Isoxazole-containing neonicotinoids: Design, synthesis, and insecticidal evaluation

Area of Science:

• Organic Chemistry
• Agricultural Science
• Entomology

Background:

• Neonicotinoids are widely used insecticides, but resistance and environmental concerns necessitate new chemical classes.
• Isoxazole derivatives offer a promising scaffold for developing novel insecticidal compounds.

Purpose of the Study:

• To synthesize and characterize novel isoxazole-containing neonicotinoids.
• To evaluate the insecticidal activity of these novel compounds against key agricultural pests.

Main Methods:

• Synthesis of isoxazole neonicotinoids via condensation of nitromethylene analogues and aromatic aldehydes.
• Catalysis using l-proline and potassium carbonate (K₂CO₃).
• Bioassays conducted against brown planthopper (Nilaparvata lugens) and cowpea aphid (Aphis craccivora).

Main Results:

• Several synthesized compounds demonstrated 40-70% mortality against brown planthoppers at 4mgL^-1, exceeding imidacloprid's 20% efficacy.
• The most active compounds achieved up to 90% mortality against cowpea aphids at 20mgL^-1.

Conclusions:

• The synthesized isoxazole neonicotinoids exhibit significant insecticidal potential.
• These compounds represent promising alternatives to existing insecticides for pest management.