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  • 1
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 111 (1978), S. 3311-3324 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Functional Riburonic Acid DerivativesThe easily available methyl 2,3-O-isopropylidene-β-D-ribofuranosiduronic acid (2) is transformed into the corresponding dibenzyl- 5 and triacetyl compound 6 respectively. Both are appropriate starting materials for selective reactions at all positions of the riburonic acid frame. Selective cleavage of the benzyl groups of 5 delivers the ribofuranosyl halogenides 14-19 free of anomers via the 1-unprotected derivatives 10 and 11a-c. With N-nucleophiles derivatives are synthesized, which are useful for the formation of N-glycosides. The debenzylated compound 12 delivers the bridged lactone 13. Phosphorous pentachloride treatment of 6 leads to the 2-O-trichloroacetylribofuranosyl chloride derivative 21.
    Notes: Aus der bequem zugänglichen Methyl-2,3-O-isopropyliden-β-D-ribofuranosiduronsäure (2) wurden die entsprechenden Dibenzyl- und Triacetylderivate 5 bzw. 6 hergestellt, welche geeignete Ausgangsverbindungen für selektive Reaktionen an allen Positionen des Riburonsäuregerüsts sind. Durch selektive Abspaltung der Benzylgruppen aus 5 wurden über die 1-ungeschützten Derivate 10 und 11a-c die Ribofuranosylhalogenide 14-19 anomerenfrei isoliert. Mit N-Nucleophilen wurden daraus Derivate für die aufbauende Synthese von N-Glycosiden zugänglich. Aus der vollständig entbenzylierten Verbindung 12 wurde das überbrückte Lacton 13 erhalten. Phosphorpentachlorid-Behandlung von 6 lieferte das 2-O-Trichloracetylribofuranosylchlorid-Derivat 21.
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  • 2
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 113 (1980), S. 1775-1789 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Stereospecific Synthesis of Nucleoside-5′-carboxylic Acid Derivatives with Pyrimidines as Hetero-cyclic BasePyrimidine nucleoside-5′-carboxylic acid derivatives were synthesized by condensation of riburonic acid glycosyl halides with heterocyclic bases via different methods. According to the investigations, the benzoyl-protected riburonic acid glycosyl halides 3b and 16b are valuable starting materials for the synthesis of β-nucleosides. Silver perchlorate proved to be the best catalyst in these condensation reactions with respect to stereoselectivity and yield. The methyl esters and the ethyl amides of uridine-, cytidine-, and thymidine-5′-carboxylic acid 8b, 11b, 18b, 19b and 20b were synthesized by this method stereospecifically and in good yield.
    Notes: Pyrimidinnucleosid-5′-carbonsäure-Derivate wurden durch Kondensation von Riburonsäure-glycosylhalogeniden mit heterocyclischen Basen nach verschiedenen Methoden hergestellt. Nach den Untersuchungen eignen sich als Ausgangskomponenten zur Synthese der β-Nucleoside am besten die benzoyl-geschützten Riburonsäure-glycosylhalogenide 3b und 16b. Die Verwendung von Silberperchlorat als Katalysator für die Kondensation ergab insgesamt die besten Ergebnisse bezüglich Stereoselektivität und Ausbeute. Die Methylester bzw. Ethylamide 8b, 11b, 18b, 19b und 20b der Uridin-, Cytidin- und Thymidin-5′-carbonsäure wurden auf diese Weise stereospezifisch und mit guten Ausbeuten synthetisiert.
    Additional Material: 2 Tab.
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  • 3
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 114 (1981), S. 2834-2843 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Glycosylhydrazines, 5. Synthesis of pyrazole-, Pyrazolo[3,4-d]pyrimidine-, and 1H-1,2,4-Triazol-Nucleoside 5′-amide Derivatives via Riburonamide HydrazonesIn a single step reaction the 3,5-dimethylpyrazole nucleoside-5′-amides 6a,c, the functionally substituted pyrazole nucleoside-5′-amides 9a and 10b, and the 1H-1,2,4-triazol-nucleoside-5′-amide 18 were obtained regio- and stereoselectively from the riburonamide hydrazones 4a-c.9a and 10b were transformed into the unprotected pyrazolo[3,4-d]pyrimidine nucleoside-5-amide 14a and 15b, derivatives of allopurinol riboside. likewise the ethylamide 20 of virazole-5′-acid was synthesized from 18.
    Notes: Aus den Riburonamid-hydrazonen 4a-c wurden in einer Eintopfreaktion regio- und stereoselektiv die 5′-Säureamid-Derivate des 3,5-Dimethylpyrazol-nucleosids 6a,c, der funktionell substituierten Pyrazol-nucleoside 9a) und 10n) und des 1H-1,2,4-Triazole-nucleosids 18 direkt aufgebaut. Als Allopurinolribosid-Derivate wurden aus 9a und 10b die ungeschützten pyrazolo[3,4-d]pyrimidin-nucleosid-5′-säureamide 14a und 15b hergestellt. Entsprechend wurde aus 18 das Ethylamid 20, der Virazol-5′-säure erhalten.
    Additional Material: 1 Tab.
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  • 4
    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.
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  • 5
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1989 (1989), S. 1099-1106 
    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.
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  • 6
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1992 (1992), S. 377-382 
    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.
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  • 7
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1979 (1979), S. 1426-1439 
    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.
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  • 8
    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.
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  • 9
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1988 (1988), S. 1013-1014 
    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.
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  • 10
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1993 (1993), S. 859-864 
    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.
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