Ruan B, Wilson W K, Schroepfer G J
Department of Chemistry, Rice University, Houston, Texas 77005, USA.
Steroids. 1999 Jun;64(6):385-95. doi: 10.1016/s0039-128x(98)00116-0.
Asymmetric dihydroxylation of (20(22)E)-cholesta-5,20(22)-dien-3beta-ol acetate (2a), prepared from pregnenolone, gave a 1:1 mixture (67% yield) of (20R,22R)-cholest-5-ene-3beta,20,22-triol 3-acetate (3a) and its 20S,22S isomer 3b. Highly purified 3a and 3b were obtained by semipreparative silver ion high performance liquid chromatography. Saponification of 3a and 3b gave (20R,22R)-cholest-5-ene-3beta,20,22-triol (4a) and its 20S,22S isomer 4b. This simple approach provided the natural isomer 4a more efficiently than previously described chemical or enzymatic syntheses. Full 1H and 13C nuclear magnetic resonance data were presented for triols 4a and 4b and their synthetic precursors. Side-chain conformations of 2a, its 20(22)Z isomer, 4a, and 4b were studied by molecular mechanics and nuclear Overhauser effect difference spectroscopy.
由孕烯醇酮制备的(20(22)E)-胆甾-5,20(22)-二烯-3β-醇乙酸酯(2a)的不对称二羟基化反应，得到了(20R,22R)-胆甾-5-烯-3β,20,22-三醇3-乙酸酯(3a)及其20S,22S异构体3b的1:1混合物(产率67%)。通过半制备型银离子高效液相色谱法获得了高度纯化的3a和3b。3a和3b的皂化反应得到了(20R,22R)-胆甾-5-烯-3β,20,22-三醇(4a)及其20S,22S异构体4b。这种简单的方法比先前描述的化学或酶促合成更有效地提供了天然异构体4a。给出了三醇4a和4b及其合成前体的完整的1H和13C核磁共振数据。通过分子力学和核Overhauser效应差光谱研究了2a及其20(22)Z异构体、4a和4b的侧链构象。
