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  • 1
    Electronic Resource
    Electronic Resource
    Substituent effects on carbon-13 chemical shifts and the stereochemistry of ent-beyeranic and ent-beyer-15-enic compounds substituted on the bicyclo[3.2.1]octane moiety (1986)
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 24 (1986), S. 853-861 
    Details
    ISSN: 0749-1581
    Keywords: 13C NMR ; Diterpenes ; ent-Beyeranes ; ent-Beyer-15-enes ; Bicyclo[3.2.1]octanes ; Substituent effects ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A detailed analysis of the 13C NMR spectra of 39 isomeric ent-beyer-15-enes and ent-beyeranes functionalized at C-7, C-14, C-15 and C-16 has been performed. This diterpenic skeleton is a good example of a semirigid bicyclo[3.2.1]octane system. The sensitivity of 13C shielding to the stereochemical environment, particularly in polyfunctional compounds, has been confirmed. In some cases the ent-beyer-15-enes and ent-beyeranes show similar behaviour to that of similarly functionalized bicyclo[3.2.1]octane derivatives, but in other cases the shielding effects are very different. The compounds studied are a good model for the evaluation of shielding effects in exo/endo isomers of strained and rigid carbocyclic compounds.
    Additional Material: 12 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrc.1260241003
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  • 2
    Electronic Resource
    Electronic Resource
    13C NMR study of quipazines (1990)
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 28 (1990), S. 299-304 
    Details
    ISSN: 0749-1581
    Keywords: 13C NMR ; Quipazines Substituted quinolines ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The complete assignment of the 13C NMR spectra of a series of biologically active quipazines substituted at position C-5, C-6 or C-7 of the quinoline moiety provides evidence for a strong conjugation between the π-electron cloud of the pyridine ring and the nitrogen lone pair of the piperazinyl residue. The SCS values of these quipazines are compared with those of the analogous quinolines, and their deviations are discussed in terms of conjugation effects.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrc.1260280404
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  • 3
    Electronic Resource
    Electronic Resource
    Dependence of 13C NMR methoxy substituent chemical shift values on π-bond orders of fused aromatic compounds (1990)
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 28 (1990), S. 311-314 
    Details
    ISSN: 0749-1581
    Keywords: 13C NMR ; Substituent chemical shift values ; π bond orders ; Methoxy-substituted aromatic compounds ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The substituent chemical shift values induced by the methoxy group at the two ortho positions of aromatic compounds which include naphthalenes, quinolines, indoles, coumarins, flavones and benzofurans were linearly correlated with π-bond orders, affording the equation Δδortho(13C) = -98.68Pπ + 50.38 (correlation coefficient = 0.929; root mean square error = 1.95 ppm) when 40 pairs of values are considered. Elimination of six points corresponding to ring-junction quaternary carbons improves the correlation coefficient to 0.961 (root mean square error = 1.4 ppm) for the equation Δδortho(13C) = -126.85Pπ + 69.66.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrc.1260280406
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  • 4
    Electronic Resource
    Electronic Resource
    35Cl/37Cl one-bond isotope effects on 13C chemical shifts in a series of para-substituted chlorobenzenes (1995)
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 33 (1995), S. 149-151 
    Details
    ISSN: 0749-1581
    Keywords: NMR ; 13C NMR ; Chlorine isotope effect ; 13C chemical shifts ; para-Substituted chlorobenzenes ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: One-bond isotope shifts of 35Cl/37Cl natural abundance chlorine isotopomers were measured in the 75.4 MHz 13C NMR spectra of a series of para-substituted chlorobenzenes. The high-field isotope shift effect 1Δ13C(37Cl) was established from the relationship between the chlorine isotopomeric ratio and the carbon peak intensities. It was found that the 1Δ13C(37Cl) values are in the range of -4.0 to -5.2 ppb. The isotope shifts tend to decrease as the electron-attracting character of the substituent increases, providing a linear correlation between the isotope shift and the chemical shift of the chlorine-bearing carbon.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrc.1260330212
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