Catalytic C-H oxidation by a triazamacrocyclic ruthenium complex

A method for oxygenation of tertiary and benzylic C-H bonds is described that uses 1-10 mol% (1,4,7-trimethyl-1,4,7-triazacyclo-nonane) ruthenium(III) trichloride as catalyst and ceric (IV) ammonium nitrate (CAN) as the terminal oxidant. The reaction is conveniently performed in aqueous solvent mixtures on substrates bearing a number of common, polar functional groups. The scope and efficiency of this process are comparable or superior to other known catalytic C-H oxidation technologies. Chemoselectivity trends and kinetic isotope effect data implicate a stepwise, radical-rebound mechanism for this transformation.