RECENT PROGRESS IN COMMERCIAL RETINOIDS AND CAROTENOIDS

Among the retinoids vitamin A has an exceptional position both by volume and in its field of application. The competing technical syntheses are discussed. The other retinoids namely (all E)- and (13 Z)-Retinoic acid and Etretinate are used as topical and systemic agents in dermatology. Commercial synthetic carotenoids are mainly used as pigmenters for food in vivo; examples are egg yolk - and broiler pigmentation with beta-apo-8'-carotenoic acid ethylester and pigmentation of farm-raised salmon with astaxanthin. Another field of application is direct coloration of food, e.g. of margarine with beta-carotene. Presently beta-carotene is booming as a substitute for vitamin A without teratogenic potential and as a biological antioxidant. Two strategies compete in manufacture of these carotenoids - synthesis of beta-apo-8'-carotenoids and beta-carotene starting from vitamin A and its precursors followed by the stepwise oxidation of beta-carotene to canthaxanthin and astaxanthin - conversion of oxo-isophorone to C-15-phosphonium salts of different oxidation pattern in the beta-ionone-ring followed by Witting condensation with C-10-dialdehyde.