Transition metal-free phosphonocarboxylation of alkenes with carbon dioxide via visible-light photoredox catalysis

Modulated Multicomponent Reaction Pathway by Pore-Confinement Effect in MOFs for Highly Efficient Catalysis of Low-Concentration CO2

The conversion of flue gas CO2 into high-value chemicals via multicomponent reactions (MCRs) offers the advantages of atom economy, bond-formation efficiency and product complexity. However, because of the competition between reaction sequences and pathways among substrates, the efficient synthesize the desired product is a great challenge. Herein, a porous noble-metal-free framework (Cu-TCA) was synthesized, which can highly effectively catalyze the multicomponent conversion of CO2 by modulating reaction pathways. The pores with the size of 6.5 Å×6.5 Å in Cu-TCA selectively permit the entry of propargylamine and CO2 at simulated flue gas concentrations, At the same time, the larger-sized phosphine oxide is hindered outside the pores. Control experiments and NMR spectroscopy revealed that CO2 and propargylamine in the pores preferentially reacted to form oxazolidinones, which further reacted with phosphine oxide outside the pores to produce phosphorylated 2-oxazolidinones. Therefore, the reaction pathways and sequence of the substrates were controlled by the confinement effect of the pores in Cu-TCA. Density functional theory (DFT) calculations supported the coordination of Cu-TCA with the alkyne, significantly reducing the reaction barrier and promoting catalytic reaction. This study developed a new strategy for regulating the reaction pathways to promote MCRs via the confinement effect of MOF.

Photocatalytic reductive incorporation of carbon dioxide into double bonds

Carbon dioxide (CO2) is a challenging molecule to incorporate into olefins due to its inherent inert properties. Silanes have now been shown to rapidly react selectively with CO2, catalysed by the presence of a caesium base, to form formate salts which can undergo a hydrogen atom transfer (HAT) to give the desired CO2˙- adducts in the presence of activated olefins.

CsPbBr3-Modified Oxygen-Doped g-C3N4 Heterojunctions for Sulfurization of Alkenes to Sulfoxides

Z-scheme heterostructures have become a novel class of photocatalysts that hold substantial significance in the domains of environmental and energy-related applications. This can be attributed to their distinctive charge separation and transfer pathways, which endow Z-scheme heterojunctions with robust redox capabilities. In this paper, we report a straightforward method for fabricating a perovskite-based Z-scheme heterojunction by integrating CsPbBr3 nanocrystals with oxygen-doped g-C3N4 (OCN). This heterojunction exhibited a high photocatalytic activity in the selective sulfoxidation reaction of alkenes with thiols. Under aerobic conditions, moderate to excellent yields of high-value sulfoxides with good functional compatibilities were achieved. This heterojunction showcases outstanding photocatalytic performance, remarkable stability, operational simplicity, high atom efficiency, and eco-friendly energy sources. The formation of Z-scheme heterojunction was corroborated by in situ X-ray photoelectron spectroscopy. These spectra revealed a negative shift in the binding energies of Cs 1s, Pb 4f, and Br 3d in CsPbBr3, while a positive shift was observed for C 1s, N 1s, and O 1s in OCN upon light irradiation. This specific shift pattern effectively promotes the Z-scheme electron transfer from OCN to CsPbBr3, which is conducive to the separation of electrons and holes, thereby enhancing the photoredox catalytic activity.

Photocatalytic stereoselective synthesis of amido-substituted (E)-α-trifluoromethyl allylamines via Heck-type alkylation

A Heck-type alkylation of enamides with N-trifluoroethyl hydroxylamine reagents was developed under photocatalytic conditions. This stereoselective reaction provides amido-substituted (E)-α-trifluoromethyl allylamines in yields up to 96%. In the mechanism, photoredox-induced 1,2-H shift of the in situ generated N-trifluoroethyl radical was involved.

Potassium Phosphate-Mediated Synthesis of C4-Phosphorylated Quinolines via Cascade Cycloisomerization of Ynones

A cascade phosphorylation cycloisomerization of readily accessible ynones and diphenylphosphine oxides facilitated by potassium phosphate is described, allowing for the straightforward synthesis of C4-phosphorylated quinoline scaffolds. The formation of a C-P bond and a C-N bond is achieved in a single procedure without the need for pre-assembled quinoline cores prior to phosphorylation. This transformation operates without the requirement for metals or oxidants and exhibits excellent compatibility with various functional groups. Furthermore, antimicrobial activity evaluation demonstrated that the synthesized C4-phosphorylated quinoline derivatives exhibited potent inhibitory activity against Staphylococcus aureus.

