Copper/Imidazolium/TEMPO-Catalyzed Aerobic Oxidation of Benzylic Alcohols in Water

Various imidazolium salts bearing hydrophilic groups were prepared that reacted with copper powder to afford water-soluble copper complexes of N-heterocyclic carbenes. These copper complexes can catalyze the selective oxidation of benzyl alcohols to the corresponding aldehydes in water at room temperature without the need for a base.