Influence of copper(II) acetate on Ni/AcOH-promoted 5-endo and 5-exo radical cyclisations of trichloroacetamides

Incorporation of Cu(OAc)₂ as oxidant in Ni/AcOH-promoted 5-endo radical cyclisations of N-alkenyl-trichloroacetamides allows an interesting control of the oxidation level of the products, as illustrated by the conversion of 3 into either 4 or 5. In addition, allylic trichloroacetamides 13a-f under the same conditions underwent a 5-exo radical cyclisation-oxidation sequence leading to unsaturated hydroindolones, which represent valuable synthetic intermediates.