Polyhydroxyalkanoate(PHA),a well-known biodegradable polymer,featuresβ-lactones as its monomers,which can be selectively synthesized through ring-expansion carbonylation of epoxides using well-defined[Lewis acid]^(+)...Polyhydroxyalkanoate(PHA),a well-known biodegradable polymer,featuresβ-lactones as its monomers,which can be selectively synthesized through ring-expansion carbonylation of epoxides using well-defined[Lewis acid]^(+)[Co(CO)_(4)]^(-)catalysts.However,the decomposition of[Co(CO)_(4)]^(-)species at temperatures exceeding 80℃presents a hurdle for the development of commercially viable processes under high-temperature reaction conditions to reduce reaction time.Drawing insights from stable{(acyl)Co(CO)n}intermediates involved in historical HCo(CO)_(4)-catalyzed hydroformylation processes,we sought to the high-temperature catalytic activity of epoxide ring-expansion carbonylation.The developed catalyst system,[(acetyl)Co(CO)_(2)dppp]and[(TPP)CrCl],exhibited exceptional catalytic performance with an unprecedented initial turnover frequency of 4700 h^(-1)at 100℃and a turnover numbers of 93000.Notably,the catalyst displayed outstanding stability,operating at 80℃for 168 h while selectively generatingβ-lactones.展开更多
Objective:Soluble epoxide hydrolase(sEH)emerges as a target of interest for inflammatory diseases.Piperine is a natural amide alkaloid from Piper nigrum and displays an inhibitory effect toward sEH,its chemical struct...Objective:Soluble epoxide hydrolase(sEH)emerges as a target of interest for inflammatory diseases.Piperine is a natural amide alkaloid from Piper nigrum and displays an inhibitory effect toward sEH,its chemical structural transformation was carried out in order to obtain a library of sEH inhibitors based on its skeleton.Methods:Structural transformation of piperine was carried out by chemical methods,and piperine derivatives were assayed for their sEH potentials.A mouse acute lung injury model was constructed by lipopolysaccharide(LPS).Hematoxylin and eosin(H&E)staining,immunofluorescence staining,Western Blot,and enzyme-linked immunosorbent assay were used for investigating the protective potential of sEH inhibitor 11h.Results:Piperine derivatives 11e,11h,11j,and 11o showed inhibitory potentials toward sEH with values of half maximal inhibitory concentration(IC50)from 20 to 70 nM.Compound 11h attenuated the pathological course of LPS-mediated acute lung injury(ALI)in vivo.Furthermore,levels of cytokines tumor necrosis factor alpha(TNF-α),interleukin 6(IL-6),myeloperoxidase(MPO),and lactate dehydrogenase(LDH)were decreased after administration of 11h.The LPS-mediated inflammation and redox unbalance,including expressions of cyclooxygenase-2(COX-2),heme oxygenase-1(HO-1),intercellular cell adhesion molecule-1(ICAM-1),vascular cell adhesion molecule-1(VCAM-1),p-p65/p65,glutamate-cysteine ligase modifier subunit(GCLM),and nuclear factor erythroid-2-related factor 2(Nrf2),were ameliorated through nuclear factor kappa B(NF-κB)and Nrf2 pathways via enhancing levels of epoxyeicosatrienoic acids(EETs)in LPS-exposed ALI mice after compound 11h treatment.Molecular docking demonstrated that the aromatic unsaturated group of 11h occupied a hydrophobic pocket and its urea group formed three hydrogen bonds with Asp333,Tyr381,and Tyr465,which stabilized the active conformation of the ligand.Conclusions:These findings demonstrated that compound 11h may serve as a lead compound for developing sEH inhibitors and treating inflammation related to diseases,such as ALI.展开更多
The ring-opening alternating copolymerization(ROAC)of 3,4-dihydrocoumarin(DHC)/epoxides has been successfully developed using an imidazolium salt of 1-ethyl-3-methylimidazolium chloride(EMIMCl)as a catalyst.The result...The ring-opening alternating copolymerization(ROAC)of 3,4-dihydrocoumarin(DHC)/epoxides has been successfully developed using an imidazolium salt of 1-ethyl-3-methylimidazolium chloride(EMIMCl)as a catalyst.The resulting copolymer has a molecular weight of 13.7kg·mol^(-1),a narrow molecular weight distribution of 1.03 and a strictly alternating structure.The MALDI-TOF MS characterization and DFT calculations including electrostatic potential(ESP),hydrogen-atom abstraction(HAA),independent gradient model based on hirshfeld partition(IGMH)and atoms-in-molecules(AIM)analysis were used to investigate the metal-free catalytic process.The synergistic effect of anions and cations of EMIMCl for ROAC of DHC and epoxides was demonstrated.This study provides a metal-free catalytic system for the facile synthesis of alternating polyesters from DHC.展开更多
