Synthesis and insecticidal activity of tenuazonic acid and derivatives

In order to find tetramic acids with high insecticidal activity, the natural product tenuazonic acid (TeA) was used as lead compound, 26 tetramic acid derivatives 4a-4s , 5a-5g , 7a and 8a were designed and synthesized using acyl Meldrum's acid as acylation reagent with different substituted groups of tetramic acids at 3-position and 5-position, in which fourteen target compounds were not reported in the literature. The target compounds were confirmed by ¹H NMR, ¹³C NMR and HRMS. The preliminary insecticidal activity eveluation showed that the target compounds had good insecticidal activity against wheat aphids (Macrosiphum avenae (Fabricius)) with systemic action at 100 μg/mL concentration for 72 h. Compounds 5d and 7a showed excellent insecticidal activities with the lethal rate of 100% in 48 h at the concentration of 100 μg/mL, which was higher than that of spirotetramat. 5d and 7a could be used as lead compounds for further research. The residues of 4e , 5c , 7a and 8a in wheat plants showed that the target compounds could be well absorbed. The study may provide a guideline of further studies on for structure-insecticidal activity relationships of tetramic acid derivatives.