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  • 1
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1397-1402 
    ISSN: 0009-2940
    Keywords: Cyclobutane-1,3-diones ; Cyclobutane-1,3-dithiones ; Radical anions ; Diradical dianions ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 2,4-Bis(diphenylmethylene)-1,3-cyclobutanedione (1) is transformed into its sulphur analogues 2 and 3 with Lawesson's or Davy's reagent 5a,b. An X-ray structural analysis is performed on 3. The electrochemistry of these compounds is surveyed. The products of the electrochemical reduction exhibit ESR spectra, which could not be attributed to the radical anions 1-•, 2-•, and 3-•. Extensive semiempirical AM1/Cl calculations suggest the spectra to correspond to the diradical dianions. The experimental data are discussed in terms of the theoretical results.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 0947-3440
    Keywords: Domino reaction ; Functionalized cyclopentanes, -hexanes and -heptanes ; Tetrahydrofurans ; Oxetanes ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 1,3-Functionalized cyclopentanes, -hexanes and -heptanes are obtained by addition of lithiated silyldithioacetals 7 to epoxyhomoallyl tosylates 4-6, The reaction involves a cascade of epoxide ring opening, of Brook 1,4-rearrangement and tosylate substitution. The method is particularly suitable for the preparation of cyclopentanes, whereas cyclohexanes and -heptanes are formed in yields only up to 49%. Use of enantiomerically pure epoxides provides optically active cyclopentanes (S)-10b, d, 11a as well as oxetanes (S)-14a, b. Hydrolysis of the dithioacetal function leads to the corresponding ketones 12, Cyclization of epoxide 24b gives an anellated cyclopentane 26, the configuration of which was established by X-ray structural analysis of dinitrobenzoate 27. Use of epoxide 29b provides the anellated tetrahydrofuran 30.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
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