A strategy for copper-catalyzed and biphosphine ligand controlled boracarboxylation of 1,3-dienes and CO_(2) with 3,4-selectivity was developed.The Cu Cl coupled with DPPF(1,1-bis(diphenylphosphino)ferrocene)was assig...A strategy for copper-catalyzed and biphosphine ligand controlled boracarboxylation of 1,3-dienes and CO_(2) with 3,4-selectivity was developed.The Cu Cl coupled with DPPF(1,1-bis(diphenylphosphino)ferrocene)was assigned to be the best catalyst,with 84%yield and exclusive3,4-selectivity.The ligand effect on both catalytic activity and regioselectivity of boracarboxylation was disclosed,which is rarely reported in any copper catalyzed boracarboxylation.The borocupration process is revealed to be a vital step for the biphosphine participated boracarboxylation of 1,3-dienes with CO_(2).The minimal substrate distortion occurring in 3,4-borocupration favors the 3,4-regioselectivity of boracarboxylation.The“pocket”confinement and suitableβ_(n)(92°–106°)of bisphosphine ligands are demonstrated to be in favour of the interaction between LCu-Bpin complex(the catalytic precursor)and1,3-diene substrate to decrease their interaction energyΔE_(int)(ζ)in 3,4-borocupration,thus promoting the 3,4-boracarboxylation.展开更多
Carbon dioxide is a cheap, abundant and renewable C1 building block. Over the last two decades, considerable re- search efforts have been devoted to developing new reactions for the efficient incorporation of carbon d...Carbon dioxide is a cheap, abundant and renewable C1 building block. Over the last two decades, considerable re- search efforts have been devoted to developing new reactions for the efficient incorporation of carbon dioxide into a broad range of compounds for the production of value-added materi- als [1]. Notably, these efforts have culminated in the develop- ment of several transition-metal-catalyzed methods capable of providing access to numerous synthetically important carbox- ylic acids and derivatives using carbon dioxide as a carboxyla- tive reagent [2].展开更多
In a scale-up microbial transformation of（–）-huperzine A（1） by Streptomyces griseus CACC 200300, a specific carboxylated derivative（2） was yielded together with two known hydroxylated metabolites. The structure...In a scale-up microbial transformation of（–）-huperzine A（1） by Streptomyces griseus CACC 200300, a specific carboxylated derivative（2） was yielded together with two known hydroxylated metabolites. The structure of 2 was characterized as 16-carboxyl huperzine A on the basis of IR, HRMS and NMR spectroscopic data analysis.展开更多
A feasible synthesis route is developed for achieving the direct carboxylation of thiophene and CO_(2) in a relatively mild solvent-free carboxylate-assisted carbonate(semi)molten state.The effects of reaction factors...A feasible synthesis route is developed for achieving the direct carboxylation of thiophene and CO_(2) in a relatively mild solvent-free carboxylate-assisted carbonate(semi)molten state.The effects of reaction factors on the carboxylate yield are investigated in the preliminary screening experiments,and the phase behavior analysis of the reaction medium is detected through the thermal characterization analysis of insitu high temperature X-ray diffraction measurement(in-situ XRD).The application of response surface methodology(RSM)based on the Box-Behnken design(BBD)is conducted to investigate the effect of the reaction parameters,such as reaction temperatu re,carbonate proportion,CO_(2) pressure and thiophene amount,on the product yield.The regressed second-order polynomial model equation well correlates all the independent variables.The analysis of variance(ANOVA)results reveal that the quadratic effect of reaction temperature is the most effective parameter in this carboxylation reaction owing to it’s the highest contribution to the sum of square(30.18%).The optimum reaction conditions for maximum product yield are the reaction temperature of 287℃,carbonate proportion of 32.20%,CO_(2) pressure of 1.0MPa and thiophene amount of 9.35 mmol.Operating under these selected experimental conditions,a high product yield(50.98%)can be achieved.展开更多
Visible light‐driven carboxylation with CO_(2) have emerged as a sustainable and powerful way to transfer waste to treasure.However,it is still challenging for aryl fluorides due to the low reactivities of both C(sp2...Visible light‐driven carboxylation with CO_(2) have emerged as a sustainable and powerful way to transfer waste to treasure.However,it is still challenging for aryl fluorides due to the low reactivities of both C(sp2)−F bonds and CO_(2).Herein,we report the first photocatalytic carboxylation of aryl C−F bonds with CO_(2).The visible‐light photoredox catalysis enables selective carboxylation of strong C(sp2)−F bonds in diverse polyluoroarenes,such as penta‐,tetra‐,and tri‐fluoroarenes under mild conditions,providing a facile access to a series of important polyfluoroaryl carboxylic acids with good yields.In contrast to previous reports of direct capture of polyfluoroaryl radicals,mechanistic studies suggest that the reduction of fleeting polyfluoroaryl radicals into polyfluoroaryl anions might be involved in this transformation,which may open a new avenue for photocatalytic functionalization of aryl C−F bonds.展开更多
