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  • 1
    Electronic Resource
    Electronic Resource
    Nucleoside, IX. Synthese und Eigenschaften von Lumazin-nucleosiden  -  Strukturanaloga des Uridins und Thymidins (1973)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 106 (1973), S. 1401-1417 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Nucleosides, IX. Synthesis and Properties of Lumazine Nucleosides  -  Structural Analogs of Uridine and ThymidineGlycosidation reactions of lumazine (1) and its 6,7-dimethyl (2) and 6,7-diphenyl derivative (3) with 1-halo- and 1-acyloxyribose and 2-deoxyribose derivatives respectively via the silyl method are described. The main reaction products turned out to be the lumazine-N-1 nucleosides. 1,3-Diglycosides are formed in minor amounts whereas in most cases the N-3 nucleosides are present only in trace quantities. The structures of the newly synthesized reaction products have been established by u. v. and n. m. r. spectra.
    Notes: Die Umsetzungen von Lumazin (1), seinem, 6,7-Dimethyl- (2) und 6,7-Diphenyl-Derivat (3) mit I-Halogen- bzw. 1-Acyloxyribose- und 2-Desoxyribose-Derivaten nach der Silyl-Methode werden beschrieben. Als Hauptprodukte werden die Lumazin- N-1-nucleoside gebildet. l,3-Diglycoside entstehen in untergeordnetem Maße, während die N-3-Nucleoside meist nur in Spuren nachweisbar sind. Die Strukturen der neu synthetisierten Produkte werden durch UV- und NMR-spektroskopische Untersuchungen gesichert.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19731060506
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  • 2
    Electronic Resource
    Electronic Resource
    Nucleoside, XXXII. Über die Ribosidierung des 7-Oxo-7,8-dihydrolumazins und seines 6-Methyl- und 6-Phenyl-Derivates (1980)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 113 (1980), S. 1524-1534 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Nucleosides, XXXII. Ribosylations of 7-Oxo-7,8-dihydrolumazine and its 6-Methyl- and 6-Phenyl DerivativesRibosylation reactions of 7-oxo-7,8-dihydrolumazine (1) and its 6-methyl- (2) and 6-phenyl derivative, respectively, are described. Treatment of the trimethylsilyl derivatives 6 - 8 with 2,3,5-tri-O-benzoyl-1-bromo-D-ribofuranose (9) in the presence of Hg-salts leads to mixtures of the corresponding N-1-mono- (11 - 13) an N-1,N-3-diribosides (17 - 19), whereas the analogous reaction with 1-O-acetyl-2,3,5-tri-O-benzoyl-β-D-ribofuranose (10) and SnCl4 gave N-3-nucleosides (23 - 25). N-8-Substitution has not been observed. On debenzoylations the free nucleosides 14 - 16, 22, and 26 - 28 are formed. The structures of the newly synthesized compounds have been established by UV- and NMR spectra as well as pK determinations.
    Notes: 7-Oxo-7,8-dihydrolumazin (1), sein 6-Methyl-(2) und 6-Phenyl-Derivat (3) werden in Form ihrer Trimethylsilyl-Derivate 6 - 8 Ribosidierungsreaktionen unterworfen. 2,3,5-Tri-O-benzoyl-1-brom-D-ribofuranose (9) führt unter Hg-Salz-Katalyse zu den entsprechenden N-1-Mono-(11 - 13) und N-1,N-3-Diribosiden (17 - 19), während mit 1-O-Acetyl-2,3,5-tri-O-benzoyl-β-D-ribofuranose (10) und SnCl4 die N-3-Nucleoside 23 - 25 gebildet werden. Eine N-8-Substitution wird nicht beobachtet. Entbenzoylierungen führen zu den freien Nucleosiden 14 - 16, 22 und 26 - 28. Die Verbindungen werden durch UV- und NMR-Spektren sowie pK-Werte charakterisiert.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19801130432
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  • 3
    Electronic Resource
    Electronic Resource
    Nucleoside, XII. Syn- und anti-isomere Pentofurano-nucleoside (1973)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 106 (1973), S. 2975-2981 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Nucleosides, XII  -  Syn- and anti-isomeric Pentofurano-nucleosidesThe barriers to internal rotation around the glycosidic bond (syn-anti-isomerism) of 6-substituted uracil furanosides as well as several lumazine nucleosides were measured by variable temperature proton magnetic resonance. β-Ribosides, α-2′-deoxyribosides and an α-arabinoside all show ΔG+-values in the range of 9 to 13 kcal/mol. In all cases in thc equilibria around -100°C the anti-form predominates slightly over the syz-rotamer. The syn-anti-barrier is discussed in terms of steric interactions of aglycon and pentose.
