Optimization, Substrate Scope, and Mechanistic Studies of the Suzuki-Miyaura Reaction Catalyzed by a Nickel Pincer Complex

The catalytic activity of an air-stable, well-defined nickel(II) PNP pincer complex has been established for the Suzuki-Miyaura reaction. The catalyst is capable of coupling both electron-rich and electron-deficient aromatic chlorides, bromides, iodides, and triflates with a range of aromatic boronic acids at elevated temperatures in the presence of potassium phosphate. Investigations into the mechanism have resulted in the identification of several putative intermediates, supporting a catalytic cycle involving single-electron transfer steps and a key role for substrate radicals.