Homogeneous electromediated reduction of the 2-cyclohexen-1-one by transition metals

The reduction of the 2-cyclohexen-1-one, mediated by some transition metal ions (Zn2+, Cu2+, Ni2+, Co2+ and Fe2+) and complexes ([NiII(bipy)]Br2 and [FeII(bipy)]Br2, where bipy = 2,2′-bipyridine), was carried out by using a homogeneous electromediated system: sacrificial anode, nickel cathode, (0.2 M) NaI as supporting electrolyte and undivided cell. A constant current of <100 mA was applied with a maximum cell potential of 2.0 V. Cyclohexanone was the principal product in major cases yielding 98%. Cyclohexanol was also detected in some cases. The selectivity of the process can be controlled by choosing Ni as mediator and Zn or Ni as sacrificial anode. A more reactive system can be reached when Fe sacrificial anode is used, giving cyclohexanol as major product (87%).