Hydroformylation of olefins is one of the highest-volume industrial reactions to meet the vast demands for aldehydes as well as their derivatives.Homogeneous Co complexes were the original catalysts industrialized sin...Hydroformylation of olefins is one of the highest-volume industrial reactions to meet the vast demands for aldehydes as well as their derivatives.Homogeneous Co complexes were the original catalysts industrialized since 1960s.Heterogeneous catalysis is considered superior owing to the facile separation of catalysts from products,shorter technical process,and reduced manufacturing costs.Unexpectedly,there has not been a single case of plant using heterogenized Co-based catalyst successfully.To address the separation issue and understand the catalytic mechanism of the reactions,this review summarizes the progress in heterogeneous systems and provides a detailed discussion of their catalytic performance.Strategies for stabilizing Co species through support modification and additive incorporation are carefully considered to elucidate why heterogeneous systems have not yet succeeded on an industrial scale.Furthermore,we provide our insights for the development of heterogeneous catalytic hydroformylation,including the challenges,opportunities,and outlooks.The aim is to deepen the fundamental understanding of heterogeneous alkene hydroformylation,guiding the community's research efforts towards realizing its successful application in the future.展开更多
The direct difunctionalization of alkenes serves as one of the most straightforward strategies toward complex nitrogen-containing compounds.The existing approach is extensively promoted by using C/Xcentered radicals a...The direct difunctionalization of alkenes serves as one of the most straightforward strategies toward complex nitrogen-containing compounds.The existing approach is extensively promoted by using C/Xcentered radicals and N-nucleophiles to conduct 1,2-difunctional amination/azolization of alkenes.In contrast,2,1-difunctional amination/azolization of alkenes by using nitrogen-centered radicals(NCRs) and nucleophiles still remains rarely underexplored.It is possibly due to the highly active electron properties of NCRs and the relatively poor nucleophilicity of aromatic NCRs to be trapped by arylalkenes.Herein,we demonstrate an unprecedented 2,1-hydroxazolization reactions of arylalkenes through electrochemically enabled addition of NCRs from azoles and nucleophiles(NuH) in high yields and with high regioselectivity.This conversion is characterized by the fact that neither metal catalysts nor external chemical oxidants are required.This electrochemical oxidation synthesis method can also be applied for a broad range of NuH including pyridine hydrofluoride,ammonia,water,alcohols,and acids which enables the formation of C-N and C-X(X=F/N/O) bonds in one-pot fashion to furnish efficient fluoroamination,diamination and oxoamination of alkenes.展开更多
This study has employed the master chemical mechanism(MCM)to investigate the influence of the ozone oxidation pathways in the atmospheric formation of H_(2)SO_(4)from shortchain olefins in industrialized areas.In-situ...This study has employed the master chemical mechanism(MCM)to investigate the influence of the ozone oxidation pathways in the atmospheric formation of H_(2)SO_(4)from shortchain olefins in industrialized areas.In-situ H_(2)SO_(4)formation data were obtained using a high-resolution chemical ionization time-of-flight mass spectrometer,and the simulated H_(2)SO_(4)concentrations calculated using updated parameters for the MCM model exhibited good agreementwith observations.In the simulation analysis of different reaction pathways involved in H_(2)SO_(4)formation,hydroxyl radicals were found to dominate H_(2)SO_(4)production during the daytime,while olefin ozone oxidation contributed up to 65%of total H_(2)SO_(4)production during the night-time.A sensitivity analysis of the H_(2)SO_(4)production parameters has revealed a high sensitivity to changes in sulfur dioxide,and a relatively high sensitivity to olefins with fast ozonolysis reaction rates and bimolecular reaction rates of resulting stabilized Criegee Intermediates.A high relative humidity promotes daytime H_(2)SO_(4)formation,but has an inhibiting effect during the night-time due to the different dominant reaction pathways.展开更多