Herein, we report the first visible-light photoredox-catalyzed carboxylation of aryl epoxides with CO_(2)to synthesize hydroxy acid derivatives. A variety of valuable β-, γ-, δ-, ε–hydroxy acid derivatives are ob...Herein, we report the first visible-light photoredox-catalyzed carboxylation of aryl epoxides with CO_(2)to synthesize hydroxy acid derivatives. A variety of valuable β-, γ-, δ-, ε–hydroxy acid derivatives are obtained in moderate to high yields under mild conditions. This protocol shows noteworthy functionalgroup compatibility, high chemo-and regioselectivities under transition-metal-free conditions with an inexpensive organo-dye as photosensitizer. Mechanistic studies indicate that the benzylic carbanion is generated as an intermediate via the sequential single electron transfer(SSET) process.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
Three new cyclohexene epoxides,polysyphoside A,B and C,along with a known compound crotepoxide(4),were isolated from Piper polysyphorum C.DC.Based on spectroscopic analysis,their structures were established as 1-benzo...Three new cyclohexene epoxides,polysyphoside A,B and C,along with a known compound crotepoxide(4),were isolated from Piper polysyphorum C.DC.Based on spectroscopic analysis,their structures were established as 1-benzoyloxymethylene-2-hydroxy-3-benzoyloxy-1,6- epoxycyclohex-4-ene(1),1-benzoyloxymethylene-2-hydroxy-5-benzoyloxy-1,6-epoxycyclohex-3-ene (2)and 2-hydroxy-3-benzoyloxymethylene-5-benzoyloxy-1,6-epoxycyclohex-3-ene(3),respectively.It was the first time that(1),(2)and(3)had been isolated from a natural source.展开更多
Polyesters,as a class of high-performance and versatile polymer materials,often suffer from some drawbacks,such as hydrophobicity and brittleness due to their single structure nature.Thus,modifications have attracted ...Polyesters,as a class of high-performance and versatile polymer materials,often suffer from some drawbacks,such as hydrophobicity and brittleness due to their single structure nature.Thus,modifications have attracted much attention for enhancing their desirable properties,of which one efficient way is incorporating the aliphatic polyether segment into the main chain of the polyester.However,this approach is of much challenge because the obtained polyesters are problematic in either low alternating degree or low molecular weight.Herein,we describe an efficient strategy to incorporate polyether fragment into polyester by developing a novel Co-Al based heterodinuclear complex for mediating the copolymerization of propylene oxide(PO)withε-caprolactone(CL).The tracking experiments reveal that PO and CL convert into the polymer chain throughout the polymerization process.Especially,the linear increase in the molecular weight with conversion of CL indicates the controllable nature of the copolymerization.The competition polymerization,offering the monomer reactivity ratios of rCL=0.96 and rPO=1.04,suggests that the tendency of self-propagation or incorporation of monomers is nearly identical.interestingly,the obtained polymers with different ether contents exhibit tunable thermal properties with enhanced decomposition temperature for the polymer with higher ether content.The newly developed heterodinuclear complex for new polymerization provides an idea to synthesize new functional polymeric materials.展开更多
Copolymerization is a commonly employed method for optimizing the properties of polymer materials.Incorporating ether segments into polyesters main chain to obtain polyether-polyester copolymers is an effective strate...Copolymerization is a commonly employed method for optimizing the properties of polymer materials.Incorporating ether segments into polyesters main chain to obtain polyether-polyester copolymers is an effective strategy to realize the integration of multiple properties of polyester and polyether,and to develop more high-performance,multi-purpose polymer materials.Herein,the synthesis of poly(ether-ester)s is accessible by employing the biphenyl-linked heterodinuclear salen Cr-AI complex in the presence of PPNCI for the copolymerization of epoxides and£-caprolactone(CL).Monitoring the copolymerization process reveals that catalyst 1 exhibited good performance for the copolymerization of epoxides and CL,affording copolymers with a gradient sequence structure.The dynamic thermomechanical analysis(DMA)study indicates the obtained poly(ether-ester)s possess enhanced flexibility compared with the block copolymers or blend of PPO and PCL homopolymers with the same ratio.This study provides a theoretical basis for the preparation of high-performance polymer materials.展开更多
An EPDDMAC-GE polymer （hydrophilic molecule） has been synthesized based on epoxypropyl dodecyl dimethyl ammonium chloride （EPDDMAC） and gelatin. A DEEPSAC-GE polymer （hydrophobic molecule） has been synthesized b...An EPDDMAC-GE polymer （hydrophilic molecule） has been synthesized based on epoxypropyl dodecyl dimethyl ammonium chloride （EPDDMAC） and gelatin. A DEEPSAC-GE polymer （hydrophobic molecule） has been synthesized based on diethyl-2,3-epoxypropyl-[3-methyldimethoxyl] silpropyl ammonium chloride （DEEPSAC） and gelatin. Compared with initial gelatin, the gelatin modified with quaternary ammonium salts containing epoxide groups exhibits stronger antibacterial activity.展开更多