The visible‐light photoredox‐catalyzed carboxylation of benzyl chlorides and bromides with CO_(2) has been reported.With inexpensive organic dyes as photocatalysts and amines as electron donors,this carboxylation pr...The visible‐light photoredox‐catalyzed carboxylation of benzyl chlorides and bromides with CO_(2) has been reported.With inexpensive organic dyes as photocatalysts and amines as electron donors,this carboxylation proceeds well in the absence of sensitive organometallic reagents,transition metal catalysts,or metallic reductants.A wide range of commercially available and inexpensive benzyl halides undergo such carboxylation to give valuable aryl acetic acids,including several pharmaceutical molecules and drug precursors,in moderate to high yields.Moreover,this reaction features mild reaction conditions(one atmospheric pressure of CO_(2) and room temperature),broad substrate scope,good functional group tolerance,easy scalability,and low catalyst loading,thus providing an efficient approach for the assembly of aryl acetic acids.展开更多
Carboxylation of aromatics by CO2 to generate corresponding carboxylic acids is recently providing a novel approach to utilize the green gas CO2, in which the activation of CO2 is the key procedure. Among the many cat...Carboxylation of aromatics by CO2 to generate corresponding carboxylic acids is recently providing a novel approach to utilize the green gas CO2, in which the activation of CO2 is the key procedure. Among the many catalytic systems employed in the carboxylation, the concept of “Frustrated Lewis Pairs” (FLPs) was scarcely mentioned, which perform excellently in activating small molecules like CO2. The FLPs are combinations of Lewis acids and Lewis bases which failed to form adducts due to their bulky steric congestion. In this paper, we first attempted various Si/Al Based FLPs to catalyze the carboxylation of aromatics through the activation of CO2, and a good yield of 62% - 97% was obtained. The reaction mechanism was proposed, involving the activation of CO2 mainly contributed by AlCl3 in cooperation with organosilane, forming an intermediate consisting of CO2, AlCl3, and R4Si, as well as the subsequent electrophilic attack to aromatics, thus to promote the carboxylation reaction.展开更多
As an attractive C1 synthon,carbon dioxide(CO_(2))has been extensively used in organic synthesis to produce carboxylic acids.In this research,stereoselective electrochemical carboxylation ofα,β-unsaturated sulfones ...As an attractive C1 synthon,carbon dioxide(CO_(2))has been extensively used in organic synthesis to produce carboxylic acids.In this research,stereoselective electrochemical carboxylation ofα,β-unsaturated sulfones has been developed under transition-metal-free conditions.All the cinnamic acids and the derivatives are obtained selectively in the E-configuration.Besides,arylpropiolates also can be produced from alkynyl sulfones.展开更多
The recent Ir/Pd co-catalyzed photo carboxylation of aromatic halides with CO_(2) has shown high efficiency and excellent functional group tolerance for preparing aromatic carboxylic acids and esters.With the aid of d...The recent Ir/Pd co-catalyzed photo carboxylation of aromatic halides with CO_(2) has shown high efficiency and excellent functional group tolerance for preparing aromatic carboxylic acids and esters.With the aid of density functional theory(DFT)calculations,the carboxylation starts with two parallel steps,i.e.,oxidative addition of aromatic halides on Pd~0 and reductive quenching of the photocatalyst Ir(ppy)_(2)(dtbpy)~+with amine.Thereafter,a successive oxidation of Pd~Ⅱwith the amine radical(generated by the reaction of cationic radical amine and Cs_(2) CO_(3)and Ir~Ⅱspecies occurs to generate Pd~0,from which the carboxylation occurs easily via a coordination,Pd-C insertion step.The release of the carboxylate product then regenerates the catalyst.展开更多
Photo‐catalyzed tandem dearomatization/carboxylation of benzyl o‐halogenated aryl ether with CO_(2) was achieved,which affords spirocyclic carboxylic acids under mild conditions.The reaction has good functional grou...Photo‐catalyzed tandem dearomatization/carboxylation of benzyl o‐halogenated aryl ether with CO_(2) was achieved,which affords spirocyclic carboxylic acids under mild conditions.The reaction has good functional group tolerance with high yields.Mechanism studies indicate that the transformation was realized via intramolecular radical addition and nucleophilic addition.展开更多
