Nickel-Catalyzed Homocoupling of Aryl Ethers with Magnesium Anthracene Reductant

Nickel-catalyzed reductive homocoupling of aryl ethers has been achieved with Mg(anthracene)(thf)(3) as a readily available low-cost reductant. DFT calculations provided a rationale for the specific efficiency of the diorganomagnesium-type two-electron reducing agent. The calculations show that the dianionic anthracene-9,10-diyl ligand reduces the two aryl ether substrates, resulting in the homocoupling reaction through supply of electrons to the Ni-Mg bimetallic system to form organomagnesium nickel(0)-ate complexes, which cause two sequential C-O bond cleavage reactions. The calculations also showed cooperative actions of Lewis acidic magnesium atoms and electron-rich nickel atoms in the C-O cleavage reactions.