Synthesis and structure–activity relationships of carbohydrazides and 1,3,4‐oxadiazole derivatives bearing an imidazolidine moiety against the yellow fever and dengue vector, Aedes aegypti

BACKGROUND 1,3,4‐Oxadiazole and imidazolidine rings are important heterocyclic compounds exhibiting a variety of biological activities. In this study, novel compounds with oxadiazole and imidazolidine rings were synthesized from 3‐(methylsulfonyl)‐2‐oxoimidazolidine‐1‐carbonyl chloride and screened for insecticidal activities. The proposed structures of the 17 synthesized compounds were confirmed using elemental analysis, infrared (IR), proton nuclear magnetic resonance (1H‐NMR), and mass spectroscopy. RESULTS None of the compounds showed larvicidal activity at the tested concentrations against first‐instar Aedes aegypti larvae. However, nine compounds exhibited promising adulticidal activity, with mortality rates of ≥80% at 5 µg per mosquito. Further dose–response bioassays were undertaken to determine median lethal dose (LD50) values. Compounds 1, 2b, 2c, 2d, 2 g, 3b, 3c, 3 g, and 3 h were effective, with typical LD50 values of about 5 − 10 µg per mosquito against female Ae. aegypti. Compounds 2c (bearing a nitro group on the aromatic ring; LD50 = 2.80 ± 0.54 µg per mosquito) and 3 h (double halogen groups at 2,4 position on the phenyl ring; LD50 = 2.80 ± 0.54 µg per mosquito) were the most promising compounds. CONCLUSION Preliminary mode of action studies failed to show consistent evidence of either neurotoxic or mitochondria‐directed effects. Further chemical synthesis within this series may lead to the development of new effective insecticides. © 2017 Society of Chemical Industry The recent outbreak of Zika virus infection has accelerated research for novel mosquito control agents. Therefore, seventeen novel compounds containing oxadiazole and imidazolidine rings were synthesized and evaluated for larvicidal and adulticidal activity against Ae. aegypti.