α-Nucleophilic Addition to α,β-Unsaturated Carbonyl Compounds via Photocatalytically Generated α-Carbonyl Carbocations

We report the photocatalytic oxidation of α-carbonyl radicals of amides or esters to the corresponding α-carbonyl carbocations through super photoreductant CBZ6 induced redox-neutral photocatalysis. The α-carbonyl radicals are formed by the β-addition of alkyl radicals generated in situ by the photocatalytic fragmentation of N-hydroxyphthalimide esters to the α,β-unsaturated amides and esters. This method enables the α-nucleophilic addition of hydroxyl or alkoxyl radicals to amides and esters without any prefunctionalization.

Nickel-Catalyzed Atroposelective Carbo-Carboxylation of Alkynes with CO2: En Route to Axially Chiral Carboxylic Acids

Precise synthesis of carboxylic acids via catalytic carboxylation with CO2 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 CO2. A variety of valuable axially chiral carboxylic acids are obtained with good yields and high chemo-, regio-, Z/E and enantio-selectivities. Notably, an unexpected anti-selective carbo-carboxylation is observed in the sp2-hybrid carbo-electrophile-initiated reductive carboxylation of alkynes. Mechanistic studies including DFT calculation elucidate the origin of chiral induction and anti-selectivity in vinyl-carboxylation of alkynes.

Dehydrogenative α,γ-Diphosphinylation of Allylamines Enabled by Photoinduced Cobaloxime Catalysis

A regioselective radical α,γ-diphosphinylation of allylamines with secondary phosphine oxides by photoinduced cobaloxime catalysis is described. The reaction tolerates a wide range of allylamines and phosphine oxides, affording α-amino diphosphine dioxides in moderate to good yields with hydrogen evolution. The synthesis of new diphosphine monoxide and diphosphine ligands and the promising antitumor activities of products demonstrate the great potential applications of this approach in catalysis and drug discovery. The detailed mechanism studies indicate that this reaction likely proceeds through a dehydrogenative allylic phosphinylation and nucleophilic addition process.

Visible-Light Photoredox-Catalyzed Direct Carboxylation of Tertiary C(sp3)-H Bonds with CO2: Facile Synthesis of All-Carbon Quaternary Carboxylic Acids

Direct carboxylation of C-H bonds with CO2 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(sp3)-H bonds still remains challenging due to their inherent inertness and significant steric hindrance. Herein, we report a direct carboxylation of tertiary benzylic C(sp3)-H bonds with CO2 via visible-light photoredox catalysis. Various all-carbon quaternary carboxylic acids, which are of significant importance in medicinal chemistry, are successfully obtained with high yields. This direct carboxylation is characterized by good functional group tolerance, broad substrate scope, and mild operational conditions. Furthermore, our methodology enables the efficient and rapid synthesis of key drug or bioactive molecules, such as carbetapentane, caramiphen, and PRE-084 (σ1 receptor agonist), and facilitates various functionalizations of C(sp2)-H bonds using the directing ability of target carboxylic acids, thus highlighting its practical applications. Mechanistic studies indicate that a carbanion, which serves as the key intermediate to react with CO2, is catalytically generated via a single electron reduction of a benzylic radical through a consecutive photoinduced electron transfer process.

Photoredox/NHC Dual Catalysis Enabled de Novo Synthesis of α-Amino Acids Derivatives

Herein, we report a mild and operationally simple photoredox/NHC dual catalysis strategy for the α-carboxylation of tertiary amine C(sp3)-H bonds using diethyl pyrocarbonate. This method offers a novel approach for synthesizing α-amino acid derivatives. The protocol features a broad substrate scope, accommodating both N-aryl tetrahydroisoquinolines (THIQ) and N-methyl aniline and is scalable to gram quantities. Additionally, it is suitable for the late-stage derivatization of certain pharmaceutical compounds.

Electrochemically Enabled Hydroxyphosphorylation of 1,3-Enynes to Access Phosphinyl-Substituted Propargyl Alcohols

Catalytic difunctionalization with the direct activation of (O)P-H bonds has been recently established as a potentially robust platform to generate valuable organophosphorus compounds. In terms of 1,3-enynes, despite of the various catalytic methods developed for hydrophosphorylation, the radical-mediated hetero-functionalization of two different atoms has been less explored. In this study, we disclosed an electrochemically induced hydroxyphosphorylation of 1,3-enynes for the construction of phosphinyl-substituted propargyl alcohols. The system involves the direct activation of both arylphosphine oxides and oxygen in ambient air with no external metal or additive needed. The use of electrochemistry ensures the regioselective, atom-economic and eco-friendly for the difunctionalization process. This strategy highlights the advantages of mild reaction conditions, readily available starting materials and broad substrate scope, showing its practical synthetic value in organic synthesis.

