Fast Microwave-Assisted Ullmann-Type Coupling for the Synthesis of Multisubstituted Diaryl Ethers.

A mild and rapid microwave-assisted Ullmann-type C-O coupling protocol catalyzed by copper-(II) complexes was developed and optimized for the efficient synthesis of a wide variety of diaryl ethers. The synthetic methodology is general and tolerant toward both electron-rich and electron-poor phenols and aryl halides. Furthermore, this protocol provides a practical and rapid methodology for preparing diaryl ethers with potential biological and pharmacological relevance and represents a rapid and operationally efficient alternative to conventional thermal methods, thereby widening the use of copper catalysis in organic synthesis.