Synthesis and Fungicidal Activity of Novel Substituted Pyrimidine-5-carboxamides Bearing Cyclopropyl Moiety
In order to develop novel pyrimidine compounds with excellent fungicidal activity,thirteen N-substituted phenyl-2-cyclopropyl-4-methylpyrimidine-5-carboxamides and three analogues without cyclopropyl moiety were designed and synthe-sized by means of the active substructure splicing method.The structures of target compounds were characterized by 1H nuclear magnetic resonance(1H NMR),13C nuclear magnetic resonance(13C NMR),infrared spectrometry(IR)and high-resolution mass spectra(HRMS).The preliminary fungicidal activities against plant fungi were evaluated,and the result revealed that some compounds exhibited high activity at a concentration of 100 mg/L.For example,N-(4-chlorophenyl)-2-cyclopropyl-4-methylpyrimidine-5-carboxamide(4e),N-(4-brorophenyl)-2-cyclopropyl-4-methylpyrimidine-5-carboxamide(4h)and N-(3,4-dichlorophenyl)-2-cyclopropyl-4-methylpyrimidine-5-carboxamide(4k)showed inhibitory rates of 87.9％,84.4％and 85.2％against Botrytis cinerea,respectively,and 4k showed inhibitory rate of 84.6％against Sclerotinia scleroti-orum.Further bioassay indicated that 4k possessed a lower effective concentration value of 4.67 mg/L,which meant that its activity was comparable to that of cyprodimol and was higher than that of boscalid.A bioactivity comparison between target compounds and the analogues without cyclopropyl moiety,demonstrated that the intrduction of cyclopropyl to the pyrimidine ring is beneficial for improving the fungicidal activity.
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