Palladium-Catalyzed Suzuki–Miyaura Coupling Reactions of Boronic Acid Derivatives with Aryl Chlorides

A series of new biphenyl N,P-monophosphine ligands L have been developed by introduction of two methoxy groups to the biphenyl backbone. The ligands were found to be much more effective than their counterpart Buchwald ligands in Suzuki–Miyaura coupling reactions of sterically hindered and electron-rich aryl chlorides with aryl boronic acids. A variety of tri-ortho-substituted or tetra-ortho-substituted biaryls or hetero-biaryls were conveniently prepared in up to 99 % yield by using L1-[Pd₂(dba)₃] (dba=dibenzylideneacetone) as the catalyst.