The hydroformylation of olefins,known as the"oxo reaction",involves the use of syngas(CO/H_(2))to produce aldehyde with an additional carbon atom.However,side reactions such as the isomerization or hydrogena...The hydroformylation of olefins,known as the"oxo reaction",involves the use of syngas(CO/H_(2))to produce aldehyde with an additional carbon atom.However,side reactions such as the isomerization or hydrogenation of olefins often result in unexpected products and other by-products.Recent efforts in developing efficient ligands represent the most effective approach to addressing these challenges.In this study,we described a Bis-OPNN phosphorus ligand facilitated Rh-catalyzed hydroformylation with a high degree of linear selectivity across various olefins.Under mild conditions,a broad range of olefins were efficiently converted into linear aldehydes with high yields and excellent regioselectivity.The protocol also showed impressive functional group tolerance and was successfully applied to modify drugs and natural products,including the total synthesis of(±)-crispine A.Preliminary mechanistic studies revealed that this Bis-OPNN phosphorus ligand anchoring the rhodium catalyst is crucial for controlling the linear selectivity.展开更多
Herein,we describe a nickel-catalyzed reductive decarboxylative difluoromethylation reaction of alkenes using inexpensive and easy-to-handle difluoroacetic anhydride(DFAA)/pyridine N-oxide reagent system.A variety of ...Herein,we describe a nickel-catalyzed reductive decarboxylative difluoromethylation reaction of alkenes using inexpensive and easy-to-handle difluoroacetic anhydride(DFAA)/pyridine N-oxide reagent system.A variety of C(sp^(3))-CF_(2)H containing compounds were prepared through a hydrodifluoromethylation process.Besides,various gem–difluoroalkenes bearing CF_(2)H group were synthesized via defluorinative reductive cross-coupling process from trifluoromethyl-substituted alkenes using this new reaction system.Difluoroacetic anhydride has been then extended to other common alkyl anhydrides,and the corresponding hydroalkylation and defluoroalkylation processes have been successfully achieved.This method features broad substrate scope,good functional group tolerance as well as high efficiency.展开更多
Catalytic electron donor-acceptor(EDA) complex photochemistry has recently emerged as a popular and sustainable alternative to photoredox synthetic methods. Yet, the catalytic EDA strategy is still in its infancy for ...Catalytic electron donor-acceptor(EDA) complex photochemistry has recently emerged as a popular and sustainable alternative to photoredox synthetic methods. Yet, the catalytic EDA strategy is still in its infancy for organic synthesis due to the challenges of designing novel catalytic paradigm and expanding the substrate and reaction scope. Here, we disclose a catalytic EDA/Cu cooperative strategy by employing Na I as a catalytic donor for copper-catalyzed radical asymmetric carbocyanation. A diverse range of synthetically useful chiral benzyl nitriles are produced with high enantioselectivities. This synergetic EDA/copper catalysis enables the decarboxylative cyanation without request of any photoredox catalysts, further expanding the synthetic potential of catalytic EDA chemistry in organic synthesis.展开更多
Here we present a highly efficient protocol utilizing nickel-hydride hydrogen atom transfer catalysis for the regio-and enantioselective hydrofluorination of internal alkenes.This method efficiently assembles a wide a...Here we present a highly efficient protocol utilizing nickel-hydride hydrogen atom transfer catalysis for the regio-and enantioselective hydrofluorination of internal alkenes.This method efficiently assembles a wide array of enantioenrichedβ-fluoro amides with excellent regio-and enantioselectivity from internal unactivated alkenes.Mechanistic investigations suggest that this transformation proceeds via a NiHhydrogen atom transfer to alkene,followed by a stereoselective fluorine atom transfer process.The weak coordination effect of the tethered amide group is identified as a crucial factor governing the observed regio-and enantioselectivity.展开更多
The accompanied forge of C(sp^(3))–S and C(sp^(3))–C(sp^(3))bonds across alkene frameworks serves as a potent strategy to construct biologically important compounds.Here,we report a metal-free,photochemically mediat...The accompanied forge of C(sp^(3))–S and C(sp^(3))–C(sp^(3))bonds across alkene frameworks serves as a potent strategy to construct biologically important compounds.Here,we report a metal-free,photochemically mediated fluoroalkyl-mono/disulfuration of unactivated alkenes with high efficiency and high selectivity.A wide range of terminal and internal alkenes are good coupling partners,affording the expected products in moderate to good yields(>90 examples).The exceedingly mild reaction conditions,exceptional functional group tolerance,broad substrate scope,and the potential for late-stage modifications of pharmaceutical molecules highlight the utility of this method in the preparation of privileged motifs from readily available disulfides,tetrasulfides,and diselenides.Mechanistic studies suggest that a secondary alkyl radical intermediate undergoes efficient homolytic substitution with disulfides,facilitating the modular synthesis of a diverse array of unsymmetrical thioethers.展开更多
