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  • 1
    ISSN: 1434-193X
    Keywords: Amino acids ; coupling ; N-Substituted amide ; Cyclizations ; Cyclic dipeptides ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---A short synthesis of new, functionalized seven-membered ring cyclic dipeptides is described. After the coupling of N-protected β-amino acids to N-substituted α-amino tert-butyl esters, the protective groups of the terminal functions were removed and the cyclization took place diastereoselectively in the presence of the coupling agent BOP. Amide substitution was found to be effective in promoting the cyclization of linear dipeptides.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1979 (1979), S. 639-649 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Chemistry of 1,2,4-Triazepines, XIV. - Condensations of β-Dicarbonyl Compounds with 1,2-Diaminoimidazoles
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 11 (1976), S. 1002-1017 
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: The mass spectra of 49 1,2,4-triazines with oxo, thioxo, methoxy and methylmercapto groups in the 3 and 5 positions are reported and analysed. Five distinct patterns have been observed upon electron impact but an initial loss of N2 has not been identified. A tautomeric equilibrium has been shown to occur in the vapour phase from some fragmentation pathways.
    Notes: Les spectres de masse de 49 triazines-1,2,4 différemment substituées en position 6, possédant les groupes oxo, thioxo, méthylmercapto en position 3 et 5 et de leurs dérivés N-méthylés sont décrits. Cinq processus de fragementation du cycle traizine, liés á la structure et notamment á la nature du groupement fonctionnel en position 5 sont mis en évidence. L'un d'eux, engageant les ruptures des liaisons N-1—N-2 et C-5—C-6, est identifié dans tous les cas. Les pertes d'azote et de monoxyde de carbone ne sont pas observées. Pour certains composés la participation á l'équilibre, á l'état vapeur, de certaines formes tautoméres a été discutée.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 12 (1977), S. 136-144 
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: The mass spectra of 21 1,4-pyrazolo[3,4-b]diazepines are reported and analysed. Each of the five structures of the diazepine ring present is characterized by a particular group of fragmentations; among them one is common to all the compounds under study: the cleavage of C-5—C-6 and C-7—N-8 bonds leading to pyrazoloimidazoles ions.
    Notes: Les spectres de masse de 21 pyrazolo[3,4-b]diazépines-1,4 dans lesquelles le cycle diazépine peut présenter cinq structures différentes, sont décrits et analysis. Chaque structure a été caractérisée par un ensemble original de ruptures. Parmi celles-ci un mode de fragmentation commun à tous les composés étudiés a été identifié: il s'agit de la rupture des liaisons C-5—C-6 et C-7—N-8 avec formation d'ions pyrazoloimidazoles.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: The mass spectra of several pyrido [2,3-b] and [3,4-b], pyrimido [4,5-b], pyrazolo [3,4-b] diazepinones-1,4 and as-triazino [4,3-b], s-triazolo [4,3-b]triazepinones-1,2,4 are reported and analysed. Five different fragmentation pathways of the molecular ion are generally observed, but the main one is an initial loss of CH2CO which gives rise to 2-methylazabenzimidazole or 2-methyl azabenzotriazole ions. The behaviour of triazolotriazepines which have two further fragmentation pathways is described.
    Notes: Les spectres de masse des pyrido[2,3-b], pyrimido[3,4-b], pyrimido [4,5-b], pyrazolo[3,4-b]- diazépinones-1,4 et des as-triazino[4,3-b] et s-triazolo[4,3-b]triazépinones-1,2,4 sont décrits et analysés. Cinq processus de fragmentation de l'ion moléculaire sont le plus souvent identifiés, le mode principal d déradation étant l'expulsion d'une moléule de cétène avec formation des ions méthyl-2 azabenzimidazoles ou méthyl-2 azabenzotriazoles. Le comprotement particulier des triazolotriazépines, présentant deux antres types de rupture, est mis en évidence.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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