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  • 1
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1978 (1978), S. 214-226 
    ISSN: 0075-4617
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Mechanism of Pyrolytic Formation of 10-Aryl-9-arsaanthracenesA cross-over experiment with 5b and 5c has proved the novel, synthetically useful pyrolytic formation of 10-aryl-9-arsaanthracenes 8 from 9-aryl-10-benzyl-9,10-dihydro-9-arsaanthracenes 5 to proceed by a radical mechanism involving intramolecular 1,4-migration of the aryl group (Scheme 2, pathway A). Radicals 6 and 9 are intermediates. When generated at lower temperature in solution, radicals of type 6 dimerize to yield tetraarylethanes (Scheme 6).
    Notes: Durch einen Kreuzungsversuch mit 5b und 5c wird bewiesen, daß die neuartige, synthetisch brauchbare pyrolytische Bildung von 10-Aryl-9-arsaanthracenen 8 aus 9-Aryl-10-benzyl-9, 10-dihydro-9-arsaanthracenen 5 radikalisch unter intramolekularer 1,4-Wanderung der Arylgruppe verläuft (Schema 2, Weg A). Zwischenstufen sind die Radikale 6 und 9. Wenn Radikale vom Typ 6 bei niedriger Temperatur in Lösung erzeugt werden, dimerisieren sie zu Tetraarylethanen (Schema 6).
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 763 (1972), S. 155-161 
    ISSN: 0075-4617
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: ArsatriptyceneStarting with triphenylmethane-2-arsonic acid (2) arsatriptycene oxide (4), and further by reduction arsatriptycene (1g) are prepared. The quaternisation reactions and the UV-spectra of 1g and of some analogues and derivatives have been studied and are discussed with respect to the reactivity and bonding.
    Notes: Ausgehend von der Triphenylmethan-2-arsonsäure (2) werden Arsatriptycenoxid (4) und daraus durch Reduktion Arsatriptycen (1g) dargestellt. Anhand der Quaternisierungsreaktion und der UV-Spektren von 1g sowie einiger Analoga und Derivate werden Reaktivität und Bindungsverhältnisse besprochen.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 3 (1990), S. 295-300 
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The molecular structure of [4]paracyclophane was optimized at the semiempirical MNDO and the ab initio STO-3G level. A comparison of the results showed that the benzene ring is much less bent at the STO-3G level. Although some bond alternation is predicted at both levels of theory, the aromatic carbon-carbon bond lengths are still in the range typical of highly delocalized compounds. The calculated strain energy [SE(tot.)] of [4]paracyclophane is larger for the STO-3G structure. Nevertheless, the distributions of SE(tot.) over the bent benzene ring [SE(bb.)] and the oligomethylene bridge [SE(br.)] are the same for the MNDO and STO-3G structures.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 0075-4617
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 7-tert.-Butyloxy-norbornadien (1) wird zu 4 epoxidiert, zu 5 und 6 methyleniert und zu isomeren Hydroxy-tert.-butyloxy-norbornenen (10-13) hydroboriert; die Addition von Phenylazid ergibt Triazoline vom Typ 23, die zu Aziridinen vom Typ 7 zerfallen. Dabei ergibt sich eine auffallende Bevorzugung der Addition an die syn-Doppelbindung, die auch in vereinzelten früheren Untersuchungen und bei syn-7-tert.-Butyloxy-norbornen zu finden ist. Die Rolle von sterischen und elektronischen Einflüssen auf die Stereochemie von Reaktionen im Bicyclo[2.2.1]heptan-System wird diskutiert.  -  Demnach erscheint die exo-Regel nur für solche Fälle gültig, in denen Substituenten ausschließlich sterisch wirksam sind. Bei anderen Substituenten müssen zur Beurteilung des sterischen Verlaufs sämtliche Wechselwirkungen innerhalb des reagierenden Systems berücksichtigt werden.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 0075-4617
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Bifunctional and Cyclic Organomagnesium Compounds, II. - 1-Oxa-5-magnesiacyclooctaneFrom association measurements it is concluded that the di-Grignard compound 1 formed from 3,3′-dibromodi-n-propyl ether (3) in tetrahydrofuran completely disproportionates to monomeric 1-oxa-5-magnesiacyclooctane (2) and magnesium bromide. The preference for 2 is ascribed to intramolecular coordination between magnesium and oxygen. At higher temperatures 2 decomposes to cyclopropane and trimeric 1-oxa-2-magnesiacyclopentane (6a).
    Notes: Durch Assoziationsmessungen wird festgestellt, daß die aus 3.3′-Dibrom-di-n-propyläther (3) erhältliche Di-Grignard-Verbindung 1 in Tetrahydrofuran vollständig zu monomerem 1-Oxa-5-magnesiacyclooctan (2) und Magnesiumbromid disproportioniert. Die Bevorzugung von 2 wird auf intramolekulare Koordination zwischen Magnesium und Sauerstoff zurückgeführt. Bei höherer Temperatur zersetzt sich 2 zu Cyclopropan und trimerem 1-Oxa-2-magnesiacyclopentan (6a).
    Type of Medium: Electronic Resource
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