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Preparation and (E/Z)-Isomerization of the Diastereoisomers of Violaxanthin

✍ Scribed by Péter Molnár; József Deli; Ferenc Zsila; Andrea Steck; Hanspeter Pfander; Gyula Tóth

Publisher
John Wiley and Sons
Year
2004
Tongue
German
Weight
239 KB
Volume
87
Category
Article
ISSN
0018-019X

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✦ Synopsis

Abstract

Violaxanthin A (=(all‐E,3__S__,5__S__,6__R__,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,3__S,5__S,6__R__,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 I~2~‐catalyzed photoisomerization. The structure of the main products, i.e., (9__Z)‐5, (13__Z)‐5, (9__Z__)‐6, (9′Z)‐6, (13__Z__)‐6, and (13′Z)‐6, was determined by their UV/VIS, CD, ^1^H‐NMR, ^13^C‐NMR, and mass spectra.

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(E/Z)-Isomerization of 3′-Epilutein
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✍ Péter Molnár; József Deli; Erzsébet Ősz; Zoltán Matus; Gyula Tóth; Ferenc Zsila 📂 Article 📅 2004 🏛 John Wiley and Sons 🌐 German ⚖ 250 KB

## Abstract 3′‐Epilutein (=(all‐__E__,3__R__,3′__S__,6′__R__)‐4′,5′‐didehydro‐5′,6′‐dihydro‐__β__,__β__‐carotene‐3,3′‐diol; **1**), isolated from the flowers of __Caltha palustris__, was submitted to both thermal isomerization and I~2~‐catalyzed photoisomerization. The structures of the main produc