A rhodium(Ⅲ)-catalyzed hydrosilylation/cyclization reaction of cyclohexadienone-tetheredα,β-unsaturated aldehydes(1,6-dienes)with triethylsilane is described,providing a series of cishydrobenzofurans,cis-hydroindol...A rhodium(Ⅲ)-catalyzed hydrosilylation/cyclization reaction of cyclohexadienone-tetheredα,β-unsaturated aldehydes(1,6-dienes)with triethylsilane is described,providing a series of cishydrobenzofurans,cis-hydroindoles,and cishydroindenes bearing silyl enol ether in good to excellent yields and excellent stereoselectivities.Additionally,the versatility of this method was demonstrated through a gram-scale experiment and various downstream transformations,highlighting its utility.展开更多
Difluoromethyl compounds are widely found in natural products,bioactive molecule and pharmaceuticals.A visible-light induced difluoromethylation/cyclization of 2-aryl indoles is described to construct indolo[2,1-a]iso...Difluoromethyl compounds are widely found in natural products,bioactive molecule and pharmaceuticals.A visible-light induced difluoromethylation/cyclization of 2-aryl indoles is described to construct indolo[2,1-a]isoquinolin-6(5H)-one derivatives using the inexpensive and easy-to-handle HCF_(2)SO_(2)Na as an HCF2 sources.Diverse difluoromethylated indolo[2,1-a]isoquinolines were readily obtained in moderate to good yields.Mechanistic studies demonstrate that the reaction may involve a radical process.展开更多
Indole[2,1-α]isoquinolines are an important class of bioactive molecules and show good antibacterial activity.In the present study,an efficient copper(I)-catalyzed acylation/cyclization has been developed for the con...Indole[2,1-α]isoquinolines are an important class of bioactive molecules and show good antibacterial activity.In the present study,an efficient copper(I)-catalyzed acylation/cyclization has been developed for the construction of indolo[2,1-α]isoquinoline derivatives by utilizing 2-aryl-N-acryloyl indole and benzohydrazide as reactants in the presence of CuI as catalyst and tert-butyl hydroperoxide as oxidant.The present protocol exhibits good functional group tolerance,and a series of acylated indole[2,1-α]isoquinolines were synthesized in moderate to good yields.Radical trapping experiments indicated that the reaction may involve a radical process.展开更多
The Meinwald rearrangement has proven to be one of the most useful tools in organic synthesis.However,examples of asymmetric Meinwald rearrangements are quite scarce,and these reactions have so far been limited to the...The Meinwald rearrangement has proven to be one of the most useful tools in organic synthesis.However,examples of asymmetric Meinwald rearrangements are quite scarce,and these reactions have so far been limited to the use of chiral Br?nsted acids as catalysts.Here,we report a copper-catalyzed asymmetric cascade cyclization/Meinwald rearrangement reaction,allowing the practical and atom-economic synthesis of a range of chiral tricyclic pyrroles bearing a chiral oxa-quaternary carbon stereocenter in high yields and enantioselectivities.Thus,this protocol not only represents the first transition-metal-catalyzed enantioselective Meinwald rearrangement,but also constitutes the first example of asymmetric formal monocarbon insertion into C-O bond of ester.Moreover,theoretical calculations provide further evidence for this multiple cascade cyclization and elucidate the origin of enantioselectivity.展开更多
Asperfilasin A(1),featuring a unique 5/5 cyclopenta[c]pyrrol-one bicyclic core,represents a newly discovered skeletal cytochalasan isolated from Aspergillus flavipes.The enantioselective total synthesis was efficientl...Asperfilasin A(1),featuring a unique 5/5 cyclopenta[c]pyrrol-one bicyclic core,represents a newly discovered skeletal cytochalasan isolated from Aspergillus flavipes.The enantioselective total synthesis was efficiently accomplished from the key intermediate(S)-6 with three contiguous stereocenters in 5 steps and the synthetic 1 induced G2/M-phase cell cycle arrest of HT29 cells and apoptosis of HL60 and NB4 cells by activation of caspase-3 and degradation of PARP.(S)-6,bearing three contiguous chiral centers,was efficiently constructed by a novel Nazarov cyclization reaction containing basic nitrogen,which was less developed,primarily due to the incompatibility of basic nitrogen under acidic reaction conditions.This reaction allows a wide range of pentadienone substrates containing basic nitrogen to undergo Nazarov cyclization in a single regioselective and diastereoselective manner and is capable of generating three stereocenters simultaneously.Furthermore,the mechanism of the Nazarov cyclization and the origin of the regio-and diastereoselectivity were elucidated by DFT calculations and deuteration experiments,providing valuable insights into the reaction and serving as a guide for future applications involving substrates containing basic nitrogen.展开更多
