The design and synthesis of a novel π-conjugated fiuorescent framework by external ligand-assisted C-H olefination of heterocycles with excellent regioselectivity and broad substrate scope are reported herein.These n...The design and synthesis of a novel π-conjugated fiuorescent framework by external ligand-assisted C-H olefination of heterocycles with excellent regioselectivity and broad substrate scope are reported herein.These novel fiuorescent materials could present full-color-tunable emissions with large Stokes shifts. Furthermore, the protocol provides an opportunity to rapidly screen novel organic single-molecule whitelight materials with high fiuorescence quantum yields. The robust organic and low-cost white lightemitting diodes could rapidly be fabricated using the white-light-emitting material. Experimental data and theoretical calculations indicate that in the white-light dual emission the relatively short wavelength from high-lying singlet state emission and the relatively long wavelength from low-lying singlet state emission. The anti-Kasha dual-emission systems will provide a foundation for the development and application of organic single-molecule white light materials, effectively promoting the development and innovation of luminescent materials. In addition, this method demonstrated its potential application in the synthesis of new near-infrared(NIR) fiuorescence materials with large Stokes shifts based on the olefination of heterocycles.展开更多
A rhodium-catalyzed directing group promoted selective C-H olefination reaction of indolizines at the 8-position is re ported.Di-olefination at 2,8-positions also achieved with silver hexafluoroantimonate as an additi...A rhodium-catalyzed directing group promoted selective C-H olefination reaction of indolizines at the 8-position is re ported.Di-olefination at 2,8-positions also achieved with silver hexafluoroantimonate as an additive under similar reaction conditions.Weakly coordinating groups,such as ketone,alde hyde,amide and ester,were used as directing groups.The ester group can be removed under acid conditions and therefore is used as a traceless directing group.展开更多
A simple and efficient process involving the Rh(II)-catalyzed[1+1+3]annulation of diazooxindoles and vinyl azides has been developed for the synthesis of spiropyrrolidine oxindoles with potential biological activity a...A simple and efficient process involving the Rh(II)-catalyzed[1+1+3]annulation of diazooxindoles and vinyl azides has been developed for the synthesis of spiropyrrolidine oxindoles with potential biological activity and significant synthetic applications.This process involves a novel rhodium-catalyzed olefination of diazo compounds,followed by annulation with vinyl azides.This method is compatible with a broad range of substrates and affords moderate to good yields under mild reaction conditions.展开更多
An efficient, convergent and enantioselective synthetic approach to the trihydroxy core structure 2 of Taurospongin A 1 is described. The featured step is a classic Wittig coupling reaction between C1-C4 aldehyde segm...An efficient, convergent and enantioselective synthetic approach to the trihydroxy core structure 2 of Taurospongin A 1 is described. The featured step is a classic Wittig coupling reaction between C1-C4 aldehyde segment 4 and C5-C10 phosphate salt segment (5).展开更多
A simple, efficient and low-cost methodology for the synthesis of α-aryl-α,β-unsaturated esters using paraformaldehyde as a source of carbon was developed. Factors that control reaction yields such as temperature, ...A simple, efficient and low-cost methodology for the synthesis of α-aryl-α,β-unsaturated esters using paraformaldehyde as a source of carbon was developed. Factors that control reaction yields such as temperature, concentration and reaction time were evaluated. A mechanism is proposed based on experimental structures of the intermediates.展开更多
Concise assembly of spirooxindoles is of great significance but a challenging task in modern organic synthesis.Described herein is an unusual base-promoted[4+2]spiroannulation of rarely used isatin-derivedβ-silylcarb...Concise assembly of spirooxindoles is of great significance but a challenging task in modern organic synthesis.Described herein is an unusual base-promoted[4+2]spiroannulation of rarely used isatin-derivedβ-silylcarbinols with o-halogen aromatic ketones,which enables rapid and modular synthesis of six-membered carbocyclic spirooxindoles in high yields with excellent functional group tolerance(>50 examples).Mechanistic experiments revealed that this reaction involved a Peterson olefination,Michael addition and intramolecular C(sp^(3))arylation cascade.The variegated synthetic derivatization of target products and successful construction of bioactive molecules further illustrate the synthetic potential in spirooxindole-related drug discovery.展开更多
