6-<i>s</i>-<i>cis</i> Locked Analogues of the Steroid Hormone 1α,25-Dihydroxyvitamin D<sub>3</sub>. Synthesis of Novel A-Ring Stereoisomeric 1,25-Dihydroxy-3-<i>e</i><i>pi</i>-19-<i>nor</i>-previtamin D<sub>3</sub> Derivatives
作者:Mónica Díaz、Miguel Ferrero、Susana Fernández、Vicente Gotor
DOI:10.1021/jo000443l
日期:2000.9.1
Efficient syntheses of A-ring synthons 24 and 32 are described from hydroxy ester 16, which is easily available on a preparative scale from (-)-quinic acid. Key features of the syntheses were (a) the ability to selectively perform desilylations in the presence of p-nitrobenzoate esters and (b) the excellent yield and complete stereospecificity with which the configuration of alcohols 16, 18, and 26
由羟基酯16描述了A-环合成子24和32的有效合成,其可以容易地以制备规模由(-)-奎尼酸得到。合成的主要特征是(a)在对硝基苯甲酸酯存在下选择性地进行脱甲硅烷基化的能力,以及(b)在Mitsunobu下可以颠倒醇16、18和26的构型的优异收率和完全立体特异性。条件。因此,从共同的前体16制备A环合成子24和32都以35-38%的产率(八个步骤)。A环合成子24和32与合适的CD环/侧链片段7的偶联提供了访问类固醇激素1alpha,25-二羟基维生素D(3)的新型6-s-顺式类似物:1alpha,25-dihydroxy-3-epi-19-nor-previtamin D(3)(37)和1beta,25-dihydroxy-3-epi-19-nor-previtamin D(3)(38),由于没有C-19甲基而无法重新排列为相应的维生素D形式。化合物37和38可用作研究激素1α,25-二