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: R¹=2-Cl, 2-I, 2-OMe, 4-tBu, 4-CH₂CH(NHCOOtBu)CO₂Me, 3,5-tBu₂; R²=2-Me, 3-OMe, 3-NO₂, 4-H, 4-F, 4-OMe.