Palladium-Catalyzed, Highly Efficient, Regiocontrolled Arylation of Electron-Rich Allylamines with Aryl Halides

The highly efficient and regioselective palladium-catalyzed Heck coupling of aryl bromides with electron-rich allylamine derivatives is described. It was found that the choice of solvent, olefin, ligand and additive had a fundamental influence on the regioselectivity and reactivity of the reaction. The combination of palladium acetate [Pd(OAc)2] and 1,3-bis(diphenylphosphino)propane (dppp) in ethylene glycol (EG) constitutes a highly effective catalyst system for internal arylation of N-Boc-allylamine (tert-butyl methyl allyliminodicarbonate) with aryl bromides to give good to excellent regioselectivities, while the catalyst system consisting of Pd(OAc)2, tetrabutylammonium bromide (TBAB) and 2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPO) additive allows for a variety of aryl bromides to react efficiently with N,N-(Boc)2-allylamine (di-tert-butyl allyliminodicarbonate) in water to exclusively afford the linear (E)-allylamine products in high yields.