The three apocarotenoids methyl (9Z)-8'-oxo-6,8'-diapocaroten-6-oate (2), m
ethyl (9Z)-10'-oxo-6,10'diapocaroten-6-oate (4). and methyl (9Z)-14'-oxo-6,
14'-diapocaroten-6-oate (5), recently isolated from annatto, were synthesiz
ed. The key step of all three syntheses was the Wittig reaction of the (Z)-
terminus 6 with the phosphonium salts 15, 18, and 24, carrying the polyene
chain. Bixin (1) was synthesized from 2 in a Horner-Emmons reaction.