Transition metal-catalyzed C–H functionalization of N-oxyenamine internal oxidants

The transition metal-catalyzed C–H functionalization with hydroxylamine derivatives serving as both reactants and internal oxidants has attracted a lot of interest. These reactions obviate the need for external oxidants and therefore result in high reactivity and selectivity, as well as excellent functional group tolerance under mild reaction conditions, and moreover, water, methanol or carboxylic acid is generally released as the by-product, thus leading to reduced waste. This review focuses on the transition metal-catalyzed oxidative C–H functionalization of N-oxyenamine internal oxidants, with an emphasis on the scope and limitations, as well as the mechanisms of these reactions.