C-H Bond Carboxylation with Carbon Dioxide

Area of Science:

• Organic Chemistry
• Catalysis
• Sustainable Chemistry

Background:

• Carbon dioxide (CO2) is an abundant, renewable, and non-toxic C1 feedstock.
• C-H bond functionalization is crucial for atom- and step-economical synthesis of C-C and C-heteroatom bonds.
• The direct carboxylation of C-H bonds using CO2 is a highly desirable transformation.

Purpose of the Study:

• To review the recent advances in the carboxylation of various C-H bonds using carbon dioxide.
• To categorize synthetic strategies based on the type of C-H bond undergoing functionalization.
• To highlight innovative catalytic systems, including transition-metal-free, organocatalytic, electrochemical, and photoredox methods.

Main Methods:

• Systematic review of literature on CO2 carboxylation of diverse C-H bonds.
• Classification of reactions based on C(sp)-H, C(sp2)-H, and C(sp3)-H bond functionalization.
• Summary of multicomponent, tandem reactions, and theoretical studies.

Main Results:

• Detailed overview of carboxylation strategies for terminal alkynes, (hetero)arenes, alkenes, diazo compounds, aldehydes, and various aliphatic C-H bonds.
• Demonstration of the versatility of CO2 as a carboxylating agent across a wide range of substrates.
• Highlighting of efficient and sustainable methodologies, including metal-free and light-driven approaches.

Conclusions:

• The direct carboxylation of C-H bonds with CO2 is a powerful strategy for synthesizing carboxylic acids and derivatives.
• Diverse C-H bonds can be effectively functionalized using various catalytic systems.
• Emerging methods offer greener and more efficient routes for CO2 utilization in organic synthesis.