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  • Inorganic Chemistry  (2)
  • Analytical Chemistry and Spectroscopy  (1)
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  • 1
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 105 (1972), S. 262-272 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Mass Spectrometry of Adenosine AnaloguesThe mass spectra of 23 trifluoroacetylated analogues of adenosine differing in the sugar moiety are investigated. The α- and β-anomers show characteristic intensity differences in the molecular ion and in the fragment ions m/e 310 and 424 (in pentose derivatives) as well as in m/e 550 and 680 (in hexose derivatives). The intensity differences can be explained by steric effects. The orientation of the hydroxyl groups does not influence the fragmentation process to such a degree that it is possible to draw systematic conclusions. For the identification of conformational isomers it is necessary to measure reference spectra. The ring size of the sugar is indicated by unique but low intensity fragments at m/e 524 and 410 (in furanosides of pentose derivatives), m/e 524 and 295 (in furanosides of hexose derivatives) as well as at m/e 508 and 433 (in pyranosides of hexose derivatives). Substitution at C-1' in hexose derivatives is indicated by ions at m/e 496 and 386.
    Notes: Die Massenspektren von 23 trifluoracetylierten Adenosin-Analoga (1-23), die sich in ihrem Zuckeranteil unterscheiden, weisen bei α- und β-Anomeren charakteristische Intensitätsunterschiede beim Molekül-Ion sowie bei den Fragment-Ionen m/e 310 und 424 (bei Pentose-Derivaten) bzw. m/e 550 und 680 (bei Hexose-Derivaten) auf. Die Intensitätsunterschiede lassen sich durch sterische Effekte erklären. Die Orientierung der Hydroxylgruppen beeinflußt die Fragmentierung nicht in dem Maße, daß eine systematische Zuordnung möglich ist. Für die Identifizierung der Konformationsisomeren ist die Aufnahme von Vergleichsspektren nötig. Die Ringgröße der Zucker ist durch das Auftreten von einzigartigen, allerdings wenig intensiven Fragment-Ionen bei m/e 524 und 410 (bei Furanosiden der Pentose-Derivate), m/e 524 und 295 (bei Furanosiden der Hexose-Derivate) und m/e 508 und 433 (bei Pyranosiden der Hexose-Derivate) erkennbar. Substitution an C-1' ist bei Hexose-Derivaten durch die Ionen m/e 496 und 386 gekennzeichnet.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 105 (1972), S. 3650-3657 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Application of the 13C n.m.r. Spectroscopy to the Control of Peptide SynthesisThe advantage of the pulse Fourier transform 13C n.m.r. spectroscopy for the control of the synthesis of amino acid derivatives and peptide intermediates is shown for the eight step synthesis of tert-butyloxycarbonyl aspartic acid β-tert-butyl ester and some dipeptides. The resonances of the aspartic acid and glycine residues and the signals of some important protecting groups of peptides can be assigned by comparison of the spectra of derivatives.
    Notes: Anhand einer achtstufigen Synthese von N-tert.-Butyloxycarbonyl-L-asparaginsäure-β-tert.-butylester und einiger Dipeptide wird der vorteilhafte Einsatz der Impuls-Fourier-Transform-13C-NMR-Spektroskopie zur Syntheseüberwachung in der Peptidchemie gezeigt. Die Resonanzen der Asparaginsäure- und Glycinreste und die Signale einiger wichtiger Peptidschutzgruppen können durch Spektrenvergleich von Derivaten zugeordnet werden.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 11 (1984), S. 211-216 
    ISSN: 0306-042X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The identification of biotransformation products of the new antihypertensive drug urapidil in mouse, rat, dog and man has been performed by means of high-performance liquid chromatographic and mass spectrometric techniques. In urine, three metabolites were found in addition to the unchanged drug. The para-hydroxylated product (1) (6-{3-[4-(o-methoxy-p-hydroxyphenyl) piperazinyl]-propylamino}-1,3-dimethyl-uraci), the O-demethylated compound (2) (6-{3-[4-(o-hydroxyphenyl) piperazinyl]-propylamino}-1,3-dimethyluracil) and the uracil-N-dealkylated compound (3) (6-{3-[4-(o-methoxyphenyl)piperazinyl]-propylamino}-1-methyl-uracil). In urine of dog, the metabolite with the N-oxide structure (5) was also identified, but only in trace arnounts (6-{3-[4-(o-methoxyphenyl)piperazinyl-N-oxide]-propylamino}-1,3-dimethyluracil).
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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