Abstract
Three of the title compounds, canthaxanthin (I), echinenone (II) and isozeaxanthin (III), were oxidized with perphthalic acid or H_2O_2 and the products were evaluated spectroscopically. I gave no epoxides in either method and was mostly recovered together with small amounts of neo-I A-F and unidentified pigments. II was oxidized with perphthalic acid to give 5', 6'-monoepoxide (IV), mp. 179-180℃, accompanied by considerable amounts of corresponding cis and 3', 4'-dehydro-II, while II-5,6-mono- or 5,6,5', 6'-diepoxide was not obtained. III was smoothly epoxidized with perphthalic acid to give its 5,6-monoepoxide (V), mp. 177-178℃, and 5,6,5', 6'-diepoxide (VI), mp. 203-204℃, together with small amounts of 5,6,5', 8'-diepoxide. On treating V and VI with chloroform containing HCl gas, they were transformed to III-5,8-mono- and 5,8,5', 8'-diepoxide, respectively, although IV gave 5'-hydroxy-5', 6'-dihydro-II.
