Abstract
Positional isomers of various aromatic heterocyclic carboxamides were synthesized and their fungicidal activity was examined. Among them, N-(biphenyl-2-yl) and N-[2-(1,3-dimethylbutyl)-3-thienyl]-1-methyl-3-CF3-pyrazole-4-carboxamides showed high activity against gray mold, while their corresponding 5-CF3 carboxamide isomers showed no fungicidal activity. Similar results were observed for carboxamide isomers containing CF3-thiazole as well as methyl-substituted thiophene and furan derivatives. Docking studies were performed on these carboxamides with a fungus succinate dehydrogenase homology model. Based on our docking study, we proposed a model for the interaction between carboxamides and a conserved histidine residue in succinate dehydrogenase.