The hydrosilylation of unsaturated carbon-carbon bonds is one of the most critical reactions in silicone industrial production.The homogeneous Speier's catalyst,Karstedt's catalyst,and other noble metal-based ...The hydrosilylation of unsaturated carbon-carbon bonds is one of the most critical reactions in silicone industrial production.The homogeneous Speier's catalyst,Karstedt's catalyst,and other noble metal-based catalysts are widely used.However,simplifying the separation of the homogeneous catalyst from reaction products and reducing the high cost of precious metals is still challenging.This review describes the recent development of heterogeneous catalysts for alkene,alkyne,and allene hydrosilylations,which can effectively solve problems in homogeneous hydrosilylation.展开更多
3-Sulfenylindoles are widely found in natural products,bioactive molecules and organic functional materials.BF_(3)·OEt_(2)mediated electrophilic cyclization reaction of 2-alkynylaniline with N-(arylthio)succinimi...3-Sulfenylindoles are widely found in natural products,bioactive molecules and organic functional materials.BF_(3)·OEt_(2)mediated electrophilic cyclization reaction of 2-alkynylaniline with N-(arylthio)succinimide was developed leading to the efficient synthesis of various biologically active 3-sulfenylindoles in moderate to high yields under very mild conditions.This protocol has the advantages of broad scope,functional group diversity,mild conditions and ease of operation.Moreover,gram-scale preparation portends the practical application.展开更多
Carbon dioxide(CO_(2))serves as a sustainable carbon source for building biomass,fossil fuels,and organic chemicals.Converting CO_(2) into value-added chemicals or fuels is an ideal approach to achieve carbon cycling....Carbon dioxide(CO_(2))serves as a sustainable carbon source for building biomass,fossil fuels,and organic chemicals.Converting CO_(2) into value-added chemicals or fuels is an ideal approach to achieve carbon cycling.The reduction and conversion of CO_(2),a pivotal aspect of C1 chemistry,have long been a subject of intense research interest.Previous studies have demonstrated that through transition metal catalysis,hydrogen,boranes,and silanes(E-H,E=H,B or Si)act as effective reducing agents to transform CO_(2) into a range of C1 chemicals,such as formate,formaldehyde,and methanol.Over the past decade,research focus in this field has shifted towards utilizing cost-effective metals as catalysts for selective CO_(2) reduction.A comprehensive review of homogeneous iron-catalyzed CO_(2)reduction using E-H is presented,emphasizing reaction mechanisms and selectivity.展开更多
Early diagnosis and treatment of cancer requires the development of tools that are both sensitive and selective in detecting spermine.In this study,we presented a"supramolecular cyclization-induced emission enhan...Early diagnosis and treatment of cancer requires the development of tools that are both sensitive and selective in detecting spermine.In this study,we presented a"supramolecular cyclization-induced emission enhancement"strategy for the sensitive and selective detection of spermine.A new pillar[5]arene probe(P1)demonstrated excellent solution/solid dual-state emission properties,and the addition of certain spermine(Spm)resulted in fluorescence enhancement due to the synergy of multiple weak interactions that restricted the free motion of P1 in the P1⊃Spm complex.This mechanism was further confirmed by time-resolved spectroscopy,DFT calculations,and IGM analysis.With its low limit of detection and high selectivity,P1 is a promising tool for measuring spermine in artificial urine samples.展开更多
Cyclic polymers are a class of polymers that feature endless topology,and the synthesis of cyclic polymers has attracted the attention of many researchers.Herein,cyclic polymers were efficiently constructed by self-fo...Cyclic polymers are a class of polymers that feature endless topology,and the synthesis of cyclic polymers has attracted the attention of many researchers.Herein,cyclic polymers were efficiently constructed by self-folding cyclization technique at high concentrations.Linear poly((oligo(ethylene glycol)acrylate)-co-(dodecyl acrylate))(P(OEGA-co-DDA))precursors with different ratios of hydrophilic and hydrophobic moieties were synthesized by reversible addition-fragmentation chain transfer(RAFT)polymerization using a bifunctional chain transfer agent with two anthryl end groups.The amphiphilic linear precursors underwent the self-folding process to generate polymeric