Transition metal-catalyzed olefination of aryl C-H bond is a powerful tool for the synthesis of alkenes. While the Pd-catalyzed oxidative C-H olefination of arenes, also known as Fujiwara-Moritani reaction, has been e...Transition metal-catalyzed olefination of aryl C-H bond is a powerful tool for the synthesis of alkenes. While the Pd-catalyzed oxidative C-H olefination of arenes, also known as Fujiwara-Moritani reaction, has been established as one of the most efficient methods, the substrates are largely limited to terminal olefins with electron-withdrawing group(s). Herein, we report a synergistic silver-mediated and palladium-catalyzed non-directed C-H olefination of arenes with vinyl(pseudo)halides, which offers a complementary strategy to the typical Fujiwara-Moritani reaction. The reactions proceeded well for a variety of halogenated arenes, heteroarenes, and olefin substrates, providing an efficient access to various multi-substituted aryl olefins, including trisubstituted/tetrasubstituted olefins and several complex olefins derived from medicines or natural products. Mechanistic studies indicated a bimetallic Pd/Ag cooperation is operative in the catalysis, i.e., the reaction is initiated by aryl C-H bond cleavage via ligation with phosphine/Ag species, followed by transferring of the aryl moiety to a vinyl palladium intermediate,which is in turn formed by oxidative addition of vinyl(pseudo)halide to a Pd complex. This method enables the synthesis of a wide range of challenging multi-substituted vinyl products from simple arenes(directing-group free) in a streamlined and controllable fashion.展开更多
Phosphine-relayed olefination and aza-Wittig reactions of readily available aldehydes with 2,2,2-trifluorodiazoethane （CF3CHN2） have been realized. This protocol enables the facile construction of a series of triflu...Phosphine-relayed olefination and aza-Wittig reactions of readily available aldehydes with 2,2,2-trifluorodiazoethane （CF3CHN2） have been realized. This protocol enables the facile construction of a series of trifluoromethylated alkenes and hydrazones in good to high yield under mild conditions.展开更多
Axially chiral N-arylindoles bearing a stereogenic C—N axis are unique important scaffolds in natural products,advance materials,pharmaceuticals and privileged chiral ligands or catalysts.Herein,we report the direct ...Axially chiral N-arylindoles bearing a stereogenic C—N axis are unique important scaffolds in natural products,advance materials,pharmaceuticals and privileged chiral ligands or catalysts.Herein,we report the direct synthesis of C—N axially chiral N-arylindoles through a Pd-catalyzed free amine-directed atroposelective C—H olefination enabled by a spiro phosphoric acid(SPA)ligand.A wide range of enantioenriched N-aromatic amine indoles were obtained in high yields with good enantioselectivities(35 examples,up to 91%yield and up to 96%ee).The chiral products with free amine group offer an effective functional handle for down-stream diversity-oriented synthesis.展开更多
Main observation and conclusion A general synthesis of chiral 1,3-disubstituted allylsilanes is established through copper(I)-catalyzed asymmetric 1,4-conjugate silylation ofα,β-unsaturated sulfones and subsequent J...Main observation and conclusion A general synthesis of chiral 1,3-disubstituted allylsilanes is established through copper(I)-catalyzed asymmetric 1,4-conjugate silylation ofα,β-unsaturated sulfones and subsequent Julia-Kocienski olefination.By modification of McQuade's NHC ligand,the catalytic asymmetric conjugate silylation with a broad substrate scope is achieved in high enantioselectivity.展开更多
Double bonds of internal olefins can be efficiently migrated to the terminal carbons and regioselectively hydroesterified with formates in the presence of Pd(OAc)_(2) and 1,2-DTBPMB under mild reaction conditions,prov...Double bonds of internal olefins can be efficiently migrated to the terminal carbons and regioselectively hydroesterified with formates in the presence of Pd(OAc)_(2) and 1,2-DTBPMB under mild reaction conditions,providing a wide variety of corresponding linear carboxylic esters bearing various functional groups in good yields and>20:1 linear/branch ratios.The reaction is optionally simple and does not need to use CO gas and acid co-catalysts.展开更多
Modifying the electronic density of states and the synergistic effect of the active centers by introducing a second metal present an efficient strategy to tune physi/chemi-sorption,probably lead to improving catalytic...Modifying the electronic density of states and the synergistic effect of the active centers by introducing a second metal present an efficient strategy to tune physi/chemi-sorption,probably lead to improving catalytic performances.Herein,bimetallic Ni_(3)Mo/Al_(2)O_(3)catalyst was demonstrated and exhibited over 5 times more active than Pt/Al_(2)O_(3)toward the ethane dehydrogenation(EDH)as well as 2-10 times activity enhancement compared with their monometallic Ni and Mo counterparts and other Ni-based bimetallic nanoparticles.Kinetic studies revealed that the activation energy over Ni_(3)Mo/Al_(2)O_(3)(111 kJ mol^(-1))was much lower than that of Ni(157 kJ mol^(-1))and Mo(171 kJ·mol^(-1)).DFT calculations showed ethane was adsorbed on the Ni or Mo surface in a more parallel configuration,whereas over Ni_(3)Mo it adopted an inclined configuration.This change promoted ethane adsorption and pre-activation of the C-H bond,thereby benefiting the ethane dehydrogenation process on the Ni_(3)Mo surface.展开更多
