Electrochemical studies of Ni(cyclam)2+-catalyzed annulation reactions

Cyclic voltammetry and preparative-scale electrochemical studies on the intramolecular cyclization of allyl 2-halophenyl ethers catalyzed by Ni(II)-cyclam complexes leads us to propose a mechanism involving Ni(I) and Ni(III) intermediate species. The role of Mg2+ ions in the reactivity and selectivity of the process is discussed. The Nit cyclam)Br-2-catalyzed electrosynthesis of dihydrobenzofurans and dihydrobenzopyrans from unsaturated side-chain aryl halide derivatives is effected in good yields in the presence of a magnesium anode.