    Notes: Die Barrieren der behinderten Rotation um die glycosidische Bindung (syn-anti-Isomerie) 6-substituierter Uracil-furanoside und verschiedener Lumazin-nucleoside werden aus der temperaturabhängigkeit der NMR-Spektren bestimmt. β-Riboside, α-2′-Desoxyriboside und ein α-Arabinosid zeigen ΔG+-Werte im Bereich 9-13 kcal/mol. in Fällen ist im Gleichgewicht bei -100°C die anti-Form vor dem syn-Rotameren etwas bevorzugt. Die syn-anti-Barriere wird auf der Basis einer sterischen Wechselwirkung zwischen Aglycon und Pentose diskutiert.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19731060928
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  • 4
    Electronic Resource
    Electronic Resource
    Nucleoside, XIII. Synthese und Eigenschaften von Lumazin- und Isopterin-glucosiden (1973)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 106 (1973), S. 2982-2991 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Nucleosides, XIII. Synthesis and Properties of Lumazine and Isopterin GlucosidesThe glucosidation of lumazine (l), isopterin (2) and its 6,7-dimethyl derivative (3) via the „silyl method“ is described. The reaction favours N-1 substitution and the tetra-O-acetyl derivatives 8, 10 and 14 as well as the free glucosides 9 and 11 have been isolated and characterized by u.v.- and n.m.r. spectrophotometric studies. The latter provided for the first time an experimental proof for the existence of rotationally restricted syn-anti-isomers at room temperature. The free energies of activation of the isomerization have values around 18 kcal/mol.
    Notes: Die Glucosidierung von Lumazin (l), Isopterin (2) sowie seinem 6,7-Dimethyl-Derivat (3) nach der „Silyl-Methode“ wird beschrieben. Als Hauptreaktionsprodukte entstehen die N-l-Substitutionsprodukte, die in Form ihrer Tetra-O-acetyl-Derivate (8, 10, 14) und der freien Glucoside 9 und 11 isoliert werden. Die Charakterisierung erfolgt durch UV- und NMR-spektroskopische Untersuchungen, wobei aus letzteren erstmals ein experimenteller Beweis über das Vorliegen von rotationsgehinderten syn-anti-Isomeren erbracht werden kann. Die freien Aktivierungsenergien der Isomerisierung haben Werte um 18 kcal/mol.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19731060929
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  • 5
    Electronic Resource
    Electronic Resource
    Nucleoside, XXXIII. Über die Synthese des 7-Oxo-8-β-D-ribofuranosyl-7,8-dihydro-lumazins und seines 6-Methyl-Derivates (1980)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 113 (1980), S. 1535-1548 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Nucleosides, XXXIII. Synthesis of 7-Oxo-8-β-D-ribofuranosyl-7,8-dihydrolumazine and its 6-Methyl DerivativeThe synthesis of 7-oxo-8-β-D-ribofuranosyl-7,8-dihydrolumazine (26) and its 6-methyl derivative (28) has been achieved by a ribosylation reaction of 2,4-bis(benzyloxy)- (18) and 2,4-bis(benzyl-oxy)-6-methyl-7-oxo-7,8-dihydropteridine (19), respectively, under Hg(CN)2-catalysis. 7-O-Ribosides are formed in the first step of the reaction and undergo 7-O→N-8-rearrangements (29, 30) as well as intermolecular transglycosidations with formation of N-1,7-O-di- (23, 24) and N-1,N-3,7-O-triribosides (32), respectively, on prolonged heating in the presence of Hg-salts. The reaction mixtures have been separated chromatographically and the structures of the various components proven by spectrophotometrical and chemical means. The blocking groups in 2,4-bis(benzyloxy)-7-oxo-8-(2,3,5-tri-O-benzoyl-β-D-ribofuranosyl)-7,8-dihydropteridine (29) and its 6-methyl derivative (30), respectively, have been cleaved by catalytic hydrogenation on Pd/C to 25 and 27 and by ammonia in methanol to 26 and 28. Attempts for the synthesis of 26 starting from 6-amino-2,4-dimethoxy-5-nitropyrimidine (3) are also described, leading however only to the formation of 8-D-ribityl-(12) and 8-β-D-ribofuranosyl-2,4-dimethoxy-7-oxo-7,8-dihydropteridine (14), respectively.
