Synthesis and insecticidal activity of novel dihalopropene derivatives containing benzoxazole moiety: A structure–activity relationship study

The combination of pharmacophore 3,3-dichloroallyloxybenzene of the commercialized product pyridalyl with benzoxazole ring which is used widely in both agrichemicals and pharmaceuticals, resulted in discovering a new dihalopropene compounds with good insecticidal activity. 5-Trifluomethyl group plays an important role in enhancing the biological activity of target compounds. •Application of the strategies of active substructure combination and bioisosteric replacement.•Trifluomethyl, a very strong electron withdrawing group, plays an important role on insecticidal activity.•Characterization of target compounds using 1H NMR, MS and elemental analyses.•Moderate to excellent insecticidal activity against Spodoptera exigua.•Detailed structure and activity relationship of target compounds. Ten dichloropropene derivatives containing benzoxazole moiety were synthesized and bioassayed in order to determine their in vivo insecticidal activity. The structures of obtained compounds were identified by 1H NMR, MS and elemental analyses. The bioassay results indicated that compound 2-(3-(2,6-dichloro-4-(3,3-dichloroallyloxy)phenoxy)propoxy)-5-(trifluoromethyl)benzo[d]oxazole (5i, R1 is trifluoromethyl, R2 is H and n is 3) had the optimal structure with best insecticidal activity against Spodoptera exigua (100%) at 1mg/L concentration, highlighting the importance of trifluoromethyl group. The structure–activity relationship of the synthesized compounds was discussed as well.