Mechanism of the cycloadditional formaldehyde has been investigated reaction between singlet with MP2/6-31G^＊ method, dichloro-germylidene and including geometry optimization, vibrational analysis and energies for t...Mechanism of the cycloadditional formaldehyde has been investigated reaction between singlet with MP2/6-31G^＊ method, dichloro-germylidene and including geometry optimization, vibrational analysis and energies for the involved stationary points on the potential energy surface. From the potential energy profile, we predict that the cyeloaddition reaction between singlet dichloro-germylidene and formaldehyde has two competitive dominant reaction pathways, going with the formation of two side products （INT3 and INT4）, simultaneously. Both of the two competitive reactions consist of two steps, two reactants firstly form a three-membered ring intermediate INT1 and a twisted four-membered ring intermediate INT2, respectively, both of which are barrier-free exothermic reactions of 41.5 and 72.3 kJ/mol; then INT1 isomerizes to a four-membered ring product P1 via transition state TS1, and INT2 isomerizes to a chlorine-traasfer product P2 via transition state TS2, with the barriers of 2.9 and 0.3 kJ/mol, respectively. Simultaneously, P1 and INT2 further react with formaldehyde to form INT3 and INT4, respectively, which are also barrier-free exothermic reaction of 74.9 and 88.1 kJ/mol.展开更多
The high porosity and tunable chemical functionality of metal-organic frameworks(MOFs)make it a promising catalyst design platform.High-throughput screening of catalytic performance is feasible since the large MOF str...The high porosity and tunable chemical functionality of metal-organic frameworks(MOFs)make it a promising catalyst design platform.High-throughput screening of catalytic performance is feasible since the large MOF structure database is available.In this study,we report a machine learning model for high-throughput screening of MOF catalysts for the CO_(2) cycloaddition reaction.The descriptors for model training were judiciously chosen according to the reaction mechanism,which leads to high accuracy up to 97%for the 75%quantile of the training set as the classification criterion.The feature contribution was further evaluated with SHAP and PDP analysis to provide a certain physical understanding.12,415 hypothetical MOF structures and 100 reported MOFs were evaluated under 100℃ and 1 bar within one day using the model,and 239 potentially efficient catalysts were discovered.Among them,MOF-76(Y)achieved the top performance experimentally among reported MOFs,in good agreement with the prediction.展开更多
Isothiocyanates(ITCs)are an important class of organic compounds characterized by the functional group R-N=C=S.These functional groups are widely found in multiple natural products and pharmaceutical important drugs.M...Isothiocyanates(ITCs)are an important class of organic compounds characterized by the functional group R-N=C=S.These functional groups are widely found in multiple natural products and pharmaceutical important drugs.Moreover,due to their high and versatile reactivity,they are widely used as an intermediate in organic synthesis.Keeping in view ITCs importance,this review summarizes their synthesis from nitrogen rich raw materials like amines,isocyanides,azides and some other compounds like oximes.Besides their synthesis,their application in organic compound synthesis as an intermediate will also be covered.Future research will likely focus on optimizing the synthesis of multifunctional isothiocyanates,understanding their complex biological mechanisms,exploring new applications,and highlighting the continued importance of isothiocyanates in modern chemistry and biotechnology.展开更多
The first efficiently N-heterocyclic carbene-catalyzed[4+2]cycloaddition of salicylaldehydes and pyrazole-4,5-diones to directly synthesis of spiro-ketal-pyrazolones bearing both oxygens of the ketal unit in the same ...The first efficiently N-heterocyclic carbene-catalyzed[4+2]cycloaddition of salicylaldehydes and pyrazole-4,5-diones to directly synthesis of spiro-ketal-pyrazolones bearing both oxygens of the ketal unit in the same ring was disclosed.This reaction was qualified with broad substrate scope,achieving moderate to excellent yield(up to 98%).This method has mild reaction conditions and simple operation,providing a new attractive strategy for the practical syntheses of multifunctionalized spiroketals including pyrazolone structures with mild reaction condition and operational simplicity.Furthermore,the gram scale and derivative transformations have also been achieved.展开更多
A Silver-catalyzed enantioselective[3+2]cycloaddition of azomethine ylides with activated alkenes by using a P-stereogenic ligand Ganphos is reported.The method provides an efficient strategy for the effective synthes...A Silver-catalyzed enantioselective[3+2]cycloaddition of azomethine ylides with activated alkenes by using a P-stereogenic ligand Ganphos is reported.The method provides an efficient strategy for the effective synthesis of spirocyclic scaffolds containing a pyrroline motif.Notable features of this approach include good yields,remarkable enantioselectivity,as well as a broad substrate scope and significant step efficiency.展开更多
A visible-light-promoted[1+2]cycloaddition of gem-difluoroalkenes with aryl diazo esters provides an efficient and important route to 1,1-difluorocyclopropanes.The reaction conditions are mild,and the operation is ver...A visible-light-promoted[1+2]cycloaddition of gem-difluoroalkenes with aryl diazo esters provides an efficient and important route to 1,1-difluorocyclopropanes.The reaction conditions are mild,and the operation is very simple.A number of diazo esters and gem-difluoroalkenes are suitable for this reaction(36 examples),providing the desired products in good yields with excellent diastereoselectivity(>20∶1).展开更多
