Recent Advance of Transition Metal-Catalyzed Direct C-H Bond Carboxylation with CO2

Carbon dioxide represents the most abundant carbon source in the world. It is obvious that the utilization of CO2 to generate chemical products will provide a new strategy for clean energy. Meanwhile, as the main product of CO2 reactions, carboxylic acids and derivatives have wide application. Among various CO2 involved carboxylation reactions, the direct carboxylation of C-H bond with CO2 has attracted much attention recently, which lies in its high efficiency for the synthesis of carboxylic acids. This review summarizes the direct carboxylation of different hybrid C-H bonds with CO2 in recent years, which focus on transition metal catalyzed reactions for the synthesis of carboxylic acids and its derivatives from CO2.