Photo-induced carboxylation of C(sp)-S bonds in aryl thiols and derivatives with CO.

Aryl thiols have proven to be a useful class of electron donors and hydrogen atom sources in photochemical processes. However, the direct activation and functionalization of C(sp)-S bonds in aryl thiols remains elusive in the field of photochemistry. Herein, a photochemical carboxylation of C(sp)-S bonds in aryl thiols with CO is reported, providing a synthetic route to important aryl carboxylic acids.

Nickel-Catalyzed Atroposelective Carbo-Carboxylation of Alkynes with CO: En Route to Axially Chiral Carboxylic Acids.

Precise synthesis of carboxylic acids via catalytic carboxylation with CO is highly appealing. Although considerable advancements have been achieved in difunctionalizing carboxylation of unsaturated hydrocarbons, the asymmetric variants are conspicuously underdeveloped, particularly in addressing axially chiral alkenes. Herein, we report the first catalytic atroposelective carboxylation of alkynes with CO.

Dearomative hydroamination of heteroarenes catalyzed by the phenolate photocatalyst.

Dearomative functionalization of heteroarenes offers an attractive and sustainable approach for the rapid construction of complex 3D heterocyclic scaffolds from planar structures. Despite progress in this field, dearomative amination of heteroarenes a radical anion intermediate remains a challenge. Here, we report a photoredox-catalyzed dearomative hydroamination of heteroarenes with hydrazodiformates under mild and transition-metal-free reaction conditions.

Visible-Light Photoredox-Catalyzed Direct Carboxylation of Tertiary C(sp)-H Bonds with CO: Facile Synthesis of All-Carbon Quaternary Carboxylic Acids.

Direct carboxylation of C-H bonds with CO represents an attractive strategy to synthesize valuable carboxylic acids with high atom, step, and redox economy. Although great progress has been achieved in this field, catalytic carboxylation of tertiary C(sp)-H bonds still remains challenging due to their inherent inertness and significant steric hindrance. Herein, we report a direct carboxylation of tertiary benzylic C(sp)-H bonds with CO via visible-light photoredox catalysis.

Recent Advances in Electrochemical Carboxylation with CO.

ConspectusCarbon dioxide (CO) is recognized as a greenhouse gas and a common waste product. Simultaneously, it serves as an advantageous and commercially available C1 building block to generate valuable chemicals. Particularly, carboxylation with CO is considered a significant method for the direct and sustainable production of important carboxylic acids.

Atropisomeric Carboxylic Acids Synthesis via Nickel-Catalyzed Enantioconvergent Carboxylation of Aza-Biaryl Triflates with CO.

Upgrading CO 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 CO has never been reported to date. Herein, we report the first catalytic asymmetric synthesis of axially chiral carboxylic acids with CO, which is enabled by nickel-catalyzed dynamic kinetic asymmetric reductive carboxylation of racemic aza-biaryl triflates.

Cu-Catalyzed Asymmetric Dicarboxylation of 1,3-Dienes with CO.

Dicarboxylic acids and derivatives are important building blocks in organic synthesis, biochemistry, and the polymer industry. Although catalytic dicarboxylation with CO represents a straightforward and sustainable route to dicarboxylic acids, it is still highly challenging and limited to generation of achiral or racemic dicarboxylic acids. To date, catalytic asymmetric dicarboxylation with CO to give chiral dicarboxylic acids has not been reported.

Arylcarboxylation of unactivated alkenes with CO via visible-light photoredox catalysis.

Photocatalytic carboxylation of alkenes with CO 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 CO, 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.

Electroreductive Dicarboxylation of Unactivated Skipped Dienes with CO.

Carboxylation of easily available alkenes with CO 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 CO remains unexplored. Herein, we report the first dicarboxylation of unactivated skipped dienes with CO via electrochemistry, affording valuable dicarboxylic acids.

Photocatalytic Carboxylation of C-N Bonds in Cyclic Amines with CO by Consecutive Visible-Light-Induced Electron Transfer.

Visible-light photocatalytic carboxylation with CO 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 CO via consecutive photo-induced electron transfer (ConPET).

Electrochemical reactor dictates site selectivity in N-heteroarene carboxylations.

Pyridines and related N-heteroarenes are commonly found in pharmaceuticals, agrochemicals and other biologically active compounds. Site-selective C-H functionalization would provide a direct way of making these medicinally active products. For example, nicotinic acid derivatives could be made by C-H carboxylation, but this remains an elusive transformation.

Electrochemical Ring-Opening Dicarboxylation of Strained Carbon-Carbon Single Bonds with CO: Facile Synthesis of Diacids and Derivatization into Polyesters.