Photocatalytic CO_(2)cycloaddition reaction presents a promising CO_(2)conversion strategy to establish carbon neutrality.Among emerging catalysts,metal‑organic frameworks(MOFs)have been regarded as paradigmshifting p...Photocatalytic CO_(2)cycloaddition reaction presents a promising CO_(2)conversion strategy to establish carbon neutrality.Among emerging catalysts,metal‑organic frameworks(MOFs)have been regarded as paradigmshifting photocatalysts for their atomic precision in active site engineering,controllable porosity,and exceptional photochemical stability under ambient conditions.However,inherent limitations persist in conventional MOFs,including restricted solar spectrum utilization,inefficient charge carrier separation,and inadequate epoxide activation ability.Recent breakthroughs address these challenges through multiple strategies:ligand engineering,dopant incorporation,and composite construction.This review systematically maps the evolutionary trajectory of MOF‑based photocatalysts,providing mechanistic insights into structure‑activity relationships and providing insights and directions for the design of high‑performance MOF‑based photocatalysts.展开更多
Pyrazolidinones,as significant analogs ofβ-lactam antibiotics,have garnered substantial interest for their enantioselective synthesis.Azomethine imines,recognized as valuable building blocks for the construction of t...Pyrazolidinones,as significant analogs ofβ-lactam antibiotics,have garnered substantial interest for their enantioselective synthesis.Azomethine imines,recognized as valuable building blocks for the construction of these nitrogen-containing compounds,underscore the continuous pursuit of novel building blocks and reaction methodologies within the chemical community.In this paper,we present a cascade cyclization between alkenyl azomethine imines and furan-2(5H)-one to generate chiral coronal polyheterocyclic compounds with high yields and enantioselectivities,catalyzed by dipeptide-derived phosphonium salts.In-vitro biological activity assays highlight the potential of these chiral compounds in drug discovery.Additionally,density functional theory(DFT)calculations elucidate the pivotal role of phosphonium salts,demonstrating their cooperative activations via hydrogen bonding and ion-pairing interactions.展开更多
High-energy-density(HED)fuel(e.g.widely used JP-10 and RJ-4),featuring compact 3D polycyclic structure with high strain,is of critical importance for volume-limited military aircraft,since their high density and combu...High-energy-density(HED)fuel(e.g.widely used JP-10 and RJ-4),featuring compact 3D polycyclic structure with high strain,is of critical importance for volume-limited military aircraft,since their high density and combustion heat can provide more propulsion energy.To reduce the reliance on petroleum source,it is highly desirable to develop renewable alternatives for the production of strained polycyclic HED fuel,but which remains a big challenge because of the inaccessibility caused by the high strain,We herein demonstrate a three-step catalytic route towards highly strained C_(17)and C_(18)spirofuel with biomass feedstocks.The process includes catalytic aldol condensation of renewable cyclohexanone/cyclopentanone with benzaldehyde,catalytic spiro Diels-Alder(D-A)reaction of aldol adduct with isoprene,and catalytic hydrodeoxygenation.The key spiro D-A reaction is enabled by the catalysis of heterogeneous Lewis acidic ionic liquid.The chloroaluminate IL,formed by benign urea and AICl3,exhibits good catalytic performance and reusability for this step.An eventual hydrodeoxygenation(HDO)over Pd/C and H-Y produces strained tricyclic spirofuel with density>0.93 g/mL,combustion heat>41 MJ/L and freezing point<-40℃,which are better than the properties of tactical fuel RJ-4.Therefore,it is anticipated that the as-prepared renewable fuels have the potential to replace traditional petroleum-derived HED fuels.展开更多
The first synthesis of flavanostilbenes with a 2-cyclohepten-1-one core was carried out by applying an effective strategy in three steps from abundant polymerized flavanol resources.A key regio-and stereoselective Cu-...The first synthesis of flavanostilbenes with a 2-cyclohepten-1-one core was carried out by applying an effective strategy in three steps from abundant polymerized flavanol resources.A key regio-and stereoselective Cu-mediated[5+2]cycloaddition/decarboxylation cascade was explored and applied without the use of protecting groups,and water as an environmentally friendly solvent contributed to the cascade.The intramolecular[5+2]cycloaddition mechanism,involving oxidation and dearomatization of the flavanol unit as a diene,was proposed and supported by the synthesis of the intermediate.The regioselectivity of the cyclization was found to be dependent on the substitution effects of the stilbene units by the exploration of substrate scope.展开更多
The development of general and practical strategies toward the construction of medium-sized rings is still challenging in organic synthesis,especially for the multiple stereocenters control of substituted groups on th...The development of general and practical strategies toward the construction of medium-sized rings is still challenging in organic synthesis,especially for the multiple stereocenters control of substituted groups on the ring owing to the long distance between groups.Thus,stereoselective synthesis of multi-substituted ten-membered rings is attractive.Herein,a rapid assembly of various highly substituted ten-membered nitrogen heterocycles between two 1,3-dipoles through a tandem[3+3]cycloaddition/aza-Claisen rearrangement of N-vinyl-α,β-unsaturated nitrones and aza-oxyallyl or oxyallyl cations are disclosed.Products containing two or multiple stereocenters could be obtained in up to 96%yield with high regioselectivity and diastereoselectivity.Selective N-O bond cleavages of ten-membered nitrogen heterocycles lead to various novel 5,6,6-perifused benzofurans,bicyclo[4.4.0]or bicyclo[5.3.0]skeletons containing three or multiple continuous stereocenters in good yields and high diastereoselectivity.Biological tests show that the obtained ten-membered N-heterocycles and bicyclo[4.4.0]skeletons inhibited nitric oxide generation in LPS-stimulated RAW264.7 cells and might serve as good anti-inflammatory agents.展开更多
