Ligand-free Sonogashira coupling reactions with heterogeneous Pd/C as the catalyst

A variety of aryl iodides were coupled with aromatic and aliphatic terminal alkynes to give the corresponding 1,2-distributed aromatic alkynes in good yields by using only 0.4 mol% of the heterogeneous 10% Pd/C as the catalyst without a ligand, copper salt, or amine in an aqueous medium.