A versatile heteropoly acid(H_(3)PMo_(12)O_(40))-catalyzed coupling of diarylmethanols with epoxides was established for the synthesis of polyaryl-substituted aldehydes.Furthermore,the catalytic system was also suitab...A versatile heteropoly acid(H_(3)PMo_(12)O_(40))-catalyzed coupling of diarylmethanols with epoxides was established for the synthesis of polyaryl-substituted aldehydes.Furthermore,the catalytic system was also suitable for the reaction of diarylmethanols and diols/aldehydes.The application of such an earthabundant,readily accessible,and nontoxic catalyst provides a green approach for the construction of polyaryl-substituted aldehydes.展开更多
Various novel double metal cyanide （DMC） catalysts were successfully prepared by modifying the central metal （M） and one of cyanide ion （CN-） in Zna[M（CN）b]c complex. Such modifications have significant impact...Various novel double metal cyanide （DMC） catalysts were successfully prepared by modifying the central metal （M） and one of cyanide ion （CN-） in Zna[M（CN）b]c complex. Such modifications have significant impact on the catalytic efficiency as well as the polymer selectivity for the reaction of PO/CO2. Zn-Ni（Ⅱ） DMC is a potential catalyst for alternating copolymerization of PO/CO2,and DMC catalysts based on Zn3[Co（CN）5X]2 （X = Br^- and N3^-） exhibit moderate efficiency for the production of polycarbonates.This research presents the preliminary exploration of novel DMC complex via chemical modification of its central metal and ligand.展开更多
Silk fabrics is finished with epoxide TDEA or TDEB. By the determination of washing fastness, DSC, IR spectrum and amino acid contents tests, TDEA or TDEB is confirmed to react with silk fibroin. By means of tests of ...Silk fabrics is finished with epoxide TDEA or TDEB. By the determination of washing fastness, DSC, IR spectrum and amino acid contents tests, TDEA or TDEB is confirmed to react with silk fibroin. By means of tests of silk fibroin swelling and solubility in some solvents, crosslinking reactions between TDEA or TDEB and silk fibroin arc further proved, which is obviously responsible to the increase of wet-crease recovery of silk fabrics finished with epoxide TDEA or TDEB.展开更多
A new C 60 derivative hydroxylated fullerene epoxide [C 60 (OH) x (O) y ] was prepared by the reaction of C 60 benzene solution with aqueous NaOH and H 2O 2 in the presence of tetrabutylammoni...A new C 60 derivative hydroxylated fullerene epoxide [C 60 (OH) x (O) y ] was prepared by the reaction of C 60 benzene solution with aqueous NaOH and H 2O 2 in the presence of tetrabutylammonium hydroxide(TBAH) as the catalyzer. The structure of hydroxylated fullerene epoxide was characterized by FT IR, NMR and MS , and it was found that it is easy to hydrolyze to fullerol.展开更多
A highly effective and mild protocol for ring opening of epoxides with NH4SCN in the presence of catalytic amount of a multi- site phase-transfer catalyst, α,α＇,α＂-N-hexakis（triethylammoniummethylene chloride）-...A highly effective and mild protocol for ring opening of epoxides with NH4SCN in the presence of catalytic amount of a multi- site phase-transfer catalyst, α,α＇,α＂-N-hexakis（triethylammoniummethylene chloride）-melamine, is developed. A variety of ^-hydroxy thiocyanates as important intermediates in agricultural and pharmaceutical chemistry were obtained in high yields with excellent regioselectivity and in short reaction times. 2009 Ali Reza Kiasat. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved.展开更多
Metal(Al,Ti,Zr)triflate grafted mesoporous SBA‐15(AlTf/S,TiTf/S,ZrTf/S)samples were synthesizedas inexpensive solid acid materials by a simple one‐pot‐two‐step synthesis methodology.These materials were characteri...Metal(Al,Ti,Zr)triflate grafted mesoporous SBA‐15(AlTf/S,TiTf/S,ZrTf/S)samples were synthesizedas inexpensive solid acid materials by a simple one‐pot‐two‐step synthesis methodology.These materials were characterized by X‐ray diffraction,N2‐sorption,thermogravimetric analysis,Fourier transform infrared spectroscopy(FT‐IR),in‐situ pyridine FT‐IR spectroscopy,and elementalanalysis.ZrTf/S was found to be a highly efficient and reusable solid acid catalyst for ring opening ofepoxides with amines and alcohols and producedβ‐amino alcohols andβ‐alkoxy alcohols respectivelyunder ambient reaction conditions.The ZrTf/S catalyst showed the highest activity,whichwas attributed to its high acidity compared with that of the Ti and Al containing samples.展开更多