In the context of peaking carbon dioxide emissions and carbon neutrality,development of feasible methods for converting CO_(2)into high value-added chemicals stands out as a hot subject.In this study,P[D+COO^(−)][Br^(...In the context of peaking carbon dioxide emissions and carbon neutrality,development of feasible methods for converting CO_(2)into high value-added chemicals stands out as a hot subject.In this study,P[D+COO^(−)][Br^(−)][DBUH^(+)],a series of novel heterogeneous dual-ionic poly(ionic liquid)s(PILs)were synthesized readily from 2-(dimethylamino)ethyl methacrylate(DMAEMA),bromo-substituted aliphatic acids,organic bases and divinylbenzene(DVB).The structures,compositions and morphologies were characterized or determined by nuclear magnetic resonance(NMR),thermal gravimetric analysis(TGA),infrared spectroscopy(IR),scanning electron microscopes(SEM),and Brunauer-Emmett-Teller analysis(BET),etc.Application of the P[D+COO^(−)][Br^(−)][DBUH^(+)]series as catalysts in converting CO_(2)into cyclic carbonates showed that P[D+COO^(−)][Br^(−)][DBUH^(+)]-2/1/0.6was able to catalyze epiclorohydrin-CO_(2)cycloaddition the most efficiently.This afforded chloropropylene carbonate(CPC)in 98.4%yield with≥99%selectivity in 24 hr under solvent-and additive-free conditions at atmospheric pressure.Reusability experiments showed that recycling of the catalyst 6 times only resulted in a slight decline in the catalytic performance.In addition,it could be used for the synthesis of a variety of differently substituted cyclic carbonates in good to excellent yields.Finally,key catalytic active sites were probed,and a reasonable mechanism was proposed accordingly.In summary,this work poses an efficient strategy for heterogenization of dual-ionic PILs and provides amild and environmentally benign approach to the fixation and utilization of carbon dioxide.展开更多
Bridged bicyclic cores have been recognized as valuable bioisosteres of benzene ring,which are of great value in medicinal chemistry.However,the development of fluorinated bicyclic skeletons,which encompass two privil...Bridged bicyclic cores have been recognized as valuable bioisosteres of benzene ring,which are of great value in medicinal chemistry.However,the development of fluorinated bicyclic skeletons,which encompass two privileged elements widely acknowledged for fine tuning the working effect of target molecules,are far less common.Herein,we present a general and practical synthesis of gem-difluorobicyclo[2.1.1]hexanes(diF-BCHs)from readily available difluorinated hexa-1,5-dienes through energy transfer photocatalysis.By taking advantage of an efficient Cope rearrangement,the preparation of both constitutional isomers of diF-BCHs is readily achieved under identical conditions.The operational simplicity,mild conditions and wide scope further highlight the potential application of this protocol.Moreover,computational studies indicated a positive effect of fluorine atoms in lowering either the triplet or FMO energies of the hexa-1,5-diene substrates,thus promoting the present photoinduced[2+2]cycloaddition.展开更多
The aim of ＂green chemistry＂ and ＂atom economy＂ is to utilize carbon dioxide and replace harmful reactants such as CO and phosgene for the production of cyclic carbonates. In this paper, metal-free catalysts inclu...The aim of ＂green chemistry＂ and ＂atom economy＂ is to utilize carbon dioxide and replace harmful reactants such as CO and phosgene for the production of cyclic carbonates. In this paper, metal-free catalysts including organic bases, ionic liquids, supported catalysts, organic copolymers and carbon materials for the synthesis of cyclic carbonates by the cycloaddition of carbon dioxide to epoxides are reviewed. Recent advances in the design of the catalysts and the understanding of the reaction mechanism are summarized and discussed. The synergistic effects of organic bases and hydrogen bond donors, organic bases and nucleophilic anions, hydrogen bond donors and nucleophilic anions and active components and supports are highlighted. The challenge is to develop metal-free catalysts suitable for carbon dioxide capture and fixation. The ultimate goal is to synthesize cyclic carbonates in a flow reactor directly using carbon dioxide from industrial flue gas at ambient temperature and atmospheric pressure. By using synergetic effects, a multi-functional approach can meet the design strategy of metal-free catalysts for carbon dioxide adsorption and activation as well as epoxide ring opening.展开更多
Copper catalyzed asymmetric formal [3＋2] cycloaddition of propargylic esters toβ‐keto phospho‐nates for the synthesis of chiral phosphonylated 2,3‐dihydrofurans was developed. By using a bulky and structurally ri...Copper catalyzed asymmetric formal [3＋2] cycloaddition of propargylic esters toβ‐keto phospho‐nates for the synthesis of chiral phosphonylated 2,3‐dihydrofurans was developed. By using a bulky and structurally rigid tridentate ketimine P,N,N ligand, a series of optically active phosphonylated 2,3‐dihydrofurans were prepared in high yield and up to 92%ee.展开更多
