Four diastereoisomers at the C-24 and C-25 positions of 3α, 7α, 12α, 24-tetrahydroxy-5β-cholestan-26-oic acid (varanic acid) were synthesized in a stereochemically defined manner and also by a non-stereoselective route, followed by chromatographic separation. Their stereochemistry at the C-24 and C-25 positions was established on the basis of the known stereochemical course of the reactions employed for the synthesis, and 1H and 13C-nuclear magnetic resonance spectroscopic data of these isomers. It is concluded from the present work that the previous stereochemical assignment for the (24R, 25S) and (24R, 25R) isomers must be revised.
在C-24和C-25位点合成了四个3α, 7α, 12α, 24-四羟基-5β-胆烷-26-酸(varanic acid)的立体异构体,既采用了立体
化学定义的方法,也通过非立体选择性路线,然后进行色谱分离。根据用于合成的反应已知的立体
化学过程以及这些异构体的1H和13C核磁共振光谱数据,确定了它们在C-24和C-25位点的立体
化学。本研究得出的结论是,之前对(24R,25S)和(24R,25R)异构体的立体
化学分配必须进行修正。