The preparation of carotenoid thiones has been investigated, beta,beta
-Caroten-4-thione. 4'-thioxo-beta,beta-caroten-4-one and 4'.5'-didehyd
ro-4,5'-retro-beta,beta-caroten-3-one were synthesized from echinenone
, canthaxanthin and rhodoxanthin respectively. Characteristic spectros
copic properties of the polyene thiones are discussed and potential ap
plications are outlined.