Copper-catalyzed Selective Oxygenation of Methyl and Benzyl Substituents in Pyridine with O2

A selective oxygenation of picolines and their derivatives has been achieved by using a simple copper salt as a catalyst and molecular oxygen as an oxidant, where the α-position of the alkyl substituent is selectively oxidized to give the corresponding aldehydes or ketones. Addition of a catalytic amount of water enhances the catalytic activity, which could be attributed to the role of the proton donor to activate the substrates.