Silica sulfuric acid was developed as a stable and efficient heterogeneous catalyst in organic synthesis. This solid acid catalyzed the regioselective ring opening of epoxides by thiocyanate anion to give thiocyanohyd...Silica sulfuric acid was developed as a stable and efficient heterogeneous catalyst in organic synthesis. This solid acid catalyzed the regioselective ring opening of epoxides by thiocyanate anion to give thiocyanohydrins as key intermediates in agricultural and pharmaceutical chemistry in high yields under solvent-free conditions.展开更多
The ring-opening alternating copolymerization processes of epoxides with small-molecule monomers,such as carbon dioxide(CO_(2)),carbonyl sulfide(COS)and cyclic anhydrides,are powerful strategies for preparing polymeri...The ring-opening alternating copolymerization processes of epoxides with small-molecule monomers,such as carbon dioxide(CO_(2)),carbonyl sulfide(COS)and cyclic anhydrides,are powerful strategies for preparing polymeric materials with degradable carbonate/ester/thiocarbonate main-chain backbone units.The catalysts selected for copolymerization processes play crucial roles in determining their reaction rates and productivities,as well as the selectivity,regio-and stereochemistry,compositions,and the molecular weights of their resultant copolymers.These processes often generate undesirable byproducts such as polyether or ether linkages dispersed randomly within the copolymer's chain,and/or more thermodynamically stable cyclic products.In this account,we outline our efforts of over a dozen years on developing highly active well-defined metal catalysts based on inter-and intra-molecular synergistic strategies to selectively produce completely alternating copolymers from epoxides and various small-molecule monomers.Much attention was paid to the enantioselective resolution copolymerization processes of racemic epoxides via regioselective ring-openings,and the asymmetric copolymerization processes of meso-epoxides with CO_(2),COS,or cyclic anhydrides via dissymmetrical ring-openings using multichiral catalytic systems,and affording isotactic copolymers with main-chain chirality.In addition,this account provides a thorough mechanistic understanding of the high reactivities,excellent selectivity,and unprecedented stereochemical controls of these copolymerization systems,mediated by interand intramolecular synergistic catalysis.展开更多
A series of novel cobalt carbonyl ionic liquids based on1,1,3,3‐tetra‐alkyl‐guanidine,such as[1,1‐dimethyl‐3,3‐diethylguanidinium][Co(CO)4](3a),[1,1‐dimethyl‐3,3‐dibutylguanidinium][Co(CO)4](3b),[1,1‐dimethy...A series of novel cobalt carbonyl ionic liquids based on1,1,3,3‐tetra‐alkyl‐guanidine,such as[1,1‐dimethyl‐3,3‐diethylguanidinium][Co(CO)4](3a),[1,1‐dimethyl‐3,3‐dibutylguanidinium][Co(CO)4](3b),[1,1‐dimethyl‐3,3‐tetramethyleneguanidinium][Co(CO)4](3c),and[1,1‐dimethyl‐3,3‐pentamethyleneguanidinium][Co(CO)4](3d),were synthesized in good yields and were also characterized using infrared spectroscopy,ultraviolet‐visible spectroscopy,1H nuclear magnetic resonance(NMR)spectroscopy,13C NMR spectroscopy,high‐resolution mass spectrometry,differential scanning calorimetry,and thermogravimetric analysis.The four compounds exhibited high thermal and chemical stability.In addition,the catalytic performance of these compounds was investigated in the carbonylation of epoxides,with3a exhibiting the best catalytic activity without the aid of a base as the additive.The catalyst could be reused at least six times without significant decreases of the selectivity or conversion rate.Moreover,the catalyst system exhibited good tolerance with terminal epoxides bearing alkyl,alkenyl,aryl,alkoxy,and chloromethyl functional groups.展开更多
Urinary prothrombin fragment 1 （UPTFl） is a potent inhibitor of urinary stone formation. UPTF1 exerts such inhibitory effect by effective 7-carboxylation in which vitamin K epoxide reductase complex subunit 1 （VKO...Urinary prothrombin fragment 1 （UPTFl） is a potent inhibitor of urinary stone formation. UPTF1 exerts such inhibitory effect by effective 7-carboxylation in which vitamin K epoxide reductase complex subunit 1 （VKORC1）, the rate-limiting enzyme, is involved. This study examined the correlation between VKORC1 expression and calcium oxalate urolithiasis. The renal cortex samples were obtained from patients undergoing nephrectomy and then divided into 3 groups： urolithiasis group, control group A [hydronephrosis-without-stone （HWS） group], control group B （normal control group）, The localization and expression of VKORC1 in renal tissues were determined by using immunohistochemistry, immunofluorescence microscopy, Western blotting and SYBR Green I real-time reverse-transcription PCR. The rapid amplification of cDNA ends （RACE） were conducted to obtain the 3＇- and 5＇-untranslated region （UTR） of VKORC1. The results showed that VKORC1 was located in the cytoplasm of renal tubular epithelial cells. The expression of VKORC1 in the uro- lithiasis group was significantly lower than that in the other two control groups （P〈0.05）. Moreover, the 3＇- and 5＇-UTR sequence of the VKORC1 gene was successfully cloned. No insertion or deletion was found in the 3＇- and 5＇-UTR. However, a 171-bp new base sequence was discovered in the up- stream of 5＇-UTR end in the urolithiasis group. It was concluded that the decreased expression of VKORC 1 may contribute to the development of calcium oxalate urolithiasis in the kidney.展开更多
