81703-24-4Relevant academic research and scientific papers
Synthesis of Condensed Tannins. Part 14. Biflavanoid Profisetinidins as Synthons. The Acid-Induced 'Phlobaphene'Reaction
Young, Desmond A.,Cronje, Annemarie,Botes, Adrienne L.,Ferreira, Daneel,Roux, David G.
, p. 2521 - 2528 (2007/10/02)
Free phenolic - and -2,3-trans-(-)-fisetinidol-(+)-catechin diastereoisomers of both 3,4-trans and 3,4-cis configuration, which serve as synthons for higher oligomers, are available in improved yields from direct condensation, and also via novel 6-iodo-(+)-catechin as an intermediate substrate.Acid-induced transformations of the predominant -all-trans isomer, illustrative of the well-known 'phlobaphene reaction' of condensed tannins, is shown to include ring-isomerization and fission of the inter-flavanoid bond, followed in the latter instance by the alternatives of anthocyanidin formation, positional rearrangement and self-condensation.
Synthesis of Condensed Tannins. Part 5. The First Angular -Triflavanoids and Their Natural Counterparts
Botha, Jacobus J.,Vivers, Phillip M.,Young, Desmond A.,Preez, I. Cornelius du,Ferreira, Daneel,et al.
, p. 527 - 533 (2007/10/02)
Angular triflavanoids comprising a group of four diastereoisomeric -bi--(+)-catechins with definable absolute configurations (2R,3S,4S-and 2R,3S,4R-2R,3S-2R,3S,4S; 2R,3S,4S- and 2R,3S,4R-2R,3S-2R,3S,4R) result from flavanyl-4-carbocation mediated condensation of (2R,3S,4R)-flavan-3,3',4,4',7-pentaol at C-6 of the (+)-catechin units of all-trans-(2R,3S,4S-2R,3S)--(-)-fisetinidol-(+)-catechin and its 3,4-cis-(2R,3S,4R-2R,3S) diastereomer respectively.The natural coexistence of some of the forementioned species of bi- and tri-flavanoids and their precursors indicate a comparable sequence of 4,8 preceding 4,6 condensation with (+)-catechin as common nucleophile.
Synthesis of Condensed Tannins. Part 6. The Sequence of Units, Coupling Positions and Absolute Configuration of the First Linear -Triflavanoid with Terminal 3,4 Diol Function
Viviers, Phillip M.,Young, Desmond A.,Botha, Jacobus J.,Ferreira, Daneel,Roux, David G.,Hull, William E.
, p. 535 - 540 (2007/10/02)
The first linear triflavanoid with a terminal 3,4-diol function, (2R,3S,4S:2'R,3'S,4'R:2''R,3''S,4''R)-bi--(+)-mollisacacidin, is associated with a set of four diastereoisomeric biflavanoid homologues, -(-)-fisetinidol-(+)-mollisacacidins, in the heartwood of the black wattle tree, Acacia mearnsii.The sequence of units in the triflavanoid and its bonding points have been determined by n.m.r. spectroscopy at 500 MHz using spin-decoupling techniques.The triflavanoid and two biflavanoids with (2R,3S,4S)-2,3-trans-3,4-cis-configurations in their "upper" units, result from the in vitro self-condensation of their putative precursor (2R,3S,4R)-flavan-3,3'4,4',7-pentaol, thus permitting definition of their respective absolute configurations.