An efficient and E-selective monoisomerization of 1-alkenes is developed with a bis(phosphine)-based PCP-type Co complex as the catalyst.The protocol provides an atom-economical approach to trans-2-alkenes with high r...An efficient and E-selective monoisomerization of 1-alkenes is developed with a bis(phosphine)-based PCP-type Co complex as the catalyst.The protocol provides an atom-economical approach to trans-2-alkenes with high regio-and stereoselectivity,featuring mild conditions and wide substrate scope.Mechanistic investigation supports a cobalt-hydride pathway involving reversible alkene insertion/β-H elimination,and the step ofβ-H elimination at the allylic position is likely the rate-determining step.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 highly site-selective intermolecular trifluoromethylimination of activated and unactivated olefins was reported under transition-metal-and photosensitizer-free conditions.This newly developed strategy provides strai...A highly site-selective intermolecular trifluoromethylimination of activated and unactivated olefins was reported under transition-metal-and photosensitizer-free conditions.This newly developed strategy provides straightforward and efficient access to diverse value-added vicinal trifluoromethyl amines without resorting to the pre-functionalized reagents.Mechanistic experiments demonstrate that the approach proceeded through CF_(3)and iminyl two-radicals process,which were generated directly from commercially available benzophenone imine in a novel electron-donor mode via a SET process activated by the bifunctional hypervalent iodine reagents.The synthetic potential of the protocols was further showcased via the condensation/amination sequential cascade,and transformations to accessβ-CF_(3)primary amines.展开更多
The generation of multifunctional isolated active sites in zeolite supports is an attractive method for integrating multistep sequential reactions into a single‐pass tandem catalytic reaction.In this study,bifunction...The generation of multifunctional isolated active sites in zeolite supports is an attractive method for integrating multistep sequential reactions into a single‐pass tandem catalytic reaction.In this study,bifunctional TiSn‐Beta zeolite was prepared by a simple and scalable post‐synthesis approach,and it was utilized as an efficient heterogeneous catalyst for the tandem conversion of alkenes to 1,2‐diols.The isolated Ti and Sn Lewis acid sites within the TiSn‐Beta zeolite can efficiently integrate alkene epoxidation and epoxide hydration in tandem in a zeolite microreactor to achieve one‐step conversion of alkenes to 1,2‐diols with a high selectivity of>90%.Zeolite confinement effects result in high tandem rates of alkene epoxidation and epoxide hydration as well as high selectivity toward the desired product.Further,the novel method demonstrated herein can be employed to other tandem catalytic reactions for sustainable chemical production.展开更多
A series of carboxylated long chain polyethylene glycols(abbreviated as PEGCOOH) has been synthesized and used to support chloroplatinic acid.These supported catalysts were then tested for their efficiency in the hydr...A series of carboxylated long chain polyethylene glycols(abbreviated as PEGCOOH) has been synthesized and used to support chloroplatinic acid.These supported catalysts were then tested for their efficiency in the hydrosilylation of alkenes.The factors affecting their catalytic properties,e.g.relative molecular mass of polyethylene glycol,reaction temperature,platinum content,and type of alkenes,have been studied.It was found that the activity of the platinum catalyst decreased with increasing length of the polyethylene glycol chain,and increased with reaction temperature.Moreover,these catalysts could be reused several times without a noticeable decrease in activity or selectivity.The reaction pathway leading to excellent selectivity for the β-adduct of hydrosilylation of alkenes with triethoxysilane catalyzed by this catalysis system was discussed.展开更多
