Copper-Catalyzed Transamidation of Unactivated Secondary Amides via C-H and C-N Bond Simultaneous Activations

Here, we demonstrate that alpha-C-H and C-N bonds of unactivated secondary amides can be activated simultaneously by the copper catalyst to synthesize alpha-ketoamides or alpha-ketoesters in one step, which is a challenging and underdeveloped transformation. Using copper as a catalyst and air as an oxidant, the reaction is compatible with a broad range of acetoamides, amines, and alcohols. The preliminary mechanism studies and density functional theory calculation indicated that the reaction process may undergo first radical alpha-oxygenation and then transamidation with the help of the resonant six-membered N,O-chelation and molecular oxygen plays a role as an initiator to trigger the transamidation process. The combination of chelation assistance and dioxygen selective oxygenation strategy would substantially extend the modern mild synthetic amide cleavage toolbox, and we envision that this broadly applicable method will be of great interest in the biopharmaceutical industry, synthetic chemistry, and agrochemical industry.

Automated summary

Here, we demonstrate the simultaneous activation of alpha-C-H and C-N bonds in unactivated secondary amides by a copper catalyst to synthesize alpha-ketoamides or alpha-ketoesters in one step. This challenging and underdeveloped transformation is achieved using copper as a catalyst and air as an oxidant, and is compatible with a wide range of acetoamides, amines, and alcohols. The mechanism studies suggest that the reaction involves radical alpha-oxygenation followed by transamidation, with the assistance of N,O-chelation and molecular oxygen as an initiator.