Synthesis, Insecticidal Activity, Crystal Structure, and Molecular Docking Studies of Nitenpyram Analogues with an ω-Hydroxyalkyl Ester Arm Anchored on the Tetrahydropyrimidine Ring

摘要

On the basis of the research of the proposed modes of action between neonicotinoids and insect nicotinic acetylcholine receptor (nAChR), a new series of nitenpyram analogues with an ω-hydroxyalkyl ester arm anchored on the tetrahydropyrimidine ring was designed and synthesized to. further enhance the strength of the hydrogen-bonding action they display in binding with the nAChR. The structures of the target compounds were characterized by ~1H NMR, IR, and elemental analysis, and the cis configuration was confirmed by X-ray diffraction. Preliminary bioassays indicated that all of the nitenpyram analogues exhibited good insecticidal activity against Nilaparvata lugens and Myzus persicae at 100 mg/L, whereas analogues 4d and 6a afforded the best in vitro activity that had >95% mortality at 4 mg/L; the LC_(50) values of the analogues 4d and 6a were 0.170 and 0.154 mg/L, respectively. Structure-activity relationship (SAR) studies suggested that their insecticidal potency was also dual-controlled by the flexibility and size of the molecule. In addition, molecular docking simulations revealed that analogues 4d and 6a displayed stronger hydrogen-bonding action in binding with the nAChR, which explained the SARs observed in vitro and implied that the designed nitenpyram analogues are both practical and feasible.