Simple, efficient catalyst system for the palladium-catalyzed amination ofaryl chlorides, bromides, and triflates

Palladium complexes supported by (o-biphenyl)P(t-Bu)(2) (3) or (o-biphenyl) PCy2 (4) are efficient catalysts for the catalytic amination of a wide vari ety of aryl halides and triflates. Use of ligand 3 allows for the room-temp erature catalytic amination of many aryl chloride, bromide, and triflate su bstrates, while ligand 4 is effective for the amination of functionalized s ubstrates or reactions of acyclic secondary amines. The catalysts perform w ell for a large number of different substrate combinations at 80-110 degree s C, including chloropyridines and functionalized aryl halides and triflate s using 0.5-1.0 mol % Pd; some reactions proceed efficiently at low catalys t levels (0.05 mol % Pd). These ligands are effective for almost all substr ate combinations that have been previously reported with various other liga nds, and they represent the most generally effective catalyst system report ed to date. Ligands 3 and 4 are air-stable, crystalline solids that are com mercially available. Their effectiveness is believed to be due to a combina tion of steric and electronic properties that promote oxidative addition, P d-N bond formation, and reductive elimination.