Cyclopropane formation by nickel-catalysed electroreductive coupling of activated olefins and unactivated gem-dibromo compounds

Cyclopropyl derivatives have been prepared with good yields by transition-metal catalysed electroreductive coupling of activated olefins and unactivated gem-dibromo compounds. This electrolysis is characterized by the use of a Fe/Ni catalyst system, acetonitrile as the solvent and a catalytic amount of triphenylphosphine as ligand. This procedure is a good alternative to the classical preparations of cyclopropyl derivatives from activated olefins (Simmons–Smith reaction, 1,3-dipolar addition of diazomethane, 1,4-addition of phosphorus and sulfur ylides).