Palladium nanoparticles supported on modified single-walled carbon nanotubes: a heterogeneous and reusable catalyst in the Ullmann-type N-arylation of imidazoles and indoles

Air-and moisture-stable and recyclable palladium nanoparticles supported on modified single-walled carbon nanotubes (SWCNT-Met/Pd) behave as very efficient heterogeneous catalysts in the Ullmann coupling of imidazoles and indoles with aryl iodides to afford the corresponding C-N coupling reactions under aerobic conditions. These cross coupled products were produced in excellent yields at low palladium loading (similar to 0.2 mol%) and the heterogeneous catalyst can be readily recovered by simple filtration and reused five times without a noticeable loss in its catalytic activity.