A modified silicon-containing arylacetylene resin with a well-defined organic-inorganic POSS functionality was successfully synthesized by Huisgen azide-alkyne 1,3-dipolar cycloaddition. The POSS hybridized resin exhi...A modified silicon-containing arylacetylene resin with a well-defined organic-inorganic POSS functionality was successfully synthesized by Huisgen azide-alkyne 1,3-dipolar cycloaddition. The POSS hybridized resin exhibits excellent thermal properties which were characterized by differential scanning calorimetry （DSC） and thermogravimetric analyses （TGA）. Scanning electron microscope （SEM） was used to characterize fracture surface of the hybridized polymer. The results show that phase separation occurs. The POSS moieties are aggregated each other in the polymer to form 200-400 nm domains.展开更多
Catalytic properties of the metal-organic framework Cr-MIL-101 in solvent-free cycloaddition of CO2 to epoxides to produce cyclic carbon- ates using tetrabutylammonium bromide as co-catalyst have been explored under m...Catalytic properties of the metal-organic framework Cr-MIL-101 in solvent-free cycloaddition of CO2 to epoxides to produce cyclic carbon- ates using tetrabutylammonium bromide as co-catalyst have been explored under mild reaction conditions （8 bar CO2, 25 ~C）. Styrene and propylene carbonates were formed with high yields （95% and 82%, respectively）. Catalytic performance of Cr-MIL-101 was compared with other MOFs： Fe-MIL-101, Zn-MOF-5 and HKUST-1, The catalytic properties of different quaternary ammonium bromides, Cr-MIL-101 as well as PW12/Cr-MIL-101 composite material have been assessed in oxidative carboxylation of styrene in the presence of both tert-butyl hydroperoxide and H202 as oxidants at 8-100bar CO2 and 25-80 ~C with selectivity to styrene carbonate up to 44% at 57% substrate conversion.展开更多
The cycloaddition of CO2 with epoxides catalyzed by ionic liquids(ILs)has been a widely ongoing studied hot topic over the years.Recent experimental research has shown that the protic ionic liquids(PILs)behave stronge...The cycloaddition of CO2 with epoxides catalyzed by ionic liquids(ILs)has been a widely ongoing studied hot topic over the years.Recent experimental research has shown that the protic ionic liquids(PILs)behave stronger hydrogen proton donating ability than aprotic ionic liquids(APILs),and can effectively catalyze the cycloaddition of CO2.Unfortunately,the mechanistic explanation remains primarily unraveled.Herein,a detailed simulation study on the cycloaddition reaction catalyzed by PIL([HDBU][Mim])in comparison with APIL([MeDBU][Mim])re-action catalysts was conducted,including the three-step route(ring-opening of PO(propylene oxide),insertion of CO2 and ring-closure of propylene carbonate(PC))and two-step route(simultaneously ring-opening of PO and addition of CO2,and then ring-closure of PC).Based on the activation energy barrier of the rate-determining step,PIL preferentially activates PO as the optimal route for the reaction with the energy barrier of 23.2 kcal mol-1,while that of APIL is 31.2 kcal mol-1.The role of[HDBU]+in the reaction was also explored and found that the direct formation of intermolecular hydrogen bond(H-bond)between[HDBU]+and the reactants(PO+CO2)was unfavorable for the reaction,while the cooperation with the anion[Mim]-to assist indirectly was more conducive.To fully consider the reaction microenvironment of ILs,ONIOM calculation was used to study the solvent effect.At last,the above conclusions were further verified by the analysis of intermediates with charge,non-covalent interaction(NCI),and atoms in molecules(AIM)methods.The computational findings show that ILs studied in this work have dual functions of catalyst and solvent,enabling a microscopic understanding of the ILs catalyst for CO2 utilization as well as providing guidance for the rational design of more efficient ILs-based catalysts.展开更多
This review summarizes the very recent advances in asymmetric reactions catalyzed by chiral phosphoric acids（CPAs）, a family of versatile catalysts that catalyze a broad range of reactions to afford diverse chiral m...This review summarizes the very recent advances in asymmetric reactions catalyzed by chiral phosphoric acids（CPAs）, a family of versatile catalysts that catalyze a broad range of reactions to afford diverse chiral molecules. In the past years, different kinds of chiral phosphoric acids have been designed and developed into a privileged class of catalysts in asymmetric synthesis. A number of remarkable achievements have been made by many groups around the world. Due to length limitation, this review only summarizes those works published from January 2016 to November 2017. Meanwhile, catalytic systems which combine metal catalysts and chiral phosphoric acids will not be discussed in this review.展开更多
文摘Mechanism of the cycloadditional formaldehyde has been investigated reaction between singlet with MP2/6-31G^＊ method, dichloro-germylidene and including geometry optimization, vibrational analysis and energies for the involved stationary points on the potential energy surface. From the potential energy profile, we predict that the cyeloaddition reaction between singlet dichloro-germylidene and formaldehyde has two competitive dominant reaction pathways, going with the formation of two side products （INT3 and INT4）, simultaneously. Both of the two competitive reactions consist of two steps, two reactants firstly form a three-membered ring intermediate INT1 and a twisted four-membered ring intermediate INT2, respectively, both of which are barrier-free exothermic reactions of 41.5 and 72.3 kJ/mol; then INT1 isomerizes to a four-membered ring product P1 via transition state TS1, and INT2 isomerizes to a chlorine-traasfer product P2 via transition state TS2, with the barriers of 2.9 and 0.3 kJ/mol, respectively. Simultaneously, P1 and INT2 further react with formaldehyde to form INT3 and INT4, respectively, which are also barrier-free exothermic reaction of 74.9 and 88.1 kJ/mol.
