Easy Copper-, Ligand- and Amine-Free Sonogashira Coupling Reaction Catalyzed by Palladium on Carbon at Low Catalyst Loading and by Exposure to Air

An easy copper-, ligand and amine-free Sonogashira coupling reaction catalyzed by commercially available palladium on carbon with air at low catalyst loading (0.2 mol% Pd) has been developed. Aryl iodides coupled with aromatic alkynes gave good to excellent yields and with aliphatic alkyne gave moderate to good yields. The reaction system is easy to handle.