Oxidative Carbonylation of aliphatic Amines catalysed by Nickel-Complexes

The catalytic activity of some nickel-complexes in the dioxygen-induced carbonylation of amines has been studied. N,N?-oxamides expected on the basis of a previous report. The study of the reaction mechanism shows that amines are carbonylated in a reductive step, during which either ureas or oxamides can be obtained depending on the amount of water present. When dioxygen is used as the oxidant the oxidative step produces water, which promotes the urea formation. The oxygen is also responsible for the low yields owing to a side reaction involving amine oxidation. These conclusions were confirmed when the carbonylations were carried out under pseudo-catalysis conditions, or when oxidants which do not produce water in the oxidative step were used.