Synthesis of Bixin and Three Minor Carotenoids from Annatto (Bixa orellana) 

 -  Helvetica Chimica Acta, 82(5), p.696-706, 1999 .
<br/><br/> The three apocarotenoids methyl (9Z)-8'-oxo-6,8'-diapocaroten-6-oate (2), methyl (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 synthesized. 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.