Succinate dehydrogenase (SDH), a pivotal enzyme linking the respiratory electron transport chain and tricarboxylic acid (TCA) cycle, has been identified as an ideal target for developing effective fungicides. In this study, 20 novel trifluoromethyl pyrimidine derivatives containing 1,3,4-oxadiazole and thioether moieties were prepared and characterized their structures by ¹H NMR, ¹³C NMR, and HRMS. Bioassay results showed that some of the target compounds revealed moderate to good in vitro antifungal activities toward Rhizoctonia solani (R. solani), Botryosphaeria dothidea (B. dothidea), Phomopsis sp., Botrytis cinerea (B. cinerea), Fusarium oxysporum (F. oxysporum), Sclerotinia sclerotiorum (S. sclerotiorum), Phytophthora infestans (P. infestans), and Magnaporthe oryzae (M. oryzae). In particular, compounds 6g and 6i had better in vitro antifungal activity against B. cinerea, with the EC₅₀ values of 19.43 and 28.22 μg/mL, respectively, than that of Pyrimethanil (57.30 μg/mL). As well, compound 6r exhibited good in vitro antifungal activity against F. oxysporum, with the EC₅₀ value of 3.61 μg/mL, which were lower than that of Boscalid (0.40 μg/mL). In addition, the molecular docking simulation revealed that compound 6r interacted with GLN-150, ASP-153, LYS-151, GLY-154, and GLY-228 of SDH through hydrogen bond, which could explain the probable mechanism of action between the target compounds and SDH. This is the first report on the antifungal activity of novel trifluoromethyl pyrimidine derivatives containing 1,3,4-oxadiazole and thioether moieties as potential SDH inhibitors.

中文翻译：

---

作为潜在琥珀酸脱氢酶抑制剂的含有 1,3,4-恶二唑和硫醚部分的新型三氟甲基嘧啶衍生物的设计、合成、抗真菌活性和分子对接

琥珀酸脱氢酶（SDH）是一种连接呼吸电子传递链和三羧酸（TCA）循环的关键酶，已被确定为开发有效杀菌剂的理想靶点。在本研究中，制备了20种含有1,3,4-恶二唑和硫醚部分的新型三氟甲基嘧啶衍生物，并通过¹ H NMR、¹³ C NMR和HRMS表征了它们的结构。生物测定结果表明，部分目标化合物对立枯丝核菌（R. solani）、葡萄孢菌（B. dothidea）、拟茎点霉（ Phomopsis sp.）、灰葡萄孢（ Botrytis cinerea）具有中等至良好的体外抗真菌活性。B. cinerea )、尖孢镰刀菌( F. oxysporum )、核盘菌( S. sclerotiorum )、致病疫霉( P. infestans ) 和稻瘟病菌( M. oryzae )。特别是，化合物6g和6i对灰霉病菌具有更好的体外抗真菌活性，其EC ₅₀值分别为19.43和28.22 μg/mL，优于嘧霉胺(57.30 μg/mL)。此外，化合物6r对F. oxysporum表现出良好的体外抗真菌活性，EC 值₅₀值为3.61 μg/mL，低于啶酰菌胺（0.40 μg/mL）。此外，分子对接模拟显示化合物6r与SDH的GLN-150、ASP-153、LYS-151、GLY-154和GLY-228通过氢键相互作用，这可以解释化合物6r之间可能的作用机制。目标化合物和SDH。这是关于含有 1,3,4-恶二唑和硫醚部分的新型三氟甲基嘧啶衍生物作为潜在 SDH 抑制剂的抗真菌活性的第一份报告。