Partial Syntheses of Diastereomeric Carotenols.

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Abstract
The application of the Mitsunobu reaction was successfully tested on (3R,3''R)-zeaxanthin, giving the (3S,3''S)-enantiomer and the meso form. Applied to natural (3R,3''R,6''R)-lutein, this inversion reaction allowed the preparation of the three other 6''R diastereomers. (3S,3''S,6''R)-lutein with 3'',6''-cis-configuration of the .epsilon.-ring has not been synthesized before. The observed Cotton effects of the eight lutein diastereomers are rationalized by application of the additivity hypothesis. New trivial names are suggested for the eight lutein isomers on the basis of structural relationships.