Design, synthesis, nematicidal and fungicidal activities of imidazo [1,2-a] pyridine derivatives containing amino acids

In this study, thirty-two 8-chloro-6-(trifluoromethyl) imidazo [1,2-a] pyridine derivatives were designed and synthesized. Their nematicidal and fungicidal activities were systematically evaluated. In vitro assays revealed that compounds 1 (LC 50 = 61.34 mg/L) and 10 (LC 50 = 40.31 mg/L) exhibited greater activity against Caenorhabditis elegans than fosthiazate (LC 50 = 73.26 mg/L). In vivo testing against Meloidogyne incognita demonstrated superior efficacy for compounds 10 (67.44 %, 75.58 %, 83.72 %) and 18 (64.19 %, 77.21 %, 87.79 %) at concentrations of 50, 100, and 200 mg/L, respectively, outperforming fluopyram (44.65 %, 64.19 %, 80.47 %). Compounds 13 (EC 50 = 3.33 mg/L) and 29 (EC 50 = 25.62 mg/L) also displayed significantly enhanced antifungal activity against Rhizoctonia solani compared to fluopyram (EC 50 = 112.74 mg/L) in vitro . In pot assays, compound 13 provided 83.95 % and 91.26 % protection at 100 and 200 mg/L, respectively, comparable to carbendazim (86.90 % and 96.67 %). The effects of substituent type and position on biological activity were investigated, and preliminary structure–activity relationships were summarized. This work represents the first report of amino acid-containing imidazo [1,2-a] pyridine derivatives exhibiting both potent nematicidal and fungicidal activities, laying a foundation for future development of novel agrochemicals.