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  • 1
    Electronic Resource
    Electronic Resource
    Structure determination of a new saponin from the plant Alphitonia zizyphoides by NMR spectroscopy (1993)
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 31 (1993), S. 472-480 
    Details
    ISSN: 0749-1581
    Keywords: Alphitonia zizyphoides ; Saponin ; 2D NMR ; INADEQUATE ; Molecular structure ; Computerized spectral analysis ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: High-field NMR experiments, including the 2D INADEQUATE technique coupled with a computerized spectral analysis, were used to determine the full structure of a new saponin extracted from a plant (Alphitonia zizyphoides) found in the Samoan rain forests. The saponin, which shows significant pharmacological activity, consists of an aglycone framework of six rings (three saturated six-membered rings, two oxygen-containing five-membered rings and a five-membered carbon ring) to which are attached four sugar units and a six-carbon side-chain. The INADEQUATE experiment, which was carried out on 60 mg of sample, provided absolute confirmation of the assignments for 35 of the possible 53 C—C bonds from the 13C-13C connectivities.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrc.1260310511
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Computerized analysis of 2D INADEQUATE spectra to assign chemical shifts in aromatic compounds (1995)
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 33 (1995), S. 803-811 
    Details
    ISSN: 0749-1581
    Keywords: NMR ; 13C NMR ; 2D INADEQUATE ; polycyclic benzenoid aromatics ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A computerized analysis of a single 2D INADEQUATE spectra assigns all of the 13C chemical shifts in fairly complex aromatic systems. Without the aid of the computer this information is often difficult, if not impossible, to retrieve owing to overlap of the signals in the double quantum dimension. In addition, the use of the computerized analysis allows for the interpretation of INADEQUATE spectra with much lower signal-to-noise ratios than are practical if the analysis were to be done visually. Finally, narrowing the spectral window to a subset of the entire spectrum and the companion advantages are demonstrated. The assignments of the aromatic chemical shifts in 2-methoxydibenzofuran, 6-methylchrysene, 1-decylpyrene, and 7-methylbenzo[a]pyrene illustrate the power of automated pattern recognition methods while supplying previously unavailable chemical shift assignments on these complex fused polycyclic aromatic systems.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrc.1260331007
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Solid-state 13C NMR study of drugs: Aspirin (1986)
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 24 (1986), S. 768-771 
    Details
    ISSN: 0749-1581
    Keywords: Solid-state ; 13C NMR ; Aspirin ; Drugs ; Polymorphism ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Natural abundance 13C NMR spectra of different crystal habits of pure aspirin and several aspirin tablets in the solid state have been measured by using the combined techniques of high-power decoupling, cross-polarization and magic angle spinning. Solid-state NMR of aspirin had excellent sensitivity compared with liquid-state NMR, and the carbon signals were assigned using a modified pulse sequence to detect non-protonated carbons. The solid-state 13C NMR spectra of two crystalline forms of aspirin were identical, suggesting that the origin of their difference is not polymorphic.The solid-state 13C NMR spectra of several commercial aspirin tablets, some of them containing buffer components, indicated that there were no interactions among the aspirin and the buffer components; only after dissolving the tablets and lyophilization did the 13C NMR spectra of the dry lyophilized powders show strong interactions between aspirin and the buffer components.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrc.1260240907
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    Paper (German National Licenses)
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