Synthesis and fungicidal activity of 2-(methylthio)-4-methylpyrimidine carboxamides bearing a carbamate moiety

A series of 1-[2-(4-methyl-2-(methylthio)pyrimidine-5-carboxamido)phenyl]ethyl-substitutedphenyl carbamates (3a–3i) were designed and synthesized, using 4-methyl-2-(methylthio)pyrimidine-5-carboxylic acid, (2-aminophenyl)ethan-1-one, and substituted phenyl isocyanates as starting materials. Their structures were characterized by 1H NMR, 13C NMR, IR and HRMS. The in vitro fungicidal activities against Sclerotinia sclerotiorum were evaluated, and the result showed that some compounds displayed moderate antifungal activity with >60% inhibitory rates, among which 1-[2-(4-methyl-2-(methylthio)pyrimidine-5-carboxamido)phenyl] ethyl-(2- methyl phenyl)carbamate (3a) and 1-[2-(4-methyl-2-(methylthio)pyrimidine-5- carboxamido)phenyl] ethyl-(3-trifluoromethyl phenyl)carbamate (3g) held inhibitory rates of 69.5% and 70.3% at 100 mg/L, respectively. Molecular docking study showed that 3g can form two hydrogen bonds and a cation-π interaction with succinate dehydrogenase.