Over the past few years, dimethyl carbonate （DMC） has been proven to be an efficient methylating, methoxylating, and methoxycarbonylating agent in organic syntheses, in which DMC is used to replace the toxic methyl ...Over the past few years, dimethyl carbonate （DMC） has been proven to be an efficient methylating, methoxylating, and methoxycarbonylating agent in organic syntheses, in which DMC is used to replace the toxic methyl halides, dimethyl sulfate or carbon monoxide, and so forth. Furthermore, DMC has been used in the syntheses of polycarbonates and polyurethane to develop the nonphosgene routes Therefore, DMC has become one of the most important compounds in the development of green synthetic chemistry.展开更多
文摘Polyhydroxyalkanoate(PHA),a well-known biodegradable polymer,featuresβ-lactones as its monomers,which can be selectively synthesized through ring-expansion carbonylation of epoxides using well-defined[Lewis acid]^(+)[Co(CO)_(4)]^(-)catalysts.However,the decomposition of[Co(CO)_(4)]^(-)species at temperatures exceeding 80℃presents a hurdle for the development of commercially viable processes under high-temperature reaction conditions to reduce reaction time.Drawing insights from stable{(acyl)Co(CO)n}intermediates involved in historical HCo(CO)_(4)-catalyzed hydroformylation processes,we sought to the high-temperature catalytic activity of epoxide ring-expansion carbonylation.The developed catalyst system,[(acetyl)Co(CO)_(2)dppp]and[(TPP)CrCl],exhibited exceptional catalytic performance with an unprecedented initial turnover frequency of 4700 h^(-1)at 100℃and a turnover numbers of 93000.Notably,the catalyst displayed outstanding stability,operating at 80℃for 168 h while selectively generatingβ-lactones.
基金supported by the National Natural Science Foundation of China(82274069 and 82003580)Shenzhen science and technology research and development funds(JCYJ20190808171803553 and 2022071718149001)+4 种基金Young Scientific and Technological Talents(Level Two)in Tianjin(QN20230212)Tianjin Education Commission Research Program Project(2024KJ004)Young Elite Scientists Sponsorship Program by China Association of Chinese Medicine(2022-QNRC2-B09)“1+X”Research Project of the Second Hospital of Dalian Medical University(2024JJ11PT005)Eaglet Plan Project of Tianjin University of Traditional Chinese Medicine(XJS2024101)。
文摘Objective:Soluble epoxide hydrolase(sEH)emerges as a target of interest for inflammatory diseases.Piperine is a natural amide alkaloid from Piper nigrum and displays an inhibitory effect toward sEH,its chemical structural transformation was carried out in order to obtain a library of sEH inhibitors based on its skeleton.Methods:Structural transformation of piperine was carried out by chemical methods,and piperine derivatives were assayed for their sEH potentials.A mouse acute lung injury model was constructed by lipopolysaccharide(LPS).Hematoxylin and eosin(H&E)staining,immunofluorescence staining,Western Blot,and enzyme-linked immunosorbent assay were used for investigating the protective potential of sEH inhibitor 11h.Results:Piperine derivatives 11e,11h,11j,and 11o showed inhibitory potentials toward sEH with values of half maximal inhibitory concentration(IC50)from 20 to 70 nM.Compound 11h attenuated the pathological course of LPS-mediated acute lung injury(ALI)in vivo.Furthermore,levels of cytokines tumor necrosis factor alpha(TNF-α),interleukin 6(IL-6),myeloperoxidase(MPO),and lactate dehydrogenase(LDH)were decreased after administration of 11h.The LPS-mediated inflammation and redox unbalance,including expressions of cyclooxygenase-2(COX-2),heme oxygenase-1(HO-1),intercellular cell adhesion molecule-1(ICAM-1),vascular cell adhesion molecule-1(VCAM-1),p-p65/p65,glutamate-cysteine ligase modifier subunit(GCLM),and nuclear factor erythroid-2-related factor 2(Nrf2),were ameliorated through nuclear factor kappa B(NF-κB)and Nrf2 pathways via enhancing levels of epoxyeicosatrienoic acids(EETs)in LPS-exposed ALI mice after compound 11h treatment.Molecular docking demonstrated that the aromatic unsaturated group of 11h occupied a hydrophobic pocket and its urea group formed three hydrogen bonds with Asp333,Tyr381,and Tyr465,which stabilized the active conformation of the ligand.Conclusions:These findings demonstrated that compound 11h may serve as a lead compound for developing sEH inhibitors and treating inflammation related to diseases,such as ALI.
