Epoxidation of Cucurbitaxanthin A: Preparation of Cucurbitaxanthin B and of Its 5′,6′‐Epimer Cucurbitaxanthin A (= (3S,5R,6R,3′S)‐3,6‐epoxy‐5,6‐dihydro‐β,β‐carotene‐5,3′‐diol; 1) isolated from red pepper (Capsicum annuum var. longum nigrum) was trimethylsiylated and then epoxidized with monoperphthalic acid. After deprotection and chromatographic separation, cucurbitaxanthin B (= (3S,5R,6R, 3′S,5′R,6′S)‐3,6:5′,6′‐diepoxy‐5,6,5′,6′‐tetrahydro‐β,β‐carotene‐5,3′‐diol; 2) and 5′,6′‐diepicucurbitaxanthin B (= (3S,5R,6R, 3′S,5′S,6′R)‐3,6:5′,6′‐diepoxy‐5,6,5′,6′‐tetrahydro‐β,β‐carotene‐5,3′‐diol; 5) were obtained and carefully characterized. They show mirror‐like CD spectra and, therefore, emphasize the importance of the torsion angle of C(6)–C(7) on the electronic interaction between the polyene chain and the chiral end group.
ASJC Scopus subject areas
- Drug Discovery
- Physical and Theoretical Chemistry
- Organic Chemistry
- Inorganic Chemistry