Two new promelacacinidin dimers,including a novel flavanone-flavanol dimer characterized by a unique C(3)-C(4) linkage,from the heartwood of <Emphasis Type="Italic">Acacia nigrescens</Emphasis> |
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Authors: | H Howell E Malan D J Brand B I Kamara B C B Bezuidenhoudt C Marais J A Steenkamp |
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Institution: | (1) Department of Chemistry, University of the Free State, P.O. Box 339, Bloemfontein, 9300, South Africa |
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Abstract: | Two new promelacacinidin biflavonoids, mesquitol-(4α,5)-epimesquitol-4β-ol and a 3′,4′,7,8-tetrahydroxyflavanone(3,4)-ent-epimesquitol, were isolated among others from the heartwood of Acacia nigrescens. The flavanone derived dimer, characterized by a unique C(3) to C(4) bridge, which links the monomers via two stereogenic
and sp3 hybridized C-atoms, is the prototype of a new subgroup of the flavonoid family. Assessment of the absolute configuration
of all five stereogenic centers of this novel flavanone-derived biflavonoid was achieved by correlating the chiroptical properties
of the benzoyl chromophore to the absolute configuration of C(2) of the flavanone moiety and hence the absolute stereochemistry
of the other four chiral centers.
Published in Khimiya Prirodnykh Soedinenii, No. 5, pp. 437–441, September–October, 2007.
Dedicated to Prof. E. Malan, who initiated and supervised this research project, for a noteworthy contribution in the flavonoid
field, and who has since retired. |
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Keywords: | Acacia nigrescens dimeric flavonoids promelacacinidin flavanone-flavan-3-ol CD-spectral properties |
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