title: Total synthesis of gobiusxanthin stereoisomers and their application to determination of absolute configurations of natural products: revision of reported absolute configuration of epigobiusxanthin.
abstract: (3R)-Gobiusxanthin stereoisomers (1a-d) were synthesized by stereoselective Wittig reaction of the (3R)-C15-acetylenic tri-n-butylphosphonium salt 7 with C25-apocarotenal stereoisomers 5a,b and 14a,b bearing four kinds of 3,6-dihydroxy-ε-end groups. The validity of the reported stereochemistry of gobiusxanthin was demonstrated by the fact that the reported spectral data of natural gobiusxanthin were in agreement with those of synthetic (3R,3'S,6'R)-gobiusxanthin (1a). On the other hand, the reported CD spectral data of natural epigobiusxanthin, which has been assigned as (3R,3'R,6'R)-isomer (3'-epigobiusxanthin), were identical with those of synthetic (3R,3'S,6'S)-isomer 1d (6'-epigobiusxanthin) rather than those of the corresponding synthetic 3'-epi-isomer 1b. It was found that the stereochemistry at C3-position has little effect on the shape of their CD spectra. Thus, in order to reinforce the validity of the absolute configurations at C3-position of natural specimens, (3S,3'S,6'R)- and (3S,3'S,6'S)-stereoisomers 1e and 1f were also synthesized and a HPLC analytical method for four stereoisomers was established by using a column carrying a chiral stationary phase. The HPLC analysis has proven that the stereochemistry of the natural epigobiusxanthin is 3R,3'S,6'S.
authors.affiliation: Department of Organic Chemistry for Life Science, Kobe Pharmaceutical University, Motoyamakita-machi, Higashinada-ku, Kobe 658-8558, Japan. y-yamano@kobepharma-u.ac.jp.
authors.forename: Yumiko
authors.initials: Y
authors.lastname: Yamano
authors.affiliation: Department of Organic Chemistry for Life Science, Kobe Pharmaceutical University, Motoyamakita-machi, Higashinada-ku, Kobe 658-8558, Japan.
authors.forename: Kotaro
authors.initials: K
authors.lastname: Ematsu
authors.affiliation: Department of Organic Chemistry for Life Science, Kobe Pharmaceutical University, Motoyamakita-machi, Higashinada-ku, Kobe 658-8558, Japan. hm090930@st.kobepharma-u.ac.jp.
authors.forename: Hiromasa
authors.initials: H
authors.lastname: Kurimoto
authors.affiliation: Research Institute for Production Development, 15 Shimogamo-morimoto-cho, Sakyo-ku, Kyoto 606-0805, Japan. maoka@mbox.kyoto-inet.or.jp.
authors.forename: Takashi
authors.initials: T
authors.lastname: Maoka
authors.affiliation: Department of Organic Chemistry for Life Science, Kobe Pharmaceutical University, Motoyamakita-machi, Higashinada-ku, Kobe 658-8558, Japan. a-wada@kobepharma-u.ac.jp.
authors.forename: Akimori
authors.initials: A
authors.lastname: Wada
mesh_terms: D001688:Biological Products / Q000138:chemical synthesis*; D002851:Chromatography, High Pressure Liquid; D015394:Molecular Structure; D013237:Stereoisomerism; D024341:Xanthophylls / Q000138:chemical synthesis* / Q000737:chemistry
chemical_list: D001688:Biological Products; D024341:Xanthophylls