The fabrication of monolithic ZSM-5 catalysts via extrusion is pivotal for industrial catalytic processes;nevertheless,the addition of adhesives might affect their catalytic performance.Herein,the rice husk-derived bi...The fabrication of monolithic ZSM-5 catalysts via extrusion is pivotal for industrial catalytic processes;nevertheless,the addition of adhesives might affect their catalytic performance.Herein,the rice husk-derived bio-SiO_(2),serving as a silicon source and natural adhesive,was introduced in the synthesis and extrusion of ZSM-5 catalysts denoted as BioZSM-5,thereby enhancing their industrial viability and catalytic performance.The f-n-BioZSM-5(obtained by extrusion of n-BioZSM-5)showcased enhanced butene and pentene selectivity,exhibiting robust stability,achieving an impressive 84.8%olefin selectivity(over 10 cycles).The biomass template significantly improved porosity,acidity,and anti-coking properties.Moreover,the f-n-BioZSM-5 exhibited a compressive strength 4.3 times superior to that of f-n-ZSM-5 without using bio-template,achieving better abrasion resistance and enhanced mechanical properties even using 1/3 of the adhesive dosage.These results will provide valuable guidance for developing shaped zeolite catalysts for industrial catalytic pyrolysis applications,especially for the production of olefin from fatty acids.展开更多
The concept of liquid-solid hybrid catalyst that featuring a truly homogeneous liquid microenvironment together with insoluble solid characteristics has been established recently by our group,which enables us to conve...The concept of liquid-solid hybrid catalyst that featuring a truly homogeneous liquid microenvironment together with insoluble solid characteristics has been established recently by our group,which enables us to conveniently bridge the gap between homo-and heterogeneous catalysis.In this study,we extend this general concept to the confinement of molecular rhodium phosphine complexes,including Rh-TPPTS,Rh-TPPMS and Rh-SXP,for olefin hydroformylation reactions.A series of hybrid catalyst materials consisting a modulated liquid interior([BMIM]NTf_(2),[BMIM]PF_(6),[BMIM]BF_(4) or H_(2)O)and a permeable silica crust were fabricated through our developed Pickering emulsion-based method,showing 9.4–24.2-fold activity enhancement and significantly improved aldehyde selectivity(from 72.2%,61.8%to 86.6%)compared to their biphasic counterparts or traditional supported liquid phase system in the hydroformylation of 1-dodecene.Interestingly,the catalytic efficiency was demonstrated to be tunable by rationally engineering the thickness of porous crust and dimensions of the liquid pool.The thus-attained hybrid catalyst could also successfully catalyze the hydroformylation of a variety of olefin substrates and be recycled without a significant loss of activity for at least seven times.展开更多
Fischer-Tropsch synthesis(FTS)and hydroformylation are pivotal chemical processes for converting syngas and olefins into valuable hydrocarbons and chemicals.Recent advancements in catalyst design,reaction mechanisms,a...Fischer-Tropsch synthesis(FTS)and hydroformylation are pivotal chemical processes for converting syngas and olefins into valuable hydrocarbons and chemicals.Recent advancements in catalyst design,reaction mechanisms,and process optimization have significantly improved the efficiency,selectivity,and sustainability of these processes.This Account introduces the relevant research activities in the Research Center for Catalysis in Syngas Conversion and Fine Chemicals(DNL0805)of Dalian Institute of Chemical Physics(DICP),Chinese Academy of Sciences.The reactions of interests include FTS,heterogeneous hydroformylation of olefins,alcohol dehydration and oxidation,andα-olefin polymerization,with the emphasis on developing innovative catalysts and processes to address the challenges of traditional processes.Exemplified by the discovery of robust Co-Co_(2)C/AC for FTS and Rh_(1)/POPs-PPh_(3) for heterogeneous hydroformylation of olefins,it demonstrates how lab-scale fundamental understandings on the active sites of catalysts leads to pilot-plant scale-up and finally commercial technologies.Perspectives on the challenges and directions for future developments in these exciting fields are provided.展开更多