Photocatalytic Three-Component Acylcarboxylation of Alkenes with CO2

γ-Keto acid is a valuable chemical motif in a wide range of fields including organic, biological, and medicinal chemistry. However, its single-step synthesis is challenging because of the mismatch of the carbonyl polarity and low tolerance of carboxylic acids. Herein, we report the single-step syntheses of γ-keto acids using alkenes and CO2. Our photocatalytic system enabled the transformation of alkenes under mild conditions in high yields (up to 95%) with broad substrate generality (35 examples).

Electroreductive Arylcarboxylation of Styrenes with CO2 and Aryl Halides via a Radical-Polar Crossover Mechanism

2,3-Diaryl propanoic acids are important structures as a result of their widespread presence in numerous bioactive compounds. However, the limitations of existing synthetic techniques include the requirement for costly catalysts and limited substrates. Here, we developed a novel electroreductive arylcarboxylation of alkenes with CO2 based on a radical-polar crossover pathway assisted by easily accessible dimethyl terephthalate as a reductive mediator. This method will provide an efficient strategy for the synthesis of 2,3-diarylpropanoic acids.

Visible-Light-Induced Regioselective Radical-Polar Crossover 1,4-Hydrophosphinylation of 1,3-Enynes: Access to Trisubstituted Allenes Bearing a Phosphine Oxide Group

The radical 1,4-functionalizations of 1,3-enynes have emerged as a powerful strategy for the synthesis of multisubstituted allenes. However, the phosphorus-centered radical-initiated transformations remain largely elusive. Herein, visible-light photoredox catalytic regioselective radical hydrophosphinylation of 1,3-enynes with diaryl phosphine oxides as phosphinoyl radical precursors has been realized. This protocol features mild conditions, a wide substrate scope, and good functional group tolerance, producing a diverse range of phosphinoyl-substituted allenes in moderate to good yields with high atom economy. Detailed mechanistic experiments revealed a radical-polar crossover process in the reaction.

Visible Light Photoredox-Catalyzed Formyl/Carboxylation of Activated Alkenes with Glyoxylic Acid Acetals and CO2

A photoredox-catalyzed sequential α-formyl/carboxylation of alkenes with glyoxylic acid acetals and CO2 has been developed to afford a range of masked γ-formyl esters in good yields, which could be readily transformed into diverse compounds, such as γ-formyl ester, hemiacetal, and 1,4-diol. This reaction features mild conditions, readily available starting materials, and operational simplicity.

Challenges and recent advancements in the synthesis of α,α-disubstituted α-amino acids

α,α-Disubstituted α-amino acids (α-AAs) have improved properties compared to other types of amino acids. They serve as modifiers of peptide conformation and as precursors of bioactive compounds. Therefore, it has been a long-standing goal to construct this highly valuable scaffold efficiently in organic synthesis and drug discovery. However, access to α,α-disubstituted α-AAs is highly challenging and largely unexplored due to their steric constraints. To overcome these, remarkable advances have been made in the last decades. Emerging strategies such as synergistic enantioselective catalysis, visible-light-mediated photocatalysis, metal-free methodologies and CO2 fixation offer new avenues to access the challenging synthesis of α,α-disubstituted α-AAs and continuously bring additional contributions to this field. This review article aims to provide an overview of the recent advancements since 2015 and discuss existing challenges for the synthesis of α,α-disubstituted α-AAs and their derivatives.

Reductive Radical-Polar Crossover Enabled Carboxylative Alkylation of Aryl Thianthrenium Salts with CO2 and Styrenes

Carboxylic functionalities are among the pivotal groups in bioactive molecules and in the synthesis of new lead compounds because of their unique character in the formation of hydrogen bonds and the possibility of constructing molecular complexes via amide couplings. We adopt the reductive radical-polar crossover strategy to introduce carboxyalkyl groups into arenes with styrenes and CO2 via thianthrenium salts. This protocol exhibits excellent potential as a straightforward and modular platform for site-selective carboxylative derivation of bioactive molecules.

