EPOXYCAROTENOIDS : (XIX)THE STRUCTURE OF NEOXANTHIN (4)THE POSITION OF HYDROXYLS

Abstract

The position of the two sec-hydroxyls in neoxanthin was revealed by studying the rather complicated reaction mixtures formed from the following reactions : l) The CHCl_3・HCl reagent and neoxanthin in benzene solution. 2) The CHCl_3・HCl reagent and neoxanthin in chlroform solution. 3) Neochrome and LiAlH_4. 4) The tetraol ex neochrome and POCl_3. The diol A, one of the products derived from the above reaction 3 was identical with natural zeaxanthin in all respects, while isozeaxanthin could not be found throughout all four reactions. Experimental results including those obtained in the previous reports strongly support the structure proposed by Weedon et al. The significance of the M-80 peak which appears in the mass spectra of epoxycarotenoids and is missing in general carotenesand xanthophylls was discussed.