Nanocrystalline magnesium oxide-stabilized palladium(0): an efficient and reusable catalyst for synthesis of N-(2-pyridyl)indoles

A selective and efficient catalytic process has been developed for the oxidative coupling between N -aryl-2-aminopyridines and alkynes using a nanocrystalline magnesium oxide (NAP–MgO)-supported palladium nanoparticle [NAP–Mg–Pd(0)] catalyst and CuCl 2 as an oxidant. The process involves the ortho C–H activation of N -aryl-2-aminopyridines to give N -pyridyl indoles in excellent yields and the true heterogeneity of the catalyst is verified by studying the recoverability and reusability for four cycles without significant loss of catalytic activity.