Cu(II)-Catalyzed Functionalizations of Aryl C−H Bonds Using O₂ as an Oxidant

Cu(II)-catalyzed acetoxylation and halogenation of aryl C-H bonds are developed. ortho-Selectivity was observed with a wide range of 2-arylpyridine substrates. Both mono- and difunctionalizations are achieved by tuning the reaction conditions. Excellent functional group tolerance and use of O2 as a stoichiometric oxidant are significant advantages over our recently developed Pd-catalyzed C-H functionalization reactions. These newly discovered reaction conditions are also applicable for cyanation, amination, etherification, and thioetherification of aryl C-H bonds. Mechanistic investigations are carried out to gain insights into the Cu(II)-catalyzed C-H functionalization reactions.