Diacids are important monomers in the polymer industry to construct valuable materials. Dicarboxylation of unsaturated bonds, such as alkenes and alkynes, with CO has been demonstrated as a promising synthetic method. However, dicarboxylation of C─C single bonds with CO has rarely been investigated.

Nickel-catalyzed electrochemical carboxylation of unactivated aryl and alkyl halides with CO.

Electrochemical catalytic reductive cross couplings are powerful and sustainable methods to construct C-C bonds by using electron as the clean reductant. However, activated substrates are used in most cases. Herein, we report a general and practical electro-reductive Ni-catalytic system, realizing the electrocatalytic carboxylation of unactivated aryl chlorides and alkyl bromides with CO.

Visible-light photoredox-catalyzed umpolung carboxylation of carbonyl compounds with CO.

Photoredox-mediated umpolung strategy provides an alternative pattern for functionalization of carbonyl compounds. However, general approaches towards carboxylation of carbonyl compounds with CO remain scarce. Herein, we report a strategy for visible-light photoredox-catalyzed umpolung carboxylation of diverse carbonyl compounds with CO by using Lewis acidic chlorosilanes as activating/protecting groups.

Radical Carboxylative Cyclizations and Carboxylations with CO.

Carbon dioxide (CO) is not only a greenhouse gas and a common waste product but also an inexpensive, readily available, and renewable carbon resource. It is an important one-carbon (C1) building block in organic synthesis for the construction of valuable compounds. However, its utilization is challenging owing to its thermodynamic stability and kinetic inertness.

Nickel-Catalyzed Asymmetric Reductive Carbo-Carboxylation of Alkenes with CO.

Reductive carboxylation of organo (pseudo)halides with CO is a powerful method to provide carboxylic acids quickly. Notably, the catalytic reductive carbo-carboxylation of unsaturated hydrocarbons via CO fixation is a highly challenging but desirable approach for structurally diverse carboxylic acids. There are only a few reports and no examples of alkenes via transition metal catalysis.

α-Amino Acids and Peptides as Bifunctional Reagents: Carbocarboxylation of Activated Alkenes via Recycling CO.

Carboxylic acids, including amino acids (AAs), have been widely used as reagents for decarboxylative couplings. In contrast to previous decarboxylative couplings that release CO as a waste byproduct, herein we report a novel strategy with simultaneous utilization of both the alkyl and carboxyl components from carboxylic acids. Under this unique strategy, carboxylic acids act as bifunctional reagents in the redox-neutral carbocarboxylation of alkenes.

Visible-Light Photoredox-Catalyzed Ring-Opening Carboxylation of Cyclic Oxime Esters with CO.

The carboxylation of cyclic oxime esters with carbon dioxide via visible-light photoredox catalysis is demonstrated for the first time. A variety of cyclic oxime esters undergo ring-opening C-C bond cleavage and carboxylation to give cyanoalkyl-containing carboxylic acids in moderate to good yields. Moreover, this methodology features mild reaction conditions (room temperature, 1 atm), wide substrate scope, good functional group tolerance as well as facile derivations of products.

Visible-Light Photoredox-Catalyzed Remote Difunctionalizing Carboxylation of Unactivated Alkenes with CO.

Remote difunctionalization of unactivated alkenes is challenging but a highly attractive tactic to install two functional groups across long distances. Reported herein is the first remote difunctionalization of alkenes with CO . This visible-light photoredox catalysis strategy provides a facile method to synthesize a series of carboxylic acids bearing valuable fluorine- or phosphorus-containing functional groups.

Light Runs Across Iron Catalysts in Organic Transformations.

Over the past decades, organometallic complexes with precious elements, such as ruthenium and iridium, are widely used as visible-light photoredox catalysts. Recently, more and more complexes based on earth-abundant and inexpensive elements have been used as sensitizers in photochemistry. Although the photoexcited state lifetimes of iron complexes are typically shorter than those of traditional photosensitizers, the utilization of iron catalysts in photochemistry has sprung up owing to their abundance, low price, nontoxicity, and novel properties, including exhibiting ligand to metal charge transfer states.

Reductive dearomative arylcarboxylation of indoles with CO via visible-light photoredox catalysis.

Catalytic reductive coupling of two electrophiles and one unsaturated bond represents an economic and efficient way to construct complex skeletons, which is dominated by transition-metal catalysis via two electron transfer. Herein, we report a strategy of visible-light photoredox-catalyzed successive single electron transfer, realizing dearomative arylcarboxylation of indoles with CO. This strategy avoids common side reactions in transition-metal catalysis, including ipso-carboxylation of aryl halides and β-hydride elimination.