Palladium(II)-Catalyzed [3 + 2] Annulation of Aromatic Triflamides via Maleimide-Relayed Dual C–H Activation Process

A palladium-catalyzed [3 + 2] annulation of substituted aromatic triflamides with maleimides affording tricyclic heterocycles bearing a free NHTf group in a highly atom- and step-economical manner has been developed. Quinoxaline serves as the key ligand, facilitating sequential two-fold C-H activation: First C-H activation takes place selectively at the benzylic position, which triggers a relayed second C-H bond activation at the meta position. Furthermore, ortho-C(sp²)-H alkenylation of the annulated product has been shown exploiting the preserved NHTf group. Additionally, mechanistic studies support a plausible pathway for the annulation.