•Selective carboxylation of C(sp3)–F bonds with CO2•Mild visible-light photoredox catalytic systems•Broad substrate scope for various C(sp3)–F bonds carboxylation•The dual role of CO2 demonstrated by mechanistic studies and DFT calculations In the past decades, carbon dioxide (CO2) has been widely used as a C1 building block in organic synthesis because of its high abundance, easy availability, and renewability. Notably, reductive carboxylations of various electrophiles with CO2 offer a straightforward access to carboxylic acids with high step economy, preventing the synthesis and handling of moisture-sensitive organometallic reagents. However, as both C–F bonds and CO2 are inert, the catalytic carboxylation of C(sp3)–F bonds with CO2 under transition-metal-free conditions has never been investigated. Herein, we report a novel selective carboxylation of C(sp3)–F bonds with CO2 via visible-light photoredox catalysis. Notably, mechanistic studies demonstrate that the unreactive fluorinated substrates would undergo single-electron transfer reduction by in situ generated CO2 radical anions, which is reductive. We anticipate that our findings could provide guidance for the general research on CO2 utilization with other inert substrates, including biomass. It is highly attractive and challenging to utilize carbon dioxide (CO2), because of its inertness, as a nontoxic and sustainable C1 source in the synthesis of valuable compounds. Here, we report a novel selective carboxylation of C(sp3)−F bonds with CO2 via visible-light photoredox catalysis. A variety of mono-, di-, and trifluoroalkylarenes as well as α,α-difluorocarboxylic esters and amides undergo such reactions to give important aryl acetic acids and α-fluorocarboxylic acids, including several drugs and analogs, under mild conditions. Notably, mechanistic studies and DFT calculations demonstrate the dual role of CO2 as an electron carrier and electrophile during this transformation. The fluorinated substrates would undergo single-electron reduction by electron-rich CO2 radical anions, which are generated in situ from CO2 via sequential hydride-transfer reduction and hydrogen-atom-transfer processes. We anticipate our finding to be a starting point for more challenging CO2 utilization with inert substrates, including lignin and other biomass. It is highly attractive and challenging to utilize carbon dioxide (CO2), because of its inertness, as a nontoxic and sustainable C1 source in the synthesis of valuable compounds. Here, we report a novel selective carboxylation of C(sp3)−F bonds with CO2 via visible-light photoredox catalysis. A variety of mono-, di-, and trifluoroalkylarenes as well as α,α-difluorocarboxylic esters and amides undergo such reactions to give important aryl acetic acids and α-fluorocarboxylic acids, including several drugs and analogs, under mild conditions. Notably, mechanistic studies and DFT calculations demonstrate the dual role of CO2 as an electron carrier and electrophile during this transformation. The fluorinated substrates would undergo single-electron reduction by electron-rich CO2 radical anions, which are generated in situ from CO2 via sequential hydride-transfer reduction and hydrogen-atom-transfer processes. We anticipate our finding to be a starting point for more challenging CO2 utilization with inert substrates, including lignin and other biomass. 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Control experiments revealed that visible-light irradiation, photocatalyst, CO2, and Cs2CO3 were all essential for the reaction (entries 2–5). When the reaction was carried out under N2 atmosphere, no desired product was obtained, demonstrating that the carboxyl group came from CO2. The reaction took place in a much lower efficiency when Et3SiH was absent (entry 6). Other common reductants, such as polymethylhydrosiloxane (PMHS) and amines, showed lower reactivity and selectivity (entries 7–8). Among different kinds of solvents and bases, we found that DMSO and Cs2CO3 were the best choice (entries 9–11). With the optimal reaction conditions in hand, we then investigated the scope of difluoroalkylarenes (Figure 3A ). 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For example, the corresponding acid of 2n is the bioisostere of diphenylacetic acid, which is an important pharmaceutical intermediate for the synthesis of antispasmodic drugs, such as adiphenine and piperidolate.53Spitzmaul G. Gumilar F. Dilger J.P. Bouzat C. The local anaesthetics proadifen and adiphenine inhibit nicotinic receptors by different molecular mechanisms.Br. J. Pharmacol. 2009; 157: 804-817Crossref PubMed Scopus (29) Google Scholar Notably, the substrate 1o bearing an aryl C–Cl bond was also applicable to such a selective carboxylation of C–F bonds, affording the desired product 2o in 75% yield with high chemoselectivity. In contrast, C–X bonds (in which X = Cl, Br, I) hardly remained intact in previous works with regard to photocatalytic functionalization of benzylic C–F bonds, and the hydrodehalogenation products were often obtained as the main products.39Vogt D.B. Seath C.P. Wang H. Jui N.T. Selective C-F functionalization of unactivated trifluoromethylarenes.J. Am. 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