Herz J E, Swaminathan S, Pinkerton F D, Wilson W K, Schroepfer G J
Department of Biochemistry, Rice University, Houston, TX 77251.
J Lipid Res. 1992 Apr;33(4):579-98.
As part of a program directed towards the chemical syntheses of potential metabolites and analogs of 3 beta-hydroxy-5 alpha-cholest-8(14)-en-15-one (I), a potent regulator of cholesterol metabolism, several routes have been explored for the preparation of 3 beta-hydroxy-15-keto-5 alpha-chol-8(14)-en-24-oic acid (IV). These investigations led to a remarkably specific and efficient side-chain oxidation of I. For example, treatment of the acetate of I with a mixture of trifluoroacetic anhydride, hydrogen peroxide, and sulfuric acid for 3.5 h at -2 degrees C gave a crude product consisting of 3 beta-acetoxy-24-trifluoroacetoxy-5 alpha-chol-8(14)-en-15-one (XI), 3 beta-acetoxy-24-hydroxy-5 alpha-chol-8(14)-en-15-one (XII), and 3 beta, 24-diacetoxy-5 alpha-chol-8(14)-en-15-one (XIII) in yields of 58%, 8%, and 3%, respectively, by HPLC analysis. XI was readily hydrolyzed to XII upon treatment with triethylamine in methanol at room temperature. Oxidation of XII with Jones reagent gave 3 beta-acetoxy-15-keto-5 alpha-chol-8(14)-en-24-oic acid (XVIII) from which its methyl ester (IX) was prepared by treatment with diazomethane. Mild alkaline hydrolysis of XVIII gave the 3 beta-hydroxy-delta 8(14)-15-keto C24 acid (IV). Hydrolysis of the crude product of the side-chain oxidation with K2CO3 in methanol gave 3 beta,24-dihydroxy-5 alpha-chol-8(14)-en-15-one (XIV) which was oxidized with Jones reagent to yield 3,15-diketo-5 alpha-chol-8(14)-en-24-oic acid (XV). Treatment of XV with diazomethane gave its methyl ester (XVI) which, upon controlled reduction with NaBH4, yielded methyl 3 beta-hydroxy-15-keto-5 alpha-chol-8(14)-en-24-oate (XVII). Compound IX was also prepared by an independent route. Full 1H and 13C NMR assignments are presented for 12 new compounds. IV caused a approximately 56% reduction of the level of 3-hydroxy-3-methylglutaryl coenzyme A reductase activity in CHO-K1 cells at a concentration of 2.5 microM. In contrast, the corresponding 3,15-diketo acid XV had no detectable effect on reductase activity under the same conditions.
作为旨在化学合成胆固醇代谢强效调节剂3β-羟基-5α-胆甾-8(14)-烯-15-酮（I）的潜在代谢产物及其类似物的项目的一部分，已探索了几条制备3β-羟基-15-酮-5α-胆甾-8(14)-烯-24-酸（IV）的路线。这些研究导致了I的侧链氧化具有显著的特异性和高效性。例如，在-2℃下，将I的乙酸酯用三氟乙酸酐、过氧化氢和硫酸的混合物处理3.5小时，得到一种粗产物，通过高效液相色谱分析，其由3β-乙酰氧基-24-三氟乙酰氧基-5α-胆甾-8(14)-烯-15-酮（XI）、3β-乙酰氧基-24-羟基-5α-胆甾-8(14)-烯-15-酮（XII）和3β,24-二乙酰氧基-5α-胆甾-8(14)-烯-15-酮（XIII）组成，产率分别为58%、8%和3%。XI在室温下用三乙胺在甲醇中处理后很容易水解为XII。用琼斯试剂氧化XII得到3β-乙酰氧基-15-酮-5α-胆甾-8(14)-烯-24-酸（XVIII），通过用重氮甲烷处理从中制备其甲酯（IX）。XVIII的温和碱性水解得到3β-羟基-δ8(14)-15-酮C24酸（IV）。用碳酸钾在甲醇中对侧链氧化的粗产物进行水解得到3β,24-二羟基-5α-胆甾-8(14)-烯-15-酮（XIV），用琼斯试剂氧化该产物得到3,15-二酮-5α-胆甾-8(14)-烯-24-酸（XV）。用重氮甲烷处理XV得到其甲酯（XVI），用硼氢化钠对其进行可控还原得到3β-羟基-15-酮-5α-胆甾-8(14)-烯-24-酸甲酯（XVII）。化合物IX也通过一条独立的路线制备。给出了12种新化合物的完整1H和13C NMR归属。在浓度为2.5μM时，IV使CHO-K1细胞中3-羟基-3-甲基戊二酰辅酶A还原酶活性水平降低了约56%。相比之下，在相同条件下，相应的3,15-二酮酸XV对还原酶活性没有可检测到的影响。
