Carbon dioxide is a nontoxic, renewable, and abundant C1 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 CO2 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(sp2)−H bonds of (hetero)arenes, vinylic C(sp2)−H bonds, the ipso‐C(sp2)−H bonds of the diazo group, aldehyde C(sp2)−H bonds, α‐C(sp3)−H bonds of the carbonyl group, γ‐C(sp3)−H bonds of the carbonyl group, C(sp3)−H bonds adjacent to nitrogen atoms, C(sp3)−H bonds of o‐alkyl phenyl ketones, allylic C(sp3)−H bonds, C(sp3)−H bonds of methane, and C(sp3)−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.

Herein we report a general electrochemical strategy for the Sandmeyer reaction.

We describe an operationally simple transition-metal-free borylation of alkyl iodides. This method uses commercially available diboron reagents as the boron source and exhibits excellent functional group compatibility. Furthermore, a diverse range of primary and secondary alkyl iodides could be effectively transformed to the corresponding alkylboronates in excellent yield. Mechanistic investigations suggest that this borylation reaction proceeds through a single-electron transfer mechanism featuring the generation of an alkyl radical intermediate.

We describe here an operationally simple and straightforward synthesis method for a series of diverse 4,5-disubstituted 1,2,3-thiadiazoles via the nucleophilic addition of α-diazo carbonyl compounds to carbon disulfide. This method features using abundant and inexpensive carbon disulfide under mild reaction conditions.