave with 1.5 equivalents of mesyl chloride exclusively the 2,3-di-O-mesyl compound 2. Treatment with NaN3 in DMF caused inversion at C-2, C-3, and C-4 and yielded benzyl 3,4-diazido-3,4-dideoxy-α-L-arabinopyranoside (11). Acid-catalyzed debenzylation and subsequent base-catalyzed treatment with trichloroacetonitrile gave the 1-O-activated trichloroacetimidate 16; reaction with the 3,4-O-unprotected 2-azido-2-deoxyxylopyranoside 18 gave regiospecifically the 3-O-connected disaccaride 20. Reduction of the azido groups, N-acetylation, and O-deacetylation led to the O-unprotected disaccaride 23. the structures of the compounds obtained or their O-acetylated derivatives, respectively, were assigned by 1H NMR data.
    Notes: Umsetzung von Benzyl-β-D-arabinopyranosid (1) mit 1.5 äquivalenten Mesylchlorid lieferte ausschließlich die 2,3-Di-O-mesyl-Verbindung 2. Behandlung mit Natriumazid in DMF ergab unter Inversion an C-2, C-3 und C-4 Benzyl-3,4-diazido-3,4-didesoxy-α-L-arabino-pyranosid (11). Säurekatalysierte Debenzylierung und anschließende basenkatalysierte Umsetzung mit Trichloracetonitril führte zum 1-O-aktivierten Trichloracetimidat 16, das mit dem 3,4-O-ungeschützten 2-Azido-2-desoxyxylopyranosid 18 regiospezifisch das 3-O-ver-knüpfte Disaccharid 20 lieferte. Reduktion der Azidgruppen, N-Acetylierung und O-Des-acetylierung führte zum O-ungeschützten Disaccharid 23. Die Strukturen der erhaltenen Verbindungen wurden, soweit erforderlich, über O-acetylierte Derivate 1H-NMR-spektroskopisch gesichert.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198519850804
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  • 2
    Electronic Resource
    Electronic Resource
    Glycosyl Imidates, 42 Selectively Protected Lactose and 2-Azido Lactose, Building Blocks for Glycolipid Synthesis (1989)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1989 (1989), S. 1099-1106 
    Details
    ISSN: 0170-2041
    Keywords: Lactose ; Azidolactose ; Glycosyl acceptors ; Glycosyl donors ; Regioselective protection ; Carbohydrates ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Glycosylimidate, 42. - Selektiv geschützte Lactose und 2-Azidolactose als Bausteine für die Synthese von GlycolipidenDurch regioselektive Alkylierung der 3′-OH-Gruppe von Benzyl-β-lactosid mit der Stannylierungsmethode wurden die 3′-OH- und 4′-OH-ungeschützten Lactosederivate 5 und 10 sowie das 4′-OH-ungeschützte Lactosederivat 9 hergestellt, das aufgrund seiner unterschiedlichen Schutzgruppe für 3′-OH für weitere Umwandlungen geeignet ist. Diese Bausteine sind wertvolle Glycosylakzeptoren für die Synthese von Glycolipiden. Zur Synthese von Glycosyldonoren mit Gal(β1 → 4)GlcNAc-Struktur wurde das 2-Azidolactosederivat 19 verwendet. Durch regioselektive Alkylierung der 3′-OH-Gruppe mit der Stannylierungsmethode sowie durch Anwendung anderer regioselektiver Schutzgruppen-Verfahren wurden die Trichloroacetimidate 17, 24 und 30 hergestellt, die aufgrund ihrer speziellen Schutzgruppen für 3′-OH, 4′-OH und 6′-OH für weitere Umwandlungen geeignet sind.
