Synthesis and biological activity evaluation of novel β-substituted nitromethylene neonicotinoid analogues.

The structure-based design and synthesis of a series of novel neonicotinoid analogues are described. The novel neonicotinoid analogues were designed based upon the reaction of enamine derivatives with electron-withdrawing β-substituents with electrophilic thiocyanogen reagents. These compounds were characterized by spectroscopic methods. Bioassays indicated that some of the synthesized compounds exhibited excellent bioactivity against cowpea aphids (Aphis craccivora). The LC₅₀ values of compounds 7, 9,12, 13, 15, 17, 19, 20 and commercial imidacloprid were 0.01567, 0.00974, 0.02494, 0.01893, 0.02677, 0.01778, 0.0220, 0.02447 and 0.03502 mmol L⁻¹, respectively, which suggested that they could be used as leads for future development of new insecticides.