Stable TEMPO and ABNO Catalyst Solutions for User-Friendly (bpy)Cu/Nitroxyl-Catalyzed Aerobic Alcohol Oxidation

Two solutions, one consisting of bpy/TEMPO/NMI and the other bpy/ABNO/NMI (bpy =2,2′-bipyridyl; TEMPO = 2,2,6,6-tetramethyl­piperidine N-oxyl, ABNO = 9-azabicyclo[3.3.1]­nonane N-oxyl; NMI = N-methylimidazole), in acetonitrile are shown to have good long-term stability (≥1 year) under air at 5 °C. The solutions may be combined in appropriate quantities with commercially available [Cu­(MeCN)₄]­OTf to provide a convenient catalyst system for the aerobic oxidation of primary and secondary alcohols.