Synthesis of Diaryl Ethers: A Long-Standing Problem Has Been Solved.

A breakthrough in the synthesis of diaryl ethers has been achieved as shown in Equation (1). The coupling of phenols with aryl boronic acids in the presence of copper(II) acetate and a base proceeds under very mild conditions (room temperature) as described simultaneously by Evans et al. and Chan et al. Examples: R(1)=2-Cl, 2-I, 2-OMe, 4-tBu, 4-CH(2)CH(NHCOOtBu)CO(2)Me, 3,5-tBu(2); R(2)=2-Me, 3-OMe, 3-NO(2), 4-H, 4-F, 4-OMe.