Ligand-free copper-catalyzed coupling of nitroarenes with arylboronic acids

The first example of copper-catalyzed coupling of nitroarenes with arylboronic acids was developed, providing diaryl ethers in moderate to excellent yields. The efficiency of this reaction was demonstrated by compatibility with a wide range of groups. Moreover, the rigorous exclusion of air/moisture is not required in these transformations. Thus, the method represents a simple and facile procedure to access diaryl ethers. Preliminary mechanistic experiments using deuterium labeling showed that the oxygen atom was derived from water.