Aerobic Oxidation of Cyclic Amines to Lactams Catalyzed by Ceria-Supported Nanogold

摘要: The oxidative transformation of cyclic amines to lactams, which are important chemical feedstocks, is efficiently catalyzed by CeO2-supported gold nanoparticles (Au/CeO2) and Aerosil 200 in the presence an atmosphere O2. complete conversion pyrrolidine was achieved 6.5 h at 160 °C, affording a 97 % yield lactam product 2-pyrrolidone (γ-butyrolactam), while 2-piperidone (δ-valerolactam) synthesized from piperidine (83 % yield) 2.5 h. Caprolactam, precursor commercially nylon-6, obtained hexamethyleneimine 37 % 3 h. During oxidation pyrrolidine, two transient species, 5-(pyrrolidin-1-yl)-3,4-dihydro-2H-pyrrole (amidine-5) 4-amino-1-(pyrrolidin-1-yl)butan-1-one, were observed. Both these compounds oxidized under catalytic conditions, indicating their role as intermediates reaction pathway. In addition reactions secondary amines, Au/CeO2 also catalyzes N-methyl tertiary corresponding lactams 80 100 °C.