基金financially supported by the National Natural Science Foundation of China(No.22161040)Natural Science Foundation of Gansu(No.24JRRA125)Science Research Project of Northwest Normal University(No.NWNU-LKZD2021-3)。
文摘The ring-opening alternating copolymerization(ROAC)of 3,4-dihydrocoumarin(DHC)/epoxides has been successfully developed using an imidazolium salt of 1-ethyl-3-methylimidazolium chloride(EMIMCl)as a catalyst.The resulting copolymer has a molecular weight of 13.7kg·mol^(-1),a narrow molecular weight distribution of 1.03 and a strictly alternating structure.The MALDI-TOF MS characterization and DFT calculations including electrostatic potential(ESP),hydrogen-atom abstraction(HAA),independent gradient model based on hirshfeld partition(IGMH)and atoms-in-molecules(AIM)analysis were used to investigate the metal-free catalytic process.The synergistic effect of anions and cations of EMIMCl for ROAC of DHC and epoxides was demonstrated.This study provides a metal-free catalytic system for the facile synthesis of alternating polyesters from DHC.
基金the National Natural Science Foundation of China (Nos. 22225106, 22301193)Fundamental Research Funds from Sichuan University (No. 2020SCUNL102)the Fundamental Research Funds for the Central Universities。
文摘Herein, we report the first visible-light photoredox-catalyzed carboxylation of aryl epoxides with CO_(2)to synthesize hydroxy acid derivatives. A variety of valuable β-, γ-, δ-, ε–hydroxy acid derivatives are obtained in moderate to high yields under mild conditions. This protocol shows noteworthy functionalgroup compatibility, high chemo-and regioselectivities under transition-metal-free conditions with an inexpensive organo-dye as photosensitizer. Mechanistic studies indicate that the benzylic carbanion is generated as an intermediate via the sequential single electron transfer(SSET) process.
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.
文摘Three new cyclohexene epoxides,polysyphoside A,B and C,along with a known compound crotepoxide(4),were isolated from Piper polysyphorum C.DC.Based on spectroscopic analysis,their structures were established as 1-benzoyloxymethylene-2-hydroxy-3-benzoyloxy-1,6- epoxycyclohex-4-ene(1),1-benzoyloxymethylene-2-hydroxy-5-benzoyloxy-1,6-epoxycyclohex-3-ene (2)and 2-hydroxy-3-benzoyloxymethylene-5-benzoyloxy-1,6-epoxycyclohex-3-ene(3),respectively.It was the first time that(1),(2)and(3)had been isolated from a natural source.
基金the National Natural Science Foundation of China(Nos.21722402 and 21674015)the Fundamental Research Funds for the Central Universities(No.DUT18ZD105).
文摘Polyesters,as a class of high-performance and versatile polymer materials,often suffer from some drawbacks,such as hydrophobicity and brittleness due to their single structure nature.Thus,modifications have attracted much attention for enhancing their desirable properties,of which one efficient way is incorporating the aliphatic polyether segment into the main chain of the polyester.However,this approach is of much challenge because the obtained polyesters are problematic in either low alternating degree or low molecular weight.Herein,we describe an efficient strategy to incorporate polyether fragment into polyester by developing a novel Co-Al based heterodinuclear complex for mediating the copolymerization of propylene oxide(PO)withε-caprolactone(CL).The tracking experiments reveal that PO and CL convert into the polymer chain throughout the polymerization process.Especially,the linear increase in the molecular weight with conversion of CL indicates the controllable nature of the copolymerization.The competition polymerization,offering the monomer reactivity ratios of rCL=0.96 and rPO=1.04,suggests that the tendency of self-propagation or incorporation of monomers is nearly identical.interestingly,the obtained polymers with different ether contents exhibit tunable thermal properties with enhanced decomposition temperature for the polymer with higher ether content.The newly developed heterodinuclear complex for new polymerization provides an idea to synthesize new functional polymeric materials.
基金the National Natural Science Foundation of China(Nos.21722402 and 21674015).
文摘Copolymerization is a commonly employed method for optimizing the properties of polymer materials.Incorporating ether segments into polyesters main chain to obtain polyether-polyester copolymers is an effective strategy to realize the integration of multiple properties of polyester and polyether,and to develop more high-performance,multi-purpose polymer materials.Herein,the synthesis of poly(ether-ester)s is accessible by employing the biphenyl-linked heterodinuclear salen Cr-AI complex in the presence of PPNCI for the copolymerization of epoxides and£-caprolactone(CL).Monitoring the copolymerization process reveals that catalyst 1 exhibited good performance for the copolymerization of epoxides and CL,affording copolymers with a gradient sequence structure.The dynamic thermomechanical analysis(DMA)study indicates the obtained poly(ether-ester)s possess enhanced flexibility compared with the block copolymers or blend of PPO and PCL homopolymers with the same ratio.This study provides a theoretical basis for the preparation of high-performance polymer materials.
