title: Differentiation between the 25R- and 25S-isomers of 5 beta-cholestane-3 alpha, 7 alpha, 26-triol by 13C NMR spectroscopy.
abstract: This study was designed to examine whether 13C nuclear magnetic resonance (NMR) spectroscopy can be used to differentiate between the 25R and 25S diastereoisomers of 5 beta-cholestane-3 alpha, 7 alpha, 26-triol, a key intermiediate in the biosynthetic pathway of chenodeoxycholic acid. Chemical shift values were assigned to the individual carbon atoms with the help of model compounds and multiplicity in the single-frequency off-resonance decoupled spectra. It was found that the corresponding carbons 1-20 afforded identical chemical shifts for both compounds, whereas five of the remaining side-chain carbons gave observed shift differences of 0.05-0.20 ppm. Thus 13C NMR can be used as an additional tool to distinguish between the two 5 beta-cholestanetriols isomeric at C-25.
mesh_terms: D055598:Chemical Phenomena; D002621:Chemistry; D002777:Cholestanols; D009682:Magnetic Resonance Spectroscopy; D013237:Stereoisomerism
chemical_list: D002777:Cholestanols