Metal-free anti-Markovnikov hydroalkylation of unactivated alkenes with cyanoacetate has been developed,featuring the use of a dual-component initiator containing an organic photocatalyst and a radical precursor.When ...Metal-free anti-Markovnikov hydroalkylation of unactivated alkenes with cyanoacetate has been developed,featuring the use of a dual-component initiator containing an organic photocatalyst and a radical precursor.When combined,the two components can undergo visible light-induced singleelectron transfer,and serve as a versatile and effective alkyl radical generator.展开更多
We have reported that phenyliodonium diacetate[PhI（OAc）2] can serve as an eco-friendly mild oxidant for the epoxidation of alkenes in the presence of Mn（III） complex of meso-tetrakis（4-methoxyphenylporphyrin） ac...We have reported that phenyliodonium diacetate[PhI（OAc）2] can serve as an eco-friendly mild oxidant for the epoxidation of alkenes in the presence of Mn（III） complex of meso-tetrakis（4-methoxyphenylporphyrin） acetate Mn[（T4-OCH3P）P]OAc and imidazole in CH2Cl2.The amounts of the products（%） and selectivities are very dependent upon the electronic and steric properties of the starting alkenes.To evaluate the validity of this catalytic system for C ＂H activation,cyclohexane and ethylbenzene were oxidized under the epoxidation conditions.展开更多
NaBH<sub>4</sub>, CH<sub>3</sub>CO<sub>2</sub>H, Pd/C has been described as an effective reagent system to hydrogenate alkenes. Here, we show that the hydrogenation occurs chemosele...NaBH<sub>4</sub>, CH<sub>3</sub>CO<sub>2</sub>H, Pd/C has been described as an effective reagent system to hydrogenate alkenes. Here, we show that the hydrogenation occurs chemoselectively, making it possible to hydrogenate alkenes under Pd/C catalysis with hydrogen created in situ without O- or N-debenzylation.展开更多
The dibromination of alkenes and alkynes with bromosuccinimide and sodium bromide catalyzed by FeBr_3 under mild conditions has been developed.The trans-dibromo compounds were exclusively obtained with excellent yields.
This paper studied the mechanism of the alkene insertion elementary step in the asymmetric hydroformylation （AHF） catalyzed by RhH（CO）2[（R,S）-Yanphos] using four alkene substrates （CH2=CH- Ph, CH2=CH-Ph-（p）-M...This paper studied the mechanism of the alkene insertion elementary step in the asymmetric hydroformylation （AHF） catalyzed by RhH（CO）2[（R,S）-Yanphos] using four alkene substrates （CH2=CH- Ph, CH2=CH-Ph-（p）-Me, CH2=CH-C（==O）OCH3 and CH2=CH-OC（=O）-Ph, abbreviated as A1-A4）. Interestingly, the equatorial vertical coordination mode （A mode） with respect to the Rh center was found for AI and A2 but not for A3 and A4, although the equatorial in-plane coordination mode （E mode） was found for A1 -A4. The relative energy of the E mode of the -q2-intermediates is lower than that of the A mode. In the alkene insertion step, Path 1 is more favorable than Path 2 for this system. As for AI and A2, there could be a transformation between 2eq and 2ax.展开更多
The hydrothiolations of alkynes/alkenes with thiols is an atom-economic and thus attractive method for the constructions of C‒S bonds.Here Ir_(2)S_(3)/ZnIn_(2)S_(4)nanocomposites with varied Ir_(2)S_(3)loadings were o...The hydrothiolations of alkynes/alkenes with thiols is an atom-economic and thus attractive method for the constructions of C‒S bonds.Here Ir_(2)S_(3)/ZnIn_(2)S_(4)nanocomposites with varied Ir_(2)S_(3)loadings were obtained by one-pot solvothermal method from ZnCl_(2),InCl_(3)and thioacetamide with IrCl_(3).The loading of Ir_(2)S_(3)on the surface of ZnIn_(2)S_(4)promoted the hydrothiolations of alkenes and alkynes,with an optimum performance observed over 0.5 mol%Ir_(2)S_(3)/ZnIn_(2)S_(4)nanocomposite.Based on the studies on the performance of several other cocatalysts(MoS2,NiS and Pd)loaded ZnIn_(2)S_(4)and the EIS analyses,it was proposed that the superior performance over Ir_(2)S_(3)/ZnIn_(2)S_(4)nanocomposite can be ascribed to an improved efficiency on the photogeneration of the thiyl radicals by loading Ir_(2)S_(3)as well as its inactivity for photocatalytic hydrogen evolution,a side reaction in the light initiated hydrothiolation reaction over ZnIn_(2)S_(4).This study not only demonstrates an efficient and green strategy to synthesize thiolated products under visible light based on semiconductor photocatalysis,but also provides some guidances for the design and development of photocatalytic systems for light induced organic syntheses.展开更多