Electrocarboxylation of carbon dioxide(CO_(2))using organic substrates has emerged as a promising method for the sustainable synthesis of value-added carboxylic acids due to its renewable energy source and mild reacti...Electrocarboxylation of carbon dioxide(CO_(2))using organic substrates has emerged as a promising method for the sustainable synthesis of value-added carboxylic acids due to its renewable energy source and mild reaction conditions.The reactivity and product selectivity of electrocarboxylation are highly dependent on the cathodic behavior,involving a sequence of electron transfers and chemical reactions.Hence,it is necessary to understand the cathodic reaction mechanisms for optimizing reaction performance and product distribution.In this work,a review of recent advancements in the electrocarboxylation of CO_(2)with organic substrates based on different cathodic reaction pathways is presented to provide a reference for the development of novel methodologies of CO_(2)electrocarboxylation.Herein,cathodic reactions are particularly classified into two categories based on the initial electron carriers(i.e.,CO_(2)radical anion and substrate radical anion).Furthermore,three cathodic pathways(ENE(N),ENED,and EDEN)of substrate radical anion-induced electrocarboxylation are discussed,which differ in their electron transfer sequence,substrate dissociation,and nucleophilic reaction,to highlight their implications on reactivity and product selectivity.展开更多
The carboxylation of readily available organo halides with CO_(2)represents a practical strategy to afford valuable carboxylic acids.However,efficient carboxylation of inexpensive unactivated alkyl chlorides is still ...The carboxylation of readily available organo halides with CO_(2)represents a practical strategy to afford valuable carboxylic acids.However,efficient carboxylation of inexpensive unactivated alkyl chlorides is still underdeveloped.Herein,we report the electro-reductive carboxylation of C–Cl bonds in unactivated chlorides and polyvinyl chloride with CO_(2).A variety of alkyl carboxylic acids are obtained in moderate to good yields under mild conditions with high chemoselectivity.Importantly,the utility of this electroreductive carboxylation is demonstrated with great potential in polyvinyl chloride(PVC)upgrading,which could convert discarded PVC from hydrophobic to hydrophilic functional products.Mechanistic experiments support the successive single electron reduction of unactivated chlorides to generate alkyl anion species and following nucleophilic attack on CO_(2)to give desired products.展开更多
A photoredox-catalyzed cascade carbon/carboxylation of activated alkenes with malonates acetals and CO_(2) has been achieved,leading to a range of functionalized 1,1,3-tricarboxylates in good efficiency under mild rea...A photoredox-catalyzed cascade carbon/carboxylation of activated alkenes with malonates acetals and CO_(2) has been achieved,leading to a range of functionalized 1,1,3-tricarboxylates in good efficiency under mild reaction conditions.This reaction provides a facile and sustainable method for the synthesis of tricarboxylates by using CO_(2) as the carboxylic source.展开更多
A feasible synthesis route is devised for realizing direct carboxylation of thiophene and CO_(2) in a relatively mild solvent-free carboxylate-assisted carbonate(semi)molten medium.The effects of reaction factors on p...A feasible synthesis route is devised for realizing direct carboxylation of thiophene and CO_(2) in a relatively mild solvent-free carboxylate-assisted carbonate(semi)molten medium.The effects of reaction factors on product yield are investigated,and the phase behavior analysis of the reaction medium is detected through the thermal characterization techniques.Product yield varies with the alternative carboxylate co-salts,which is attributed to the difference in deprotonation capacity caused by the base effect within the system.Besides,the detailed mechanism of this carbonate-promoted carboxylation reaction is studied,including two consecutive steps of the formation of carbanion through breaking the C-H bond(s)via the carbonate and the nucleophile attacking the weak electrophile CO_(2) to form C-C bond(s).The activation energy barrier in C-H activation step is higher than the following CO_(2) insertion step whether for the formation of the mono-and/or di-carboxylate,which is in good agreement with that of kinetic isotope effect(KIE)experiments,indicating that the C-H deprotonation is slow and the forming presumed carbanion reacts rapidly with CO_(2).Both the activation energy barriers in deprotonation steps are the minimal for the cesium cluster system since there have the weak the cesium Cs-heteroatom S(thiophene)and Cs-the broken proton interactions compared to the K2CO3 system,which is likely to enhance the acidity of C-H bond,lowering the C-H activation barrier.Besides,these mechanistic insights are further assessed by investigating base and C-H substrate effects via replacing Cs2CO3 with K2CO3 and furoate(la)with thiophene monocarboxylate(1b)or benzoate(1c).展开更多
