Synthesis and herbicidal activity of pyrimidyl‐1,2,4‐triazole derivatives containing aryl sulfonyl moiety

Abstract To discover novel heterocyclic compounds with high herbicidal activity, a series of new pyrimidyl‐1,2,4‐triazole derivatives ( Ι‐1 to Ι‐41 ) was designed and synthesized by incorporating the activating 1,2,4‐triazole, pyrimidine, and phenyl sulfonyl structural templets. Their structures were clearly identified by proton nuclear magnetic resonance ( 1 H NMR), carbon‐13 nuclear magnetic resonance ( 13 C NMR), high‐resolution mass spectroscopy (HRMS), and X‐ray single‐crystal diffraction (compound Ι‐3 ). Their herbicidal activities against monocotyledons ( Echinochloa crusgalli , Sorghum bicolor ) and dicotyledons ( Raphanus sativus , Brassica campestris , Cucumis sativus , and Medicago sativa ) were evaluated using a Petri dish culture method. The results indicated that most of title compounds exhibited significant herbicidal potencies against the plant growth at 100 mg·L −1 , while some of them, such as Ι‐2 and Ι‐4 , showed remarkable inhibitory effects on weed control at 10 mg·L −1 and 100 mg·L −1 . On the whole, compound Ι‐3 , which was found to possess an even broader spectrum of inhibitory activities against the roots and stalks of Echinochloa crusgalli , Raphanus sativus , Brassica campestris , Cucumis sativus , and Medicago sativa at 10 and 100 mg·L −1 than that of the commercial herbicide Flumetsulam, could be employed as a new lead structure for further optimization to find more potent herbicides.