We have synthesized dendroamide A and three new analogs having a differently oriented azole moiety to reveal the effect of the orientation of the azole rings on the P-glycoprotein inhibitory activity. The appropriate assembly of modified azole units and dimers from natural-type azole units is examined. Although linear trimers including a modified thiazole unit were hard to cyclize compared with a derivative containing a modified oxazole unit, the yields of cyclization were successfully improved by changing the reaction conditions or the position of ring closure. Evaluation of P-glycoprotein inhibitory activity also reported.

中文翻译：

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Dendroamide A和三个具有反向唑环作为P-糖蛋白抑制剂的区域异构体的合成和评价

我们已经合成了树状酰胺A和三个新的类似的具有不同取向的唑部分的类似物，以揭示吡咯环的取向对P-糖蛋白抑制活性的影响。检查了改性的唑单元和天然型吡咯单元的二聚体的适当组装。尽管与包含修饰的恶唑单元的衍生物相比，包含修饰的噻唑单元的线性三聚体难以环化，但是通过改变反应条件或闭环位置可以成功地提高环化的产率。还报道了对P-糖蛋白抑制活性的评估。