Dearomative carboxylation of aromatic compounds with carbon dioxide(CO_(2))could be utilized for the synthesis of cyclic carboxylative frameworks.The dearomative carboxylation exhibits advantages such as reconstitutio...Dearomative carboxylation of aromatic compounds with carbon dioxide(CO_(2))could be utilized for the synthesis of cyclic carboxylative frameworks.The dearomative carboxylation exhibits advantages such as reconstitution molecular spatial structure,environmental friendliness,mild conditions,high yield,and high selectivity,and is of significant importance in pharmaceutical synthesis and natural product chemistry.The recent advancements in the dearomative carboxylation of aromatics with CO_(2) are summarized,including elucidation of the reaction characteristics and the scope of substrates via transition-metal catalysis,photoredox catalysis,and electropromoted chemistry.展开更多
Manganese（Ⅲ） meso-tetraphenylporphyrin acetate [Mn（TPP）OAc] served as an effective catalyst for the oxidative decarboxylation of carboxylic acids with （diacetoxyiodo）benzene [PhI（OAc）2] in CH2CI2-H2O（95：5, ...Manganese（Ⅲ） meso-tetraphenylporphyrin acetate [Mn（TPP）OAc] served as an effective catalyst for the oxidative decarboxylation of carboxylic acids with （diacetoxyiodo）benzene [PhI（OAc）2] in CH2CI2-H2O（95：5, volume ratio）. The aryl substituted acetic acids are more reactive than the less electron rich linear carboxylic acids in the presence of catalyst Mn（TPP）OAc. In the former case, the formation of carbonyl products was complete within just a few minutes with 〉97% selectivities, and no further oxidation of the produced aldehydes was achieved under these catalytic conditions. This method provides a benign procedure owing to the utilization of low toxic（diacetoxyiodo） benzene, biologically relevant manganese porphyrins, and carboxylic acids.展开更多
The role of carbodiimide as dehydrant in the chemo‐,regio‐and stereoselective Pd(Ⅱ/0)‐catalyzed hydrocarboxylation of various alkynes with HCOOH releasing CO in situ is reported for the first time to obtainα,β‐...The role of carbodiimide as dehydrant in the chemo‐,regio‐and stereoselective Pd(Ⅱ/0)‐catalyzed hydrocarboxylation of various alkynes with HCOOH releasing CO in situ is reported for the first time to obtainα,β‐unsaturated carboxylic acids.Both symmetrical and unsymmetrical monoalkynes show good reactivity.Importantly,2,2’‐(1,4‐phenylene)diacrylic acid can also be synthesized in high yield through the dihydrocarboxylation of 1,4‐diethynylbenzene.Besides,an excellent result in gram scale experiment and TON up to 900 can be obtained,displaying the efficiency of this protocol.Notably,regulating the types and concentrations of dehydrant can control the CO generation,avoiding directly operating toxic CO and circumventing sensitivity issue to the CO amount.On the basis of the attractive features of formic acid including easy preparation through CO_(2) hydrogenation and efficient liberation of CO,this protocol using formic acid as bridging reagent between CO_(2) and CO can be perceived as an indirect utilization of CO_(2),offering an alternative method for preparing acrylic acid analogues.展开更多
A direct regioselective preparation of 2-hydroxynaphthalene-6-carboxylic acid, a useful industrial intermediate of aro-matic polyester from 2-naphthol was conducted by use of excess amount of K2CO3 (10-fold molar to 2...A direct regioselective preparation of 2-hydroxynaphthalene-6-carboxylic acid, a useful industrial intermediate of aro-matic polyester from 2-naphthol was conducted by use of excess amount of K2CO3 (10-fold molar to 2-naphthol) under supercritical CO2 at 10 MPa and 473 K. The obtained yield under this condition was ca. 20 mol% to 2-naphthol. The further investigations may provide an alternative process to the conventional Kolbe-Schmitt reaction, because of no use of strong alkali and recoverability of K2CO3. Theoretical explanation about the regioselectivity was achieved by means of DFT calculations.展开更多
The mechanism and the final outcome of the Knoevenagel-Doebner reaction are discussed. The condensation reaction between different hydroxy-substituted aromatic aldehydes and malonic acid is performed using piperidine ...The mechanism and the final outcome of the Knoevenagel-Doebner reaction are discussed. The condensation reaction between different hydroxy-substituted aromatic aldehydes and malonic acid is performed using piperidine as organocatalyst. The key role of the catalyst is clearly pointed out during the decarboxylation of ferulic acid, without the use of a strong decarboxylating agent, leading to a 4-vinylphenol derivative. Based on the results obtained, the studied pathway may be important in the understanding of vinylphenol production during malting and brewing of wheat and barley grains. Finally, changing the solvent of the reaction from pyridine to water in the Knoevenagel-Doebner reaction of 4-hydroxybenzaldehydes, dimerization of resulting styrene derivatives is observed. These results can be of interest also in the field of food chemistry, since cinnamic acids are frequently found in fruits and vegetables used for human consumption.展开更多
