Design, Synthesis and Biological Evaluation of Isothiazole Based 1,2,4-Trizaole Derivatives

A series of novel 3,4-dichloroisothiazole based 1,2,4-triazole derivatives were rationally designed and synthesized. Their structures were confirmed by H-1 NMR, C-13 NMR, HRMS or elemental analysis; the typical crystal structure was determined by X-ray diffraction for validation. All target compounds were evaluated for their in vitro fungicidal and in vivo anti-TMV activities. The bioassay results indicated that compound 6b, namely 1-(3,4-dichloroisothiazol-5-yl)-1-(4-fluorophenyl)-2-(1H-1,2,4-triazol-1-yl)ethanol, exhibited excellent growth inhibition against B. cinerea, C. arachidicola and P. piricola with median effective concentrations (EC50) of 6.98, 2.73 and 3.07 g/mL, respectively, and good in vivo anti-TMV activity of over 60% of inactivation and induction activity at 100 g/mL. These data demonstrate that compound 6b is both a fungicide and an anti-TMV lead, deserving further studies.