Dayal B, Batta A K, Shefer S, Tint G S, Salen G
Steroids. 1978 Oct;32(3):337-44. doi: 10.1016/0039-128x(78)90085-5.
This paper describes a new and convenient procedure for the synthesis of 5beta-cholestane-3alpha,7alpha,12alpha,24-tetrol (24R and 24 S) and 5beta-cholestane-3alpha,7alpha,12alpha,26-tetrol starting from 5beta-cholestane-3alpha,7alpha,12alpha,25-tetrol. Dehydration of the 25-hydroxytetrol with glacial acetic acid and acetic anhydride yielded a mixture of 5beta-cholest-24-ene-3alpha,7alpha,12alpha-triol and the corresponding delta25 compound. Hydroboration and oxidation of the mixture of delta24 and delta25 unsaturated bile alcohols resulted in the formation of 5beta-cholestane-3alpha,7alpha,12alpha,24epsilon-tetrol and 5beta-cholestane-3alpha,7alpha,12alpha,26-tetrol. In addition, smaller amounts of 5beta-cholestane-3alpha,7alpha,12alpha,23epsilon-tetrol and 5beta-cholestane-3alpha,7alpha,12alpha-triol were also obtained. The bile alcohols epimeric at C-24 were resolved by analytical and preparative TLC, characterized by gas-liquid chromatography and mass-spectrometry. Tentatively assignments of the 24R and 24S configuration was made on the basis of molecular rotation differences. These compounds will be useful for biological studies of cholic acid biosynthesis.
本文描述了一种从5β-胆甾烷-3α,7α,12α,25-四醇出发合成5β-胆甾烷-3α,7α,12α,24-四醇（24R和24S）以及5β-胆甾烷-3α,7α,12α,26-四醇的新颖且简便的方法。25-羟基四醇与冰醋酸和乙酸酐脱水反应生成5β-胆甾-24-烯-3α,7α,12α-三醇和相应的δ25化合物的混合物。δ24和δ25不饱和胆汁醇混合物的硼氢化和氧化反应生成了5β-胆甾烷-3α,7α,12α,24ε-四醇和5β-胆甾烷-3α,7α,12α,26-四醇。此外，还得到了少量的5β-胆甾烷-3α,7α,12α,23ε-四醇和5β-胆甾烷-3α,7α,12α-三醇。通过分析型和制备型薄层色谱法拆分了C-24位差向异构的胆汁醇，并用气相色谱法和质谱法对其进行了表征。基于分子旋光差异对24R和24S构型进行了初步归属。这些化合物将有助于胆酸生物合成的生物学研究。
