Design, synthesis, and evaluation of new 4(3H)‐quinazolinone derivatives containing a pyrazole carboxamide moiety

Abstract

AbstractA total of 15 new 4(3H)‐quinazolinone derivatives containing a pyrazole carboxamide moiety were designed and synthesized in this study. The structures of the target compounds were elucidated using 1H NMR, 13C NMR, MS, and elemental analysis. Then, antifungal activities against Gibberella zeae (G. zeae), Fusarium oxysporum (F. oxysporum), Cytospora mandshurica (C. mandshurica), Phytophthora infestans (P. infestans), and Pellicularia sasakii (P. sasakii) as well as antibacterial activities against Ralstonia solanacearum (R. solanacearum) and Xanthomomu oryzae pv. oryzae (Xoo) were assayed. Bioassay results revealed that the target compounds have certain antifungal and antibacterial activities. Especially, compound 5‐chloro‐1,3‐dimethyl‐N‐(2‐(4‐oxo‐2‐(m‐tolylamino)quinazolin‐3(4H)‐yl)ethyl)‐1H‐pyrazole‐4‐carboxamide (7g) exhibited better antibacterial activities against R. solanacearum (60%) and Xoo (53%) than those of thiodiazole‐copper (52% and 38%, respectively) at 200 μg/ml. This study provided a practical tool for guiding the design and synthesis of novel and more promising active small molecules of 4(3H)‐quinazolinone derivatives containing a pyrazole carboxamide moiety for controlling plant bacterial and fungal diseases.