Design, Synthesis, Antibacterial, and Antifungal Activity Evaluation of Novel Pyrimidine Derivatives Incorporating Amide and 1,3,4-Thiadiazole Thioether Moieties

In this study, a series of novel pyrimidine derivatives incorporating amide and 1,3,4-thiadiazole thioether moieties were synthesized and their structures were confirmed using 1H NMR, 13C NMR, and HRMS analyses. Bioassay results demonstrated that compound 2-{[4-methyl-6-(trifluoromethyl)pyrimidin-2-yl]thio}-N-[5-(propylthio)-1,3,4-thiadiazol-2-yl]acetamide exhibited superior antibacterial activity against Xanthomonas oryzae pv. oryzae (Xoo), with an inhibition rate of 100% at a concentration of 200 μg/mL, compared to thiodiazole copper. Meanwhile, compound 2-[(4,6-dimethylpyrimidin-2-yl)thio]-N-[5-(ethylthio)-1,3,4-thiadiazol-2-yl]acetamide displayed remarkable antifungal activity against Gilbertella persicaria (G. persicaria), with an EC50 value of 6.71 μg/mL, surpassing that of prochloraz. To the best of our knowledge, this study represents the first report on the synthesis and bioactivity evaluation of pyrimidine derivatives incorporating amide and 1,3,4-thiadiazole thioether moieties.