Both sulfur and fluorine play important roles in organic synthesis, the life science, and materials science.The direct incorporation of these elements into organic scaffolds with precise control of the oxidation state...Both sulfur and fluorine play important roles in organic synthesis, the life science, and materials science.The direct incorporation of these elements into organic scaffolds with precise control of the oxidation states of sulfur moieties is of great significance. Herein, we report the highly selective electrochemical vicinal fluorosulfenylation and fluorosulfoxidation reactions of alkenes, which were enabled by the unique ability of electrochemistry to dial in the potentials on demand. Preliminary mechanistic investigations revealed that the fluorosulfenylation reaction proceeded through a radical-polar crossover mechanism involving a key episulfonium ion intermediate. Subsequent electrochemical oxidation of fluorosulfides to fluorosulfoxides were readily achieved under a higher applied potential with the adventitious H;O in the reaction mixture.展开更多
文摘Hydroformylation of olefins is one of the highest-volume industrial reactions to meet the vast demands for aldehydes as well as their derivatives.Homogeneous Co complexes were the original catalysts industrialized since 1960s.Heterogeneous catalysis is considered superior owing to the facile separation of catalysts from products,shorter technical process,and reduced manufacturing costs.Unexpectedly,there has not been a single case of plant using heterogenized Co-based catalyst successfully.To address the separation issue and understand the catalytic mechanism of the reactions,this review summarizes the progress in heterogeneous systems and provides a detailed discussion of their catalytic performance.Strategies for stabilizing Co species through support modification and additive incorporation are carefully considered to elucidate why heterogeneous systems have not yet succeeded on an industrial scale.Furthermore,we provide our insights for the development of heterogeneous catalytic hydroformylation,including the challenges,opportunities,and outlooks.The aim is to deepen the fundamental understanding of heterogeneous alkene hydroformylation,guiding the community's research efforts towards realizing its successful application in the future.
基金the National Science Foundation of China(No.22071058)the Fundamental Research Funds for the Central Universities for financial support。
文摘The direct difunctionalization of alkenes serves as one of the most straightforward strategies toward complex nitrogen-containing compounds.The existing approach is extensively promoted by using C/Xcentered radicals and N-nucleophiles to conduct 1,2-difunctional amination/azolization of alkenes.In contrast,2,1-difunctional amination/azolization of alkenes by using nitrogen-centered radicals(NCRs) and nucleophiles still remains rarely underexplored.It is possibly due to the highly active electron properties of NCRs and the relatively poor nucleophilicity of aromatic NCRs to be trapped by arylalkenes.Herein,we demonstrate an unprecedented 2,1-hydroxazolization reactions of arylalkenes through electrochemically enabled addition of NCRs from azoles and nucleophiles(NuH) in high yields and with high regioselectivity.This conversion is characterized by the fact that neither metal catalysts nor external chemical oxidants are required.This electrochemical oxidation synthesis method can also be applied for a broad range of NuH including pyridine hydrofluoride,ammonia,water,alcohols,and acids which enables the formation of C-N and C-X(X=F/N/O) bonds in one-pot fashion to furnish efficient fluoroamination,diamination and oxoamination of alkenes.
基金supported by the National Natural Science Foundation of China(Nos.41975172,42275116,and 41730106).
文摘This study has employed the master chemical mechanism(MCM)to investigate the influence of the ozone oxidation pathways in the atmospheric formation of H_(2)SO_(4)from shortchain olefins in industrialized areas.In-situ H_(2)SO_(4)formation data were obtained using a high-resolution chemical ionization time-of-flight mass spectrometer,and the simulated H_(2)SO_(4)concentrations calculated using updated parameters for the MCM model exhibited good agreementwith observations.In the simulation analysis of different reaction pathways involved in H_(2)SO_(4)formation,hydroxyl radicals were found to dominate H_(2)SO_(4)production during the daytime,while olefin ozone oxidation contributed up to 65%of total H_(2)SO_(4)production during the night-time.A sensitivity analysis of the H_(2)SO_(4)production parameters has revealed a high sensitivity to changes in sulfur dioxide,and a relatively high sensitivity to olefins with fast ozonolysis reaction rates and bimolecular reaction rates of resulting stabilized Criegee Intermediates.A high relative humidity promotes daytime H_(2)SO_(4)formation,but has an inhibiting effect during the night-time due to the different dominant reaction pathways.
基金financial support from the National Key Research and Development Program of China(No.2021YFF0600704).
