Design, Synthesis, Crystal Structures, and Insecticidal Activities of Eight-Membered Azabridge Neonicotinoid Analogues

Three series of novel azabridge neonicotinoid
analogues were designed
and synthesized, which were constructed by starting material A, glutaraldehyde, and primary amine hydrochlorides (aliphatic
amines, phenylhydrazines, and anilines). Most of the eight-membered
azabridge compounds presented higher insecticidal activities than
oxabridged compound B against cowpea aphid (Aphis craccivora) and brown planthopper (Nilaparvata lugens). Compared with imidacloprid,
some azabridged compounds exhibited excellent insecticidal activity
against brown planthopper. The crystal structures and bioassay indicated
that changing bridge atoms from O to N could lead to entirely different
conformations, which might be the important influential factor of
the bioactivities.