Aryllead triacetates: regioselective reagents for N-arylation of amines

Abstract

Aryllead triacetates have been found to be regioselective reagents for the mono N-arylation of a range of aromatic, heterocyclic and aliphatic amines under mild and neutral conditions in a reaction catalysed by copper diacetate. The arylation of arylamines was unaffected by the steric hindrance of the arylamine but was dependent on the arylamine basicity. In addition, the position of oxidisable substituents on both the aryllead triacetate and the arylamine was found to be important due to a competing oxidation-reduction reaction. The arylation of heterocyclic amines proceeded in modest to good yields whilst aliphatic amines were arylated in poor to modest yields. The mechanism proposed for these reactions involves transfer of the aryl group onto copper forming a copper(III) intermediate which subsequently undergoes ligand coupling to give the N-arylated amine and the catalytic Cu^I species.