Synthesis of biaryls via a nickel(0)-catalyzed cross-coupling reaction of chloroarenes with arylboronic acids

The cross-coupling reaction of arylboronic acid with chloroarenes to give biaryls was carried out in high yields at 70-80 degrees C in the presence of a nickel(0) catalyst and K3PO4 (3 equiv) in dioxane or benzene. The nickel(0) catalyst in situ prepared from NiCl2 . L (L = dppf, 2PPh(3)) (3-10 mol %) and 4 equiv of BuLi at room temperature was recognized to be most effective. The reaction can be applicable to a wide range of chloroarenes having an electron-withdrawing or an electron-donating group such as 4-NC, 4-CHO, 2- or 4-CO2Me, 4-COMe, 4-NHAc, 4-Me, 4-OMe, 4-NH2, and 4-NMe2. The Hammett's plot of the substituent effect of chloroarenes revealed that the reaction involves a rate-determining oxidative addition of chloroarenes to the nickel(0) complex.