文摘The hydroformylation of olefins,known as the"oxo reaction",involves the use of syngas(CO/H_(2))to produce aldehyde with an additional carbon atom.However,side reactions such as the isomerization or hydrogenation of olefins often result in unexpected products and other by-products.Recent efforts in developing efficient ligands represent the most effective approach to addressing these challenges.In this study,we described a Bis-OPNN phosphorus ligand facilitated Rh-catalyzed hydroformylation with a high degree of linear selectivity across various olefins.Under mild conditions,a broad range of olefins were efficiently converted into linear aldehydes with high yields and excellent regioselectivity.The protocol also showed impressive functional group tolerance and was successfully applied to modify drugs and natural products,including the total synthesis of(±)-crispine A.Preliminary mechanistic studies revealed that this Bis-OPNN phosphorus ligand anchoring the rhodium catalyst is crucial for controlling the linear selectivity.
基金financial support from the National Natural Science Foundation of China(NSFC,No.21877067)Tsinghua-Peking Centre for Life Science。
文摘Herein,we describe a nickel-catalyzed reductive decarboxylative difluoromethylation reaction of alkenes using inexpensive and easy-to-handle difluoroacetic anhydride(DFAA)/pyridine N-oxide reagent system.A variety of C(sp^(3))-CF_(2)H containing compounds were prepared through a hydrodifluoromethylation process.Besides,various gem–difluoroalkenes bearing CF_(2)H group were synthesized via defluorinative reductive cross-coupling process from trifluoromethyl-substituted alkenes using this new reaction system.Difluoroacetic anhydride has been then extended to other common alkyl anhydrides,and the corresponding hydroalkylation and defluoroalkylation processes have been successfully achieved.This method features broad substrate scope,good functional group tolerance as well as high efficiency.
基金the National Natural Science Foundation of China (No. 22201087) for the financial support。
文摘Catalytic electron donor-acceptor(EDA) complex photochemistry has recently emerged as a popular and sustainable alternative to photoredox synthetic methods. Yet, the catalytic EDA strategy is still in its infancy for organic synthesis due to the challenges of designing novel catalytic paradigm and expanding the substrate and reaction scope. Here, we disclose a catalytic EDA/Cu cooperative strategy by employing Na I as a catalytic donor for copper-catalyzed radical asymmetric carbocyanation. A diverse range of synthetically useful chiral benzyl nitriles are produced with high enantioselectivities. This synergetic EDA/copper catalysis enables the decarboxylative cyanation without request of any photoredox catalysts, further expanding the synthetic potential of catalytic EDA chemistry in organic synthesis.
基金This research was made possible as a result of a generous grant from the Fundamental Research Funds for the Central Universities(Nos.2232024Y-01,2232024A-03)the National Science Fund for Excellent Young Scholars(No.22122101).
文摘Here we present a highly efficient protocol utilizing nickel-hydride hydrogen atom transfer catalysis for the regio-and enantioselective hydrofluorination of internal alkenes.This method efficiently assembles a wide array of enantioenrichedβ-fluoro amides with excellent regio-and enantioselectivity from internal unactivated alkenes.Mechanistic investigations suggest that this transformation proceeds via a NiHhydrogen atom transfer to alkene,followed by a stereoselective fluorine atom transfer process.The weak coordination effect of the tethered amide group is identified as a crucial factor governing the observed regio-and enantioselectivity.
文摘The accompanied forge of C(sp^(3))–S and C(sp^(3))–C(sp^(3))bonds across alkene frameworks serves as a potent strategy to construct biologically important compounds.Here,we report a metal-free,photochemically mediated fluoroalkyl-mono/disulfuration of unactivated alkenes with high efficiency and high selectivity.A wide range of terminal and internal alkenes are good coupling partners,affording the expected products in moderate to good yields(>90 examples).The exceedingly mild reaction conditions,exceptional functional group tolerance,broad substrate scope,and the potential for late-stage modifications of pharmaceutical molecules highlight the utility of this method in the preparation of privileged motifs from readily available disulfides,tetrasulfides,and diselenides.Mechanistic studies suggest that a secondary alkyl radical intermediate undergoes efficient homolytic substitution with disulfides,facilitating the modular synthesis of a diverse array of unsymmetrical thioethers.
