Synthesis And Bioactivities Of Neonicotinoids Containing Pyrrole Or Azebridged Heterocyclic Rings

Neonicotinoids were the fourth-generation insecticides and shared about one quarter of the worldwide market. Pyrrole-and azebridged-congtaining neonicotinoids were previously discovered in Professor Li’s group with excellent insecticidal activities, but their improper properties promoted us to undertake further modification. Therefore, novel pyrrole-or azebridged-heterocyclic neonicotinoids were prepared aiming at exploring the factors influencing the activity and improving physical and chemical properties.1. Pyrrole fused neonicotinoids:dihydropyrrole-fused diol was constructed by nitromethylene analogue of imidacloprid and glyoxal via nonsolvent and noncatalyst method. Twenty-nine derivatives were obtained by selective etherification and esterification, diversifying and increasing analogues. Most of them exhibited excellent insecticidal activities against cowpea aphid (Aphis craccivora), brown planthopper (Nilaparvata lugens) and army worm (Mythimna separata), particularly, some compounds improved the bioactivity against army worm in comparison to cycloxaprid.2. Azabridged heterocyclic neonicotinoids:fourteen seven-membered azebridged neonicotinoids and eleven eight-membered azebridged neonicotinoids were constructed by nitromethlene analogue of imidacloprid, succinaldehyde or glutaraldehyde and corresponding primary amine via’one-pot’method, which changed the type of heterocyclic rings and the size of azebridged ring. The appropriate catalysts were screened to synthesize the target compounds for improving yields. Most of the azebridged compounds displayed excellent bioactivities against cowpea aphid, brown planthopper and army worm. Compound IPP197715 exhibited obvious bioactivity against cowpea aphid at 4 mg L-1. According to the stability test, pyridyl substituted compound IPP197702 remaining 52% after 293.5h in water, which was more stable than phenyl substituted lead compound IPP167225 (T1/2=1.89 h).