Abstract:
In order to find novel succinate dehydrogenase inhibitors, based on the previous discovery of the pyrazole-benzoic scaffold, the scaffold hopping strategy was used to design and synthesize 18
N-substitutedphenyl-4-(1-methyl)-1
H-pyrazol-5-yl)thiophene-2-carboxamide derivatives (
3a -
3n ,
4a -
4d ), of which 17 are new compounds. Their structures were confirmed by
1H NMR,
13C NMR and HRMS . The fungicidal activity test
in vitro showed that some compounds had good activity against
Fusarium graminearum,
Alternaria solani and
Botrytis cinerea. Among them, the EC
50 values of compound
3k and
4d against
F. graminearum were 18.5 mg/L and 14.3 mg/L, respectively. The EC
50 value of compound
4d against
A. solani was 15.7 mg/L. It was higher than 27.8 mg/L of thiafluzamide. The EC
50 value of compound
3k and
3m against
B. cinerea were 15.3 mg/L and 9.9 mg/L, which was equivalent to that of the control agent thiafluzamide (EC
50 10.4 mg/L). The molecular docking study revealed that strong hydrogen bond was formed between the compound
N-(4-fluorophenylethyl)-4-(1-methyl-1
H-pyrazol-5-yl) thiophene-2-carboxamide (
3m ) and succinate dehydrogenase (SDH).