Synthesis of condensed tannins. Part 2. Synthesis by photolytic rearrangement, stereochemistry, and circular dichroism of the first 2,3-cis-3,4-cis-4-arylflavan-3-ols
作者:Jan H. van der Westhuizen、Daneel Ferreira、David G. Roux
DOI:10.1039/p19810001220
日期:——
Photolytic rearrangements of those 2,3-trans-3,4-trans- and 2,3-trans-3,4-cis-4-arylflavan-3-ols in which the nucleophilicity of D-ring (4-aryl group) functionality exceeds that of the A-ring, provide the first access to 2,3-cis-3,4-cis-diastereoisomers. The circular dichroism of these new isomers is at variance with the proposed general rule for assessing the absolute configuration at C-4. In terms
Flavan-3.4-diols and Leuco-anthocyanidins of Guibourtia spp.
作者:D. G. ROUX
DOI:10.1038/183890a0
日期:1959.3
carbohydrates soluble in water. Examination of the latter fraction with the toluene-P-sulphonicacid spraying reagent on two-way paper chromatograms shows the probable presence of flavan-3.4-diols with RF values corresponding to 0.45–0.55 in 2 per cent acetic acid (second irrigant), but with differing RF values in the partitioning mixture used (butan-2-ol saturated with water: first irrigant)5.