The combination of a low cost source of Biofine＇s levulinic acid with available way of valeric acid synthesis opens up new opportunities for valeric acid as a promising bio-derived source for synthesis of valuable co...The combination of a low cost source of Biofine＇s levulinic acid with available way of valeric acid synthesis opens up new opportunities for valeric acid as a promising bio-derived source for synthesis of valuable compounds for transportation sector. The present review illustrates the development of different approaches to one–pot synthesis of fuel-like alkanes from lignocellulose derived carboxylic acids where particular focus is given to valeric acid consecutive decarboxylative coupling（ketonization） and ketone hydrodeoxygenation in a single reactor over one catalyst bed. The key factors that influence the catalytic performance on both ketonization and hydrodeoxygenation steps as well as their cross-influence will be clarified to provide insights for the design of more efficient catalysts for the one-pot transformation. Valeric acid is considered as a potential acid source from viewpoint of cost effectiveness and feasibility of such transformation with reasonable alkane yield. The both reaction mechanisms and kinetics will also be discussed to understand deeply how the selective C–C coupling and following C=O hydrogenation can be achieved.展开更多
基金the National Key R&D Program of China(No.2022YFB4101900)National Natural Science Foundation of China(Nos.22278305,U21B2096)Natural Science Foundation of Tianjin City(No.23JCZDJC00040)。
文摘A strategy for copper-catalyzed and biphosphine ligand controlled boracarboxylation of 1,3-dienes and CO_(2) with 3,4-selectivity was developed.The Cu Cl coupled with DPPF(1,1-bis(diphenylphosphino)ferrocene)was assigned to be the best catalyst,with 84%yield and exclusive3,4-selectivity.The ligand effect on both catalytic activity and regioselectivity of boracarboxylation was disclosed,which is rarely reported in any copper catalyzed boracarboxylation.The borocupration process is revealed to be a vital step for the biphosphine participated boracarboxylation of 1,3-dienes with CO_(2).The minimal substrate distortion occurring in 3,4-borocupration favors the 3,4-regioselectivity of boracarboxylation.The“pocket”confinement and suitableβ_(n)(92°–106°)of bisphosphine ligands are demonstrated to be in favour of the interaction between LCu-Bpin complex(the catalytic precursor)and1,3-diene substrate to decrease their interaction energyΔE_(int)(ζ)in 3,4-borocupration,thus promoting the 3,4-boracarboxylation.
文摘Carbon dioxide is a cheap, abundant and renewable C1 building block. Over the last two decades, considerable re- search efforts have been devoted to developing new reactions for the efficient incorporation of carbon dioxide into a broad range of compounds for the production of value-added materi- als [1]. Notably, these efforts have culminated in the develop- ment of several transition-metal-catalyzed methods capable of providing access to numerous synthetically important carbox- ylic acids and derivatives using carbon dioxide as a carboxyla- tive reagent [2].
基金National Natural Science Foundation of China(Grant No.81072541)
文摘In a scale-up microbial transformation of（–）-huperzine A（1） by Streptomyces griseus CACC 200300, a specific carboxylated derivative（2） was yielded together with two known hydroxylated metabolites. The structure of 2 was characterized as 16-carboxyl huperzine A on the basis of IR, HRMS and NMR spectroscopic data analysis.
文摘A feasible synthesis route is developed for achieving the direct carboxylation of thiophene and CO_(2) in a relatively mild solvent-free carboxylate-assisted carbonate(semi)molten state.The effects of reaction factors on the carboxylate yield are investigated in the preliminary screening experiments,and the phase behavior analysis of the reaction medium is detected through the thermal characterization analysis of insitu high temperature X-ray diffraction measurement(in-situ XRD).The application of response surface methodology(RSM)based on the Box-Behnken design(BBD)is conducted to investigate the effect of the reaction parameters,such as reaction temperatu re,carbonate proportion,CO_(2) pressure and thiophene amount,on the product yield.The regressed second-order polynomial model equation well correlates all the independent variables.The analysis of variance(ANOVA)results reveal that the quadratic effect of reaction temperature is the most effective parameter in this carboxylation reaction owing to it’s the highest contribution to the sum of square(30.18%).The optimum reaction conditions for maximum product yield are the reaction temperature of 287℃,carbonate proportion of 32.20%,CO_(2) pressure of 1.0MPa and thiophene amount of 9.35 mmol.Operating under these selected experimental conditions,a high product yield(50.98%)can be achieved.
