Design, Synthesis, and Insecticidal Activity of Novel meta-Diamide Compounds Bearing a Phthalimide as a Potential GABA Receptor Antagonist

In pursuit of potent and environmentally benign insecticides targeting the γ-aminobutyric acid (GABA) receptor, a series of novel meta-diamide compounds bearing a phthalimide were rationally designed and synthesized. Bioassay studies revealed that most of the target compounds exhibited promising larvicidal activity against Mythimna separata (M. separata) and Plutella xylostella (P. xylostella). Notably, the most active compound N15 displayed exceptional potency with LC50 values of 3.82 and 3.42 mg·L–1 against M. separata and P. xylostella, respectively. Electrophysiological studies using Xenopus oocytes confirmed that compound N15 exerted its insecticidal activity by targeting the GABA receptors.