The Design, Synthesis, and Evaluation of 1,5,7-Trisubstituted-3-Pyridyl-Xanthones for Use as Insecticides Starting from Pyripyropene A.

A readily accessible template of 1,5,7-trisubstituted-3-pyridyl-xanthones was designed starting from naturally occurring pyripyropene A for agrichemical development. Our originally developed Ag2 CO3 -mediated oxidative cyclization enabled ready access to the key scaffold, 1,5,7-trihydroxy-3-chloro-xanthone. The chemo- and regioselective sequential introduction of four substituents to the scaffold rapidly afforded the desired, structurally diverse 1,5,7-trisubstituted-3-pyridyl-xanthones. An evaluation of insecticidal activity revealed that one of the synthesized compounds retained insecticidal activity against vetch aphid and green peach aphid. The observed insecticidal spectrum was similar to that of pyripyropene A. The developed template could be a valuable aid for future agrichemical development.