The design of low-cost and high-performance cyclic olefin copolymers remains challenging.Ethylene copolymers with dicyclopentadiene(DCPD)were prepared using Ph_(2)C(Cp)(Flu)ZrCl_(2)(Cat.1),rac-Et(Ind)_(2)ZrCl_(2)(Cat....The design of low-cost and high-performance cyclic olefin copolymers remains challenging.Ethylene copolymers with dicyclopentadiene(DCPD)were prepared using Ph_(2)C(Cp)(Flu)ZrCl_(2)(Cat.1),rac-Et(Ind)_(2)ZrCl_(2)(Cat.2),Me_(2)C(Cp)(Flu)ZrCl_(2)(Cat.3)andMe_(2)Si(Ind)_(2)ZrCl_(2)(Cat.4)combined with[Ph_(3)C][B(C_(6)F_(5))_(4)]/iBu_(3)Al.Ni(acac)_(2)/iBu_(3)Al was then used to catalyze the hydrogenation of the intracyclic double bonds of ethylene/DCPD copolymers.The results showed that compared to C_(2) symmetric catalysts(Cat.2 and Cat.4),Cs symmetric catalysts(Cat.1 and Cat.3)facilitated the incorporation of copolymers with higher DCPD.1H-and ^(13)C-NMR spectra indicated that ethylene/DCPD copolymerization occurred via enhancement of the norbornene ring.Additionally,measurement of the reactivity ratios provided further confirmation that the copolymers had random sequence distributions.All these samples demonstrated transmittance values above 90%in the visible wavelength range from 400 nm to 800 nm.By changing the fraction of monomers,the glass transition temperature,refractive index,Young's modulus,and tensile strength of the copolymer increased as the incorporation of DCPD increased,whereas the Abbe number and elongation at break decreased.Compared with ethylene/norbornene and ethylene/tetracyclicdodecene copolymers,ethylene/DCPD copolymers,with excellent optical and mechanical properties,are promising materials.展开更多
We have disclosed a novel,efficient radicalmediated intermolecular fluoroalkylative olefination of unactivated alkenes.The transformation proceeded through a radical docking-migration cascade,in which a portfolio of s...We have disclosed a novel,efficient radicalmediated intermolecular fluoroalkylative olefination of unactivated alkenes.The transformation proceeded through a radical docking-migration cascade,in which a portfolio of strategically designed dual-function alkenylating reagents was harnessed to afford vinylated products with exclusive E-configuration.The reaction featured mild conditions,broad functional group compatibility,and unique chemo-,regio-,and stereoselectivities.The protocol has also provided a useful approach for late-stage olefination of complex natural products and drug derivatives containing alkenyl moieties.展开更多
Direct conversion of syngas to light olefins(STO)on bifunctional catalysts has garnered significant attention,yet a comprehensive understanding of the reaction pathway and reaction kinetics remains elusive.Herein,we t...Direct conversion of syngas to light olefins(STO)on bifunctional catalysts has garnered significant attention,yet a comprehensive understanding of the reaction pathway and reaction kinetics remains elusive.Herein,we theoretically addressed the kinetics of the direct STO reaction on typical ZnAl_(2)O_(4)/zeolite catalysts by establishing a complete reaction network,consisting of methanol synthesis and conversion,water gas shift(WGS)reaction,olefin hydrogenation,and other relevant steps.The WGS reaction occurs very readily on ZnAl_(2)O_(4) surface whereas which is less active towards alkane formation via olefin hydrogenation,and the latter can be attributed to the characteristics of the H_(2) heterolytic activation and the weak polarity of olefins.The driving effect of zeolite component towards CO conversion was demonstrated by microkinetic simulations,which is sensitive to reaction conditions like space velocity and reaction temperature.Under a fixed ratio of active sites between oxide and zeolite components,the concept of the“impossible trinity”of high CO conversion,high olefin selectivity,and high space velocity can thus be manifested.This work thus provides a comprehensive kinetic picture on the direct STO conversion,offering valuable insights for the design of each component of bifunctional catalysts and the optimization of reaction conditions.展开更多
Fe-based catalysts are widely used for CO_(2)hydrogenation to light olefins(C_(2–4)=);however,precise regulation of active phases and the balance between intermediate reactions remain significant challenges.Herein,we...Fe-based catalysts are widely used for CO_(2)hydrogenation to light olefins(C_(2–4)=);however,precise regulation of active phases and the balance between intermediate reactions remain significant challenges.Herein,we find that the addition of moderate amounts of Ti forms a strong interaction with Fe compositions,modulating the Fe_(3)O_(4)and Fe_(5)C_(2)contents.Enhanced interaction leads to an increased Fe_(5)C_(2)/Fe_(3)O_(4)ratio,which in turn enhances the adsorption of reactants and intermediates,promoting CO hydrogenation to unsaturated alkyl groups and facilitating C–C coupling.Furthermore,the strong Fe-Ti interaction induces the preferential growth of Fe_(5)C_(2)into prismatic structures that expose the(020),(–112),and(311)facets,forming compact active interfacial sites with Fe_(3)O_(4)nanoparticles.These facet and interfacial effects significantly promote the synergistic coupling of the reverse water gas shift and Fischer-Tropsch reactions.The optimized 3K/FeTi catalyst with the highest Fe_(5)C_(2)/Fe_(3)O_(4)ratio of 3.6 achieves a 52.2%CO_(2)conversion rate,with 44.5%selectivity for C2–4=and 9.5%for CO,and the highest space-time yield of 412.0 mg gcat^(–1)h^(–1)for C_(2–4)=.展开更多
