目的 在有4-烯-3-酮结构的甾体化合物4-位上引入二甲基。方法 以7个带有4-烯-3-酮结构的甾体化合物为底物，按文献方法以相同的反应条件与碘甲烷-叔丁醇钾-叔丁醇反应系统反应。结果 4个底物反应结果和文献一致，顺利得到了4-位二甲基化的产物，而另外3个底物则以高收率转化成为3-位氧甲基化的产物。结论 7个甾体底物A、B、C 3个环的结构基本一致，只是D环的结构不同，所以这7个化合物的不同反应结果表明甾体D环结构通过远程效应对4-位二甲基化和3-位氧甲基化反应的选择性产生了影响。

Objective To introduce dimethyl on 4-position of 4-ene-3-one steroids.MethodsSeven 4-ene-3-one steroids were treated with methyl iodide (CH3I) and potassium tert-butoxide (t-BuOK) in tert-butanol (t-BuOH). Results Four substrates were smoothly converted to 4,4-dimethyl products, while other three substrates afforded 3-O-methylation products with high yields. Conclusions The different reaction results revealed a high remote effect of D ring moiety on the selectivity between 3-O-methylation and 4-dimethylation.