文摘Visible light‐driven carboxylation with CO_(2) have emerged as a sustainable and powerful way to transfer waste to treasure.However,it is still challenging for aryl fluorides due to the low reactivities of both C(sp2)−F bonds and CO_(2).Herein,we report the first photocatalytic carboxylation of aryl C−F bonds with CO_(2).The visible‐light photoredox catalysis enables selective carboxylation of strong C(sp2)−F bonds in diverse polyluoroarenes,such as penta‐,tetra‐,and tri‐fluoroarenes under mild conditions,providing a facile access to a series of important polyfluoroaryl carboxylic acids with good yields.In contrast to previous reports of direct capture of polyfluoroaryl radicals,mechanistic studies suggest that the reduction of fleeting polyfluoroaryl radicals into polyfluoroaryl anions might be involved in this transformation,which may open a new avenue for photocatalytic functionalization of aryl C−F bonds.
文摘The visible‐light photoredox‐catalyzed carboxylation of benzyl chlorides and bromides with CO_(2) has been reported.With inexpensive organic dyes as photocatalysts and amines as electron donors,this carboxylation proceeds well in the absence of sensitive organometallic reagents,transition metal catalysts,or metallic reductants.A wide range of commercially available and inexpensive benzyl halides undergo such carboxylation to give valuable aryl acetic acids,including several pharmaceutical molecules and drug precursors,in moderate to high yields.Moreover,this reaction features mild reaction conditions(one atmospheric pressure of CO_(2) and room temperature),broad substrate scope,good functional group tolerance,easy scalability,and low catalyst loading,thus providing an efficient approach for the assembly of aryl acetic acids.
文摘Carboxylation of aromatics by CO2 to generate corresponding carboxylic acids is recently providing a novel approach to utilize the green gas CO2, in which the activation of CO2 is the key procedure. Among the many catalytic systems employed in the carboxylation, the concept of “Frustrated Lewis Pairs” (FLPs) was scarcely mentioned, which perform excellently in activating small molecules like CO2. The FLPs are combinations of Lewis acids and Lewis bases which failed to form adducts due to their bulky steric congestion. In this paper, we first attempted various Si/Al Based FLPs to catalyze the carboxylation of aromatics through the activation of CO2, and a good yield of 62% - 97% was obtained. The reaction mechanism was proposed, involving the activation of CO2 mainly contributed by AlCl3 in cooperation with organosilane, forming an intermediate consisting of CO2, AlCl3, and R4Si, as well as the subsequent electrophilic attack to aromatics, thus to promote the carboxylation reaction.
基金Financial support from the National Natural Science Foundation of China(No.21901041)the Fuzhou University(No.0041/511095)。
文摘As an attractive C1 synthon,carbon dioxide(CO_(2))has been extensively used in organic synthesis to produce carboxylic acids.In this research,stereoselective electrochemical carboxylation ofα,β-unsaturated sulfones has been developed under transition-metal-free conditions.All the cinnamic acids and the derivatives are obtained selectively in the E-configuration.Besides,arylpropiolates also can be produced from alkynyl sulfones.
基金the financial support from the National Natural Science Foundation of China(Nos.21672001,51961135104)the technical support of high-performance computing platform of Anhui University。
文摘The recent Ir/Pd co-catalyzed photo carboxylation of aromatic halides with CO_(2) has shown high efficiency and excellent functional group tolerance for preparing aromatic carboxylic acids and esters.With the aid of density functional theory(DFT)calculations,the carboxylation starts with two parallel steps,i.e.,oxidative addition of aromatic halides on Pd~0 and reductive quenching of the photocatalyst Ir(ppy)_(2)(dtbpy)~+with amine.Thereafter,a successive oxidation of Pd~Ⅱwith the amine radical(generated by the reaction of cationic radical amine and Cs_(2) CO_(3)and Ir~Ⅱspecies occurs to generate Pd~0,from which the carboxylation occurs easily via a coordination,Pd-C insertion step.The release of the carboxylate product then regenerates the catalyst.
