Carotenoids and related compounds. Part 37. Stereochemistry and synthesis of capsorubin

Abstract

The two oxygen substituents in the end groups of capsorubin were shown to be trans to one another by synthesis of optically inactive forms of the carotenoid, and of the isomers which have the corresponding cis-structure. The 3S,5R,3′S,5′R configuration thus established for the natural carotenoid was confirmed by synthesis of this stereoisomer from (+)-camphor.

Cryptocapsin has the 3′S,5′R configuration, and the racemic form has been synthesised.

Capsanthin has the 3R,3′S,5′R configuration.