Collective Synthesis of Phenanthridinone through C–H Activation Involving a Pd-Catalyzed Aryne Multicomponent Reaction

A palladium-catalyzed multicomponent reaction (MCR) involving aryne, CO, and aniline is established for straightforward assembly of a phenanthridinone scaffold through C–H bond activation. Free combination with multiple kinds of readily available anilines and arynes is facilely achieved for phenanthridinone construction without prefunctionalization. Representative natural products were subsequently synthesized through this MCR strategy highly efficiently. Control experiments and interval NMR tracking revealed the mechanism, particularly the key role of CuF2 in determining the aryne-releasing rate from the precursor in this transformation.