Efficient Ullmann and Suzuki-Miyaura cross-coupling reactions catalyzed by heterogeneous Pd-porous carbon beads catalysts in aqueous media

Carbon-carbon coupling reactions are of great interest for a wide range of applications including pharmaceutical compounds and biologically active molecules. Usually, coupling reactions were performed using a homogeneous catalyst and organic solvent. Thus, the use of greener solvents as well as the heterogenization of the classical metal-based catalyst are desirable and still under development. This contribution describes the synthesis of biaryl compounds in water by Ullmann and Suzuki reactions with carbon-supported Pd nanoparticles. As expected, the microwave activation method drastically decrease the reaction time. The utilization of trioctylphosphine (TOP) or triphenylphosphine (TPP) ligands slow down the Pd leaching without cancelling it compared to the unliganded Pd catalyst. Moreover, a treatment with H₂O₂ appears beneficial with respect to a thermal-oxidative treatment at 1500 °C due to higher hydrophilicity of the resultant carbon support. These results and methodology contribute to a greener future for C–C coupling reactions.