基金the Fundamental Research Funds for the Central Universities (Nos. 2024CDJXY0022023CDJYGRH-YB17+4 种基金2022CDJXY-025)the Venture & Innovation Support Program for Chongqing Overseas Returnees (No. cx2022061)the Natural Science Foundation of Chongqing (No. CSTB2022NSCQ-MSX1123)the Chongqing Talents: Exceptional Young Talents Project (No. cstc2021ycjh-bgzxm0067)the Hongshen Young Scholars Program from Chongqing University (No. 0247001104426) for financial support。
文摘The design and synthesis of a novel π-conjugated fiuorescent framework by external ligand-assisted C-H olefination of heterocycles with excellent regioselectivity and broad substrate scope are reported herein.These novel fiuorescent materials could present full-color-tunable emissions with large Stokes shifts. Furthermore, the protocol provides an opportunity to rapidly screen novel organic single-molecule whitelight materials with high fiuorescence quantum yields. The robust organic and low-cost white lightemitting diodes could rapidly be fabricated using the white-light-emitting material. Experimental data and theoretical calculations indicate that in the white-light dual emission the relatively short wavelength from high-lying singlet state emission and the relatively long wavelength from low-lying singlet state emission. The anti-Kasha dual-emission systems will provide a foundation for the development and application of organic single-molecule white light materials, effectively promoting the development and innovation of luminescent materials. In addition, this method demonstrated its potential application in the synthesis of new near-infrared(NIR) fiuorescence materials with large Stokes shifts based on the olefination of heterocycles.
基金Jiangsu Province(No.BK20161307 and“333”Talents Project for H.Hu)Huaiyin Normal University(No.JSKC18014)for their financial support。
文摘A rhodium-catalyzed directing group promoted selective C-H olefination reaction of indolizines at the 8-position is re ported.Di-olefination at 2,8-positions also achieved with silver hexafluoroantimonate as an additive under similar reaction conditions.Weakly coordinating groups,such as ketone,alde hyde,amide and ester,were used as directing groups.The ester group can be removed under acid conditions and therefore is used as a traceless directing group.
基金supported by the National Natural Science Foundation of China(21572225)~~
文摘A simple and efficient process involving the Rh(II)-catalyzed[1+1+3]annulation of diazooxindoles and vinyl azides has been developed for the synthesis of spiropyrrolidine oxindoles with potential biological activity and significant synthetic applications.This process involves a novel rhodium-catalyzed olefination of diazo compounds,followed by annulation with vinyl azides.This method is compatible with a broad range of substrates and affords moderate to good yields under mild reaction conditions.
文摘An efficient, convergent and enantioselective synthetic approach to the trihydroxy core structure 2 of Taurospongin A 1 is described. The featured step is a classic Wittig coupling reaction between C1-C4 aldehyde segment 4 and C5-C10 phosphate salt segment (5).
文摘A simple, efficient and low-cost methodology for the synthesis of α-aryl-α,β-unsaturated esters using paraformaldehyde as a source of carbon was developed. Factors that control reaction yields such as temperature, concentration and reaction time were evaluated. A mechanism is proposed based on experimental structures of the intermediates.
基金financial support of National Natural Science Foundation of China(21901193,22271314 and 22377097)the innovation foundation of Key Laboratory of Green Chemical Engineering Process of Ministry of Education(GCX2023002).
文摘Concise assembly of spirooxindoles is of great significance but a challenging task in modern organic synthesis.Described herein is an unusual base-promoted[4+2]spiroannulation of rarely used isatin-derivedβ-silylcarbinols with o-halogen aromatic ketones,which enables rapid and modular synthesis of six-membered carbocyclic spirooxindoles in high yields with excellent functional group tolerance(>50 examples).Mechanistic experiments revealed that this reaction involved a Peterson olefination,Michael addition and intramolecular C(sp^(3))arylation cascade.The variegated synthetic derivatization of target products and successful construction of bioactive molecules further illustrate the synthetic potential in spirooxindole-related drug discovery.
