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

Article abstract of DOI:10.1039/P19810001220

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 of the aromatic quadrant rule such discrepancies correlate with deviations from the preferred C-ring conformations.