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  • NMR conformational analysis  (1)
  • Thermal sigmatropic hydrogen shifts  (1)
  • 1
    Electronic Resource
    Electronic Resource
    INDO calculations on the sigmatropic [1, 5] H-Shift in 1,3-cyclohexadiene and 1,3,5-cycloheptatriene A homo-cyclopentadienyl transition state model (1975)
    Springer
    Theoretical chemistry accounts 38 (1975), S. 241-244 
    Details
    ISSN: 1432-2234
    Keywords: Thermal sigmatropic hydrogen shifts ; Homoconjugation ; 1,3-cyclohexadiene and 1,3,5-cycloheptatriene, transition state geometry of ∼
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract INDO calculations have been performed for the activated complex of the [1, 5] H.-shift in 1,3-cyclohexadiene and 1,3,5-cycloheptatriene. During the migration in the cyclohexadiene system a homoconjugation was calculated between the carbon atoms C1 and C5. For cycloheptatriene it could be demonstrated that one double bond does not participate in the reaction. Activation enthalpies are related to (homo)conjugation in the transition state of the reaction for cyclic conjugated dienes and trienes. The electron density on the migrating hydrogen can be related to the electron affinity of the ring system in the transition state.[/p]
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01125902
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  • 2
    Electronic Resource
    Electronic Resource
    Application of the conformational transmission effect for the assignment of diastereotopic proton resonances (1987)
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 25 (1987), S. 872-878 
    Details
    ISSN: 0749-1581
    Keywords: Conformational transmission ; Diastereotopic proton assignment ; NMR conformational analysis ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A new method is presented for the assignment of the NMR resonances of the diastereotopic protons in tetrahydrofur-furyl and pyrrolidinylmethyl groups, based on the conformational transmission effect This effect describes the conformational changes produced by an increase of coordination from four to five of a phosphorus, silicon or germanium atom attached to the tetrahydrofurfuryl or pyrrolidinylmethyl moieties. The 1H NMR conformational analysis of these cyclic four- and five-coordinated compounds yields two possible results, based on two assignments of the diastereotopic proton resonances. Comparison with the conformations of the analogous four- and five-coordinated systems with acyclic 2-methoxyethyl and dimethylaminoethyl groups (which lack diastereotopic protons) directly shows which assignment is correct, since a similar conformational transmission occurs in both the cyclic and the acyclic compounds.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrc.1260251009
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    Paper (German National Licenses)
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