- METHOD FOR THE PREPARATION OF C-4 COUPLED FLAVONOIDS, PROANTHOCYANIDINS AND ANALOGUES THEREOF
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The invention relates to a novel process for the preparation of C-4 coupled flavonoids, proanthocyanidins and analogues thereof. According to a specific application of the invention, there is provided a method for the preparation of proanthocyanidins and
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Page/Page column 13-15
(2009/12/28)
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- Synthesis of proanthocyanidins. Part 1. The first oxidative formation of the interflavanyl bond in procyanidins
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(Chemical Equation Presented) A novel and efficient method for the oxidative condensation of tetra-O-methyl-3-oxocatechin 4 with tetra-O-methylcatechin is described. Treatment of a solution of 3 (2 equiv) and 4 (1 equiv) with silver tetrafluoroborate read
- Achilonu, Matthew C.,Bonnet, Susan L.,Van Der Westhuizen, Jan H.
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supporting information; experimental part
p. 3865 - 3868
(2009/07/09)
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- Oligomeric flavanoids. Part 17a. Absolute configurations of flavan-3-ols and 4-arylflavan-3-ols via the Mosher method
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1H NMR analysis of R-(+)- and S-(+)-α-methoxy-α-trifluoromethylphenyl acetic acid (MTPA) esters of flavan-3-ols and 4-arylflavan-3-ols permits assessment of the absolute configurations at C-3 of these condensed tannin structural units.
- Rossouw,Hundt,Steenkamp,Ferreira
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p. 12477 - 12488
(2007/10/02)
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- Synthesis of Condensed Tannins. Part 1. Stereoselective and Stereospecific Syntheses of Optically Pure 4-Arylflavan-3-ols, and Assessment of their Absolute Stereochemistry at C-4 by means of Circular Dichroism
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Stereoselective and also stereospecific condensation at C-4 of flavan-3,4-diols of known absolute configuration with phloroglucinol and resorcinol in acid medium proceeds at ambient temperatures with partial retention of configuration for 2,3-trans-isomers and with inversion for 2,3-cis-analogues.Circular dichroism spectra of the resultant 4-arylflavan-3-ols all exhibit multiple Cotton effects.The sign of high intensity Cotton effects to low wavelength, contributed by aryl chromophores at C-4, may almost invariably be correlated with the absolute configuration at this chiral centre of 2,3-trans-3,4-trans, 2,3-trans-3,4-cis, and 2,3-cis-3,4-trans-isomers.
- Botha, Jacobus J.,Young, Desmond A.,Ferreira, Daneel,Roux, David G.
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p. 1213 - 1219
(2007/10/02)
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