基金financial support from the National Key Research and Development Program of China(2021YFB 3501501)the National Natural Science Foundation of China(No.22225803,22038001,22108007 and 22278011)+1 种基金Beijing Natural Science Foundation(No.Z230023)Beijing Science and Technology Commission(No.Z211100004321001).
文摘The high porosity and tunable chemical functionality of metal-organic frameworks(MOFs)make it a promising catalyst design platform.High-throughput screening of catalytic performance is feasible since the large MOF structure database is available.In this study,we report a machine learning model for high-throughput screening of MOF catalysts for the CO_(2) cycloaddition reaction.The descriptors for model training were judiciously chosen according to the reaction mechanism,which leads to high accuracy up to 97%for the 75%quantile of the training set as the classification criterion.The feature contribution was further evaluated with SHAP and PDP analysis to provide a certain physical understanding.12,415 hypothetical MOF structures and 100 reported MOFs were evaluated under 100℃ and 1 bar within one day using the model,and 239 potentially efficient catalysts were discovered.Among them,MOF-76(Y)achieved the top performance experimentally among reported MOFs,in good agreement with the prediction.
文摘Isothiocyanates(ITCs)are an important class of organic compounds characterized by the functional group R-N=C=S.These functional groups are widely found in multiple natural products and pharmaceutical important drugs.Moreover,due to their high and versatile reactivity,they are widely used as an intermediate in organic synthesis.Keeping in view ITCs importance,this review summarizes their synthesis from nitrogen rich raw materials like amines,isocyanides,azides and some other compounds like oximes.Besides their synthesis,their application in organic compound synthesis as an intermediate will also be covered.Future research will likely focus on optimizing the synthesis of multifunctional isothiocyanates,understanding their complex biological mechanisms,exploring new applications,and highlighting the continued importance of isothiocyanates in modern chemistry and biotechnology.
文摘The first efficiently N-heterocyclic carbene-catalyzed[4+2]cycloaddition of salicylaldehydes and pyrazole-4,5-diones to directly synthesis of spiro-ketal-pyrazolones bearing both oxygens of the ketal unit in the same ring was disclosed.This reaction was qualified with broad substrate scope,achieving moderate to excellent yield(up to 98%).This method has mild reaction conditions and simple operation,providing a new attractive strategy for the practical syntheses of multifunctionalized spiroketals including pyrazolone structures with mild reaction condition and operational simplicity.Furthermore,the gram scale and derivative transformations have also been achieved.
文摘A Silver-catalyzed enantioselective[3+2]cycloaddition of azomethine ylides with activated alkenes by using a P-stereogenic ligand Ganphos is reported.The method provides an efficient strategy for the effective synthesis of spirocyclic scaffolds containing a pyrroline motif.Notable features of this approach include good yields,remarkable enantioselectivity,as well as a broad substrate scope and significant step efficiency.
文摘A visible-light-promoted[1+2]cycloaddition of gem-difluoroalkenes with aryl diazo esters provides an efficient and important route to 1,1-difluorocyclopropanes.The reaction conditions are mild,and the operation is very simple.A number of diazo esters and gem-difluoroalkenes are suitable for this reaction(36 examples),providing the desired products in good yields with excellent diastereoselectivity(>20∶1).
文摘Photocatalytic CO_(2)cycloaddition reaction presents a promising CO_(2)conversion strategy to establish carbon neutrality.Among emerging catalysts,metal‑organic frameworks(MOFs)have been regarded as paradigmshifting photocatalysts for their atomic precision in active site engineering,controllable porosity,and exceptional photochemical stability under ambient conditions.However,inherent limitations persist in conventional MOFs,including restricted solar spectrum utilization,inefficient charge carrier separation,and inadequate epoxide activation ability.Recent breakthroughs address these challenges through multiple strategies:ligand engineering,dopant incorporation,and composite construction.This review systematically maps the evolutionary trajectory of MOF‑based photocatalysts,providing mechanistic insights into structure‑activity relationships and providing insights and directions for the design of high‑performance MOF‑based photocatalysts.
