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Upgrading CO2 to value‐added chiral molecules via catalytic asymmetric C−C bond formation is a highly important yet challenging task. Although great progress on the formation of centrally chiral carboxylic acids has been achieved, catalytic construction of axially chiral carboxylic acids with CO2 has never been reported to date. Herein, we report the first catalytic asymmetric synthesis of axially chiral carboxylic acids with CO2, which is enabled by nickel‐catalyzed dynamic kinetic asymmetric reductive carboxylation of racemic aza‐biaryl triflates. A variety of important axially chiral carboxylic acids, which are valuable but difficult to obtain via catalysis, are generated in an enantioconvergent version. This new methodology features good functional group tolerance, easy to scale‐up, facile transformation and avoids cumbersome steps, handling organometallic reagents and using stoichiometric chiral materials. Mechanistic investigations indicate a dynamic kinetic asymmetric transformation process induced by chiral nickel catalysis. [ABSTRACT FROM AUTHOR]

Upgrading CO2 to value‐added chiral molecules via catalytic asymmetric C−C bond formation is a highly important yet challenging task. Although great progress on the formation of centrally chiral carboxylic acids has been achieved, catalytic construction of axially chiral carboxylic acids with CO2 has never been reported to date. Herein, we report the first catalytic asymmetric synthesis of axially chiral carboxylic acids with CO2, which is enabled by nickel‐catalyzed dynamic kinetic asymmetric reductive carboxylation of racemic aza‐biaryl triflates. A variety of important axially chiral carboxylic acids, which are valuable but difficult to obtain via catalysis, are generated in an enantioconvergent version. This new methodology features good functional group tolerance, easy to scale‐up, facile transformation and avoids cumbersome steps, handling organometallic reagents and using stoichiometric chiral materials. Mechanistic investigations indicate a dynamic kinetic asymmetric transformation process induced by chiral nickel catalysis. [ABSTRACT FROM AUTHOR]

Herein, we report a photocatalytic defluorocarboxylation of benzylic C(sp3)–F bonds using formate salts as both a reductant and a carbon dioxide source. A variety of benzyl fluorides, bearing primary or secondary C(sp3)–F bonds, undergo defluorinative carboxylation smoothly with HCOOK. This transition metal-free strategy provides a mild, efficient, and sustainable approach for accessing a series of valuable aryl acetic acids, such as flurbiprofen. This protocol also features low catalyst loading, mild reaction conditions, good functional group tolerance, and ready scalability and sustainability. Mechanistic investigations indicate that a carbon dioxide radical anion (CO2˙−) is generated via hydrogen atom transfer (HAT) and acts as a strong reductant to promote single electron reduction of benzyl fluorides. The following nucleophilic attack of carbanions on CO2, both of which are in situ generated intermediates, delivers the desired products, demonstrating the high efficiency of the CO2 capture process. [ABSTRACT FROM AUTHOR]

Photocatalytic carboxylation of alkenes with CO2 is a promising and sustainable strategy to synthesize high value-added carboxylic acids. However, it is challenging and rarely investigated for unactivated alkenes due to their low reactivities. Herein, we report a visible-light photoredox-catalyzed arylcarboxylation of unactivated alkenes with CO2, delivering a variety of tetrahydronaphthalen-1-ylacetic acids, indan-1-ylacetic acids, indolin-3-ylacetic acids, chroman-4-ylacetic acids and thiochroman-4-ylacetic acids in moderate-to-good yields. This reaction features high chemo- and regio-selectivities, mild reaction conditions (1 atm, room temperature), broad substrate scope, good functional group compatibility, easy scalability and facile derivatization of products. Mechanistic studies indicate that in situ generation of carbon dioxide radical anion and following radical addition to unactivated alkenes might be involved in the process. Despite the importance of polycyclic carboxylic acids and derivatives in various fields, general methods for the arylcarboxylation of alkenes with CO2 remain elusive. Here, the authors transform unactivated alkenes into high value-added polycyclic carboxylic acids and derivatives via visible-light photoredox-catalysis, using CO2 as the one-carbon feedstock. [ABSTRACT FROM AUTHOR]

Carboxylation of easily available alkenes with CO2 is highly important to afford value‐added carboxylic acids. Although dicarboxylation of activated alkenes, especially 1,3‐dienes, has been widely investigated, the challenging dicarboxylation of unactivated 1,n‐dienes (n>3) with CO2 remains unexplored. Herein, we report the first dicarboxylation of unactivated skipped dienes with CO2 via electrochemistry, affording valuable dicarboxylic acids. Control experiments and DFT calculations support the single electron transfer (SET) reduction of CO2 to its radical anion, which is followed by sluggish radical addition to unactivated alkenes, SET reduction of unstabilized alkyl radicals to carbanions and nucleophilic attack on CO2 to give desired products. This reaction features mild reaction conditions, broad substrate scope, facile derivations of products and promising application in polymer chemistry. [ABSTRACT FROM AUTHOR]

Carboxylation of easily available alkenes with CO2 is highly important to afford value‐added carboxylic acids. Although dicarboxylation of activated alkenes, especially 1,3‐dienes, has been widely investigated, the challenging dicarboxylation of unactivated 1,n‐dienes (n>3) with CO2 remains unexplored. Herein, we report the first dicarboxylation of unactivated skipped dienes with CO2 via electrochemistry, affording valuable dicarboxylic acids. Control experiments and DFT calculations support the single electron transfer (SET) reduction of CO2 to its radical anion, which is followed by sluggish radical addition to unactivated alkenes, SET reduction of unstabilized alkyl radicals to carbanions and nucleophilic attack on CO2 to give desired products. This reaction features mild reaction conditions, broad substrate scope, facile derivations of products and promising application in polymer chemistry. [ABSTRACT FROM AUTHOR]

Difunctionalizing carboxylation of alkynes with CO2 is a sustainable and important strategy to generate valuable acrylate derivatives from both readily available starting materials. Such protocols, however, always suffer from the use of excess metallic reagents and transition metal residue. Herein, we report the first thio-carboxylation of alkynes with thiophenols and CO2, which is a visible-light-driven and transition metal-free process. In contrast to previous carboxylations of alkynes via two-electron activation of CO2, mechanistic and computational investigations suggest that the single-electron activation of CO2 is involved in the thio-carboxylation, rendering unique β-carboxylation. The following cyclizing acylation affords important thiochromones efficiently. Moreover, the one-pot method features mild reaction conditions (room temperature, 1 atmosphere of CO2), high chemo- and regio-selectivity, easy scalability and facile derivatization of products to bioactive compounds. [ABSTRACT FROM AUTHOR]

Visible‐light photocatalytic carboxylation with CO2 is highly important. However, it still remains challenging for reluctant substrates with low reduction potentials. Herein, we report a novel photocatalytic carboxylation of C−N bonds in cyclic amines with CO2 via consecutive photo‐induced electron transfer (ConPET). It is also the first photocatalytic reductive ring‐opening reaction of azetidines, pyrrolidines and piperidines. This strategy is practical to transform a variety of easily available cyclic amines to valuable β‐, γ‐, δ‐ and ϵ‐amino acids in moderate‐to‐excellent yields. Moreover, the method also features mild and transition‐metal‐free conditions, high selectivity, good functional‐group tolerance, facile scalability and product derivations. Mechanistic studies indicate that the ConPET might be the key to generating highly reactive photocatalysts, which enable the reductive activation of cyclic amines to generate carbon radicals and carbanions as the key intermediates. [ABSTRACT FROM AUTHOR]