Design, synthesis, insecticidal assay and binding mode study of benzopyrazole derivatives

Based on the recently reported structure of highly active mesoionic nAChR modulators, 30 novel benzopyrazole compounds were designed and synthesized through scaffold hopping. Their structures were confirmed by ¹H NMR, ¹³C NMR and HRMS. Insecticidal activity assays revealed compounds A1 , A7 , A16 and A22 showed about 40% mortality against Aphis craccivora at the concentration of 500 mg/L, however still less active than lead compound 1 . Preliminary analysis suggests similar binding modes for mesoionic and non-mesoionic structures, and the differences in their physicochemical properties and electrostatic potential surface between A1 and compound 1 may be the main reason for the lower activities of the target compounds than that of compound 1 .