Antifungal agents. Part 4: Synthesis and antifungal activities of novel indole[1,2-c]-1,2,4-benzotriazine derivatives against phytopathogenic fungi in vitro.

A series of novel indole[1,2-c]-1,2,4-benzotriazine derivatives were obtained by a modified Sandmeyer reaction in the presence of tert-butylnitrite (t-BuONO). As compared with hymexazol, a commercially available agricultural fungicide, at the concentration of 50 μg/mL, two indole[1,2-c]-1,2,4-benzotriazines, 5h and 5k, exhibited the more promising and pronounced antifungal activities in vitro against five phytopathogenic fungi. It clearly demonstrated that introduction of appropriate substituents on the indolyl ring of indole[1,2-c]-1,2,4-benzotriazine (5a) would lead to the more potent derivatives.