Abstract

Introduction: After using insecticides over many years, the resistance and environmental issues have become great challenges to crop protection. Modern agriculture calls for new insecticidal candidates. Phthalic diamide insecticide containing adjacent two amide group were favored for its new mode of action. Most chemical optimizations of phthalic diamide insecticide focused on amide groups. Modifications on phenyl part including fewer substituent types.

Objective: The objective of this article was to investigate the insecticidal activities variation by alter the orientation and distance of two amide by replace the phenyl part with oxydibenzene and diphenyl-amine.

Results: The target compounds were synthesized by using Cu/CuI catalyzed Ullmann coupling and sulfonyl-O-acryl mixed-anhydride as reactive intermediate. All target compounds were evaluated against armyworm (Mythimna sepatara). Two of synthetic compounds containing multifluoro-alkoxyl substituent showed mortality rate of 100% at 500 mg L^-1. DFT-based Potential energy surface scanning showed that the relative energies of three conformations of insecticidal compounds were very similar.

Conclusion: We designed, synthesized and characterized seventeen novel compounds for the insecticidal candidates. Two of them were found to be insecticidal. A preliminary structure-activity relationship showed that the multifluoro-alkoxyl groups on the benzene were preferred. The compound d5 could be a lead compound for further research.

Keywords: Activity, diamide, diphenylamine, oxydibenzene, ullmann, phthalic diamide.

Graphical Abstract