nanoparticles in water.By irradiating the aqueous solution of the nanoparticles with 365 nm UV light,cyclic polymers were synthesized successfully via coupling of anthryl groups.The effects of the ratios of hydrophilic and hydrophobic moieties in linear P(OEGA-co-DDA)copolymers and polymer concentration on the purity of the obtained cyclic polymers were explored in detail via ^(1)H nuclear magnetic resonance(^(1)H NMR),dynamic light scattering(DLS),UV‒visible(vis)analysis,three-detection size exclusion chromatography(TD-SEC)and transmission electron microscopy(TEM).It was found that by adjusting the content of the hydrophilic segments in linear precursors,single chain polymeric nanoparticles(SCPNs)can be generated at high polymer concentrations.Therefore,cyclic polymers with high purity can be constructed efficiently.This method overcomes the limitation of traditional ring-closure method,which is typically conducted in highly dilute conditions,providing an efficient method for the scalable preparation of cyclic polymers.展开更多
An organophosphoric acid catalyzed[3+3]cyclization of 2-arylidene-indan-1,3-diones with enaminones has been established,which afforded a series of structurally diverse indenoquinolinedione derivatives in moderate to e...An organophosphoric acid catalyzed[3+3]cyclization of 2-arylidene-indan-1,3-diones with enaminones has been established,which afforded a series of structurally diverse indenoquinolinedione derivatives in moderate to excellent yields.This[3+3]cyclization has some advantages such as mild reaction conditions,readily available catalyst and wide substrate range.This work not only provides an efficient method for constructing biologically important 1,4-dihydropyridine motif,but also suggests a possible reaction pathway and activation mode,therefore enriching the research contents of organophosphoric acid catalysis and[3+3]cyclization reactions.展开更多
Zeolites of *BEA framework topology containing isomorphously substituted Lewis acidic metal centers catalyze the liquid-phase intramolecular Prins cyclization of citronellal with outstanding catalytic activity and (di...Zeolites of *BEA framework topology containing isomorphously substituted Lewis acidic metal centers catalyze the liquid-phase intramolecular Prins cyclization of citronellal with outstanding catalytic activity and (dia-)stereoselectivity to the commercially most valuable product, isopulegol (IPL). Effects of the metal-center identity and solvent type were occasionally noted, yet without systematic studies hitherto reported. Here, characteristic dependences of catalytic activities and stereoselectivities on solvent and metal identity were uncovered over four M(IV)-Beta catalysts (M = Sn, Ti, Zr and Hf) in four distinct solvents (i.e., acetonitrile, tert-butanol, cyclohexane and n-hexane). Zr^(-) and Hf-Beta were the most active in acetonitrile and the most selective (> 90% to IPL) in tert-butanol, though their activities were generally lower than Ti- and Sn-Beta in solvents other than acetonitrile. By comparison, Ti-Beta was inferior to other catalysts in terms of both activity and IPL selectivity (as previously shown) in acetonitrile but became the most active in other solvents, with markedly increased IPL selectivity from 60% to 70%?80%. Combining multiple site discrimination and quantification techniques, turnover frequencies were determined for the first time in this reaction;such site-based activities, coupled with comprehensive kinetic interrogations, not only enabled a rigorous comparison of catalytic activities across M-Beta catalysts but also provided deeper insights into the free energy driving forces as solvent and metal identity are varied. The activity and selectivity trends, as well as those for the adsorption and intrinsic activation parameters are caused by solvent co-binding at the active site (acetonitrile and tert-butanol) and less quantifiable crowding effects (cyclohexane) due to the limited pore space and the need to accommodate relatively bulky reactant-derived moieties. This work exemplifies how the interplay of metal identity and solvent determines the reactivities and selectivities in Lewis-acid-catalyzed reactions within confined spaces.展开更多
MnCO_(3)represents a potentially high-capacity and low-cost anode candidate to replace graphite for enhancing energy density of commercial lithium-ion batteries,but it suffers from poor electrical conductivity and ser...MnCO_(3)represents a potentially high-capacity and low-cost anode candidate to replace graphite for enhancing energy density of commercial lithium-ion batteries,but it suffers from poor electrical conductivity and serious volumetric change,largely hindering its practical applications.展开更多
