C−H Bond Carboxylation with Carbon Dioxide

Carbon dioxide is a nontoxic, renewable, and abundant C 1 source, whereas C−H bond functionalization represents one of the most important approaches to the construction of carbon–carbon bonds and carbon–heteroatom bonds in an atom‐ and step‐economical manner. Combining the chemical transformation of CO 2 with C−H bond functionalization is of great importance in the synthesis of carboxylic acids and their derivatives. The contents of this Review are organized according to the type of C−H bond involved in carboxylation. The primary types of C−H bonds are as follows: C(sp)−H bonds of terminal alkynes, C(sp 2 )−H bonds of (hetero)arenes, vinylic C(sp 2 )−H bonds, the ipso ‐C(sp 2 )−H bonds of the diazo group, aldehyde C(sp 2 )−H bonds, α‐C(sp 3 )−H bonds of the carbonyl group, γ‐C(sp 3 )−H bonds of the carbonyl group, C(sp 3 )−H bonds adjacent to nitrogen atoms, C(sp 3 )−H bonds of o ‐alkyl phenyl ketones, allylic C(sp 3 )−H bonds, C(sp 3 )−H bonds of methane, and C(sp 3 )−H bonds of halogenated aliphatic hydrocarbons. In addition, multicomponent reactions, tandem reactions, and key theoretical studies related to the carboxylation of C−H bonds are briefly summarized. Transition‐metal‐free, organocatalytic, electrochemical, and light‐driven methods are highlighted.