Coupling of Phenols and Aryl Halides with Nano-Copper Oxide

Significance

Nanocrystalline copper oxide (nano-CuO) catalyzed the Ullmann coupling of phenols with aryl halides in the presence of Cs₂CO₃ or KOH to afford the corresponding diaryl ethers in up to 94% yield (18 examples). In the reaction of 4-methoxyphenol with iodobenzene, the catalyst was recovered by simple centrifugation and reused four times without loss of catalytic activity. TEM analysis showed almost no changes of the shape and size of the catalyst after the 4^th run.