A general method was described to synthesize a highly hydrophobic cyclic peptide,cyclo[LWLWLWLWLQ]where underlines indicate D-configuration of the amino acid,by a two-step solid-phase/solution synthesis strategy.The l...A general method was described to synthesize a highly hydrophobic cyclic peptide,cyclo[LWLWLWLWLQ]where underlines indicate D-configuration of the amino acid,by a two-step solid-phase/solution synthesis strategy.The linear decapeptide was assembled by standard Boc chemistry on solid-phase and subsequently cyclized in solution with high efficiency and reproducibility. In subsequent purification by semi-preparative HPLC,50%(v/v) DMF/H_2O was employed as the solvent to overcome the difficulty of solubilization...展开更多
The hydrosilylation of polyhydrosiloxane and unsaturated allylic polyether terminated with ester group is processed with chloroplatinic acid as catalyst and ethyl acetate as solvent to exclude the mass transfer resist...The hydrosilylation of polyhydrosiloxane and unsaturated allylic polyether terminated with ester group is processed with chloroplatinic acid as catalyst and ethyl acetate as solvent to exclude the mass transfer resistance in the system. The kinetic study is performed by means of Gel Permeation Chromatography. Within the experimental range （mass ratio of the whole reactants to solvent is 1：4, the tool ratio of Si-H bond to carbon-carbon double bond is 1： 1.3, the catalyst concentration from 1.0×10^-4mol·L^-1 （Pt） to 3.1×10^-4mol·L^-1 （Pt）, temperature between 338.15K and 350.35K）, a kinetic model of zero-th order reaction is built up and the evaluated model parameters are found to change linearly with the catalyst concentration.展开更多
A highly efficient and selective[2+2+2]cyclization of diynes and monoalkynes was catalyzed by rhodium under room temperature in water/THF mixed solvent,affording isoindolines and isobenzofurans in good to excellent yi...A highly efficient and selective[2+2+2]cyclization of diynes and monoalkynes was catalyzed by rhodium under room temperature in water/THF mixed solvent,affording isoindolines and isobenzofurans in good to excellent yields.The center atoms (N,O) in the diynes showed a significant effect for the cyclization.展开更多
Cyclopeptidomimetics are class of cyclopeptides with unnatural linkage. They usually displayed unique constrained structure, enhanced proteolytic stability, and other drug-like character; and have been widely used in ...Cyclopeptidomimetics are class of cyclopeptides with unnatural linkage. They usually displayed unique constrained structure, enhanced proteolytic stability, and other drug-like character; and have been widely used in medicinal chemistry. Therefore, development of efficient strategies for the synthesis of cyclopeptidomimetics has received many attentions. On-resin cyclization strategy is one of the effective approaches developed to overcome the competing side reaction such as oligomerization and cyclooligomers occurred in solution cyclization. This approach took advantage of the ＂pseudo-dilution＂ effect to avoid these undesired by-products and greatly simplified the downstream product purification process. This review summarized the recent on-resin peptide cyclization strategies for the synthesis of cvclooeotidomimetics.展开更多
The complexation of y-allyloxymethyl 18-crown-6(AC6) induced inferior mechanical and thermal properties of polyimide(PI) in spite of lowered dielectric constant(k). To solve this puzzle, tetrakis-(di methylsiloxy)-si ...The complexation of y-allyloxymethyl 18-crown-6(AC6) induced inferior mechanical and thermal properties of polyimide(PI) in spite of lowered dielectric constant(k). To solve this puzzle, tetrakis-(di methylsiloxy)-si lane was employed to crosslink the complex of AC6 and PI(AC6-PI) through hydrosilylation reaction. The crosslinked AC6-PI(SiAC-PI) composites possessed excellent mechanical and thermal properties as well as low k. The tensile strength and fracture energy of SiAC-PI were increased by 87% and 716%, and the glass transition temperature and 5% weight loss temperature elevated 14.5 ℃ and 38.8 ℃, respectively, compared with those of AC6-PI. The structure of SiAC-PI was characterized by FTIR spectra, crosslinked density and XRD diffraction patterns.展开更多
