Suzuki-Miyaura coupling reaction is one of the most useful methods for the selective C-C bond formation, in particular for the synthesis of biaryl derivatives, although it is usually difficult to apply to the preparation of heterobiaryl compounds which are of medicinal importance. Furthermore, such precedent works used homogeneous catalysts together with phosphine ligands which are difficult to handle and/or remove from the reaction mixture (the residual heavy metal induces a serious problem).

 We developed a mild and efficient protocol for the ligand-free and heterogeneous Pd/C-catalyzed Suzuki-Miyaura coupling reaction. The cross-coupling reaction between heteroaryl bromides and heteroaryl boronic acids were also achieved in good to excellent yields by further optimization of the reaction conditions. It is noteworthy that the present reaction is applicable to the synthesis of both herteroaryl-aryl and heteroaryl-heteroaryl derivatives.