Skip to Main Content
U.S. Forest Service
Caring for the land and serving people

United States Department of Agriculture

Home > Search > Publication Information

  1. Share via EmailShare on FacebookShare on LinkedInShare on Twitter
    Dislike this pubLike this pub
    Author(s): Richard W. Hemingway; Fred L. Tohiason; G. Wayne McGraw; Jan P. Steynberg
    Date: 1996
    Source: Magnetic Resonance in Chemistry, Vol. 34, 424-433
    Publication Series: Miscellaneous Publication
    PDF: View PDF  (313 B)

    Description

    Studies offlavan-3-01sin their biologically significant phenolic form show that both H-6 and C-6 resonances are downfield from H-8 and C-8. Therefore, assignments for the H atoms of the A-ring are inverse to those commonly reported. By contrast, in the methyl ether and methyl ether acetate derivatives, both H-8 and C-8 are downfield from H-6 and C-6 and assignments commonly reported for C-6 and C-8 are incorrect. The assignments commonly reported for the peracetate derivatives are correct. In contrast to results observed fordimericflavans,solvent effects on chemical shifts and coupling constants are small in monomeric flavan derivatives. The small heterocyclic ringJ,3 coupling constants of2,3-cis-flavanscan be defined by lineshape analysis of H-3. These results provide the first evidence for the conformations of the common2,3-cis-flavansin solution. With the exception of compounds carrying a bulky acetate at C-3, a GMMX global search protocol provides reasonable predictions of heterocyclic ring coupling constants.

    Publication Notes

    • You may send email to pubrequest@fs.fed.us to request a hard copy of this publication.
    • (Please specify exactly which publication you are requesting and your mailing address.)
    • We recommend that you also print this page and attach it to the printout of the article, to retain the full citation information.
    • This article was written and prepared by U.S. Government employees on official time, and is therefore in the public domain.

    Citation

    Hemingway, Richard W.; Tohiason, Fred L.; McGraw, G. Wayne; Steynberg, Jan P. 1996. Conformation and Complexation of Tannins: NMR Spectra and Molecular Search Modeling of Flavan-3-ols. Magnetic Resonance in Chemistry, Vol. 34, 424-433

    Keywords

    NMR, H NMR, C NMR, conformational analysis, flavonoids, condensed tannins

    Related Search


    XML: View XML
Show More
Show Fewer
Jump to Top of Page