基金Financial support from National Natural Science Foundation of China(Nos.21871282,22377113,22301309)Strategic Priority Research Program of the Chinese Academy of Sciences(No.XDB0590000)+6 种基金National Key Research and Development Program of China(No.2023YFA0914502)Taishan Scholar Program of Shandong Province(No.tsqn202306103,tsqn202306026)Postdoctoral Fellowship Program of CPSF(No.GZC20232509)Distinguished Young Scholars of Shandong Province(Overseas)(No.2022HWYQ-004)Shandong Postdoctoral Science Foundation(No.SDBX2023044)Qingdao Postdoctoral Science Foundation(No.QDBSH20230202048)the Fundamental Research Funds for the Central Universities(Ocean University of China)。
文摘Pyrazolidinones,as significant analogs ofβ-lactam antibiotics,have garnered substantial interest for their enantioselective synthesis.Azomethine imines,recognized as valuable building blocks for the construction of these nitrogen-containing compounds,underscore the continuous pursuit of novel building blocks and reaction methodologies within the chemical community.In this paper,we present a cascade cyclization between alkenyl azomethine imines and furan-2(5H)-one to generate chiral coronal polyheterocyclic compounds with high yields and enantioselectivities,catalyzed by dipeptide-derived phosphonium salts.In-vitro biological activity assays highlight the potential of these chiral compounds in drug discovery.Additionally,density functional theory(DFT)calculations elucidate the pivotal role of phosphonium salts,demonstrating their cooperative activations via hydrogen bonding and ion-pairing interactions.
基金supported by the Fundamental Research Funds for the Central Universities(2023QN1009)Xuzhou Basic Research Project(KC23018)+1 种基金China University of Mining and Technology(CUMT)Open Sharing Fund for Large-scale Instruments and Equipment(DYGX-2024-34)Priority Academic Program Development of Jiangsu Higher Education Institutions.
文摘High-energy-density(HED)fuel(e.g.widely used JP-10 and RJ-4),featuring compact 3D polycyclic structure with high strain,is of critical importance for volume-limited military aircraft,since their high density and combustion heat can provide more propulsion energy.To reduce the reliance on petroleum source,it is highly desirable to develop renewable alternatives for the production of strained polycyclic HED fuel,but which remains a big challenge because of the inaccessibility caused by the high strain,We herein demonstrate a three-step catalytic route towards highly strained C_(17)and C_(18)spirofuel with biomass feedstocks.The process includes catalytic aldol condensation of renewable cyclohexanone/cyclopentanone with benzaldehyde,catalytic spiro Diels-Alder(D-A)reaction of aldol adduct with isoprene,and catalytic hydrodeoxygenation.The key spiro D-A reaction is enabled by the catalysis of heterogeneous Lewis acidic ionic liquid.The chloroaluminate IL,formed by benign urea and AICl3,exhibits good catalytic performance and reusability for this step.An eventual hydrodeoxygenation(HDO)over Pd/C and H-Y produces strained tricyclic spirofuel with density>0.93 g/mL,combustion heat>41 MJ/L and freezing point<-40℃,which are better than the properties of tactical fuel RJ-4.Therefore,it is anticipated that the as-prepared renewable fuels have the potential to replace traditional petroleum-derived HED fuels.
基金financial surpport from the CAMS Innovation Fund for Medical Sciences(CIFMS,No.2021-I2M-1-028)supported by Biomedical High Performance Computing Platform,Chinese Academy of Medical Sciences。
文摘The first synthesis of flavanostilbenes with a 2-cyclohepten-1-one core was carried out by applying an effective strategy in three steps from abundant polymerized flavanol resources.A key regio-and stereoselective Cu-mediated[5+2]cycloaddition/decarboxylation cascade was explored and applied without the use of protecting groups,and water as an environmentally friendly solvent contributed to the cascade.The intramolecular[5+2]cycloaddition mechanism,involving oxidation and dearomatization of the flavanol unit as a diene,was proposed and supported by the synthesis of the intermediate.The regioselectivity of the cyclization was found to be dependent on the substitution effects of the stilbene units by the exploration of substrate scope.
基金the National Natural Science Foundation of China(No.22071035)the Natural Science Foundation of Guangxi(Nos.2023GXNSFDA026025,2022GXNSFBA035494)+2 种基金Guangxi Minzu University Scientific Research Funds for Talent Introduction(2022KJQD14)the Student Innovation Training Program(No.202310602014)are greatly appreciated.
