Synthesis and Biological Activity of Novel Myrtenal-Derived 2-Acyl-1,2,4-triazole-3-thione Compounds

Sixteen novel myrtenal-derived 2-acyl-1,2,4-triazole-3-thione compounds were designed and synthesized in search of new bioactive compounds. Their structures were confirmed by FTIR, NMR, ESI-MS and elemental analysis. The in vitro antifungal and herbicidal activities of the target compounds were preliminarily evaluated. Some target compounds exhibited favourable antifungal activity at 50 mg/L. Myrtenal-derived 2-(p-methylbenzoyl)-1,2,4-triazole-3-thione (7i) held 83.7% and 72.5% inhibition rates against corn southern leaf blight (Bipolaris maydis) and apple root spot (Physalospora piricola), respectively, and myrtenal-derived 2-(3',5'-dimethylbenzov1)-1,2,4-triazole-3-thione (7j) had 72.5% inhibition rate against P. piricola (the positive control commercial fungicide chlorothalonil with growth inhibition rates of 90.4% and 75.0% against B. maydis and P. piricola, respectively). Besides, most of the target compounds displayed excellent herbicidal activity against the root-growth of rape (Brassica. campestris). At 100 mg/L, 15 compounds held growth inhibition rates in the range of 80.2%similar to 99.1%, exhibiting much better herbicidal activity than that of the commercial herbicide flumioxazin (positive control) with 63.0% growth inhibition rate.