We describe in this work an alkyne-hydrosilylation approach to synthesize a series of novel polysiloxane sidechain LCPs attaching end-on or side-on mesogenic side groups. Their properties are characterized by NMR, FTI...We describe in this work an alkyne-hydrosilylation approach to synthesize a series of novel polysiloxane sidechain LCPs attaching end-on or side-on mesogenic side groups. Their properties are characterized by NMR, FTIR, gel permeation chromatography, thermogravimetric analysis, differential scanning calorimetty, polarized optical microscopy and small-angle X-ray scattering. These obtained alkenylsilane linked novel LCPs exhibit higher glass transition temperatures and clearing points, and especially display the tendency of forming smectic phases, in strong contrast with the nematic phases of their comparative conventional alkylsilane linked analogues, which manifests more rigid features of the alkenylsilane linkages and their significant influence on the mesomorphic properties.展开更多
The hydrosilylation of alkenes with triethoxysilane has been achieved at 120 C in the presence of 0.01 mol%of thioetherfunctionalized MCM-41 anchored rhodium complex,affording the corresponding addition products in 68...The hydrosilylation of alkenes with triethoxysilane has been achieved at 120 C in the presence of 0.01 mol%of thioetherfunctionalized MCM-41 anchored rhodium complex,affording the corresponding addition products in 68-91%yields.This supported rhodium complex can be reused several times without noticeable loss of activity.Our system not only solves the basic problems of catalyst separation and recovery,but also avoids the use of phosphine ligands.展开更多
基金financial support from the National Key R&D Program of China(No.2022YFF1202600)the National Natural Science Foundation of China(Nos.22001172,22071155,and22371188)+4 种基金the Science and Technology Commission of Shanghai Municipality(Nos.20XD1403600 and 20400750300)the Shanghai Municipal Education Commission(No.2019-01-07-00-10-E00072)the Innovation Team and Talents Cultivation Program of National Administration of Traditional Chinese Medicine(No.ZYYCXTD-202004)the Shanghai Municipal Health Commission/Shanghai Municipal Administration of Traditional Chinese Medicine[No.ZY(2021-2023)-0501]Organizational Key R&D Program of SHUTCM(No.2023YZZ01)。
文摘A rhodium(Ⅲ)-catalyzed hydrosilylation/cyclization reaction of cyclohexadienone-tetheredα,β-unsaturated aldehydes(1,6-dienes)with triethylsilane is described,providing a series of cishydrobenzofurans,cis-hydroindoles,and cishydroindenes bearing silyl enol ether in good to excellent yields and excellent stereoselectivities.Additionally,the versatility of this method was demonstrated through a gram-scale experiment and various downstream transformations,highlighting its utility.
文摘Difluoromethyl compounds are widely found in natural products,bioactive molecule and pharmaceuticals.A visible-light induced difluoromethylation/cyclization of 2-aryl indoles is described to construct indolo[2,1-a]isoquinolin-6(5H)-one derivatives using the inexpensive and easy-to-handle HCF_(2)SO_(2)Na as an HCF2 sources.Diverse difluoromethylated indolo[2,1-a]isoquinolines were readily obtained in moderate to good yields.Mechanistic studies demonstrate that the reaction may involve a radical process.
文摘Indole[2,1-α]isoquinolines are an important class of bioactive molecules and show good antibacterial activity.In the present study,an efficient copper(I)-catalyzed acylation/cyclization has been developed for the construction of indolo[2,1-α]isoquinoline derivatives by utilizing 2-aryl-N-acryloyl indole and benzohydrazide as reactants in the presence of CuI as catalyst and tert-butyl hydroperoxide as oxidant.The present protocol exhibits good functional group tolerance,and a series of acylated indole[2,1-α]isoquinolines were synthesized in moderate to good yields.Radical trapping experiments indicated that the reaction may involve a radical process.
基金financial support from the National Natural Science Foundation of China(Nos.22125108,22101238,22331004 and 22121001)Yunnan Fundamental Research Project(No.202401CF070024)+2 种基金Natural Science Foundation of Jiangsu Province(No.BK20211059)the Project of Science and Technology of Xuzhou Government(No.KC22080)NFFTBS(No.J1310024)。
文摘The Meinwald rearrangement has proven to be one of the most useful tools in organic synthesis.However,examples of asymmetric Meinwald rearrangements are quite scarce,and these reactions have so far been limited to the use of chiral Br?nsted acids as catalysts.Here,we report a copper-catalyzed asymmetric cascade cyclization/Meinwald rearrangement reaction,allowing the practical and atom-economic synthesis of a range of chiral tricyclic pyrroles bearing a chiral oxa-quaternary carbon stereocenter in high yields and enantioselectivities.Thus,this protocol not only represents the first transition-metal-catalyzed enantioselective Meinwald rearrangement,but also constitutes the first example of asymmetric formal monocarbon insertion into C-O bond of ester.Moreover,theoretical calculations provide further evidence for this multiple cascade cyclization and elucidate the origin of enantioselectivity.
