Copper-Free Sonogashira Coupling Reaction with PdCl₂ in Water under Aerobic Conditions

A mild protocol for the copper-free Sonogashira coupling of aryl iodides with terminal acetylenes in water under aerobic conditions has been developed. The use of 1 mol % PdCl₂ in the presence of pyrrolidine allows the coupling reaction to proceed at room temperature or 50 °C with good to excellent yields.