文摘Photo‐catalyzed tandem dearomatization/carboxylation of benzyl o‐halogenated aryl ether with CO_(2) was achieved,which affords spirocyclic carboxylic acids under mild conditions.The reaction has good functional group tolerance with high yields.Mechanism studies indicate that the transformation was realized via intramolecular radical addition and nucleophilic addition.
基金received from the National Natural Science Foundation of China(No.22278305)National Key R&D Program of China(2022YFB4101900)。
文摘Electrocarboxylation of carbon dioxide(CO_(2))using organic substrates has emerged as a promising method for the sustainable synthesis of value-added carboxylic acids due to its renewable energy source and mild reaction conditions.The reactivity and product selectivity of electrocarboxylation are highly dependent on the cathodic behavior,involving a sequence of electron transfers and chemical reactions.Hence,it is necessary to understand the cathodic reaction mechanisms for optimizing reaction performance and product distribution.In this work,a review of recent advancements in the electrocarboxylation of CO_(2)with organic substrates based on different cathodic reaction pathways is presented to provide a reference for the development of novel methodologies of CO_(2)electrocarboxylation.Herein,cathodic reactions are particularly classified into two categories based on the initial electron carriers(i.e.,CO_(2)radical anion and substrate radical anion).Furthermore,three cathodic pathways(ENE(N),ENED,and EDEN)of substrate radical anion-induced electrocarboxylation are discussed,which differ in their electron transfer sequence,substrate dissociation,and nucleophilic reaction,to highlight their implications on reactivity and product selectivity.
基金provided by the National Natural Science Foundation of China(Nos.22225106,22201027)Fundamental Research Funds for the Central Universities。
文摘The carboxylation of readily available organo halides with CO_(2)represents a practical strategy to afford valuable carboxylic acids.However,efficient carboxylation of inexpensive unactivated alkyl chlorides is still underdeveloped.Herein,we report the electro-reductive carboxylation of C–Cl bonds in unactivated chlorides and polyvinyl chloride with CO_(2).A variety of alkyl carboxylic acids are obtained in moderate to good yields under mild conditions with high chemoselectivity.Importantly,the utility of this electroreductive carboxylation is demonstrated with great potential in polyvinyl chloride(PVC)upgrading,which could convert discarded PVC from hydrophobic to hydrophilic functional products.Mechanistic experiments support the successive single electron reduction of unactivated chlorides to generate alkyl anion species and following nucleophilic attack on CO_(2)to give desired products.
文摘A photoredox-catalyzed cascade carbon/carboxylation of activated alkenes with malonates acetals and CO_(2) has been achieved,leading to a range of functionalized 1,1,3-tricarboxylates in good efficiency under mild reaction conditions.This reaction provides a facile and sustainable method for the synthesis of tricarboxylates by using CO_(2) as the carboxylic source.
文摘A feasible synthesis route is devised for realizing direct carboxylation of thiophene and CO_(2) in a relatively mild solvent-free carboxylate-assisted carbonate(semi)molten medium.The effects of reaction factors on product yield are investigated,and the phase behavior analysis of the reaction medium is detected through the thermal characterization techniques.Product yield varies with the alternative carboxylate co-salts,which is attributed to the difference in deprotonation capacity caused by the base effect within the system.Besides,the detailed mechanism of this carbonate-promoted carboxylation reaction is studied,including two consecutive steps of the formation of carbanion through breaking the C-H bond(s)via the carbonate and the nucleophile attacking the weak electrophile CO_(2) to form C-C bond(s).The activation energy barrier in C-H activation step is higher than the following CO_(2) insertion step whether for the formation of the mono-and/or di-carboxylate,which is in good agreement with that of kinetic isotope effect(KIE)experiments,indicating that the C-H deprotonation is slow and the forming presumed carbanion reacts rapidly with CO_(2).Both the activation energy barriers in deprotonation steps are the minimal for the cesium cluster system since there have the weak the cesium Cs-heteroatom S(thiophene)and Cs-the broken proton interactions compared to the K2CO3 system,which is likely to enhance the acidity of C-H bond,lowering the C-H activation barrier.Besides,these mechanistic insights are further assessed by investigating base and C-H substrate effects via replacing Cs2CO3 with K2CO3 and furoate(la)with thiophene monocarboxylate(1b)or benzoate(1c).
文摘Dearomative carboxylation of aromatic compounds with carbon dioxide(CO_(2))could be utilized for the synthesis of cyclic carboxylative frameworks.The dearomative carboxylation exhibits advantages such as reconstitution molecular spatial structure,environmental friendliness,mild conditions,high yield,and high selectivity,and is of significant importance in pharmaceutical synthesis and natural product chemistry.The recent advancements in the dearomative carboxylation of aromatics with CO_(2) are summarized,including elucidation of the reaction characteristics and the scope of substrates via transition-metal catalysis,photoredox catalysis,and electropromoted chemistry.
