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  • 1
    Electronic Resource
    Electronic Resource
    Spectroscopic properties of free phenolic 4-arylflavan-3-ols as models for natural condensed tannins (1993)
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 31 (1993), S. 1057-1063 
    Details
    ISSN: 0749-1581
    Keywords: 4-Arylflavan-3-ols ; 1H NMR ; 13C NMR ; Circular dichroism ; Condensed tannins ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A unique range of free phenolic 4-arylflavan-3-ols consisting of four sets (3′,4′,5,7-tetrahydroxyflavan-3-ol or its 5-deoxy analogue coupled to phloroglucinol or resorcinol), each composed of three diastereomers (2,3-trans-3,4-trans, 2,3-trans-3,4-cis and 2,3-cis-3,4-trans) were synthesized to assess their spectroscopic properties. 1H and 13C NMR and circular dichroism data are related to selected structural and stereochemical features with a view to modelling natural phenolic oligoflavanoids.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrc.1260311206
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  • 2
    Electronic Resource
    Electronic Resource
    Conformational analysis of oligomeric flavanoids. 2For Part 1, see Ref. 8. - methyl ether acetate derivatives of profisetinidins (1995)
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 33 (1995), S. 611-620 
    Details
    ISSN: 0749-1581
    Keywords: NMR ; 1H NMR ; condensed tannins ; profisetinidins ; stereochemistry ; conformation ; rotational isomers ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The profisetinidins are the most important polyflavanoids of commerce, making up the major constituents of wattle and quebracho tannins. Even within the dimeric profisetinidins, substantial complexity exists because of stereo-, regio-, rotational and conformational isomers. Definition of the stereochemistry of the upper and lower flavan units, the location of the interflavanoid bond, the conformation of the heterocyclic rings in the upper and lower flavan units and the conformations of major and minor rotational isomers in a series of methyl ether acetate derivatives of dimeric profisetinidin diastereomers is possible by application of COSY and NOE experiments. All compounds studied were present in two rotameric forms with the more compact conformation favored. The heterocyclic ring in the upper chain extender unit was predominantly in an E-conformation (i.e. half-chair in 2R,3S isomers and a ‘reverse’ half-chair in the 2S,3R isomers). The heterocyclic ring conformation of the terminal cate-chin unit, although mostly in an E-conformation, was often represented by significant proportions of A-conformers.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrc.1260330802
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