32603-26-2Relevant articles and documents
Application of diphenyl diselenide as a new catalyst for photochemical stereoisomerization of carotenoids
Strand, Aase,Liaaen-Jensen, Synnove
, p. 1263 - 1269 (2007/10/03)
In a comparative study, diphenyl diselenide was shown to be an alternative to iodine as a catalyst for photochemical E/Z isomerization of carotenoids. Suitable conditions for the stereomutation of zeaxanthin, violaxanthin, canlhaxanthin and fucoxanthin are reported. Photochemical allenic isomerization with increased R to S conversion was achieved by employing diphenyl diselenide rather than iodine as the catalyst. Reproducible and expedient artificial light conditions, avoiding insolation (sunlight), are reported. Diphenyl diselenide tolerated the presence of Huenig's base upon stereoisomerization of acid-sensitive carotenoids. Diphenyl ditelluride effected E/Z stereomutation, but no allenic R/S isomerization of fucoxanthin. The presence of base decreased the isomerization rate in the absence of catalyst and may serve to decrease undesirable E/Z stereoisomerization of base-stable carotenoids. Acta Chemica Scandinavica 1998.
Selected cis/trans isomers of carotenoids formed by bulk electrolysis and iron(III) chloride oxidation
Wei, Chih-Chang,Gao, Guoqiang,Kispert, Lowell D.
, p. 783 - 786 (2007/10/03)
Bulk electrolysis and chemical oxidation with FeCl3 of all-trans canthaxanthin (I) and 8′-apo-β-caroten-8′-al (II) gave primarily the 9- and 13-cis-isomers, which were separated by HPLC and identified by 1H NMR spectroscopy. Optical absorption measurements showed that the 15-cis, 9,13-di-cis isomers of I are also formed by these methods. In the case of the unsymmetrical compound II, additional isomers were formed. The cis isomers account for about 40-60% of products formed. Formation of the isomers is believed to occur by rotation about certain bonds in the cation radicals or dications, which are formed in the oxidation processes. The neutral cis species are then formed by an electron exchange reaction of the cis-cation radicals with neutral all-trans carotenoids in solution. The electrochemical and iron(III) chloride oxidation induced isomerization are shown to be efficient and improved methods for forming selected carotenoid isomers.