Design, Synthesis and Evaluation of Novel Isoxazolines/Oxime Sulfonates of 2′(2′,6′)-(Di)Chloropodophyllotoxins as Insecticidal Agents

A series of 2′(2′,6′)-(di)halogeno-isoxazolopodophyllic acids-based esters, and oxime sulfonates of 2′(2′,6′)-(di)halogenopodophyllones were prepared by structural modifications of podophyllotoxin as insecticidal agents against Mythimna separata Walker. It was found that when 2′(2′,6′)-(di)halogenopodophyllones or 2′(2′,6′)-(di)chloropicropodophyllones reacted with hydroxylamine hydrochloride, the desired products were related with the configuration of their lactones. Three key single-crystal structures of Ie, IIe and IIIb were determined by X-ray diffraction. Especially compounds IIc and Vc showed the highest insecticidal activity. Moreover, some interesting results of structure-insecticidal activity relationships of tested compounds were also observed.