Synthesis and biological evaluation of novel pyridylpyrazole amides containing benzothiazole/thiourea/urea motif as pesticidal agents

A series of novel pyridylpyrazole amide compounds which contain benzothiazole, thiourea, and urea moieties, respectively, were successfully synthesized. Their structures were confirmed by IR, ¹H NMR, ¹³C NMR, and HRMS. Some of the compounds were found to have favorable insecticidal potentials; particularly, the insecticidal activities of 3-chloro-1-(3-chloropyridin-2-yl)-<i>N</i>-(6-(trifluoromethyl)benzo[<i>d</i>]thiazol-2-yl)-1<i>H</i>-pyrazole-5-carboxamide (<b>3b</b>), 1-(3-chloropyridin-2-yl)-<i>N</i>-(4,6-dichlorobenzo[<i>d</i>]thiazol-2-yl)-3-(trifluoromethyl)-1<i>H</i>-pyrazole-5-carboxamide (<b>3g</b>), 3-bromo-<i>N</i>-(4-chloro-2-(3-ethylthioureido)phenyl)-1-(3-chloropyridin-2-yl)-1<i>H</i>-pyrazole-5-carboxamide (<b>6e</b>), 3-bromo-<i>N</i>-(4-chloro-2-(3-isopropylthioureido)-6-methylphenyl)-1-(3-chloropyridin-2-yl)-1<i>H</i>-pyrazole-5-carboxamide (<b>6g</b>), 3-bromo-1-(3-chloropyridin-2-yl)-<i>N</i>-(2-(3-isopropylureido)-6-methylphenyl)-1<i>H</i>-pyrazole-5-carboxamide (<b>7c</b>), 3-bromo-<i>N</i>-(4-chloro-2-(3-isopropylureido)phenyl)-1-(3-chloropyridin-2-yl)-1<i>H</i>-pyrazole-5-carboxamide (<b>7d</b>), 3-bromo-<i>N</i>-(4-chloro-2-(3-isopropylureido)-6-methylphenyl)-1-(3-chloropyridin-2-yl)-1<i>H</i>-pyrazole-5-carboxamide (<b>7f</b>), and 3-bromo-<i>N</i>-(2-(3-(tert-butyl)ureido)-4-chloro-6-methylphenyl)-1-(3-chloropyridin-2-yl)-1<i>H</i>-pyrazole-5-carboxamide (<b>7g</b>) were close to and even superior to those of the insecticide triflumuron toward diamondback moth, and can be used as novel insecticidal leading structures for further investigations. Some of the compounds showed good fungicidal potentials against a broad spectrum of tested fungi including <i>Sclerotinia sclerotiorum</i>, <i>Cercospora arachidicola</i>, <i>Physalospora piricala</i> and <i>Rhizoctonia cerealis</i>, and were comparable with the commercial fungicide controls, among others, <b>3b</b>, 3-bromo-1-(3-chloropyridin-2-yl)-<i>N</i>-(6-(trifluoromethyl)benzo[d]thiazol-2-yl)-1<i>H</i>-pyrazole-5-carboxamide (<b>3d</b>), and <i>N</i>-(4-chloro-2-methyl-6-(3-methylthioureido)phenyl)-1-(3-chloropyridin-2-yl)-3-(trifluoromethyl)-1<i>H</i>-pyrazole-5-carboxamide (<b>6i</b>) could serve as novel fungicidal leading compounds for further research. The structure-activity relationships were analyzed and discussed in detail. This research provides useful information for the design and discovery of novel insecticidal/fungicidal agents.