Transition Metal-Free Incorporation of CO2

Carbon dioxide can be regarded as an ideal C1 chemical feedstock in both academic and pharmaceutical laboratories owing to its abundance, low cost, non-toxicity, and nonflammability. However, due to CO2 inherent thermodynamic stability and kinetic inertness, it is difficult to convert CO2 to value-added chemicals under mild conditions. In order to overcome such barriers, numerous useful synthetic methodologies by strategically using highly active catalysts have been developed for the incorporation of CO2 to organic compounds. Transition metal-free compounds are proved to be promising efficacious catalysts able to activate CO2 molecule for efficient transformation of CO2 on the basis of mechanistic understanding at the molecular level. This chapter features recent advances at methodologies for catalytic transformation of CO2 promoted by organocatalysts (e.g., N-heterocyclic carbenes, frustrated Lewis pairs and superbases), ionic liquids, and main group metal to produce value-added chemicals such as linear or cyclic carbonates, quinazoline-2,4(1H,3H)-diones, alkylidene cyclic carbonates, amino acids, and so on.