Synthesis and Fungicidal Activity of (E)‐Methyl 2‐(2‐((1‐cyano‐2‐hydrocarbylidenehydrazinyl)methyl)phenyl)‐2‐(methoxyimino)acetates

BACKGROUND Strobilurin fungicides are some of the most potent and successful agrochemicals. However, continued use of traditional strobilurins has led to the emergence of fungicide‐resistant biotypes. Thus, a supply of new strobilurin fungicides is highly valuable. In this study, a series of novel methoxyacrylate analogs containing a cyano‐substituted hydrazine moiety as the side chain was synthesized and evaluated for their anti‐plant pathogenic activities. RESULTS Compounds 2‐04, 2‐05, 2‐07 and 2‐14 exhibited a relatively broad range of fungicidal activity. Compounds 2‐04, 2‐13 and 2‐14 exhibited good fungicidal activity against Sclerotinia sclerotiorum with median effective concentrations (EC50) of 3.84, 3.50 and 3.80 μg mL−1, respectively. Most of these compounds showed excellent inhibition of spore germination in Magnaporthe grisea at 25 μg mL−1. Moreover, in an in vivo test, compounds 2‐02, 2‐04, 2‐07 and 2‐13 exhibited potent fungicidal activities against the tested plant diseases at 400 μg mL−1. Notably, compound 2‐07 showed comparable or better activity than the commercially positive controls, azoxystrobin and procloraz, against powdery mildew of cucumber and rice blast fungus in the field trails at the same application dosages. CONCLUSON This study indicated that methoxyacrylate analogs containing a cyano‐substituted hydrazone side chain can serve as potential fungicidal candidates for crop protection.