文摘The development of general and practical strategies toward the construction of medium-sized rings is still challenging in organic synthesis,especially for the multiple stereocenters control of substituted groups on the ring owing to the long distance between groups.Thus,stereoselective synthesis of multi-substituted ten-membered rings is attractive.Herein,a rapid assembly of various highly substituted ten-membered nitrogen heterocycles between two 1,3-dipoles through a tandem[3+3]cycloaddition/aza-Claisen rearrangement of N-vinyl-α,β-unsaturated nitrones and aza-oxyallyl or oxyallyl cations are disclosed.Products containing two or multiple stereocenters could be obtained in up to 96%yield with high regioselectivity and diastereoselectivity.Selective N-O bond cleavages of ten-membered nitrogen heterocycles lead to various novel 5,6,6-perifused benzofurans,bicyclo[4.4.0]or bicyclo[5.3.0]skeletons containing three or multiple continuous stereocenters in good yields and high diastereoselectivity.Biological tests show that the obtained ten-membered N-heterocycles and bicyclo[4.4.0]skeletons inhibited nitric oxide generation in LPS-stimulated RAW264.7 cells and might serve as good anti-inflammatory agents.
基金supported by the Applied Basic Research Foundation of Guangdong Province(No.2019A1515110551)the Science Foundation for Distinguished Scholars of Dongguan University of Technology(No.196100041051).
文摘In the context of peaking carbon dioxide emissions and carbon neutrality,development of feasible methods for converting CO_(2)into high value-added chemicals stands out as a hot subject.In this study,P[D+COO^(−)][Br^(−)][DBUH^(+)],a series of novel heterogeneous dual-ionic poly(ionic liquid)s(PILs)were synthesized readily from 2-(dimethylamino)ethyl methacrylate(DMAEMA),bromo-substituted aliphatic acids,organic bases and divinylbenzene(DVB).The structures,compositions and morphologies were characterized or determined by nuclear magnetic resonance(NMR),thermal gravimetric analysis(TGA),infrared spectroscopy(IR),scanning electron microscopes(SEM),and Brunauer-Emmett-Teller analysis(BET),etc.Application of the P[D+COO^(−)][Br^(−)][DBUH^(+)]series as catalysts in converting CO_(2)into cyclic carbonates showed that P[D+COO^(−)][Br^(−)][DBUH^(+)]-2/1/0.6was able to catalyze epiclorohydrin-CO_(2)cycloaddition the most efficiently.This afforded chloropropylene carbonate(CPC)in 98.4%yield with≥99%selectivity in 24 hr under solvent-and additive-free conditions at atmospheric pressure.Reusability experiments showed that recycling of the catalyst 6 times only resulted in a slight decline in the catalytic performance.In addition,it could be used for the synthesis of a variety of differently substituted cyclic carbonates in good to excellent yields.Finally,key catalytic active sites were probed,and a reasonable mechanism was proposed accordingly.In summary,this work poses an efficient strategy for heterogenization of dual-ionic PILs and provides amild and environmentally benign approach to the fixation and utilization of carbon dioxide.
基金the National Natural Science Foundation of China(No.22271151)the Distinguished Youth Foundation of Jiangsu Province.
文摘Bridged bicyclic cores have been recognized as valuable bioisosteres of benzene ring,which are of great value in medicinal chemistry.However,the development of fluorinated bicyclic skeletons,which encompass two privileged elements widely acknowledged for fine tuning the working effect of target molecules,are far less common.Herein,we present a general and practical synthesis of gem-difluorobicyclo[2.1.1]hexanes(diF-BCHs)from readily available difluorinated hexa-1,5-dienes through energy transfer photocatalysis.By taking advantage of an efficient Cope rearrangement,the preparation of both constitutional isomers of diF-BCHs is readily achieved under identical conditions.The operational simplicity,mild conditions and wide scope further highlight the potential application of this protocol.Moreover,computational studies indicated a positive effect of fluorine atoms in lowering either the triplet or FMO energies of the hexa-1,5-diene substrates,thus promoting the present photoinduced[2+2]cycloaddition.
基金supported by the National Science and Technology Support Project of China(2013BAC11B03)the National Natural Science Foundation of China(21401054,21476065,21273067)the Graduate Student Scientific Research Innovation Fund Project of Hunan Province(CX2015B082)~~
文摘The aim of ＂green chemistry＂ and ＂atom economy＂ is to utilize carbon dioxide and replace harmful reactants such as CO and phosgene for the production of cyclic carbonates. In this paper, metal-free catalysts including organic bases, ionic liquids, supported catalysts, organic copolymers and carbon materials for the synthesis of cyclic carbonates by the cycloaddition of carbon dioxide to epoxides are reviewed. Recent advances in the design of the catalysts and the understanding of the reaction mechanism are summarized and discussed. The synergistic effects of organic bases and hydrogen bond donors, organic bases and nucleophilic anions, hydrogen bond donors and nucleophilic anions and active components and supports are highlighted. The challenge is to develop metal-free catalysts suitable for carbon dioxide capture and fixation. The ultimate goal is to synthesize cyclic carbonates in a flow reactor directly using carbon dioxide from industrial flue gas at ambient temperature and atmospheric pressure. By using synergetic effects, a multi-functional approach can meet the design strategy of metal-free catalysts for carbon dioxide adsorption and activation as well as epoxide ring opening.
