In order to find new pyrrole pesticides, twenty one new pyrrole compounds based on the structure of fludioxonil were designed and synthesized. And a methyl group was introduced into the pyrrole ring to explore the effect of N-position substituent on the activity. All the structures of target products and intermediates were characterized and confirmed by H-1 NMR, FTIR, and single crystal X-ray diffraction, HRMS, elemental analysis and melting point determination. The single crystals of sixteen final products were obtained by volatilizing at room temperature. The antibacterial activity test results on the five pathogens show that under the concentration of 10 mg/L, 4-(2-chlorophenyl)-1H-pyrrole-3-carbonitrile (4b), 4-(2-bromopheny)-1H-pyrrole-3-carbonitrile (4c), 4-(2-(trifluoromethyl)phenyl)-1H-pyrrole-3-carbonitrile (4d), 4-(2-chloro-3-fluorophenyl)-1H-pyrrole-3-carbonitrile (4g), and 4-(2,3-dichlorophenyl)-1H-pyrrole-3-carbonitrile (4h) showed even better or higher antibacterial effect on the four pathogens, the inhibitory effect of compound 4g on the three pathogens at a concentration of 1 mg/L also reached more than 80%. The target compounds substituted with methyl at the nitrogen position showed specific antibacterial activity against Rhizoctonia solani. In order to develop more effective antifungal compounds against Rhizoctonia solani, the three-dimensional quantitative structure activity relationship (3D-QSAR) study on the activity of 20 compounds against Rhizocionia solani was preliminary conducted using comparative molecular force field analysis (CoMFA). A CoMFA model (q(2) =0.503. r(2) -0.974) was established, which showed good predictive ability, and also provided theoretical support for the further optimization of this series of compounds.
