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Novel base-catalysed rearrangements of (–)-fisetinidol-(+)-catechin profisetinidins with 2,3-trans-3,4-cis-flavan-3-ol constituent units

1988; Royal Society of Chemistry; Issue: 15 Linguagem: Inglês

10.1039/c39880001055

2050-5639

Jan P. Steynberg, Johann F. W. Burger, Desmond A. Young, E. Vincent Brandt, Jacobus A. Steenkamp, Daneel Ferreira,

Tea Polyphenols and Effects

The (–)-fisetinidol-(4β, 8)-(+)-catechin-O-methyl ether (1) is subject to facile C-ring isomerizations in NaHCO3–Na2CO3 buffer solution to form a range of novel 8,9-cis-9,10-trans- and 8,9-trans-9,10-trans-3,4,9,10-tetrahydro-2H,8H-pyrano-[2,3-h]chromenes (2)–(5); analogues (4) and (5) are representative of an unique class of phlobatannins in which the resorcinol A- and pyrocatechol B-rings are interchanged.