CO2: More Than a Carbon Source

Carbon dioxide (CO₂), traditionally regarded as an abundant greenhouse gas and thermodynamic end-product of combustion, has emerged as an attractive C1 feedstock for sustainable chemical synthesis. However, its synthetic potential extends far beyond its direct incorporation into organic molecules. Our research has focused on redefining the role of cin organic synthesis, from a passive carbon source to an active and versatile reagent capable of promoting, mediating, and controlling chemical transformations.

This lecture will highlight our contributions toward exploiting the multifaceted reactivity of CO₂ through four complementary concepts. First, we have demonstrated the use of CO₂ as a promoter for functional-group transformations, where reversible interactions with substrates can alter their intrinsic reactivity and enable transformations under milder or more selective conditions. Second, our efforts in CO₂ fixation illustrate strategies for incorporating this abundant C1 building block into value-added organic molecules, providing new opportunities for constructing carboxylated and related functional architectures. Moving beyond carbon incorporation, we introduced the concept of utilizing CO₂ as an oxygen-transfer reagent, revealing that its oxygen atoms can be strategically harnessed for oxidative transformations. This unconventional reactivity challenges the classical perception of CO₂ as an inert terminal oxidation product and establishes it as a potential alternative oxygen source in synthetic chemistry. More recently, we have expanded this paradigm by employing CO₂ as a redox shuttle in functional-group conversions, where CO₂ participates dynamically in redox processes without necessarily being retained in the final molecular framework. Such an approach enables the redox potential embedded within CO₂ to be exploited for synthetically useful transformations while opening new mechanistic possibilities for reaction design.

Together, these studies establish a broader conceptual framework for CO₂ utilization beyond fixation, in which CO₂ can function as a carbon source, reaction promoter, oxygen-transfer reagent, and redox mediator. By uncovering and controlling these unconventional modes of CO₂ reactivity, we aim to transform one of the most abundant waste molecules into a versatile synthetic tool and provide new directions for more resource-efficient and sustainable organic synthesis.

References: (a) Qin et al. Science 2026, 392, eaed6068. (b) Qin et al. Nature Commun. 2023, 14, 7604. (c) Piccirilli et al. J. Am. Chem. Soc. 2023, 145, 5655. (d) Hu et al. Angew. Chem. Int. Ed. 2026, e9277722. (e) Reimer et al. ACS Catal. 2018, 8, 3030.