Dedicated to Prof. Masahiro Murakami for his unparalleled contributions on the topic
of CO2 utilization in organic synthesis.
Abstract
Carbon dioxide (CO2) is widely known as being a sustainable C1 synthon for the synthesis of various carboxylic
acid derivatives, including essential natural and unnatural amino acids. While it
is sustainable, the high thermodynamic stability and kinetic inertness of the CO2 molecule is a major drawback to its wider use in organic synthesis. However, the
reduction of this inert and highly stable CO2 molecule has been carried out successfully over the past few years using various
stoichiometric as well as catalytic approaches. Initially, chemists employed transition-metal/transition-metal-free
thermochemical methods for the incorporation of CO2 into organic compounds, however, gradually, the introduction of greener approaches
such as visible-light-induced photoredox catalysis and electrocatalysis became revolutionary
for the synthesis of carboxylic acids under mild reaction conditions. In this short
review, we discuss the recent advances in carboxylation reactions via functionalization
of the (sp3)C–H bonds of various organic molecules with CO2 using thermochemical, photochemical and electrochemical methods.
1 Introduction
2 Transition-Metal/Transition-Metal-Free Thermochemical Carbox ylations of C(sp3)–H Bonds
2.1 C(sp3)–H Bond Carboxylation of Carbonyls
2.2 Allylic, Benzylic and Alkyl C(sp3)–H Bond Carboxylation
3 Photochemical C(sp3)–H Bond Carboxylation
3.1 Allylic C(sp3)–H Bond Carboxylation
3.2 Benzylic C(sp3)–H Bond Carboxylation
4 Electrochemical Carboxylation of C(sp3)–H Bonds
5 Conclusion and Outlook
Key words
carbon dioxide - transition-metal - transition-metal-free - thermochemical strategy
- visible-light-induced photocatalysis - electrocatalysis - reductive C–H carboxylations
- carboxylic acids
