Ionic hydrogenation-directed stereoselective construction of C-20(H) stereogenic center in steroid side chains: Scope and limitations
作者:Bapurao B. Shingate、Braja G. Hazra
DOI:10.1016/j.tet.2017.03.029
日期:2017.4
Stereoselective synthesis of steroidal C-20 tertiary alcohols with n-butyl, vinyl, furyl, thienyl, thiazolyl, aryl and pyridyl side chains via Grignard reaction or organolithium reagents have been realized starting from readily available 16-dehydropregnenolone acetate. The ionic hydrogenation of steroidal C-20 tertiary alcohols having furyl, methylfuryl, thienyl, phenyl and 4-methoxyphenyl side chains, resulted
用甾族C-20叔醇的立体选择性合成Ñ丁基,乙烯基,呋喃基,噻吩基,噻唑基,芳基和吡啶基的侧链通过从容易获得的16-脱氢孕烯醇酮乙酸酯开始已经实现了格氏反应或有机锂试剂。具有呋喃基,甲基呋喃基,噻吩基,苯基和4-甲氧基苯基侧链的甾族C-20叔醇的离子加氢,以优异的产率得到具有C-20天然构型的脱氧产物。然而,在相同反应条件下,烷基,噻唑基和吡啶基并入的甾族C-20叔醇失败。通过用呋喃基,噻吩基和4-甲氧基苯基侧链将甾体C-20,21-烯化合物立体选择性还原,得到具有C-20天然构型的饱和化合物,可以进一步突出离子氢化的范围。