Synthesis of diaryl-azo derivatives as potential antifungal agents.

As compared with a commercially available agricultural fungicide hymexazol, some phenyl-azo phenol derivatives (e.g., 4a, 4b, 4f, 4n, 4q, 4u, and 4v) exhibited the more promising and pronounced antifungal activities in vitro against seven phytopathogenic fungi. It seemed that 4-((un)substituted phenylazo)-phenol and 4-((un)substituted phenylazo)-3-methylphenol might be considered as new lead structures for further design of agricultural fungicides.