Design, Synthesis, and Herbicidal Activities of 3-Aryl-4-substituted-5-[3-(trifluoromethyl)phenoxy]-1,2,4-triazoles

• Published in: Journal of heterocyclic chemistry 2014-08, Vol.51 (S1), p.E335-E339
• Main Authors: Liu, Man-Yun, Shi, De-Qing
• Format: Article
• Language: English
• ISSN: 0022-152X; 1943-5193
• DOI: 10.1002/jhet.1920

In order to find novel bleaching herbicide lead compounds, a series of novel 3‐aryl‐4‐substituted‐5‐[3‐(trifluoromethyl)phenoxy]‐1,2,4‐triazoles were designed and synthesized by the multi‐step reactions. N‐(Arylformamido)phenylthioureas undergo ring closure in the presence of sodium hydroxide to generate 3‐aryl‐4‐substituted‐4H‐[1,2,4]triazol‐5‐thiols 1, which reacted with methyl sulfate in the presence of K2CO3 to give 3‐aryl‐5‐methylsulfanyl‐4‐substituted‐4H‐[1,2,4]triazoles 2. The target compounds 4 were synthesized by the oxidation of 2 in the presence of H2O2 and Na2WO4, followed by the substitution with 3‐(trifluoromethyl)phenol in moderate to good yields. Their structures were confirmed by IR, 1H NMR, EI–MS, and elemental analyses. The preliminary bioassay indicated that some of them displayed moderate to good selective herbicidal activity against Brassica campestris L at the concentration of 100 µg/mL. Compounds 4c and 4i possessed 75.0% and 82.6% inhibition against Brassica campestris L at the concentration of 100 µg/mL. However, the target compounds 4 showed weak herbicidal activity against Echinochloa crus‐galli at the concentration of 100 and 10 µg/mL.