ALGAL CAROTENOIDS .55. STRUCTURE ELUCIDATION OF (3S,5R,6R,3'S,5'R,6'S)-13'-CIS-7',8'-DIHYDRONEOXANTHIN-20'-AL 3'-BETA-D-LACTOSIDE (P457) .1. REISOLATION, DERIVATIZATION AND SYNTHESIS OF MODEL COMPOUNDS

The structure of the title compound, a minor glycosidic carotenoid isolated from peridinin-producing dinoflagellates, has been investigated by chemical and spectroscopic methods. This carotenoid represents one of the most complex carotenoid structures known, containing structural elements such as lactoside (first example), cross-conjugated C40-carotenal, allene, 5,6-epoxide and saturated C-7,8 bond. By comparison of the H-1 NMR data for the syn- and anti-hydroxy epoxide model compounds prepared here with H-1 NM R data for P457, published in detail elsewhere, the position of the epoxide function and the glycosylated C-3' hydroxy group appears to be anti in P457.