Amination of aryl bromides catalysed by supported palladium

Palladium particles immobilised onto a metal oxide support or Pd(0), Pd(II) and [Pd(NH3)4]2+ in NaY zeolite have been prepared and characterised. They exhibit a good activity towards the amination of aryl bromides using secondary amines such as piperidine and diethyl amine with a good regio-selectivity for these reactions. Low Pd concentrations (1 mol%) are required to observe a reasonable regio-selectivity. The catalysts can easily be separated from the reaction mixture (filtration) and reused without loss of activity and selectivity. The electronic nature of the aryl halides plays an important role for both the reaction yields and the regio-control of the reaction. It depends on the relation of the direct amination via a benzyne intermediate versus the Pd-catalysed route.