基金supported by the National Natural Science Foundation of China(Nos.81725021,81903461)the National Key R&D Program of China(No.2022YFA1503200)the Natural Science Foundation of Hubei Province(No.ZRMS2023000340)。
文摘Asperfilasin A(1),featuring a unique 5/5 cyclopenta[c]pyrrol-one bicyclic core,represents a newly discovered skeletal cytochalasan isolated from Aspergillus flavipes.The enantioselective total synthesis was efficiently accomplished from the key intermediate(S)-6 with three contiguous stereocenters in 5 steps and the synthetic 1 induced G2/M-phase cell cycle arrest of HT29 cells and apoptosis of HL60 and NB4 cells by activation of caspase-3 and degradation of PARP.(S)-6,bearing three contiguous chiral centers,was efficiently constructed by a novel Nazarov cyclization reaction containing basic nitrogen,which was less developed,primarily due to the incompatibility of basic nitrogen under acidic reaction conditions.This reaction allows a wide range of pentadienone substrates containing basic nitrogen to undergo Nazarov cyclization in a single regioselective and diastereoselective manner and is capable of generating three stereocenters simultaneously.Furthermore,the mechanism of the Nazarov cyclization and the origin of the regio-and diastereoselectivity were elucidated by DFT calculations and deuteration experiments,providing valuable insights into the reaction and serving as a guide for future applications involving substrates containing basic nitrogen.
基金the financial support from the National Natural Science Foundation of China(No.22001227)the Natural Science Foundation of Jiangsu Province(No.BK20200919)+1 种基金the“Jiangsu Specially-Appointed Professor Plan”the Priority Academic Program Development of Jiangsu Higher Education Institutions。
文摘The hydrosilylation of unsaturated carbon-carbon bonds is one of the most critical reactions in silicone industrial production.The homogeneous Speier's catalyst,Karstedt's catalyst,and other noble metal-based catalysts are widely used.However,simplifying the separation of the homogeneous catalyst from reaction products and reducing the high cost of precious metals is still challenging.This review describes the recent development of heterogeneous catalysts for alkene,alkyne,and allene hydrosilylations,which can effectively solve problems in homogeneous hydrosilylation.
文摘3-Sulfenylindoles are widely found in natural products,bioactive molecules and organic functional materials.BF_(3)·OEt_(2)mediated electrophilic cyclization reaction of 2-alkynylaniline with N-(arylthio)succinimide was developed leading to the efficient synthesis of various biologically active 3-sulfenylindoles in moderate to high yields under very mild conditions.This protocol has the advantages of broad scope,functional group diversity,mild conditions and ease of operation.Moreover,gram-scale preparation portends the practical application.
文摘Carbon dioxide(CO_(2))serves as a sustainable carbon source for building biomass,fossil fuels,and organic chemicals.Converting CO_(2) into value-added chemicals or fuels is an ideal approach to achieve carbon cycling.The reduction and conversion of CO_(2),a pivotal aspect of C1 chemistry,have long been a subject of intense research interest.Previous studies have demonstrated that through transition metal catalysis,hydrogen,boranes,and silanes(E-H,E=H,B or Si)act as effective reducing agents to transform CO_(2) into a range of C1 chemicals,such as formate,formaldehyde,and methanol.Over the past decade,research focus in this field has shifted towards utilizing cost-effective metals as catalysts for selective CO_(2) reduction.A comprehensive review of homogeneous iron-catalyzed CO_(2)reduction using E-H is presented,emphasizing reaction mechanisms and selectivity.
基金the National Natural Science Foundation of China(Nos.22071066,22071065)the National Key Research and Development Program of China(No.2016YFA0602900)+1 种基金the Guangdong Natural Science Foundation,China(No.2018B030311008)the Guangzhou Science and Technology Project,China(No.202102020802).
文摘Early diagnosis and treatment of cancer requires the development of tools that are both sensitive and selective in detecting spermine.In this study,we presented a"supramolecular cyclization-induced emission enhancement"strategy for the sensitive and selective detection of spermine.A new pillar[5]arene probe(P1)demonstrated excellent solution/solid dual-state emission properties,and the addition of certain spermine(Spm)resulted in fluorescence enhancement due to the synergy of multiple weak interactions that restricted the free motion of P1 in the P1⊃Spm complex.This mechanism was further confirmed by time-resolved spectroscopy,DFT calculations,and IGM analysis.With its low limit of detection and high selectivity,P1 is a promising tool for measuring spermine in artificial urine samples.
基金The financial support from the National Natural Science Foundation of China(Nos.22201276,22131010,52021002)the Fundamental Research Funds for the Central Universities(No.WK2060000012)is gratefully acknowledged.