基金supported by Shandong Provincial Natural Science Foundation (Nos. Y2008B35 and ZR2010BQ002)the Star Youth Science and Technology Plans Project of Ji’nan City (No. 20110103)
文摘An EPDDMAC-GE polymer （hydrophilic molecule） has been synthesized based on epoxypropyl dodecyl dimethyl ammonium chloride （EPDDMAC） and gelatin. A DEEPSAC-GE polymer （hydrophobic molecule） has been synthesized based on diethyl-2,3-epoxypropyl-[3-methyldimethoxyl] silpropyl ammonium chloride （DEEPSAC） and gelatin. Compared with initial gelatin, the gelatin modified with quaternary ammonium salts containing epoxide groups exhibits stronger antibacterial activity.
基金the financial support from the National Natural Science Foundation of China(Nos.21871026,21971224)Research Found of East China University of Technology(Nos.DHBK2019265,DHBK2019267,DHBK2019264)。
文摘A versatile heteropoly acid(H_(3)PMo_(12)O_(40))-catalyzed coupling of diarylmethanols with epoxides was established for the synthesis of polyaryl-substituted aldehydes.Furthermore,the catalytic system was also suitable for the reaction of diarylmethanols and diols/aldehydes.The application of such an earthabundant,readily accessible,and nontoxic catalyst provides a green approach for the construction of polyaryl-substituted aldehydes.
基金the National Natural Science Foundation of China(No.50273031)China Postdoctoral Science Foundation(No.20060400339).
文摘Various novel double metal cyanide （DMC） catalysts were successfully prepared by modifying the central metal （M） and one of cyanide ion （CN-） in Zna[M（CN）b]c complex. Such modifications have significant impact on the catalytic efficiency as well as the polymer selectivity for the reaction of PO/CO2. Zn-Ni（Ⅱ） DMC is a potential catalyst for alternating copolymerization of PO/CO2,and DMC catalysts based on Zn3[Co（CN）5X]2 （X = Br^- and N3^-） exhibit moderate efficiency for the production of polycarbonates.This research presents the preliminary exploration of novel DMC complex via chemical modification of its central metal and ligand.
文摘Silk fabrics is finished with epoxide TDEA or TDEB. By the determination of washing fastness, DSC, IR spectrum and amino acid contents tests, TDEA or TDEB is confirmed to react with silk fibroin. By means of tests of silk fibroin swelling and solubility in some solvents, crosslinking reactions between TDEA or TDEB and silk fibroin arc further proved, which is obviously responsible to the increase of wet-crease recovery of silk fabrics finished with epoxide TDEA or TDEB.
文摘A new C 60 derivative hydroxylated fullerene epoxide [C 60 (OH) x (O) y ] was prepared by the reaction of C 60 benzene solution with aqueous NaOH and H 2O 2 in the presence of tetrabutylammonium hydroxide(TBAH) as the catalyzer. The structure of hydroxylated fullerene epoxide was characterized by FT IR, NMR and MS , and it was found that it is easy to hydrolyze to fullerol.
基金the partial support of this work by Shahid Chamran Research Council
文摘A highly effective and mild protocol for ring opening of epoxides with NH4SCN in the presence of catalytic amount of a multi- site phase-transfer catalyst, α,α＇,α＂-N-hexakis（triethylammoniummethylene chloride）-melamine, is developed. A variety of ^-hydroxy thiocyanates as important intermediates in agricultural and pharmaceutical chemistry were obtained in high yields with excellent regioselectivity and in short reaction times. 2009 Ali Reza Kiasat. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved.
基金supported by the CAS President’s International Fellowship Initiative (2016PT028)the National Natural Science Foundation of China (21273225 and 21403219)~~
文摘Metal(Al,Ti,Zr)triflate grafted mesoporous SBA‐15(AlTf/S,TiTf/S,ZrTf/S)samples were synthesizedas inexpensive solid acid materials by a simple one‐pot‐two‐step synthesis methodology.These materials were characterized by X‐ray diffraction,N2‐sorption,thermogravimetric analysis,Fourier transform infrared spectroscopy(FT‐IR),in‐situ pyridine FT‐IR spectroscopy,and elementalanalysis.ZrTf/S was found to be a highly efficient and reusable solid acid catalyst for ring opening ofepoxides with amines and alcohols and producedβ‐amino alcohols andβ‐alkoxy alcohols respectivelyunder ambient reaction conditions.The ZrTf/S catalyst showed the highest activity,whichwas attributed to its high acidity compared with that of the Ti and Al containing samples.
文摘Silica sulfuric acid was developed as a stable and efficient heterogeneous catalyst in organic synthesis. This solid acid catalyzed the regioselective ring opening of epoxides by thiocyanate anion to give thiocyanohydrins as key intermediates in agricultural and pharmaceutical chemistry in high yields under solvent-free conditions.
