Separation of carotenoid mixtures using centrifugal chromatography

Conformation and Circular Dichroism ofβ,β-Carotene Derivatives with Nitrogen-, Sulfur-, and Selenium-Containing Substituents

“…Cotton effects of substituents directly bound to the end groups have so far not been assigned because of the inaccessibility of chirally perturbed CÀO transitions by usual dichrographs [21] [22]. Racemic b,b-carotene derivatives with N-, S-, Br-, and Clsubstituents have been known for a long time [23] [24], but it was only recently that optically active heteroatom-substituted b,b-carotene derivatives were synthesized [25 ± 28]. It was, therefore, of interest to study the impact of different substituents on the ring conformation, and to detect possible substituent contributions.…”