Functionalized pyrimidines: Synthesis, characterization, structure-activity relationship and insecticidal evaluation of some new neonicotinoid analogues against cotton aphid

Seven novel pyrimidine derivatives were synthesized through a one-pot three-component reaction involving cyanoguanidine, ethylcyanoacetate, and various aromatic aldehydes. The chemical structures of these newly synthesized pyrimidine compounds were confirmed by using both elemental and spectral analysis. All compounds feature the characteristic NCN group, which is a defining trait of neonicotinoid insecticides. Given this structural feature, these compounds were selected for testing their toxicological activity against one of the major pests affecting cotton crops, Aphis gossypii, which is responsible for significant cotton yield loss. Neonicotinoid insecticides are known for their effectiveness in controlling this pest. Insecticidal activity was evaluated by testing five different concentrations of each compound against both adults and nymphs of A. gossypii. Laboratory results indicated that compounds 2 and 6 exhibited the highest levels of activity against both adults and nymphs of A. gossypii pest. These findings suggest that these compounds may offer potential as new analogues within the neonicotinoid insecticide class for controlling cotton aphids.