Zobrazeno 1 - 10
of 31
pro vyhledávání: '"Johann F. W. Burger"'
Publikováno v:
Phytochemistry. 35:1559-1565
The processed leaves and stems of Aspalathus linearis contain hydroxylated benzoic and cinnamic acids, luteolin, chrysoeriol, quercetin, isoquercitrin, the C–C linked β- d -glucopyranosides based on four flavones and the dihydrochalcone aspalathin
Publikováno v:
ChemInform. 26
A new proteracacinidin analogue with a unique double linkage, ent-oritin-(4β→7, 5→6)-epioritin-4α-ol was isolated from the heartwood of Acacia caffra .
Publikováno v:
Phytochemistry. 30:1255-1258
The structure and stereochemistry of a procyanidin glycoside, catechin 3-O-rhamnosyl-(4α→8)-catechin, obtained from Erythroxylum novogranatense have been established by chemical degradation and by means of spectroscopic methods of its peracetate.
Autor:
Herbert Kolodziej, Johann F. W. Burger, Jan P. Steynberg, Richard W. Hemingway, Desmond A. Young, Daneel Ferreira
Publikováno v:
Tetrahedron. 46:5733-5740
Procyanidin B-2 3 is subject to facile C-ring isomerizations in 0.1M NaHCO3 solution to form a novel series of 3,4,9, 10-tetrahydro-2H, 8-pyrano[2,3-h]chromenes 7 , 9 , and 10 . The low percentage conversion of B- to A-type procyanidin 2 is rationali
Publikováno v:
Tetrahedron Letters. 31:3789-3792
— Proanthocyanidins of the A—type exhibit identical 1 H NMR coupling constants (J 3,4 = 3.5 Hz) irrespective of the relative configurations of their C-rings. The selective 1 H NOE association of 3—H (C-ring) to either 6—H(D) or 8—H(A) permi
Autor:
Martha S. van Dyk, Barend C. B. Bezuidenhoudt, Jan P. Steynberg, Daneel Ferreira, Johann F. W. Burger, Petrus J. Steynberg
Publikováno v:
Tetrahedron Letters. 31:2059-2062
The functionalized 2,3- trans -8,9- trans -9,10- cis -3,4,9,10-tetrahydro-2 H ,8 H -pyrano[2,3- h ]chromenes 4 and 6 represent the first naturally occurring condensed tannins with (2 S ,3 R )-2,3- trans -(−)-catechin ‘terminal’ moieties; the st
Autor:
Johann F. W. Burger, Desmond A. Young, Johannes C. S. Malan, Jan P. Steynberg, Daneel Ferreira, Susan L. Bonnet, Annemarie Cronjé
Publikováno v:
Phytochemistry. 29:2979-2989
Several members of the class of natural ‘phlobaphene’ condensed tannins, representing the products of C-ring isomerization of (−)-fisetinidol-(4α,8) and (4β,8)-(−)-epicatechin profisetinidins have been characterized. These comprise four fun
Autor:
Johann F. W. Burger, Jacobus A. Steenkamp, Daneel Ferreira, Alexander F. Hundt, Jan P. Steynberg
Publikováno v:
Tetrahedron Letters. 31:5073-5076
1 H NMR Analysis of R-(+)-α-methoxy-α-trifluoromethylphenyl acetic acid (MTPA) esters of different sets of enantiomeric flavan-3-ols and 4-arylflavan-3-ols respectively, permits assessment of the absolute configurations at C-3 of these condensed ta
Autor:
Jacobus A. Steenkamp, Daneel Ferreira, Desmond A. Young, J. P. Steynberg, Johann F. W. Burger
Publikováno v:
J. Chem. Soc., Perkin Trans. 1. :235-240
Several members of the unique class of natural phlobatannins, representing the products of stereospecific pyran rearrangement of 2,3-trans-3,4-trans-flavan-3-ol units present in, e.g., (4α,6 : 4α,8)-bis-(–)-fisetinidol-(+)-catechin triflavanoid p
Autor:
Desmond A. Young, Daneel Ferreira, Jan P. Steynberg, Johann F. W. Burger, Johannes C. S. Malan, Annemarie Cronjé
Publikováno v:
Phytochemistry. 29:275-277
The natural occurrence of the first profisetinidins associated with (−)-epicatechin is demonstrated in the heartwood of three legumes. 1 H NMR spectroscopy at 300 MHz permits assessment of the relative abundance of the predominant rotamers in each