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  • 1
    Electronic Resource
    Electronic Resource
    The 2,4-Bis(diphenylmethylene)-1,3-cyclobutane-dione Diradical Dianion and its Sulphur Analogues2) (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1397-1402 
    Details
    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
    URL: http://dx.doi.org/10.1002/cber.19911240613
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    ESR-Untersuchungen an Carbonsäureestern, 10. Bildung persistenter Benzylradikale durch Protonierung der Radikalanionen sterisch gehinderter Dithiobenzoesäureester (1989)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 122 (1989), S. 187-191 
    Details
    ISSN: 0009-2940
    Keywords: Benzyl radicals ; Dithiocarboxylates, sterically hindered ; Radical anions ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Formation of Persistent Benzyl Radicals by Protonation of the Radical Anions of Sterically Hindered Dithiobenzoic EstersESR signals due to a second species are observed besides the spectra of the corresponding radical anions when the methyl ortho-(tert-butyl)dithiobenzoates 1, 4, and 6 are electroreduced in situ in dimethylformamide. It is shown by investigation of model compounds as well as semiempirical MNDO/CI-MO calculations, that these arise from α-alkylthio-α-mercaptobenzyl radicals 3, 14, and 15 which are formed by protonation of the radical anions at the thiocarbonyl sulfur atom.
    Notes: Nach in-situ-Elektroreduktion der ortho-(tert-Butyl)dithiobenzoesäure-methylester 1, 4 und 6 in Dimethylformamid beobachteten wir neben den ESR-Spektren der entsprechenden Radikalanionen die Signale einer zweiten Spezies. Durch Untersuchung von Modellverbindungen sowie semiempirische MO-Rechnungen nach dem MNDO/CI-Verfahren wird gezeigt, daß es sich dabei um die α-Alkylthio-α-mercaptobenzyl-Radikale 3, 14 und 15 handelt, die durch Protonierung der Radikalanionen am Thiocarbonylschwefel entstehen.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19891220129
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  • 3
    Electronic Resource
    Electronic Resource
    ESR-Untersuchungen an Carbonsäureestern, 12. Bildung von 9-Fluorenon-Radikalanionen durch Elektrolyse von sterisch gehinderten Biphenyl-2-dithiocarbonsäure-methylestern (1989)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 122 (1989), S. 1009-1012 
    Details
    ISSN: 0009-2940
    Keywords: ESR, biphenyl-2-carbodithioates ; 9-Fluorenones, sterical hindrance ; Radical anions ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Formation of 9-Fluorenone Radical Anions during Electroreduction of Sterically Hindered Methyl Biphenyl-2-dithiocarboxylatesESR signals due to the radical anions of the 9-fluorenones 4 and 5 are observed besides the spectra of the radical anions of the tert-butylated methyl biphenyl-2-dithiocarboxylates 1 and 2 if the latter are electroreduced in dimethylformamide or acetonitrile. A mechanism for the observed reaction is suggested.
    Notes: Nach Elektroreduktion der tert-butylierten Biphenyl-2-dithiocarbonsäure-methylester 1 und 2 in Dimethylformamid oder Acetonitril beobachteten wir neben den ESR-Spektren der entsprechenden Radikalanionen die Signale von Radikalanionen der 9-Fluorenone 4 und 5. Ein Mechanismus für die Bildung der 9-Fluorenon-Ketyle wird vorgeschlagen.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19891220534
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  • 4
    Electronic Resource
    Electronic Resource
    C,C-Verknüpfungen mit Schwefel-stabilisierten Carbanionen, 2[1] Reaktionen des 2-(Methylthio)thiolan-Carbanions mit Elektrophilen[2] (1992)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 125 (1992), S. 1641-1646 
    Details
    ISSN: 0009-2940
    Keywords: Thioacetals, semicyclic ; Carbanions ; Alkylation ; Hydroxyalkylation ; Diastereoselectivity ; Thiolanes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: C,C Coupling with Sulfur-Stabilized Carbanions, 2[1]. - Reactions of the 2-(Methylthio)thiolane Carbanion with Electrophiles[2]The „semicyclic” thioacetal 2-(methylthio)thiolane (4) is easily prepared from thiolane (tetrahydrothiophene). It is readily deprotonated by butyllithium to give the lithium derivative 5, which reacts with alkyl halides, saturated and α,β-unsaturated carbonyl compounds, and benzonitrile to form the alkyl derivatives 6, carbinols 7, allyl alcohols 8, and - after hydrolysis - the ketone 9. The diastereoselectivity of the C,C coupling reaction is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19921250720
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  • 5
    Electronic Resource
    Electronic Resource
    Formation of δ-Sultines (1,2-Oxathiane 2-Oxides) from Thiolane 1-Oxides (1999)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1999 (1999), S. 943-947 
    Details
    ISSN: 1434-193X
    Keywords: Thiolane 1-oxides ; Oxidations ; δ-Sultines ; [Bis(trifluoroacetoxy)iodo]benzene ; Asymmetric synthesis ; Carbanions ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: -2-(Alkylthio)-2-benzylthiolane 1-oxides (1a, b) and 2-(alkylthio)-2-(α-hydroxybenzyl)thiolane 1-oxides (1c, d) are oxidized with [bis(trifluoroacetoxy)iodo]benzene (PIFA). Under ring enlargement the corresponding cyclic sulfinate esters (δ-sultines) 2 are formed. Only (1R*,2S*)-1b is reactive whereas (1R*,2R*)-1b is not attacked. This observation is explained with the formation of a cyclic intermediate 3.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Reaction of the Carbanions of 2-(Alkylthio)thiolane 1-Oxides with Oxiranes (1999)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1999 (1999), S. 1481-1488 
    Details
    ISSN: 1434-193X
    Keywords: Thiolane 1-oxides ; Carbanions ; Oxiranes ; Asymmetric synthesis ; X-ray structure ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: -Carbanions of the 2-(alkylthio)thiolane 1-oxides 1 and 2 are generated and subjected to reaction with the epoxides 3-5. The resulting carbinols 6-11 are formed with high α diastereoselectivity, which is explained by a stabilization of the trans configuration of the carbanions in the activated complex. A minor γ stereoselectivity is also observed in case of the reactions with 4 and 5. The pure enantiomers (1S,2S,2′S)-9a and (1R,2R,2′S)-11b were obtained from 2 and (S)-4 or (R)-5, respectively, and their configurations were proved by X-ray structural analyses.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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