Homocoupling of Aryl Halides Promoted by an NiCl2/bpy/Mg System in DMF

Homocoupling of aryl halides (2 ArX → Ar―Ar) promoted by NiCl2/2,2′‐bipyridine (bpy)/Mg mixtures in DMF has been studied. Mixtures of NiCl2, bpy and Mg in DMF promoted homocoupling of aryl halides such as phenyl bromide and p‐tolyl bromide to give the coupling products in good (e.g. approximately 60–75%) yields, and the homocoupling products were easily isolated from the reaction mixtures. Application of this homocoupling to dibromo‐aromatic compounds (Br–arylene–Br: 2,5‐dibromopyridine, 2,7‐dibromo‐9.9‐dioctylfluorene and 2,7‐dibromo‐9,10‐dioctyl‐9,10‐dihydrophenanthrene) gave the corresponding π‐conjugated polymers, –(arylene)n–, in good yields. Organometallic processes for the homocoupling are discussed. Copyright © 2014 John Wiley & Sons, Ltd.