Novel approach to determining the absolute configurations at the C3-positions of various types of sterols based on an induced circular dichroism
Toshio Fujiwara, Yuka Taniguchi, Yukiteru Katsumoto, Takeyuki Tanaka, Minoru Ozeki, Hiroki Iwasaki, Manabu Node, Masayuki Yamashita, Shinzo Hosoi
Circular dichroism (CD) spectra of the 2,2′-binaphthyl ester derived from Δ5-sterols showed not bisignate CD but diagnostic CD bands at around 210 and 240 nm. These bands might be attributable to an interaction between an olefinic chromophore and a binaphthyl one. Various types of unsaturated sterols were thus derivatized followed by complete hydrogenation, to give saturated sterols. As a result, CD spectra of the binaphthyl derivatives of the saturated sterols showed bisignate curves centered at 240 nm (3S(β): positive chirality; 3R(α): negative one). This suggested a straightforward and practical method for discriminating the absolute stereogenic center at the C-3 positions of sterols based on an induced CD. This finding should contribute significantly to the analysis of metabolites of various types of sterols.
Circular dichroism, Absolute configuration, Pharmaceutical