文摘Manganese（Ⅲ） meso-tetraphenylporphyrin acetate [Mn（TPP）OAc] served as an effective catalyst for the oxidative decarboxylation of carboxylic acids with （diacetoxyiodo）benzene [PhI（OAc）2] in CH2CI2-H2O（95：5, volume ratio）. The aryl substituted acetic acids are more reactive than the less electron rich linear carboxylic acids in the presence of catalyst Mn（TPP）OAc. In the former case, the formation of carbonyl products was complete within just a few minutes with 〉97% selectivities, and no further oxidation of the produced aldehydes was achieved under these catalytic conditions. This method provides a benign procedure owing to the utilization of low toxic（diacetoxyiodo） benzene, biologically relevant manganese porphyrins, and carboxylic acids.
文摘The role of carbodiimide as dehydrant in the chemo‐,regio‐and stereoselective Pd(Ⅱ/0)‐catalyzed hydrocarboxylation of various alkynes with HCOOH releasing CO in situ is reported for the first time to obtainα,β‐unsaturated carboxylic acids.Both symmetrical and unsymmetrical monoalkynes show good reactivity.Importantly,2,2’‐(1,4‐phenylene)diacrylic acid can also be synthesized in high yield through the dihydrocarboxylation of 1,4‐diethynylbenzene.Besides,an excellent result in gram scale experiment and TON up to 900 can be obtained,displaying the efficiency of this protocol.Notably,regulating the types and concentrations of dehydrant can control the CO generation,avoiding directly operating toxic CO and circumventing sensitivity issue to the CO amount.On the basis of the attractive features of formic acid including easy preparation through CO_(2) hydrogenation and efficient liberation of CO,this protocol using formic acid as bridging reagent between CO_(2) and CO can be perceived as an indirect utilization of CO_(2),offering an alternative method for preparing acrylic acid analogues.
文摘A direct regioselective preparation of 2-hydroxynaphthalene-6-carboxylic acid, a useful industrial intermediate of aro-matic polyester from 2-naphthol was conducted by use of excess amount of K2CO3 (10-fold molar to 2-naphthol) under supercritical CO2 at 10 MPa and 473 K. The obtained yield under this condition was ca. 20 mol% to 2-naphthol. The further investigations may provide an alternative process to the conventional Kolbe-Schmitt reaction, because of no use of strong alkali and recoverability of K2CO3. Theoretical explanation about the regioselectivity was achieved by means of DFT calculations.
文摘The mechanism and the final outcome of the Knoevenagel-Doebner reaction are discussed. The condensation reaction between different hydroxy-substituted aromatic aldehydes and malonic acid is performed using piperidine as organocatalyst. The key role of the catalyst is clearly pointed out during the decarboxylation of ferulic acid, without the use of a strong decarboxylating agent, leading to a 4-vinylphenol derivative. Based on the results obtained, the studied pathway may be important in the understanding of vinylphenol production during malting and brewing of wheat and barley grains. Finally, changing the solvent of the reaction from pyridine to water in the Knoevenagel-Doebner reaction of 4-hydroxybenzaldehydes, dimerization of resulting styrene derivatives is observed. These results can be of interest also in the field of food chemistry, since cinnamic acids are frequently found in fruits and vegetables used for human consumption.
基金partly supported by Russian Academy of Science Project No. V.46.4.4Part of work related to metal oxides was supported by RFBR grant 15-03-09329
文摘The combination of a low cost source of Biofine＇s levulinic acid with available way of valeric acid synthesis opens up new opportunities for valeric acid as a promising bio-derived source for synthesis of valuable compounds for transportation sector. The present review illustrates the development of different approaches to one–pot synthesis of fuel-like alkanes from lignocellulose derived carboxylic acids where particular focus is given to valeric acid consecutive decarboxylative coupling（ketonization） and ketone hydrodeoxygenation in a single reactor over one catalyst bed. The key factors that influence the catalytic performance on both ketonization and hydrodeoxygenation steps as well as their cross-influence will be clarified to provide insights for the design of more efficient catalysts for the one-pot transformation. Valeric acid is considered as a potential acid source from viewpoint of cost effectiveness and feasibility of such transformation with reasonable alkane yield. The both reaction mechanisms and kinetics will also be discussed to understand deeply how the selective C–C coupling and following C=O hydrogenation can be achieved.
