Design, Synthesis, and Fungicidal Activity of a New Class of Thiadiazolylpyrimidine Carboxamide Derivatives Against...

Effectively managing phytopathogenic fungi, which can swiftly infect a variety of crops and potentially evolve resistance to common commercial fungicides, presents substantial challenges. Rice sheath blight, caused by Rhizoctonia solani Kuhn, imperils over half of the global population and poses a severe economic threat to rice production. This disease, exacerbated by a dearth of resistance genes, intensified nitrogen fertilizer application, and the proliferation of high-yielding cultivars, is prevalent in India and beyond. Given the urgent need for novel bioactive compounds, pyrimidine derivatives have emerged as promising candidates due to their diverse biological activities. In this study, thiadiazolylpyrimidines bearing amide moieties (7a-r) were synthesized in satisfactory yields with the aim of discovering potent antifungal agents. Subsequently, their efficacy against R. solani was evaluated in vitro. Notably, compounds 7a, 7f, and 7k exhibited moderate activity, and compound 7o exhibited excellent inhibition of fungal growth, recording percent inhibitions of 50.00, 37.70, 55.70, and 100.00, at the concentration of 150 ppm, respectively.