Recent advances in industrial carotenoid synthesis

Symmetrical C-40-carotenoids are efficiently produced by double Wittig olefination of the corresponding C-15-phosphonium salts with C-10-dialdehyde. Industrial syntheses of lycopene, astaxanthin, and (3R,3'R)-zeaxanthin-C-15-phosphonium salts are discussed. An efficient route to a monoprotected C-10-dialdehyde for the synthesis of unsymmetrical C-40-carotenoids is presented. Primary polyene allyl alcohols can be converted to the corresponding aldehydes by TEMPO oxidation. A high-yield synthesis of meso-zeaxanthin as an example for syntheses of unsymmetrical carotenoids is presented.