Highly Active [Pd(μ-Cl)(Cl)(NHC)]₂ (NHC = N-Heterocyclic Carbene) in the Cross-Coupling of Grignard Reagents with Aryl Chlorides

Cross-coupling reactions of Grignard reagents with functionalized aryl, heteroaryl, and sterically hindered aryl chlorides are reported. A protocol disclosing the coupling of a wide range of substrates using complexes of the type [Pd(mu-Cl)(Cl)(NHC)](2) (NHC = N-heterocyclic carbene) as precatalysts (at low catalyst loading) under mild conditions is presented. The system allows for the synthesis of highly sterically hindered products, including tri- and tetra-ortho-substituted biaryls.