Switching the Reactivity of the Nickel-Catalyzed Reaction of 2-Pyridones with Alkynes: Easy Access to Polyaryl/Polyalkyl Quinolinones.

A Ni-catalyzed C6 followed by C5 cascade C-H activation/[2 + 2 + 2] annulation of 2-pyridone with alkynes has been achieved. A change in the reaction pathway was achieved by tuning the reaction conditions and incorporating a directing group. A wide variety of substrates and alkynes are amenable to this transformation. The key to success for this transformation is the use of sodium iodide as an additive. More importantly, we detected the five-membered metallacycle intermediate through HRMS wherein iodide is ligated to the metal.