文摘An efficient and E-selective monoisomerization of 1-alkenes is developed with a bis(phosphine)-based PCP-type Co complex as the catalyst.The protocol provides an atom-economical approach to trans-2-alkenes with high regio-and stereoselectivity,featuring mild conditions and wide substrate scope.Mechanistic investigation supports a cobalt-hydride pathway involving reversible alkene insertion/β-H elimination,and the step ofβ-H elimination at the allylic position is likely the rate-determining step.
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.
基金Financial support from the National Natural Science Foundation of China(Nos.22201239,22205192 and 22271244)the Hunan Provincial Natural Science Foundation of China(No.2022JJ40429)+2 种基金the Scientific Research Fund of Hunan Provincial Education Department(No.21B0130)the Open Research Fund of School of Chemistry and Chemical Engineering,Henan Normal University(No.2022C02)the Process Intensification&Green Chemical Engineering Innovation Team Project of Hunan Province。
文摘A highly site-selective intermolecular trifluoromethylimination of activated and unactivated olefins was reported under transition-metal-and photosensitizer-free conditions.This newly developed strategy provides straightforward and efficient access to diverse value-added vicinal trifluoromethyl amines without resorting to the pre-functionalized reagents.Mechanistic experiments demonstrate that the approach proceeded through CF_(3)and iminyl two-radicals process,which were generated directly from commercially available benzophenone imine in a novel electron-donor mode via a SET process activated by the bifunctional hypervalent iodine reagents.The synthetic potential of the protocols was further showcased via the condensation/amination sequential cascade,and transformations to accessβ-CF_(3)primary amines.
文摘The generation of multifunctional isolated active sites in zeolite supports is an attractive method for integrating multistep sequential reactions into a single‐pass tandem catalytic reaction.In this study,bifunctional TiSn‐Beta zeolite was prepared by a simple and scalable post‐synthesis approach,and it was utilized as an efficient heterogeneous catalyst for the tandem conversion of alkenes to 1,2‐diols.The isolated Ti and Sn Lewis acid sites within the TiSn‐Beta zeolite can efficiently integrate alkene epoxidation and epoxide hydration in tandem in a zeolite microreactor to achieve one‐step conversion of alkenes to 1,2‐diols with a high selectivity of>90%.Zeolite confinement effects result in high tandem rates of alkene epoxidation and epoxide hydration as well as high selectivity toward the desired product.Further,the novel method demonstrated herein can be employed to other tandem catalytic reactions for sustainable chemical production.
基金Supported by the Educational Commission of Zhejiang Province of China (Y201017419)Zhejiang Province Program(2008C14041)
文摘A series of carboxylated long chain polyethylene glycols(abbreviated as PEGCOOH) has been synthesized and used to support chloroplatinic acid.These supported catalysts were then tested for their efficiency in the hydrosilylation of alkenes.The factors affecting their catalytic properties,e.g.relative molecular mass of polyethylene glycol,reaction temperature,platinum content,and type of alkenes,have been studied.It was found that the activity of the platinum catalyst decreased with increasing length of the polyethylene glycol chain,and increased with reaction temperature.Moreover,these catalysts could be reused several times without a noticeable decrease in activity or selectivity.The reaction pathway leading to excellent selectivity for the β-adduct of hydrosilylation of alkenes with triethoxysilane catalyzed by this catalysis system was discussed.
基金supported by the Strategic Priority Research Program of the Chinese Academy of Sciences (No.XDB17000000)the National Natural Science Foundation of China (Nos.21672227, 21922113)+3 种基金the National Key Research and Development Program of China (No.2017YFA0206903)Beijing Natural Science Foundation (No.L182020)Fundamental Research Funds for the Central Universities (No.FRF-TP-19-013B1)K.C.Wong Education Foundation,and the TIPC Director’s Fund。
文摘Metal-free anti-Markovnikov hydroalkylation of unactivated alkenes with cyanoacetate has been developed,featuring the use of a dual-component initiator containing an organic photocatalyst and a radical precursor.When combined,the two components can undergo visible light-induced singleelectron transfer,and serve as a versatile and effective alkyl radical generator.
