Efficient Nickel Precatalysts for Suzuki-Miyaura Cross-Coupling of Aryl Chlorides and Arylboronic Acids Under Mild Conditions

The synthesis and catalytic properties of Ni(II) complexes with the general formula Ni(NHC)[P(OR)3](Ar)Cl are described. These complexes are air-stable and extremely effective precatalysts in the Suzuki-Miyaura cross-coupling reaction. The reaction protocols described allow for the cross-coupling of aryl chlorides and arylboronic acids, employing low catalytic loading, to deliver a large variety of functionalized biaryl compounds. For the coupling of aryl chlorides with N-heterocyclic boronic acids, TBAF was used as an additive to afford nitrogen-containing biaryl products. Overall, these reaction protocols operate at room or mild temperatures and can be applied to a variety of electronically and sterically differentiated coupling partners. Fundamental insights into the mechanism of this reaction, including the proposed formation of the catalytically active Ni(NHC)[P(Oi-Pr)3] and resting state species, are also reported.