基金supported by the National Key R&D Program of China(2021YFA1500100)the National Natural Science Foundation of China(21821002,92256303,22171278)+1 种基金Shanghai Science and Technology Committee(23ZR1482400)the Natural Science Foundation of Ningbo(2023J034)。
文摘Transition metal-catalyzed olefination of aryl C-H bond is a powerful tool for the synthesis of alkenes. While the Pd-catalyzed oxidative C-H olefination of arenes, also known as Fujiwara-Moritani reaction, has been established as one of the most efficient methods, the substrates are largely limited to terminal olefins with electron-withdrawing group(s). Herein, we report a synergistic silver-mediated and palladium-catalyzed non-directed C-H olefination of arenes with vinyl(pseudo)halides, which offers a complementary strategy to the typical Fujiwara-Moritani reaction. The reactions proceeded well for a variety of halogenated arenes, heteroarenes, and olefin substrates, providing an efficient access to various multi-substituted aryl olefins, including trisubstituted/tetrasubstituted olefins and several complex olefins derived from medicines or natural products. Mechanistic studies indicated a bimetallic Pd/Ag cooperation is operative in the catalysis, i.e., the reaction is initiated by aryl C-H bond cleavage via ligation with phosphine/Ag species, followed by transferring of the aryl moiety to a vinyl palladium intermediate,which is in turn formed by oxidative addition of vinyl(pseudo)halide to a Pd complex. This method enables the synthesis of a wide range of challenging multi-substituted vinyl products from simple arenes(directing-group free) in a streamlined and controllable fashion.
基金This work was supported financially by the National Natural Science Foundation of China （Nos. 21225208, 21472137, and 21532008）, the National Basic Research Program of China （973 Program： Nos. 2014CB745100, 2015CB856500）, and the Tianjin Municipal Science ＆ Technology Commission （No. 14JCQNJC06200）.
文摘Phosphine-relayed olefination and aza-Wittig reactions of readily available aldehydes with 2,2,2-trifluorodiazoethane （CF3CHN2） have been realized. This protocol enables the facile construction of a series of trifluoromethylated alkenes and hydrazones in good to high yield under mild conditions.
基金We thank the support from National Key R&D Program of China(2022YFA1504302,2021YFF0701603)National Natural Science Foundation of China(U22A20388,92256302,21925109 for B.-F.S.,22271250 for T.Z.)+1 种基金Fundamental Research Funds for the Central Universities(226-2023-00115,226-2022-00224,226-2022-00175)Zhejiang Provincial NSFC(LD22B030003)。
文摘Axially chiral N-arylindoles bearing a stereogenic C—N axis are unique important scaffolds in natural products,advance materials,pharmaceuticals and privileged chiral ligands or catalysts.Herein,we report the direct synthesis of C—N axially chiral N-arylindoles through a Pd-catalyzed free amine-directed atroposelective C—H olefination enabled by a spiro phosphoric acid(SPA)ligand.A wide range of enantioenriched N-aromatic amine indoles were obtained in high yields with good enantioselectivities(35 examples,up to 91%yield and up to 96%ee).The chiral products with free amine group offer an effective functional handle for down-stream diversity-oriented synthesis.
基金We gratefully acknowledge the financial support from the National Natural Science Foundation of China(Nos.21672235,21871287,and 21922114)the Science and Technology Commission of Shanghai Municipality(No.20JC1417100)+2 种基金the Strategic Priority Research Program of the Chinese Academy of Sciences(No.XDB20000000)CAS Key Laboratory of Synthetic Chemistry of Natural SubstancesShanghai Institute of Organic Chemistry.
文摘Main observation and conclusion A general synthesis of chiral 1,3-disubstituted allylsilanes is established through copper(I)-catalyzed asymmetric 1,4-conjugate silylation ofα,β-unsaturated sulfones and subsequent Julia-Kocienski olefination.By modification of McQuade's NHC ligand,the catalytic asymmetric conjugate silylation with a broad substrate scope is achieved in high enantioselectivity.
基金financial support from the National Natural Science Foundation of China(Nos.22271024,21632005)Changzhou University.
文摘Double bonds of internal olefins can be efficiently migrated to the terminal carbons and regioselectively hydroesterified with formates in the presence of Pd(OAc)_(2) and 1,2-DTBPMB under mild reaction conditions,providing a wide variety of corresponding linear carboxylic esters bearing various functional groups in good yields and>20:1 linear/branch ratios.The reaction is optionally simple and does not need to use CO gas and acid co-catalysts.