    Notes: Performing regioselective alkylation at 3′-OH of benzyl β-lactoside 1 by the stannylation method we prepared the 3′-OH- and 4′-OH-unprotected lactose derivatives 5 and 10 and the 4′-OH-unprotected lactose derivative 9 containing a different protecting group at 3′-OH, suitable for further transformations. These building blocks are valuable glycosyl acceptors in glycolipid synthesis. For the synthesis of glycosyl donors with Gal(β1 → 4)GlcNAc-structure we used the 2-azido lactose derivative 19. By regioselective alkylation of 3′-OH by the stannylation method and application of other common regioselective protecting procedures we prepared the trichloroacetimidates 17, 24, and 30 containing special protecting groups at 3′-OH, 4′-OH, and 6′-OH which are suitable for further transformations in these positions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198919890276
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  • 3
    Electronic Resource
    Electronic Resource
    Spiroketal Synthesis.  -  A Case of Intramolecular Glycoside Bond Formation (1992)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1992 (1992), S. 377-382 
    Details
    ISSN: 0170-2041
    Keywords: Glycosides ; Disaccharides ; Undecaose ; Carbohydrates ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: From 4-O-unsubstituted glucose derivatives 1a, b the 4-hydroxymethyl-substituted glucose derivatives 9a, b were obtained via oxidation to the ketone, Wittig reaction with methylenetriphenylphosphorane, borane addition, and subsequent oxidation to yield the diastereomeric galactose-derived compounds 5a, b; the required inversion of configuration at C-4 was accomplished through oxidation to the formyl derivatives, base-catalyzed isomerisation, and then reduction. Transformation of hydroxymethyl derivatives 9a, b into the iodo derivatives 11a, b and reaction with n-butyllithium generated the C-lithiated species 11aA, bA which furnished with O-benzyl-protected gluconolactone 12 the ketose derivatives 13a, b. Treatment with Et2O-BF3 afforded under concomitant 6-O-debenzylation the spiroketals 15a, b. Hydrogenolytic O-debenzylation and subsequent O-acetylation led to compounds 16a and 16b, respectively. The anomeric ketoside configuration was derived from NOE experiments.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.199219920166
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  • 4
    Electronic Resource
    Electronic Resource
    Synthesen von Glykosylhalogeniden der Riburonsäure über die entsprechenden Thioglykoside (1979)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1979 (1979), S. 1426-1439 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Syntheses of Glycosyl Halides of Riburonic Acid via Corresponding ThioglycosidesThe readily available riburonic acid derivative 1 is transformed via the 1,1-bis(ethylthio)-1-deoxo-D-riburono-5,2-lactone (2) into the 2,3-unprotected riburonic amides 7α, β and 8α, β. Both are appropriate starting materials for the introduction of different protective groups in position 2 and 3 of riburonic acid. Exchange of the 1-ethylthio group by chlorine and bromine leads to riburonic acid glycosyl halides, which are interesting synthons in nucleoside and oligosaccharide chemistry. The anomeric configuration of different glycosides of ribofuranose has been conveniently determined by the 1H-NMR chemical shift of the 2,3-O-isopropylidene groups.
    Notes: Aus dem gut zugänglichen Riburonsäurederivat 1 wurden über das 1,1-Bis(ethylthio)-1-desoxo-Driburonsäure-5,2-lacton (2) in wenigen Stufen die 2,3-ungeschützten Riburonsäureamide 7α, β und 8α, β synthetisiert, welche geeignete Zwischenprodukte zur Einführung verschiedener Schutzgruppen in Position 2 und 3 der Riburonsäure sind. Der Austausch der 1-Ethylthiogruppe durch Chlor und Brom führt zu den Riburonsäureglykosylhalogeniden 18-24, welche als Synthesebausteine in der Nucleosid- und Oligosaccharidchemie Bedeutung haben. Die Anomerenkonfiguration verschiedener Glykoside der Ribofuranose kann aus der chemischen Verschiebung der 1H-NMR-Signale der 2,3-O-Isopropylidengruppen bequem erhalten werden.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.197919790915
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  • 5
    Electronic Resource
    Electronic Resource
    Glycosyl imidates, 47. Stereospecific synthesis of α- and β-L-fucopyranosyl phosphates and of gdp-fucose via trichloroacetimidate (1991)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1991 (1991), S. 121-124 
    Details
    ISSN: 0170-2041
    Keywords: Fucopyranosyl phosphate ; Fucose 1-phosphate ; Glycosyl phosphate ; GDP-fucose ; Guanosine diphosphofucose ; Trichloroacetimidates ; Carbohydrates ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Reaction of the benzyl- and acetyl-protected α-trichloroacetimidates 1 and 6α with dialkyl and diaryl phosphates in the presence of traces of acid affords stereoelectively the thermodynamically more stable α-L-fucopyranosyl phosphates 2, 7 and 8, respectively, in high yields. The use of very pure, recrystallized dibenzyl phosphate results in the stereoeletive formation of the β-L-fucopyranosyl phosphates 3 and 9. In each case separation of the anomers is not required because of the very high stereoselectivity of the reactions. After deprotection the fucose 1-phosphate 12 is coupled with GMP morpholidate 10 to yield GDP-fucose 13. After the development of a new purification procedure for GDP-fucose 13 we have obtained a very pure compound suitable for biochemical investigations. Analytical and preparative HPLC has been performed on reversed-phase columns using a volatile buffer system (triethylammonium hydrogen carbonate) as the eluant.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.199119910122
