Bacterial Carotenoids. LII. C50-Carotenoids. 18. Synthesis of the Model Compounds (2R,6S,2'R,6'S)-2,2'-Dimethyl-gamma,gamma-carotene and (2R,2'R,6'S)-2,2'-Dimethyl-beta,gamma-carotene.

Abstract
The title compounds were synthesized from (+)-(2S,6R)-cis-.gamma.-irone. The physical properties of the C42-carotenes and intermediates are reported for future stereochemical correlation of naturally occurring carotenoids with .gamma.-end-groups.