Metal-Free Heterogeneous Photocatalysis for Carbocarboxylation of Alkenes: Efficient Synthesis of γ-Amino Carboxylic Derivatives

A metal-free heterogeneous protocol is established herein for the synthesis of value-added γ-amino acid scaffolds via carbocarboxylation of alkenes with CO2 and alkylamines under visible light irradiation. The protocol shows broad substrate scope under mild reaction conditions and good stability of the catalyst for recycle tests. Moreover, the methodology could be feasible to the late-stage derivatization of several natural products, enriching the chemical arsenal for practical application.

Deconstructive Carboxylation of Activated Alkenes with Carbon Dioxide

Carboxylation with carbon dioxide (CO2 ) represents one notable methodology to produce carboxylic acids. In contrast to carbon-heteroatom bonds, carbon-carbon bond cleavage for carboxylation with CO2 is far more challenging due to their inherent and less favorable orbital directionality for interacting with transition metals. Here we report a photocatalytic protocol for the deconstructive carboxylation of alkenes with CO2 to generate carboxylic acids in the absence of transition metals. It is emphasized that our protocol provides carboxylic acids with obviously unchanged carbon numbers when terminal alkenes were used. To show the power of this strategy, a variety of pharmaceutically relevant applications including the modular synthesis of propionate nonsteroidal anti-inflammatory drugs and the late-stage carboxylation of bioactive molecule derivatives are demonstrated.

Ferrocene catalyzed carbohydroxylation of alkenes using H2O and cycloketone oxime esters

A cyanoalkyl-hydroxylation reaction of aryl alkenes has been successfully devised, employing ferrocene as a catalyst for the addition of a cycloketone oxime ester and H2O across the double bond of the alkene. This environmentally friendly approach employs a solvent mixture consisting of water and demonstrates redox neutrality, along with exceptional regio- and chemoselectivity, leading to the formation of diverse distal hydroxy-nitrile compounds. Moreover, this research presents noteworthy contributions in terms of late-stage functionalization of complex molecules and offers valuable insights into the mechanistic aspects of the reaction.

Photoredox-Catalyzed Phosphonocarboxylation of Allenes with Phosphine Oxides and CO2

Phosphonocarboxylation of allenes with diarylphosphine oxides and CO2 via visible-light photoredox catalysis was developed for the first time. This work provided practical and sustainable access to highly valuable but otherwise difficult-to-access linear allylic β-phosphonyl carboxylic acids in moderate yields with exclusive regio- and stereoselectivity. This method was also characterized by step and atom economy and transition-metal free and mild conditions. Preliminary mechanistic studies suggested that allyl-methyl carbanion species are the key intermediates.

Arylcarboxylation of unactivated alkenes with CO2 via visible-light photoredox catalysis

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.

Redox-neutral carbon-heteroatom bond formation under photoredox catalysis

Recently, visible-light-mediated photoredox catalysis has been emerging as one of the fastest growing fields in organic chemistry because of its low cost, easy availability and environmental benignness. In the past five years, a new yet challenging trend, visible-light-induced redox-neutral carbon-heteroatom bond formation reaction involving presumed radical intermediates, has been flourishing rapidly. Although mostly transition metal-based photoredox catalysts were reported, a few organophotoredox catalysts have also shown efficacy towards carbon-heteroatom bond formation reactions. This review intends to summarize the recent research progress in redox-neutral carbon-heteroatom bond formations based on active intermediate(s) involved under photoredox catalysis.

Expanding Reaction Profile of Allyl Carboxylates via 1,2-Radical Migration (RaM): Visible-Light-Induced Phosphine-Catalyzed 1,3-Carbobromination of Allyl Carboxylates

Allyl carboxylates are useful synthetic intermediates in a variety of organic transformations, including catalytic nucleophilic/electrophilic allylic substitution reactions and 1,2-difunctionalization reactions. However, the catalytic 1,3-difunctionalization of allyl carboxylates remains elusive. Herein, we report the first photoinduced, phosphine-catalyzed 1,3-carbobromination of allyl carboxylates, affording a range of valuable substituted isopropyl carboxylates (sIPC). The transformation has broad functional group tolerance, is amenable to the late-stage modification of complex molecules and gram-scale synthesis, and expands the reaction profiles of allyl carboxylates and phosphine catalysis. Preliminary experimental and computational studies suggest a non-chain-radical mechanism involving the formation of an electron donor-acceptor complex, 1,2-radical migration (RaM), and Br-atom transfer processes. We anticipate that the 1,2-RaM reactivity of allyl carboxylates and the phosphine-catalyzed radical reaction will both serve as a platform for the development of new transformations in organic synthesis.

