Design, synthesis and biological activities of new strobilurin derivatives containing substituted pyrazoles

BACKGROUND: Strobilurins are one of the most important classes of agricultural fungicides. To discover new strobilurin analogues with high activity, a series of new strobilurin derivatives containing substituted pyrazoles in the side chain were synthesised and bioassayed. RESULTS: The compounds were identified by (1)H NMR, IR, MS and elemental analysis. Preliminary bioassays indicated that some title compounds exhibited excellent fungicidal activities against Pseudoperonospora cubensis (Burk. & Curt.) Rostovsev and Erysiphe graminis DC f. sp. tritici Marchal, protecting cucumber and wheat at 6.25 and 1.56 mg L(-1) respectively, and showed a moderately high acaricidal activity against Tetranychus cinnabarinus (Boisd.) at 20 mg L(-1). The relationship between structure and biological activity is discussed in terms of effects of the substituent of the pyrazole ring. CONCLUSION: The present work demonstrates that strobilurin analogues with substituted phenylpyrazolylmethoxymethyl side chains can be used as possible lead compounds for further developing novel fungicides and acaricides.