Ligand-free copper-catalyzed O-arylation of nitroarenes with phenols

The first example of ligand-free copper-catalyzed O-arylation of nitroarenes with phenols was developed, achieving unsymmetrical diaryl ethers in moderate to excellent yields. This arylation proceeded smoothly without promotion of the ligands, and displayed great functional group compatibility. Thus, the method represents a new, facile, and cost-effective approach to access unsymmetrical diaryl ethers.