Development of an Air-Stable, Broadly Applicable Nickel Source for Nickel-Catalyzed Cross-Coupling

The synthesis of NiCl(o-tolyl)(TMEDA) (3; TMEDA = tetramethylethylenediamine) and its application in coupling reactions is described. In combination with a suitable ligand, precatalyst 3 was applied to a wide range of transformations, such as Suzuki, amination, Kumada, Negishi, Heck, borylation, and reductive coupling. Yields of products obtained with 3 are equal or superior to those obtained with common Ni sources such as Ni(cod)(2) (1) and NiCl2(dme) (2). Importantly, and unlike 1, complex 3 is stable for months in air as a solid, which eliminates the need for a glovebox and greatly facilitates the reaction setup. Thus, complex 3 is the first highly versatile Ni source that combines the broad applicability of 1 with the air stability of 2.