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  • 6
    Electronic Resource
    Electronic Resource
    Synthese von N-Ethylguanosin-5′-carboxamid (1988)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1988 (1988), S. 1013-1014 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis of N-Ethylguanosine-5′-carboxamideN-Ethylguanosine-5′-carboxamide (5) was prepared by condensation of O-benzoyl-protected riburonic acid glycosyl halide 1 and N2-acetylguanine (2) with mercury(II) cyanide as a catalyst. The N7-isomer, obtained as a byproduct, was separated by reversed-phase medium-pressure liquid chromatography. The structures were determined by NMR and UV spectroscopy.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198819881017
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  • 7
    Electronic Resource
    Electronic Resource
    Glycosyl Imidates, 62. - Synthesis of the Heptasaccharide Moiety of Ganglioside BGM1 (1993)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1993 (1993), S. 859-864 
    Details
    ISSN: 0170-2041
    Keywords: Glycosphingolipids ; Ganglio series ; Blood group B determinant ; Glycosides ; Trichloroacetimidates ; Saccharides ; Carbohydrates ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The synthesis of the O-acetyl protected heptasaccharide moiety (2) of BGM1 was performed according to the following reaction sequence: Reaction of 2,3-di-O-acetyl-4,6-O-benzylidenegalactosyl trichloroacetimidate 4 (as donor) with 3-O-unprotected 2-azidogalactose 5 (as acceptor) gave β(1→3)-connected disaccharide 6. Subsequent O-deacetylation followed by reaction with galactosyl donor 8 afforded regioselectively trisaccharide 9 which was converted into tetrasaccharide 12 by treatment with fucosyl donor 11. Transformation of 12 via acid-catalyzed O-deisopropylidenation, O-acetylation, anomeric O-desilylation, and then base-catalyzed treatment with trichloroacetonitrile afforded trichloroacetimidate 16 as tetraosyl donor. Reaction of 16 with the known 4b-O-unprotected sialyllactose derivative 17 gave in acetonitrile at -40°C in the presence of TMSOTf as the catalyst the desired heptasaccharide 18. Azido group reduction with propanedithiol, N-acetylation, hydrogenolytic O-debenzylation, and O-debenzylidenation under acidic conditions followed by O-acetylation afforded the target molecule 2. The structural assignments were based on the 1H-NMR data.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.1993199301136
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  • 8
    Electronic Resource
    Electronic Resource
    Riburonsäurederivate zur gezielten Veränderung der Ribose (1974)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1974 (1974), S. 1856-1863 
    Details
    ISSN: 0075-4617
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Riburonic Acid Derivatives for Modification of the Ribose MoietyPermanganate oxidation of methyl-2,3-O-isopropylidene-β-D-ribofuranoside(2), which is readily available from D-ribose, provides a convenient method for the synthesis of methyl-2,3-O-isopropylidene-β-D-ribofuranosiduronic acid (5a), the methyl ester 5b of which is a key intermediate for directed chemical modification of the C-atoms 3, 4, and 5 of D-ribose. This is demonstrated by examples. The structures and conformations of the synthesized compounds are discussed.
    Notes: Die Permanganatoxidation von Methyl-2,3-O-isopropyliden-β-D-ribofuranosid (2), aus D-Ribose leicht zugänglich, stellt ein bequemes Verfahren zur Herstellung von Methyl-2,3-O-isopropyliden-β-D-ribofuranosiduronsäure (5a) dar. Ihr Methylester 5b ist eine Schlüsselsubstanz zur gezielten chemischen Veränderung der C-Atome 3, 4 und 5 der D-Ribose. Dies wird an einigen Beispielen gezeigt. Die Struktur und Konformation der hergestellten Verbindungen wird diskutiert.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.197419741116
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  • 9
    Electronic Resource
    Electronic Resource
    p-Nitrophenol-α-d-galaktosid Berichtigung und Ergänzung (1955)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 595 (1955), S. 242-242 
    Details
    ISSN: 0075-4617
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.19555950312
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  • 10
    Electronic Resource
    Electronic Resource
    Glycosyl imidates, 69. Synthesis of flavone C-glycosides vitexin, isovitexin, and isoembigenin (1995)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1995 (1995), S. 461-466 
    Details
    ISSN: 0947-3440
    Keywords: Glycosides ; Flavones ; Vitexin ; Isovitexin ; Isoembigenin ; Carbohydrates ; Trichloroacetimidates ; Fries rearrangement ; Baker-Venkataraman rearrangement ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 2-Hydroxy-4,6-dimethoxyacetophenone (4) was glycosylated with O-(2,3,4,6-tetra-O-benzyl-α-D-glucopyranosyl) trichloroacetimidate (5) and trimethylsilyl triflate as promoter to yield directly the C-glycoside 6. Construction of the flavone system by application of a Baker-Venkataraman-type rearrangement followed by deprotection yielded isoembigenin (2). Glycosylation of 4,6-bis(tert-butyldimethylsilyloxy)-2-hydroxyacetophenone (17) with the trichloroacetimidate 5 afforded the O-glycoside intermediate 18 which was converted via Fries rearrangement into the C-glycoside 21. Applying again the Baker-Venkataraman rearrangement and cyclization gave isovitexin and vitexin derivatives 25 and 26, which were completely deprotected to yield isovitexin (1b) and vitexin (1a), respectively.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.199519950362
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