基金Supported by the Yasouj University Research Council and Department of Chemistry of Yasouj University,Iran
文摘We have reported that phenyliodonium diacetate[PhI（OAc）2] can serve as an eco-friendly mild oxidant for the epoxidation of alkenes in the presence of Mn（III） complex of meso-tetrakis（4-methoxyphenylporphyrin） acetate Mn[（T4-OCH3P）P]OAc and imidazole in CH2Cl2.The amounts of the products（%） and selectivities are very dependent upon the electronic and steric properties of the starting alkenes.To evaluate the validity of this catalytic system for C ＂H activation,cyclohexane and ethylbenzene were oxidized under the epoxidation conditions.
文摘NaBH<sub>4</sub>, CH<sub>3</sub>CO<sub>2</sub>H, Pd/C has been described as an effective reagent system to hydrogenate alkenes. Here, we show that the hydrogenation occurs chemoselectively, making it possible to hydrogenate alkenes under Pd/C catalysis with hydrogen created in situ without O- or N-debenzylation.
基金the financial support by Lishui University Opening Foundation for advanced talents
文摘The dibromination of alkenes and alkynes with bromosuccinimide and sodium bromide catalyzed by FeBr_3 under mild conditions has been developed.The trans-dibromo compounds were exclusively obtained with excellent yields.
基金in part supported by the National Natural Science Foundation of China (Nos. 21072018 and 21203006)
文摘This paper studied the mechanism of the alkene insertion elementary step in the asymmetric hydroformylation （AHF） catalyzed by RhH（CO）2[（R,S）-Yanphos] using four alkene substrates （CH2=CH- Ph, CH2=CH-Ph-（p）-Me, CH2=CH-C（==O）OCH3 and CH2=CH-OC（=O）-Ph, abbreviated as A1-A4）. Interestingly, the equatorial vertical coordination mode （A mode） with respect to the Rh center was found for AI and A2 but not for A3 and A4, although the equatorial in-plane coordination mode （E mode） was found for A1 -A4. The relative energy of the E mode of the -q2-intermediates is lower than that of the A mode. In the alkene insertion step, Path 1 is more favorable than Path 2 for this system. As for AI and A2, there could be a transformation between 2eq and 2ax.
文摘The hydrothiolations of alkynes/alkenes with thiols is an atom-economic and thus attractive method for the constructions of C‒S bonds.Here Ir_(2)S_(3)/ZnIn_(2)S_(4)nanocomposites with varied Ir_(2)S_(3)loadings were obtained by one-pot solvothermal method from ZnCl_(2),InCl_(3)and thioacetamide with IrCl_(3).The loading of Ir_(2)S_(3)on the surface of ZnIn_(2)S_(4)promoted the hydrothiolations of alkenes and alkynes,with an optimum performance observed over 0.5 mol%Ir_(2)S_(3)/ZnIn_(2)S_(4)nanocomposite.Based on the studies on the performance of several other cocatalysts(MoS2,NiS and Pd)loaded ZnIn_(2)S_(4)and the EIS analyses,it was proposed that the superior performance over Ir_(2)S_(3)/ZnIn_(2)S_(4)nanocomposite can be ascribed to an improved efficiency on the photogeneration of the thiyl radicals by loading Ir_(2)S_(3)as well as its inactivity for photocatalytic hydrogen evolution,a side reaction in the light initiated hydrothiolation reaction over ZnIn_(2)S_(4).This study not only demonstrates an efficient and green strategy to synthesize thiolated products under visible light based on semiconductor photocatalysis,but also provides some guidances for the design and development of photocatalytic systems for light induced organic syntheses.
基金Financial support from the National Natural Science Foundation of China (Nos. 21901041 and 21772023)State Key Laboratory of Physical Chemistry of Solid Surfaces,Xiamen University (No.202008)Fuzhou University (No. 510841)。
文摘Both sulfur and fluorine play important roles in organic synthesis, the life science, and materials science.The direct incorporation of these elements into organic scaffolds with precise control of the oxidation states of sulfur moieties is of great significance. Herein, we report the highly selective electrochemical vicinal fluorosulfenylation and fluorosulfoxidation reactions of alkenes, which were enabled by the unique ability of electrochemistry to dial in the potentials on demand. Preliminary mechanistic investigations revealed that the fluorosulfenylation reaction proceeded through a radical-polar crossover mechanism involving a key episulfonium ion intermediate. Subsequent electrochemical oxidation of fluorosulfides to fluorosulfoxides were readily achieved under a higher applied potential with the adventitious H;O in the reaction mixture.