Copper-Catalyzed Chemo- and Enantioselective Radical 1,2-Carbophosphonylation of Styrenes

The copper-catalyzed enantioselective radical difunctionalization of alkenes from readily available alkyl halides and organophosphorus reagents possessing a P-H bond provides an appealing approach for the synthesis of α-chiral alkyl phosphorus compounds. The major challenge arises from the easy generation of a P-centered radical from the P-H-type reagent and its facile addition to the terminal side of alkenes, leading to reverse chemoselectivity. We herein disclose a radical 1,2-carbophosphonylation of styrenes in a highly chemo- and enantioselective manner. The key to the success lies in not only the implementation of dialkyl phosphites with a strong bond dissociation energy to promote the desired chemoselectivity but also the utilization of an anionic chiral N,N,N-ligand to forge the chiral C(sp³ )-P bond. The developed Cu/N,N,N-ligand catalyst has enriched our library of single-electron transfer catalysts in the enantioselective radical transformations.

Visible-light-induced reactions of methylenecyclopropanes (MCPs)

Diverse, visible-light-induced transformations of methylenecyclopropanes (MCPs) have been reported in recent years, attracting significant attention from synthetic chemists. As readily accessible strained molecules, MCPs have sufficient reactivity to selectively generate different target products, through reactions with various radical species upon visible-light irradiation under regulated reaction conditions. These transformations can be classified into three subcategories of reaction pathway, forming ring-opened products, cyclopropane derivatives, and alkynes. These products include pharmaceutical intermediates and polycyclic/heterocyclic compounds that are challenging to obtain using traditional methods. This review summarizes the recent advancements in this field.

Enantioselective Radical-Type 1,2-Alkoxy-Phosphinoylation to Styrenes Catalyzed by Chiral Vanadyl Complexes

A series of vanadyl complexes bearing 3-t-butyl-5-bromo, 3-aryl-5-bromo, 3,5-dihalo-, and benzo-fused N-salicylidene-tert-leucinates was examined as catalysts for 1,2-alkoxy-phosphinoylation of 4-, 3-, 3,4-, and 3,5-substituted styrene derivatives (including Me/t-Bu, Ph, OR, Cl/Br, OAc, NO₂ , C(O)Me, CO₂ Me, CN, and benzo-fused) with HP(O)Ph₂ in the presence of t-BuOOH (TBHP) in a given alcohol or cosolvent with MeOH. The best scenario involved the use of 5 mol % 3-(2,5-dimethylphenyl)-5-Br (i.e., 3-DMP-5-Br) catalyst at 0 °C in MeOH. The desired catalytic cross coupling reactions proceeded smoothly with enantioselectivities of up to 95 % ee of (R)-configuration as confirmed by X-ray crystallographic analysis of several recrystallized products. The origin of enantiocontrol and homolytic substitution of the benzylic intermediates by vanadyl-bound methoxide and radical type catalytic mechanism were proposed.

Visible-Light-Induced Organophotocatalytic Difunctionallization: Open-Air Hydroxysulfurization of Aryl Alkenes with Aryl Thiols

Herein, we report a regioselective visible-light-induced organophotoredox catalytic difunctionalization method to prepare β-hydroxysulfides using aryl alkenes and aryl thiols as substrates. The reaction provides a wide substrate scope of aryl alkenes (from simple styrene to complex bioactive compounds) and aryl thiols (from diverse heteroaromatic thiols to nonheteroaromatic thiols) (total 45 examples, up to 88% yield). Based on the combined experimental and computational studies, we demonstrate that in situ generated hydroperoxyl radicals from O₂ in air react with benzylic radicals, which restrains the reaction between benzylic radicals and the acidic form of thiols in a classical thiol-ene radical reaction. We show that difunctionalization is possible due to the choice of bases, diluted substrate concentrations, increment in catalyst loading, and selection of suitable aryl thiols under aerobic conditions. Considering the biological importance of heteroaromatic thiols and the lack of methods to install them, our approach offers a platform to derive various β-hydroxysulfides that contain aromatic elements.

