Direct arylation (hetero-coupling) of heteroarenes via unsymmetrical palladium-PEPPSI-NHC type complexes

The growing interest of industry in the field of bi(hetero)arenes compounds, motivated us to synthesize these compounds via homogeneous catalytic route by using Pd PEPPSI-type complexes through direct arylation. In this work, the five new Pd PEPPSI-type complexes bearing NHC spectator ligands were synthesized and characterized by a bunch of spectroscopic techniques. Further confirmations of structural details were provided by a single crystal X-ray diffraction study of one pro-ligand and one complex. All these newly synthesized Pd-carbene complexes were found significantly active as catalysts toward direct arylation of five members heterocyclic compounds such as n-propylthaizole, 2-acetylfurane and 2-acetylthiophene with aryl bromides derivatives. These catalysts give significantly good results within two hours with just 1 mol % catalyst loading.