基金supported by the National Natural Science Foundation of China (21403022,21572226)the Natural Science Foundation of Liaoning Province of China (2015020194)~~
文摘Copper catalyzed asymmetric formal [3＋2] cycloaddition of propargylic esters toβ‐keto phospho‐nates for the synthesis of chiral phosphonylated 2,3‐dihydrofurans was developed. By using a bulky and structurally rigid tridentate ketimine P,N,N ligand, a series of optically active phosphonylated 2,3‐dihydrofurans were prepared in high yield and up to 92%ee.
文摘A modified silicon-containing arylacetylene resin with a well-defined organic-inorganic POSS functionality was successfully synthesized by Huisgen azide-alkyne 1,3-dipolar cycloaddition. The POSS hybridized resin exhibits excellent thermal properties which were characterized by differential scanning calorimetry （DSC） and thermogravimetric analyses （TGA）. Scanning electron microscope （SEM） was used to characterize fracture surface of the hybridized polymer. The results show that phase separation occurs. The POSS moieties are aggregated each other in the polymer to form 200-400 nm domains.
基金the Russian Foundation for Basic Research(RFBR grant12-03-31537)
文摘Catalytic properties of the metal-organic framework Cr-MIL-101 in solvent-free cycloaddition of CO2 to epoxides to produce cyclic carbon- ates using tetrabutylammonium bromide as co-catalyst have been explored under mild reaction conditions （8 bar CO2, 25 ~C）. Styrene and propylene carbonates were formed with high yields （95% and 82%, respectively）. Catalytic performance of Cr-MIL-101 was compared with other MOFs： Fe-MIL-101, Zn-MOF-5 and HKUST-1, The catalytic properties of different quaternary ammonium bromides, Cr-MIL-101 as well as PW12/Cr-MIL-101 composite material have been assessed in oxidative carboxylation of styrene in the presence of both tert-butyl hydroperoxide and H202 as oxidants at 8-100bar CO2 and 25-80 ~C with selectivity to styrene carbonate up to 44% at 57% substrate conversion.
基金This work was supported by the National Science Fund for Excellent Young Scholars(21922813)and Key Research Program of Frontier Sciences of CAS(QYZDB-SSWSLH022)+2 种基金National Key Projects for Fundamental Research and Development of China(2017YFB0603301)DNL Cooperation Fund,CAS(DNL180202)and Youth Innovation Promotion Association of CAS(2017066).The authors sincerely appreciate Prof.Suojiang Zhang(IPE,CAS)for his careful academic guidance and great support.
文摘The cycloaddition of CO2 with epoxides catalyzed by ionic liquids(ILs)has been a widely ongoing studied hot topic over the years.Recent experimental research has shown that the protic ionic liquids(PILs)behave stronger hydrogen proton donating ability than aprotic ionic liquids(APILs),and can effectively catalyze the cycloaddition of CO2.Unfortunately,the mechanistic explanation remains primarily unraveled.Herein,a detailed simulation study on the cycloaddition reaction catalyzed by PIL([HDBU][Mim])in comparison with APIL([MeDBU][Mim])re-action catalysts was conducted,including the three-step route(ring-opening of PO(propylene oxide),insertion of CO2 and ring-closure of propylene carbonate(PC))and two-step route(simultaneously ring-opening of PO and addition of CO2,and then ring-closure of PC).Based on the activation energy barrier of the rate-determining step,PIL preferentially activates PO as the optimal route for the reaction with the energy barrier of 23.2 kcal mol-1,while that of APIL is 31.2 kcal mol-1.The role of[HDBU]+in the reaction was also explored and found that the direct formation of intermolecular hydrogen bond(H-bond)between[HDBU]+and the reactants(PO+CO2)was unfavorable for the reaction,while the cooperation with the anion[Mim]-to assist indirectly was more conducive.To fully consider the reaction microenvironment of ILs,ONIOM calculation was used to study the solvent effect.At last,the above conclusions were further verified by the analysis of intermediates with charge,non-covalent interaction(NCI),and atoms in molecules(AIM)methods.The computational findings show that ILs studied in this work have dual functions of catalyst and solvent,enabling a microscopic understanding of the ILs catalyst for CO2 utilization as well as providing guidance for the rational design of more efficient ILs-based catalysts.
基金Financial support from the National Natural Science Foundation of China (No. 21772046)the Recruitment Program of Global Experts(1000 Talents Plan)+1 种基金the Natural Science Foundation of Fujian Province(No. 2016J01064)Program of Innovative Research Team of Huaqiao University (No. Z14X0047)are gratefully acknowledged
文摘This review summarizes the very recent advances in asymmetric reactions catalyzed by chiral phosphoric acids（CPAs）, a family of versatile catalysts that catalyze a broad range of reactions to afford diverse chiral molecules. In the past years, different kinds of chiral phosphoric acids have been designed and developed into a privileged class of catalysts in asymmetric synthesis. A number of remarkable achievements have been made by many groups around the world. Due to length limitation, this review only summarizes those works published from January 2016 to November 2017. Meanwhile, catalytic systems which combine metal catalysts and chiral phosphoric acids will not be discussed in this review.
