|Title||Preparation and (E/Z)-Isomerization of the Diastereoisomers of Violaxanthin|
|Publication Type||Journal Article|
|Year of Publication||2004|
|Authors||Molnár, P, Deli, J, Zsila, F, Steck, A, Pfander, H, Tóth, G|
|Journal||Helvetica Chimica Acta|
|Pagination||11 - 27|
Violaxanthin A (=(all-E,3S,5S,6R,3′S,5′S,6′ R)-5,6:5′,6′-diepoxy-5,6,5′,6′-tetrahydro-β, β-carotene-3,3′-diol = syn,syn-violaxanthin; 5) and violaxanthin B (=(all-E,3S,5S,6R,3′S,5′R,6′S)-5,6:5′, 6′-diepoxy-5,6,5′,6′-tetrahydro-β,β-carotene-3, 3′-diol = syn,anti-violaxanthin; 6) were prepared by epoxidation of zeaxanthin diacetate (1) with monoperphthalic acid. Violaxanthins 5 and 6 were submitted to thermal isomerization and I2-catalyzed photoisomerization. The structure of the main products, i.e., (9Z)-5, (13Z)-5, (9Z)-6, (9′Z)-6, (13Z)-6, and (13′Z)-6, was determined by their UV/VIS, CD, 1H-NMR, 13C-NMR, and mass spectra.