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 degreesC with good to excellent yields.