Palladium-catalyzed double C-H activation: one-pot synthesis of benzo[c] pyrazolo[1,2-a]-cinnolin-1-ones from 5-pyrazolones and aryl iodides

A palladium-catalyzed dual C-H activation to construct C-C/C-N bonds for one-pot synthesis of benzo[c] pyrazolo[1,2-a]-cinnolin-1-ones is successfully developed. This approach involves using a pyrazolone moiety as an internal directing group for C-H activation, and provides a flexible strategy to access this polycyclic skeleton.