Synthesis and insecticidal activities of novel derivatives of podophyllotoxin: Part XII

In order to find the biorational pesticides, eight novel 4β-substituted phenoxyaniline derivatives of podophyllotoxin have been synthesized with significant stereoselectivity and improved yields by employing the BF3·Et2O/NaI reagent system and evaluated for their antifeedant effect against 5th instar larvae of Pieris rapae and effect on the development of 5th instar larvae of P. rapae as well as for insecticidal activity against P. rapae. The antifeedant activities showed that these compounds exhibited less potent than podophyllotoxin. Though these derivatives showed less potent antifeedant activities than podophyllotoxin, they acted as growth development inhibitor to 5th instar larvae of P. rapae, which were found that the animals treated with podophyllotoxin and its derivatives showed moulting disturbances and/or deformities. Also, the insecticidal activity results show that all of these derivatives of PPT showed delayed insecticidal activity, which differs from traditional neurotoxic insecticides. Among them, compounds possessing a 4β-phenoxyaniline moiety substituted (CO2C2H5, Cl and OH) at para position exhibited greater insecticidal activity against P. rapae than podophyllotoxin.