Multicomponent reactions and photo/electrochemistry join forces: atom economy meets energy efficiency

Visible-light photoredox catalysis has been regarded as an extremely powerful tool in organic chemistry, bringing the spotlight back to radical processes. The versatility of photocatalyzed reactions has already been demonstrated to be effective in providing alternative routes for cross-coupling as well as multicomponent reactions. The photocatalyst allows the generation of high-energy intermediates through light irradiation rather than using highly reactive reagents or harsh reaction conditions. In a similar vein, organic electrochemistry has experienced a fruitful renaissance as a tool for generating reactive intermediates without the need for any catalyst. Such milder approaches pose the basis toward higher selectivity and broader applicability. In photocatalyzed and electrochemical multicomponent reactions, the generation of the radical species acts as a starter of the cascade of events. This allows for diverse reactivity and the use of reagents is usually not covered by classical methods. Owing to the availability of cheaper and more standardized photo- and electrochemical reactors, as well as easily scalable flow-setups, it is not surprising that these two fields have become areas of increased research interest. Keeping these in view, this review is aimed at providing an overview of the synthetic approaches in the design of MCRs involving photoredox catalysis and/or electrochemical activation as a crucial step with particular focus on the choice of the difunctionalized reagent.

External oxidant-free and selective thiofunctionalization of alkenes enabled by photoredox-neutral catalysis

A photoredox approach was reported to realize a highly selective three-component thiohydroxylation, thioalkoxylation and thioamination of vinylarenes towards valuable vicinal S,O- and S,N-disubstituted molecules under mild conditions.

Recent advancements in visible-light-driven carboxylation with carbon dioxide

Carbon dioxide as a classic C1 source has long been investigated in organic synthetic chemistry. Diverse catalytic methods for CO2 activation were reported in the past several decades. In this...

A desulphurization strategy for Sonogashira couplings by visible light/copper catalysis

We have developed a new copper-based photocatalyst, [(binap)(tpy)Cu]Cl, and applied it in the visible-light promoted Sonogashira coupling reactions.

Three-component carboacylation of alkenes via cooperative nickelaphotoredox catalysis

Various commercially available acyl chlorides, aldehydes, and alkanes were exploited for versatile three-component 1,2-carboacylations of alkenes to forge two vicinal C–C bonds through the cooperative action of nickel and sodium decatungstate catalysis. A wealth of ketones with high levels of structural complexity was rapidly obtained via direct functionalization of C(sp²)/C(sp³)–H bonds in a modular manner. Furthermore, a regioselective late-stage modification of natural products showcased the practical utility of the strategy, generally featuring high resource economy and ample substrate scope.

Various commercially available acyl chlorides, aldehydes, and alkanes were exploited for versatile three-component 1,2-carboacylations of alkenes to forge two vicinal C–C bonds through the cooperative action of nickel and sodium decatungstate catalysis.

Visible-light-initiated regio- and stereoselective C(sp2)–H phosphorylation of enamides under transition-metal-free conditions

A visible-light-induced stereo- and regioselective phosphorylation of enamides with phosphine oxides under transition-metal-free conditions has been disclosed.

Alkylsulfonium salts for the photochemical desulphurizative functionalization of heteroarenes

A metal-free organic photoredox-catalyzed alkylation of heteroarenes using alkylsulfonium salts as alkylation reagents has been developed.

Development of Anthrazoline Photocatalyst for Promoting Amination and Amidation Reactions

In this work, we report the synthesis, optical and electrochemical properties of a series of organophotocatalysts bearing anthrazoline framework, as well as demonstrate their catalytic competencies in promoting C-N bond...

Carboxylation of Alkenes and Alkynes Using CO2 as a Reagent: An Overview

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CO2 fixation reactions are of paramount interest both from economical and environmental perspectives. As an abundant, non-toxic, and renewable C1 feedstock, CO2 can be utilized for the synthesis of fuels and commodity chemicals under elevated reaction conditions. The major challenge in the CO2 utilization reactions is its chemical inertness due to high thermodynamic stability and kinetic barrier. The carboxylation of unsaturated hydrocarbons with CO2 is an important transformation as it forms high-value reaction products having industrial as well as medicinal importance. This mini-review is mainly focused on the recent developments in the homogeneously and heterogeneously catalyzed carboxylation of alkenes and alkynes by using carbon dioxide as a reagent. We have highlighted various types of carboxylation reactions of alkenes and alkynes involving different catalytic systems, which comprise mainly C-H bond activation, hydrocarboxylation, carbocarboxylation, heterocarboxylation, and ring-closing carboxylation, including visible-light assisted synthesis processes. The mechanistic pathways of these carboxylation reactions have been described. Moreover, challenges and future perspectives of these carboxylation reactions are discussed.