Aromatic and Cyclopentanoid Carotenoids

Aromatic and Cyclopentanoid Carotenoids.—Violerythrin (40) is a blue carotenoid formed by hydrolysis and mild oxidation of the sea anemone diester actinioerythrin (41). The proposed biogenesis involving a benzilic rearrange- 

Hertzberg and S. Liaaen-Jensen, Acta Chem. Scand., 1968, 22, 1714 S. Hertzberg, S. Liaaen-Jensen, C. R. Enzell, and G. W. Francis, Acta Chem. Scand., 1969, 23, 3290. 

Certain bacteria are able to rearrange the normal carbon skeleton to give aromatic carotenoids. Phenolic examples were isolated from Streptomyces mediolani. As well as the hydrocarbon isorenieratene (43), 3-hydroxy- (44), and 3,3 -dihydroxy-isorenieratene (45) were present and their structures confirmed by synthesis. In Thiothece gelatinosa the major carotenoid was okenone 

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