Identification of naphthol derivatives as novel antifeedants and insecticides. 1

A series of β-naphthol-derived 2-aminobenzothiazolomethylnaphthol derivatives (4a-4q) were synthesized and purified in excellent yields (86-94%) using green protocols and screened for their antifeedant and toxic activities against tobacco caterpillar (Spodoptera litura) and castor semilooper (Achaea janata) using no-choice leaf disk and topical bioassay methods. Four of them, 4d, 4f, 4i, and 4j, were identified to be potent antifeedants with ED50 values of 16.4, 19.3, 7.0, and 5.2 μg/cm(2) against S. litura and 13.9, 17.2, 10.2, and 7.7 μg/cm(2) against A. janata, respectively, and the mortality rate is >95% for 4i and 4j in the case of S. litura and 4j in case of A. janata at a dosage of 0.2 μg/insect. Compounds 4d, 4i, and 4m are moderately toxic to A. janata only. Overall, this study identified a novel class of synthetic compounds that do not belong to organochlorides, organophosphates, carbamates, or neonicotinoids as strong antifeedants as well as insecticides.