New copper(I) and iron(II) complexes for atom transfer radical macrocyclisation reactions

New Cu(I) and Fe(II) complexes have been synthesized and proved to be efficient catalysts for atom transfer radical addition (ATRA) reactions. The catalytic activity was found to be greater than existing atom transfer systems based upon CuCl(bipyridine) or RuCl2(PPh3)(3), for example. The addition of a reducing agent considerably improved the efficiency of the usual procedures.