Antifungal agents. Part 5: synthesis and antifungal activities of aminoguanidine derivatives of N-arylsulfonyl-3-acylindoles.

In order to discover more promising antifungal agents, a series of aminoguanidine derivatives of N-arylsulfonyl-3-acylindoles (5a-r) were prepared and evaluated in vitro for their antifungal activities against seven phytopathogenic fungi. Especially compounds 5n and 5o exhibited more potent antifungal activities than or comparable to hymexazol, a commercially available agricultural fungicide at the concentration of 100 μg/mL. Preliminary structure-activity relationships study demonstrated that introduction of electron-donating substituents R(1) and R(2), and the proper length of substituent R(3) were usually very important for their antifungal activities.