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 LC(50) 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.