文摘Modifying the electronic density of states and the synergistic effect of the active centers by introducing a second metal present an efficient strategy to tune physi/chemi-sorption,probably lead to improving catalytic performances.Herein,bimetallic Ni_(3)Mo/Al_(2)O_(3)catalyst was demonstrated and exhibited over 5 times more active than Pt/Al_(2)O_(3)toward the ethane dehydrogenation(EDH)as well as 2-10 times activity enhancement compared with their monometallic Ni and Mo counterparts and other Ni-based bimetallic nanoparticles.Kinetic studies revealed that the activation energy over Ni_(3)Mo/Al_(2)O_(3)(111 kJ mol^(-1))was much lower than that of Ni(157 kJ mol^(-1))and Mo(171 kJ·mol^(-1)).DFT calculations showed ethane was adsorbed on the Ni or Mo surface in a more parallel configuration,whereas over Ni_(3)Mo it adopted an inclined configuration.This change promoted ethane adsorption and pre-activation of the C-H bond,thereby benefiting the ethane dehydrogenation process on the Ni_(3)Mo surface.
基金financially supported by the National Natural Science Foundation of China(U21A20324,22278167,22350410389 and 22322806)the Fujian Provincial Natural Science Foundation of China(2024J01100)。
文摘The fabrication of monolithic ZSM-5 catalysts via extrusion is pivotal for industrial catalytic processes;nevertheless,the addition of adhesives might affect their catalytic performance.Herein,the rice husk-derived bio-SiO_(2),serving as a silicon source and natural adhesive,was introduced in the synthesis and extrusion of ZSM-5 catalysts denoted as BioZSM-5,thereby enhancing their industrial viability and catalytic performance.The f-n-BioZSM-5(obtained by extrusion of n-BioZSM-5)showcased enhanced butene and pentene selectivity,exhibiting robust stability,achieving an impressive 84.8%olefin selectivity(over 10 cycles).The biomass template significantly improved porosity,acidity,and anti-coking properties.Moreover,the f-n-BioZSM-5 exhibited a compressive strength 4.3 times superior to that of f-n-ZSM-5 without using bio-template,achieving better abrasion resistance and enhanced mechanical properties even using 1/3 of the adhesive dosage.These results will provide valuable guidance for developing shaped zeolite catalysts for industrial catalytic pyrolysis applications,especially for the production of olefin from fatty acids.
文摘The concept of liquid-solid hybrid catalyst that featuring a truly homogeneous liquid microenvironment together with insoluble solid characteristics has been established recently by our group,which enables us to conveniently bridge the gap between homo-and heterogeneous catalysis.In this study,we extend this general concept to the confinement of molecular rhodium phosphine complexes,including Rh-TPPTS,Rh-TPPMS and Rh-SXP,for olefin hydroformylation reactions.A series of hybrid catalyst materials consisting a modulated liquid interior([BMIM]NTf_(2),[BMIM]PF_(6),[BMIM]BF_(4) or H_(2)O)and a permeable silica crust were fabricated through our developed Pickering emulsion-based method,showing 9.4–24.2-fold activity enhancement and significantly improved aldehyde selectivity(from 72.2%,61.8%to 86.6%)compared to their biphasic counterparts or traditional supported liquid phase system in the hydroformylation of 1-dodecene.Interestingly,the catalytic efficiency was demonstrated to be tunable by rationally engineering the thickness of porous crust and dimensions of the liquid pool.The thus-attained hybrid catalyst could also successfully catalyze the hydroformylation of a variety of olefin substrates and be recycled without a significant loss of activity for at least seven times.
文摘Fischer-Tropsch synthesis(FTS)and hydroformylation are pivotal chemical processes for converting syngas and olefins into valuable hydrocarbons and chemicals.Recent advancements in catalyst design,reaction mechanisms,and process optimization have significantly improved the efficiency,selectivity,and sustainability of these processes.This Account introduces the relevant research activities in the Research Center for Catalysis in Syngas Conversion and Fine Chemicals(DNL0805)of Dalian Institute of Chemical Physics(DICP),Chinese Academy of Sciences.The reactions of interests include FTS,heterogeneous hydroformylation of olefins,alcohol dehydration and oxidation,andα-olefin polymerization,with the emphasis on developing innovative catalysts and processes to address the challenges of traditional processes.Exemplified by the discovery of robust Co-Co_(2)C/AC for FTS and Rh_(1)/POPs-PPh_(3) for heterogeneous hydroformylation of olefins,it demonstrates how lab-scale fundamental understandings on the active sites of catalysts leads to pilot-plant scale-up and finally commercial technologies.Perspectives on the challenges and directions for future developments in these exciting fields are provided.
基金supported by the National Natural Science Foundation of China(Nos.52130307 and 5240031453).
