Synthesis Of 2′(2′,6′)-(Di)Halogenoisoxazolopodophyllic Acids-Based Amides Derived from a Naturally Occurring Lignan Podophyllotoxin and their Acaricidal Activity

In continuation of our program to discover natural product-based pesticides, a series of 2'(2',6)-(di)halogenoisoxazolopodophyllic acids-based amides were prepared by structural modification of a naturally occurring lignan podophyllotoxin. Meanwhile, their acaricidal activity was evaluated against a typically crop-threatening agricultural insect pest, Tetranychus cinnabarinus. Among all derivatives, especially compounds 10-12 displayed 4.8-7.4 folds more potent acaricidal activity than podophyllotoxin against T. cinnabarinus. This demonstrated that the carboxyl group at their C-2 position of 2'(2',6')-(di)halogenoisoxazolopodophyllic acids was very important for the acaricidal activity.