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  • 1
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    ISSN: 0570-0833
    Keywords: Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Limitation Availability
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  • 2
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    ISSN: 0044-8249
    Keywords: Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Limitation Availability
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  • 3
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    ISSN: 0044-8249
    Keywords: Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Limitation Availability
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  • 4
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    ISSN: 0570-0833
    Keywords: Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Limitation Availability
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  • 5
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: The Diaza-CopeRearrangementA notation is proposed which allows a simple and clear designation of [3.3]-sigmatropic shifts. Stereochemical investigations show that the configuration as well as the preferred conformations of the diimines 3 strongly influence the geometry of the transition state of the thermally induced Diaza-Cope rearrangement 3⇌3′. In meso-configurated 1,3,4,6-tetraaryl-2,5-diaza-1,5-hexadienes 3c rearrangement passing a boat shaped transition state is preferred, whereas the racemic double Schiffbases pass the chair form transition state. The activation barrier for the valence isomerisation is higher, if the six center transition state is involved. The ortho-hydroxy group as a factor determining the equilibrium of the valence isomerisation of the meso-dialdimines 33 is discussed. This “salicyl effect” is utilized as a very general synthetic principle: new meso-1, 2-diarylethylenediamines may easily be synthesized via stereospecific Diaza-Cope rearrangement by C—C-coupling of two carbonyl functions.
    Notes: Mit einer einfachen Notation wird zunächst versucht, die unübersichtliche Namensgebung für [3.3]-sigmatrope Reaktionen eindeutig und verständlich zu regeln. Die stereochemischen Untersuchungen zeigen, daß sowohl die Konfiguration als auch die Konformation der Diimin-Edukte(3) die Geometrie des Übergangszustandes bei der thermischen Diaza-Cope-Umlagerung 3⇌3′ entscheidend beeinflussen. Meso-Konfigurierte 1,3,4,6-Tetraaryl-2,5-diaza-1,5-hexadiene 3c lagern bevorzugt über einen wannenartigen racemische über einen sesselartigen Übergangszustand um. Die Aktivierungsbarriere für eine Valenzisomerisierung über einen wannenförmigen Übergangszustand ist auch bei der Diaza-Cope- Umlagerung höher als die über einen sesselförmigen. Die ortho- Hydroxygruppe als gleichgewichtsbestimmender Faktor bei der Valenzisomerisierung der meso-Dialdimine (33) wird diskutiert. Dieser “Salicyl-Effekt” bietet die Grundlage für ein allgemeines Syntheseprinzip zur einfachen präparativen und vor allem stereospezifischen Darstellung neuer meso-1,2-Diaryläthylendiamine durch C—C-Verknüpfung zweier Carbonylfunktionen via Diaza Cope-Umlagerung.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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