Une M, Cohen B I, Mosbach E H
J Lipid Res. 1984 Apr;25(4):407-10.
Methods are described for the chemical synthesis of three new bile acid analogs, namely, 3 alpha, 7 alpha-dihydroxy-7 beta-methyl-5 beta-cholanoic acid, 3 alpha, 7 beta-dihydroxy-7 alpha-methyl-5 beta-cholanoic acid and 3 alpha-hydroxyl-7 xi-methyl-5 beta-cholanoic acid. The starting material, 2-(3 alpha, 7 xi-dihydroxy-7 xi-methyl-24-nor-5 beta- cholanyl )-4, 4-dimethyl-2-oxazoline upon mild hydrolysis in aqueous HCl yields the two epimeric 3 alpha, 7-dihydroxy-7-methyl-5 beta-cholanoic acids which can be separated as the methyl esters by silica gel column chromatography. More rigorous hydrolysis in boiling methanolic HCl yields a mixture of unsaturated compounds which can be separated as their methyl esters into three fractions by silica gel-AgNO3 column chromatography. The fractions containing 3 alpha-hydroxy-7-methyl-5 beta-chol-6-enoic acid and 3 alpha-hydroxy-7-methylene-5 beta-cholanoic acid when subjected to catalytic hydrogenation yield 3 alpha-hydroxy-7 xi-methyl-5 beta-cholanoic acid.
描述了三种新胆汁酸类似物的化学合成方法,即3α,7α-二羟基-7β-甲基-5β-胆烷酸、3α,7β-二羟基-7α-甲基-5β-胆烷酸和3α-羟基-7ξ-甲基-5β-胆烷酸。起始原料2-(3α,7ξ-二羟基-7ξ-甲基-24-降-5β-胆烷酰基)-4,4-二甲基-2-恶唑啉在盐酸水溶液中温和水解,生成两种差向异构的3α,7-二羟基-7-甲基-5β-胆烷酸,它们可以作为甲酯通过硅胶柱色谱法分离。在沸腾的甲醇盐酸中进行更剧烈的水解,得到不饱和化合物的混合物,它们可以作为甲酯通过硅胶-硝酸银柱色谱法分离成三个馏分。含有3α-羟基-7-甲基-5β-胆-6-烯酸和3α-羟基-7-亚甲基-5β-胆烷酸的馏分在进行催化氢化时生成3α-羟基-7ξ-甲基-5β-胆烷酸。