Rates and Mechanism of Organozinc Electrosynthesis Catalyzed by Co in Pure Acetonitrile

The chemical procedure was formerly achieved by the preliminary formation of aryl-lithium reagents followed by transmetallation with zinc halides. Nevertheless, this method is not easily achieved with aryl compounds bearing reactive functional groups such as ketone, nitrile or ester, since very low reaction temperatures are required. Alternatively, the Rieke method, which uses activated zinc obtained by reduction of zinc halide with alkali metal naphtalenide, is convenient with aromatic bromides, even those bearing an electron-withdrawing group. Very recently, we discovered a new chemical synthesis of functionalized arylzinc compounds from aromatic or thienyl bromides under mild conditions and in pure acetonitrile using a simple cobalt catalyst (CoX2, X = Cl, Br) and zinc dust.