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  • 1
    Electronic Resource
    Electronic Resource
    Synthesis and X-Ray Diffraction Analysis of Bis(phenylsulphonyl)semibullvalenes. Lifting of the Degeneracy of Semibullvalenes in the Crystal Lattice[1] (1992)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 125 (1992), S. 955-968 
    Details
    ISSN: 0009-2940
    Keywords: Semibullvalenes ; [n.3.3] Propellanes, derivatives of ; Vinyl sulphides and sulphones ; Bromination, allylic ; Debromination ; Zinc-copper couple ; Cope rearrangement in the solid state ; Valence tautomers, non-equivalent ; Equilibrium constants from atomic distances ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The bicyclo[3.3.0]octanediones 4 and 9a, b and the [n.3.3]-propellanediones 9c, d, f, h react with thiophenol in the presence of titanium(IV) chloride and triethylamine to afford high yields of the vinyl sulphides 5 and mixtures of the vinyl sulphides 10/11. Sodium perborate oxidizes the vinyl sulphides 5 and 10/11 to the corresponding vinyl sulphones 6 and 12/13. N-Bromosuccinimide converts 6 into the dibromodisulfones 7. The exo,exo configuration of 7b is established by X-ray crystallography. The mixtures of disulphones 12/13 are brominated by N-bromosuccinimide to yield complex mixtures of uncharacterized dibromodisulphones 14. Debromination of the dibromodisulphones 7, and the mixtures of 14 as well, by the zinc-copper couple results in the formation of crystalline semibullvalenes 8 and 15 in moderate to high yields. - X-ray diffraction analyses of 8a, b and 15a-d reveal large variations of the apparent atomic distances in the cyclopropane rings (C2-C8) and at the open ends of the molecules (C4…C6). This result is interpreted in terms of equilibrating, non-degenerate valence tautomers resulting in averaged atomic distances. The equilibrium constants are calculated from the atomic distances on the basis of a limiting value of 157.8 pm for the C2-C8 bonds of the non-rearranging valence tautomers. The results are compared to those obtained from X-ray diffraction analyses of other substituted semibullvalenes. The lifting of the degeneracy of semibullvalenes in the solid state is attributed to subtle intermolecular interactions.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19921250430
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  • 2
    Electronic Resource
    Electronic Resource
    Cycloadditionen von 6H-1,3,4-Oxadiazin-6-onen (4,5-Diaza-α-pyronen), 13[1]. Diels-Alder-Reaktionen mit 6H-1,3,4-Oxadiazin-6-onen als Dienophil (1993)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 126 (1993), S. 1743-1748 
    Details
    ISSN: 0009-2940
    Keywords: 6H-1,3,4-Oxadiazin-6-ones ; 1,2-Bismethylenecyclohexane ; Diels-Alder reactions ; [1,3,4]Oxadiazino[4,5-b]isoquinolin-1-one derivatives ; Bicyclo[2.1.1]hexan-5-one, highly substituted ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Cycloadditions of 6H-1,3,4-Oxadiazin-6-ones (4,5-Diaza-α-pyrones), 13[1].-Diels-Alder Reactions with 6H-1,3,4-Oxadiazin-6-ones as Dienophile2,5-Diphenyl-1,3,4-oxadiazin-6-one (1b) reacted as dienophile with 2,3-dimethyl-1,3-butadiene to afford the pyridooxadiazinone 5. Analogously, the oxadiazinoisoquinolines 7c- e were formed on treatment of 2-(4-nitrophenyl)- (1c), 2-(4-tolyl)- (1d), and 2-(4-bromophenyl)-5-phenyloxadiazinone (1e) with 1,2-bis(methylene)cyclohexane (6). In contrast, the methyl oxophenyloxadiazinecarboxylate 1a gave a low yield of the cyclopentenone derivative 8 and 7a in the ratio 2.3:1.0. A third type of product, i.e. the cyclobutanone derivative 9, resulted on exposure of the anisyl(isopropyl)oxadiazinone 1f to 6. The oxadiazinones 1d, e, f have been prepared for the first time. X-ray structure analyses established the identity of the compounds 7d and 9.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19931260734
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  • 3
    Electronic Resource
    Electronic Resource
    2,6-Dicyansemibullvalen (1992)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 125 (1992), S. 969-973 
    Details
    ISSN: 0009-2940
    Keywords: Semibullvalenedicarbonitrile ; Bicyclo[3.3.0]octanes, derivatives of ; Cyanohydrins, O-trimethylsilyl ; Hydrogen fluoride-phosphorus oxychloride-pyridine, elimination by ; Bromination, N-bromosuccinimide ; Zinc-copper couple ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 2,6-Dicyanosemibullvalene[1]Bicyclo[3.3.0]octane-2,6-dione (2) adds trimethylsilyl cyanide under catalysis by zinc iodide to afford a mixture of the diastereomeric O-trimethylsilyl cyanohydrins exo,endo- and exo,exo-3 (3:7). Treatment of this mixture with the hydrogen fluoride-pyridine complex in phosphorus oxychloride as solvent and subsequent heating with an excess of pyridine yield 70% of a 1:1 mixture of the unsaturated dinitriles 4 and 5, which is separated by medium-pressure liquid chromatography. Allylic bromination of 4 by N-bromosuccinimide results in the formation of the Y,Y'-dibromodinitrile 6, the configuration of which is elucidated by means of an X-ray diffraction analysis. Reduction of 6 with the zinc-copper couple in tetrahydrofuran under ultrasonic irradiation leads to dilute solutions of the title compound 1 a. Attempts at the isolation of 1 a were frustrated by its tendency to polymerize. The structure of 1 a is based on IR, UV, 1H- and 13C-NMR spectra and a comparison with the known 1,5-dimethylsemibullvalenedicarbonitrile (1 b).
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19921250431
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    Paper (German National Licenses)
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