Construction of oxime ester derivatives of osthole from Cnidium monnieri, and evaluation of their agricultural activities and control efficiency. Issue 11 (9th September 2020) - Ren, Zili
Abstract: BACKGROUND: In order to discover natural‐product‐based pesticidal candidates, a series of coumarin‐like derivatives containing oxime ester fragments at the C‐8 position were prepared by structural modification of osthole, a natural plant product isolated from Cnidium monnieri. Their pesticidal activities were evaluated against two typically fruit trees/crop‐threatening agricultural pests, Mythimna separata Walker and Tetranychus cinnabarinus Boisduval. RESULTS: Osthole was regioselectively oxidized by selenium dioxide to give the E ‐isomer, (2′ E )‐3′‐formaldehydylosthole (2 ). Four key steric structures of 2, (2'E, 4'E)‐(o‐chloropyrid‐3‐ylcarbonyl)oximinylosthole (4o ), (2'E, 4'E)‐(styrylcarbonyl)oximinylosthole (4t ), and (2'E, 4'E)‐(acetyl)oximinylosthole (4w ) were undoubtedly confirmed by X‐ray crystallography. Against T. cinnabarinus, it is noteworthy that (2′ E, 4′ E )‐( p ‐chlorophenylcarbonyl)oximinylosthole (4c ) exhibited over three‐fold more potent acaricidal activity of the precursor osthole, with especially good control efficiency observed in the glasshouse. Against M. separata, compounds 4c and (2′ E, 4′ E )‐( p ‐nitrophenylcarbonyl)oximinylosthole (4f ) showed the most pronounced growth inhibitory activity. The relationships between their structures and agricultural activities also were studied. CONCLUSION: These results demonstrate that compound 4c could be further structurally modified as pesticidal agents. It will lay the foundation for future application of osthole derivatives as pesticides. © 2020 Society of Chemical Industry Abstract : To discover natural‐product‐based pesticidal candidates, a series of coumarin‐like derivatives containing oxime esters fragment at the C‐8 position were semi‐prepared from osthole, a plant product isolated from Cnidium monnieri. (2'E, 4'E)‐(p‐Chlorophenylcarbonyl)oximinylosthole (4c) exhibited pronounced pesticidal activities against Mythimna separata Walker and Tetranychus cinnabarinus Boisduval. © 2020 Society of Chemical Industry