文摘The design of low-cost and high-performance cyclic olefin copolymers remains challenging.Ethylene copolymers with dicyclopentadiene(DCPD)were prepared using Ph_(2)C(Cp)(Flu)ZrCl_(2)(Cat.1),rac-Et(Ind)_(2)ZrCl_(2)(Cat.2),Me_(2)C(Cp)(Flu)ZrCl_(2)(Cat.3)andMe_(2)Si(Ind)_(2)ZrCl_(2)(Cat.4)combined with[Ph_(3)C][B(C_(6)F_(5))_(4)]/iBu_(3)Al.Ni(acac)_(2)/iBu_(3)Al was then used to catalyze the hydrogenation of the intracyclic double bonds of ethylene/DCPD copolymers.The results showed that compared to C_(2) symmetric catalysts(Cat.2 and Cat.4),Cs symmetric catalysts(Cat.1 and Cat.3)facilitated the incorporation of copolymers with higher DCPD.1H-and ^(13)C-NMR spectra indicated that ethylene/DCPD copolymerization occurred via enhancement of the norbornene ring.Additionally,measurement of the reactivity ratios provided further confirmation that the copolymers had random sequence distributions.All these samples demonstrated transmittance values above 90%in the visible wavelength range from 400 nm to 800 nm.By changing the fraction of monomers,the glass transition temperature,refractive index,Young's modulus,and tensile strength of the copolymer increased as the incorporation of DCPD increased,whereas the Abbe number and elongation at break decreased.Compared with ethylene/norbornene and ethylene/tetracyclicdodecene copolymers,ethylene/DCPD copolymers,with excellent optical and mechanical properties,are promising materials.
基金the financial support from the National Natural Science Foundation of China(grant no.21971173)the Project of Scientific and Technologic Infrastructure of Suzhou(grant no.SZS201905)the Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD).
文摘We have disclosed a novel,efficient radicalmediated intermolecular fluoroalkylative olefination of unactivated alkenes.The transformation proceeded through a radical docking-migration cascade,in which a portfolio of strategically designed dual-function alkenylating reagents was harnessed to afford vinylated products with exclusive E-configuration.The reaction featured mild conditions,broad functional group compatibility,and unique chemo-,regio-,and stereoselectivities.The protocol has also provided a useful approach for late-stage olefination of complex natural products and drug derivatives containing alkenyl moieties.
文摘Direct conversion of syngas to light olefins(STO)on bifunctional catalysts has garnered significant attention,yet a comprehensive understanding of the reaction pathway and reaction kinetics remains elusive.Herein,we theoretically addressed the kinetics of the direct STO reaction on typical ZnAl_(2)O_(4)/zeolite catalysts by establishing a complete reaction network,consisting of methanol synthesis and conversion,water gas shift(WGS)reaction,olefin hydrogenation,and other relevant steps.The WGS reaction occurs very readily on ZnAl_(2)O_(4) surface whereas which is less active towards alkane formation via olefin hydrogenation,and the latter can be attributed to the characteristics of the H_(2) heterolytic activation and the weak polarity of olefins.The driving effect of zeolite component towards CO conversion was demonstrated by microkinetic simulations,which is sensitive to reaction conditions like space velocity and reaction temperature.Under a fixed ratio of active sites between oxide and zeolite components,the concept of the“impossible trinity”of high CO conversion,high olefin selectivity,and high space velocity can thus be manifested.This work thus provides a comprehensive kinetic picture on the direct STO conversion,offering valuable insights for the design of each component of bifunctional catalysts and the optimization of reaction conditions.
文摘Fe-based catalysts are widely used for CO_(2)hydrogenation to light olefins(C_(2–4)=);however,precise regulation of active phases and the balance between intermediate reactions remain significant challenges.Herein,we find that the addition of moderate amounts of Ti forms a strong interaction with Fe compositions,modulating the Fe_(3)O_(4)and Fe_(5)C_(2)contents.Enhanced interaction leads to an increased Fe_(5)C_(2)/Fe_(3)O_(4)ratio,which in turn enhances the adsorption of reactants and intermediates,promoting CO hydrogenation to unsaturated alkyl groups and facilitating C–C coupling.Furthermore,the strong Fe-Ti interaction induces the preferential growth of Fe_(5)C_(2)into prismatic structures that expose the(020),(–112),and(311)facets,forming compact active interfacial sites with Fe_(3)O_(4)nanoparticles.These facet and interfacial effects significantly promote the synergistic coupling of the reverse water gas shift and Fischer-Tropsch reactions.The optimized 3K/FeTi catalyst with the highest Fe_(5)C_(2)/Fe_(3)O_(4)ratio of 3.6 achieves a 52.2%CO_(2)conversion rate,with 44.5%selectivity for C2–4=and 9.5%for CO,and the highest space-time yield of 412.0 mg gcat^(–1)h^(–1)for C_(2–4)=.
