【摘要】 目的以甘草次酸和齐墩果酸为例探讨空间位阻对五环三萜类羧基酰化反应的影响。方法选取甘草次酸与齐墩果酸两种羧基位(非角位和角位)空间位阻不同的母核;与四元环或五元环和氮原子在环内或环外存在差异的环戊胺、环己胺、哌啶、吡咯烷四种含氮结构通过酰化反应的结果来进行对比实验分析,以期探明影响酰化反应的原因。结果甘草次酸可以和4种含氮结构正常进行酰化化反应,得到4个未见报道新结构,而齐墩果酸与其只能生成"齐墩果酸-HOBt"中间体活化酯,无法得到最终目标物。结论本实验揭示三萜类羧基酰化主要与其自身母核的空间位阻有关,而含氮杂环对酰化反应影响较小,本实验对今后三萜类羧基开展类似的酰化反应具有借鉴意义。更多还原

【Abstract】 OBJECTIVE To investigate the effect of steric hindrance on the acylation reaction of pentacyclic triterpenoids,taking glycyrrhetinic acid and oleanolic acid as examples. METHODS The parent nucleus of glycyrrhetinic acid and oleanolic acid were selected,for which the steric hindrance is different at the two carboxyl sites: one is non-angle,another is angle. The parent nucleus were combined with cyclopentylamine,cyclohexylamine,piperidine,and pyrrolidine,respectively. The four simple nitrogen-containing heterocycles are distinct from the four-membered or five-membered ring and the nitrogen atom is inside or outside the ring. By means of comparing and analyzing the acylation reaction results,the reasons influencing acylation reactions were explored. RESULTS Glycyrrhetinic acid had acylation reaction with four simple nitrogen-containing heterocycles normally,whereas oleanolic acid only formed a kind of intermediate active ester,"oleanolic acid-HOBt",and no final target object could be obtained. CONCLUSION The effect of nitrogen-containing heterocycles on the acylation reaction is almost negligible,while the steric hindrance of different parent nucleuses has significant influence on the acylation reaction. This study is of reference significance for the acylation reaction of triterpenoid carboxyl groups.更多还原