文摘Cyclic polymers are a class of polymers that feature endless topology,and the synthesis of cyclic polymers has attracted the attention of many researchers.Herein,cyclic polymers were efficiently constructed by self-folding cyclization technique at high concentrations.Linear poly((oligo(ethylene glycol)acrylate)-co-(dodecyl acrylate))(P(OEGA-co-DDA))precursors with different ratios of hydrophilic and hydrophobic moieties were synthesized by reversible addition-fragmentation chain transfer(RAFT)polymerization using a bifunctional chain transfer agent with two anthryl end groups.The amphiphilic linear precursors underwent the self-folding process to generate polymeric nanoparticles in water.By irradiating the aqueous solution of the nanoparticles with 365 nm UV light,cyclic polymers were synthesized successfully via coupling of anthryl groups.The effects of the ratios of hydrophilic and hydrophobic moieties in linear P(OEGA-co-DDA)copolymers and polymer concentration on the purity of the obtained cyclic polymers were explored in detail via ^(1)H nuclear magnetic resonance(^(1)H NMR),dynamic light scattering(DLS),UV‒visible(vis)analysis,three-detection size exclusion chromatography(TD-SEC)and transmission electron microscopy(TEM).It was found that by adjusting the content of the hydrophilic segments in linear precursors,single chain polymeric nanoparticles(SCPNs)can be generated at high polymer concentrations.Therefore,cyclic polymers with high purity can be constructed efficiently.This method overcomes the limitation of traditional ring-closure method,which is typically conducted in highly dilute conditions,providing an efficient method for the scalable preparation of cyclic polymers.
文摘An organophosphoric acid catalyzed[3+3]cyclization of 2-arylidene-indan-1,3-diones with enaminones has been established,which afforded a series of structurally diverse indenoquinolinedione derivatives in moderate to excellent yields.This[3+3]cyclization has some advantages such as mild reaction conditions,readily available catalyst and wide substrate range.This work not only provides an efficient method for constructing biologically important 1,4-dihydropyridine motif,but also suggests a possible reaction pathway and activation mode,therefore enriching the research contents of organophosphoric acid catalysis and[3+3]cyclization reactions.
文摘Zeolites of *BEA framework topology containing isomorphously substituted Lewis acidic metal centers catalyze the liquid-phase intramolecular Prins cyclization of citronellal with outstanding catalytic activity and (dia-)stereoselectivity to the commercially most valuable product, isopulegol (IPL). Effects of the metal-center identity and solvent type were occasionally noted, yet without systematic studies hitherto reported. Here, characteristic dependences of catalytic activities and stereoselectivities on solvent and metal identity were uncovered over four M(IV)-Beta catalysts (M = Sn, Ti, Zr and Hf) in four distinct solvents (i.e., acetonitrile, tert-butanol, cyclohexane and n-hexane). Zr^(-) and Hf-Beta were the most active in acetonitrile and the most selective (> 90% to IPL) in tert-butanol, though their activities were generally lower than Ti- and Sn-Beta in solvents other than acetonitrile. By comparison, Ti-Beta was inferior to other catalysts in terms of both activity and IPL selectivity (as previously shown) in acetonitrile but became the most active in other solvents, with markedly increased IPL selectivity from 60% to 70%?80%. Combining multiple site discrimination and quantification techniques, turnover frequencies were determined for the first time in this reaction;such site-based activities, coupled with comprehensive kinetic interrogations, not only enabled a rigorous comparison of catalytic activities across M-Beta catalysts but also provided deeper insights into the free energy driving forces as solvent and metal identity are varied. The activity and selectivity trends, as well as those for the adsorption and intrinsic activation parameters are caused by solvent co-binding at the active site (acetonitrile and tert-butanol) and less quantifiable crowding effects (cyclohexane) due to the limited pore space and the need to accommodate relatively bulky reactant-derived moieties. This work exemplifies how the interplay of metal identity and solvent determines the reactivities and selectivities in Lewis-acid-catalyzed reactions within confined spaces.
基金supported by the National Natural Science Foundation of China(Nos.52102088 and 22075026)support from Teli Fellowship,Beijing Institute of Technology,and facility support from Analysis&Testing Center,and Experimental Center of Materials Sciences&Engineering at Beijing Institute of Technology.
文摘MnCO_(3)represents a potentially high-capacity and low-cost anode candidate to replace graphite for enhancing energy density of commercial lithium-ion batteries,but it suffers from poor electrical conductivity and serious volumetric change,largely hindering its practical applications.
