N-Phenyl heteroarylamine analogues of fluazinam using the intermediate derivatization methods approach

Twenty-one N-phenyl heteroarylamine analogues of fluazinam 3a–3u were prepared via nucleophilic substitution reaction of 2,6-dichloro-3,5-dinitrotoluene with heteroarylamines using the intermediate derivatization method. 2,6-Dichloro-3,5-dinitrotoluene, the key intermediate, was synthesized by nitration of 2,6-dichlorotoluene. The synthesized compounds were identified by 1H NMR, 13C NMR, MS and elemental analyses. Preliminary bioassays indicated that most of the compounds showed good fungicidal activity against rice blast. The activity of 3p was equal to that of fluazinam. The relationship between molecular structure and biological activity suggested that introduction of electron-withdrawing groups in the pyridine ring was important for optimizing fungicidal activity against rice blast.