Direct catalytic diarylation with (hetero)arylhalides of arenes containing an heterocycle (pyridine, oxazoline, pyrazole) has been performed with a ruthenium catalyst assisted by a coordinating base. It constitutes a green process for cross-coupled C–C bond formation without any metal salt waste. The new catalytic system is based on [HRu(codyl)₂]BF₄/2KY (KY: KOAc, KOPiv, KPI (potassium phtalimide)] in which the assisting ligand Y promotes the initial cleavage of C–H bonds. It is shown that the efficiency of the Ru/2KY system strongly depends on the nature of both substrates.