基金financially supported by the National Natural Science Foundation of China(No.21920102006)。
文摘The ring-opening alternating copolymerization processes of epoxides with small-molecule monomers,such as carbon dioxide(CO_(2)),carbonyl sulfide(COS)and cyclic anhydrides,are powerful strategies for preparing polymeric materials with degradable carbonate/ester/thiocarbonate main-chain backbone units.The catalysts selected for copolymerization processes play crucial roles in determining their reaction rates and productivities,as well as the selectivity,regio-and stereochemistry,compositions,and the molecular weights of their resultant copolymers.These processes often generate undesirable byproducts such as polyether or ether linkages dispersed randomly within the copolymer's chain,and/or more thermodynamically stable cyclic products.In this account,we outline our efforts of over a dozen years on developing highly active well-defined metal catalysts based on inter-and intra-molecular synergistic strategies to selectively produce completely alternating copolymers from epoxides and various small-molecule monomers.Much attention was paid to the enantioselective resolution copolymerization processes of racemic epoxides via regioselective ring-openings,and the asymmetric copolymerization processes of meso-epoxides with CO_(2),COS,or cyclic anhydrides via dissymmetrical ring-openings using multichiral catalytic systems,and affording isotactic copolymers with main-chain chirality.In addition,this account provides a thorough mechanistic understanding of the high reactivities,excellent selectivity,and unprecedented stereochemical controls of these copolymerization systems,mediated by interand intramolecular synergistic catalysis.
基金supported by the National Natural Science Foundation of China(21373248,21673260,21133011)~~
文摘A series of novel cobalt carbonyl ionic liquids based on1,1,3,3‐tetra‐alkyl‐guanidine,such as[1,1‐dimethyl‐3,3‐diethylguanidinium][Co(CO)4](3a),[1,1‐dimethyl‐3,3‐dibutylguanidinium][Co(CO)4](3b),[1,1‐dimethyl‐3,3‐tetramethyleneguanidinium][Co(CO)4](3c),and[1,1‐dimethyl‐3,3‐pentamethyleneguanidinium][Co(CO)4](3d),were synthesized in good yields and were also characterized using infrared spectroscopy,ultraviolet‐visible spectroscopy,1H nuclear magnetic resonance(NMR)spectroscopy,13C NMR spectroscopy,high‐resolution mass spectrometry,differential scanning calorimetry,and thermogravimetric analysis.The four compounds exhibited high thermal and chemical stability.In addition,the catalytic performance of these compounds was investigated in the carbonylation of epoxides,with3a exhibiting the best catalytic activity without the aid of a base as the additive.The catalyst could be reused at least six times without significant decreases of the selectivity or conversion rate.Moreover,the catalyst system exhibited good tolerance with terminal epoxides bearing alkyl,alkenyl,aryl,alkoxy,and chloromethyl functional groups.
基金supported by a grant from the National Natural Science Foundation of China(No.30901482)
文摘Urinary prothrombin fragment 1 （UPTFl） is a potent inhibitor of urinary stone formation. UPTF1 exerts such inhibitory effect by effective 7-carboxylation in which vitamin K epoxide reductase complex subunit 1 （VKORC1）, the rate-limiting enzyme, is involved. This study examined the correlation between VKORC1 expression and calcium oxalate urolithiasis. The renal cortex samples were obtained from patients undergoing nephrectomy and then divided into 3 groups： urolithiasis group, control group A [hydronephrosis-without-stone （HWS） group], control group B （normal control group）, The localization and expression of VKORC1 in renal tissues were determined by using immunohistochemistry, immunofluorescence microscopy, Western blotting and SYBR Green I real-time reverse-transcription PCR. The rapid amplification of cDNA ends （RACE） were conducted to obtain the 3＇- and 5＇-untranslated region （UTR） of VKORC1. The results showed that VKORC1 was located in the cytoplasm of renal tubular epithelial cells. The expression of VKORC1 in the uro- lithiasis group was significantly lower than that in the other two control groups （P〈0.05）. Moreover, the 3＇- and 5＇-UTR sequence of the VKORC1 gene was successfully cloned. No insertion or deletion was found in the 3＇- and 5＇-UTR. However, a 171-bp new base sequence was discovered in the up- stream of 5＇-UTR end in the urolithiasis group. It was concluded that the decreased expression of VKORC 1 may contribute to the development of calcium oxalate urolithiasis in the kidney.
基金Supported by the National Natural Science Foundation of China(No20473043)
文摘Over the past few years, dimethyl carbonate （DMC） has been proven to be an efficient methylating, methoxylating, and methoxycarbonylating agent in organic syntheses, in which DMC is used to replace the toxic methyl halides, dimethyl sulfate or carbon monoxide, and so forth. Furthermore, DMC has been used in the syntheses of polycarbonates and polyurethane to develop the nonphosgene routes Therefore, DMC has become one of the most important compounds in the development of green synthetic chemistry.