基金supported by National Natural Science Foundation(No.30672546)Shanghai Municipal Committee of S & T(No.0652nm013)National Key Basic Research Program of China(No.2007CB935800)
文摘A general method was described to synthesize a highly hydrophobic cyclic peptide,cyclo[LWLWLWLWLQ]where underlines indicate D-configuration of the amino acid,by a two-step solid-phase/solution synthesis strategy.The linear decapeptide was assembled by standard Boc chemistry on solid-phase and subsequently cyclized in solution with high efficiency and reproducibility. In subsequent purification by semi-preparative HPLC,50%(v/v) DMF/H_2O was employed as the solvent to overcome the difficulty of solubilization...
文摘The hydrosilylation of polyhydrosiloxane and unsaturated allylic polyether terminated with ester group is processed with chloroplatinic acid as catalyst and ethyl acetate as solvent to exclude the mass transfer resistance in the system. The kinetic study is performed by means of Gel Permeation Chromatography. Within the experimental range （mass ratio of the whole reactants to solvent is 1：4, the tool ratio of Si-H bond to carbon-carbon double bond is 1： 1.3, the catalyst concentration from 1.0×10^-4mol·L^-1 （Pt） to 3.1×10^-4mol·L^-1 （Pt）, temperature between 338.15K and 350.35K）, a kinetic model of zero-th order reaction is built up and the evaluated model parameters are found to change linearly with the catalyst concentration.
文摘A highly efficient and selective[2+2+2]cyclization of diynes and monoalkynes was catalyzed by rhodium under room temperature in water/THF mixed solvent,affording isoindolines and isobenzofurans in good to excellent yields.The center atoms (N,O) in the diynes showed a significant effect for the cyclization.
基金supported by the National Natural Science Foundation of China (No.21472070)the Project for Jiangsu Scientific and Technological Innovation Team+1 种基金Fund for Jiangsu Distinguished Professorship ProgramProject Funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions,the 111 Project (No.111-2-06)
文摘Cyclopeptidomimetics are class of cyclopeptides with unnatural linkage. They usually displayed unique constrained structure, enhanced proteolytic stability, and other drug-like character; and have been widely used in medicinal chemistry. Therefore, development of efficient strategies for the synthesis of cyclopeptidomimetics has received many attentions. On-resin cyclization strategy is one of the effective approaches developed to overcome the competing side reaction such as oligomerization and cyclooligomers occurred in solution cyclization. This approach took advantage of the ＂pseudo-dilution＂ effect to avoid these undesired by-products and greatly simplified the downstream product purification process. This review summarized the recent on-resin peptide cyclization strategies for the synthesis of cvclooeotidomimetics.
基金supported by the National Natural Science Foundation of China(No. 51573054)the Project for Science and Technology of Guangzhou (No. 201604016080)
文摘The complexation of y-allyloxymethyl 18-crown-6(AC6) induced inferior mechanical and thermal properties of polyimide(PI) in spite of lowered dielectric constant(k). To solve this puzzle, tetrakis-(di methylsiloxy)-si lane was employed to crosslink the complex of AC6 and PI(AC6-PI) through hydrosilylation reaction. The crosslinked AC6-PI(SiAC-PI) composites possessed excellent mechanical and thermal properties as well as low k. The tensile strength and fracture energy of SiAC-PI were increased by 87% and 716%, and the glass transition temperature and 5% weight loss temperature elevated 14.5 ℃ and 38.8 ℃, respectively, compared with those of AC6-PI. The structure of SiAC-PI was characterized by FTIR spectra, crosslinked density and XRD diffraction patterns.
基金financially supported by the National Natural Science Foundation of China(No.21374016)
文摘We describe in this work an alkyne-hydrosilylation approach to synthesize a series of novel polysiloxane sidechain LCPs attaching end-on or side-on mesogenic side groups. Their properties are characterized by NMR, FTIR, gel permeation chromatography, thermogravimetric analysis, differential scanning calorimetty, polarized optical microscopy and small-angle X-ray scattering. These obtained alkenylsilane linked novel LCPs exhibit higher glass transition temperatures and clearing points, and especially display the tendency of forming smectic phases, in strong contrast with the nematic phases of their comparative conventional alkylsilane linked analogues, which manifests more rigid features of the alkenylsilane linkages and their significant influence on the mesomorphic properties.
基金National Natural Science Foundation of China(No.20862008)Natural Science Foundation of Jiangxi Province(No.2008GQH0034) for financial support
文摘The hydrosilylation of alkenes with triethoxysilane has been achieved at 120 C in the presence of 0.01 mol%of thioetherfunctionalized MCM-41 anchored rhodium complex,affording the corresponding addition products in 68-91%yields.This supported rhodium complex can be reused several times without noticeable loss of activity.Our system not only solves the basic problems of catalyst separation and recovery,but also avoids the use of phosphine ligands.
