Novel Meta-Diamide Compounds Containing Sulfide Derivatives Were Designed and Synthesized as Potential Pesticides

The meta-diamide (m-diamide) insecticide, Broflanilide, was characterized by its high efficiency, low toxicity and lack of cross-resistance with traditional GABA receptors. In accordance with the principles of drug molecular design, easily derivable sulfur with diverse bioactivities was introduced while leading with the parent Broflanilide. Twelve novel m-diamide target compounds containing sulfide derivatives were synthesized through exploration guided by the literature. Their structures were confirmed by melting points, ¹H NMR, ¹³C NMR and HRMS. Insecticidal activity assessments revealed that most target compounds A-D exhibited 100% lethality against Plutella xylostella (P. xylostella) and Aphis craccivora Koch (A. craccivora) at 500 mg·L^-1. Notably, for P. xylostella, compounds C-2, C-3, C-4 and D-2 demonstrated 60.00-100.00% insecticidal activity even at a concentration as low as 0.625 mg·L^-1. As determined by structure-activity relationship (SAR) analysis, compounds with R₁ = CH₃ and R₂ = Br (B-1, C-2 and D-2) and sulfoxide compound C-3 contained 100.00% lethality against A. craccivora at 500 mg·L^-1, surpassing the lethality when leading with the parent Broflanilide in terms of efficacy. Consequently, it can be inferred that the sulfoxide compound (C-3) requires further investigation as a potential active molecule for new insecticides. These explorations provide valuable references for future research on the synthesis and insecticidal activities of sulfide-containing m-diamide compounds.