    Notes: Die Synthese von 7-Oxo-8-β-D-ribofuranosyl-7,8-dihydrolumazin (26) und seinem 6-Methyl-Derivat (28) kann durch Ribosidierung von 2,4-Bis(benzyloxy)-(18) bzw. 2,4-Bis(benzyloxy)-6-methyl-7-oxo-7,8-dihydropteridin (19) unter Hg(CN)2-Katalyse realisiert werden. Es entstehen zunächst 7-O-Riboside (20, 21), die bei längerem Kochen in Gegenwart von Hg-Salzen sowohl einer 7-O→N-8-Umglycosidierung (29, 30) als auch einer intermolekularen Transglycosidierung unter Bildung von N-1,7-O-Di-(23, 24) und N-1,N-3,O-7-Triribosiden (32) unterliegen. Die Substanzgemische werden chromatographisch in die einzelnen Komponenten zerlegt und ihre Konstitutionen auf spektroskopischem und chemischem Wege ermittelt. Die Schutzgruppenabspaltung im 2,4-Bis(benzyloxy)-7-oxo-8-(2,3,5-tri-O-benzoyl-β-D-ribofuranosyl)-7,8-dihydropteridin (29) und seinem 6-Methyl-Derivat (30) erfolgte auf katalytischem Wege mit Pd/C und anschließender Ammoniak-Behandlung zu 25 und 27 bzw. 26 und 28. Es wird ferner über Syntheseversuche von 26, ausgehend vom 6-Amino-2,4-dimethoxy-5-nitropyrimidin (3), berichtet, die jedoch lediglich zu 8-D-Ribityl-(12) bzw. 8-β-D-Ribofuranosyl-2,4-dimethoxy-7-oxo-7,8-dihydropteridin (14) führten.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19801130433
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  • 6
    Electronic Resource
    Electronic Resource
    Nucleoside, XXIV. Verbesserte Synthesen von Lumazinnucleosiden (1977)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1977 (1977), S. 1217-1234 
    Details
    ISSN: 0075-4617
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Nucleosides, XXIV. - Improved Syntheses of Lumazine NucleosidesVarious 6- and 7-substituted lumazines 1 - 8 are converted in the form of their trimethylsiloxy derivatives 9 - 16 by three different ribosylation methods into the corresponding nucleosides. It was found that reactions of the halogenoses 17 and 18, respectively, without catalysts lead predominantly to N1-α,β-anomeric mixtures 20, 23, 26 - 45, and show a strong solvent dependence regarding the formation of the α- and β-anomers. The anomers can be separated by chromatographic methods. - Advantages in the ribosylation reactions over the mercury salt catalysed procedures with 17 could be incurred by using 1-O-acetyl-2,3,5-tri-O-benzoyl-β-D-ribofuranose (19) and BF3 as catalyst. The reactions proceed very fast under mild conditions and work-up is thereby simplified. - The newly synthesized compounds are characterized by their pKa-values as well as UV- and NMR-spectra.
    Notes: In vergleichenden Untersuchungen wurden die 6- und 7-substituierten Lumazine 1 - 8 als Trimethylsiloxy-Derivate 9 - 16 nach verschiedenartigen Methoden ribosidiert. Umsetzungen mit den Halogenosen 17 und 18 führen ohne Katalysator überwiegend zu den N1-α,β-Anomerengemischen 20, 23, 26-45, wobei die Produktverteilung stark lösungsmittelabhängig ist. Die Anomeren wurden chromatographisch getrennt. - Die Vorteile der BF3-katalysierten Ribosidierungen mit 1-O-Acetyl-2,3,5-tri-O-benzoyl-β-D-ribofuranose (19) gegenüber den Quecksilbersalz-katalysierten Reaktionen mit 17 liegen besonders in der einfacheren Durch-führung und Aufarbeitung. - Die neu synthetisierten Verbindungen wurden durch ihre pKa-Werte, UV- und 1H-NMR-Spektren charakterisiert.
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.197719770717
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  • 7
    Electronic Resource
    Electronic Resource
    Synthese von Lumazin- und Isopterin-N-1-β-D-ribofuranosiden und -(2-desoxyribofuranosiden) _ Strukturanaloga des Uridins, Cytidins und ThymidinsDiese Arbeit wurde von der Deutschen Forschungsgemeinschaft unterstützt (1971)
    Weinheim : Wiley-Blackwell
    Zeitschrift für die chemische Industrie 83 (1971), S. 975-977 
    Details
    ISSN: 0044-8249
    Keywords: Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ange.19710832312
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  • 8
    Electronic Resource
    Electronic Resource
    Synthesis of Lumazine and Isopterin N-1-β-D-Ribofuranosides and -(2-Deoxyribofuranosides) - Structural Analogs of Uridine, Cytidine, and ThymidineThis work was supported by the Deutsche Forschungsgemeinschaft. (1971)
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 10 (1971), S. 932-934 
    Details
    ISSN: 0570-0833
    Keywords: Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/anie.197109321
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