The ClCuIIOCuIICl reagent as well as the O 2Cu IOAc system oxidize trimethylamine 1a into N, N-dimethyliminium 3a, characterized by its phenolic adduct 5a. This reaction appears to be a biomimetic model for laccase or human ceruloplasmin activity towards tertiary amines. Amine N-oxides react with CuI or CuII salts to give iminiums 3a-c, likewise trapped in good yields.