Synthesis and insecticidal activities of novel derivatives of podophyllotoxin

In order to find the biorational pesticides, eight novel 4beta-substituted phenoxyaniline derivatives of podophyllotoxin (4a-h) have been synthesized with significant stereoselectivity and improved yields by employing the BF(3).Et(2)O/NaI reagent system and evaluated for insecticidal activity against Pieris rapae as well as for their antifeedant effect against fifth instar larvae of P. rapae. The results showed that all these derivatives of PPT showed delayed insecticidal activity, which is different from the traditional neurotoxic insecticides. Among them, compounds possessing a 4beta-phenoxyaniline moiety substituted at para (CO(2)C(2)H(5), Cl, and OH) position exhibited greater insecticidal activity against P. rapae than podophyllotoxin. Also, the antifeedant activities showed that these compounds exhibited less potency than podophyllotoxin.