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
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
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
Mechanistic studies of the cleavage and transformation of unactivated C_(sp3)-H bonds are a significant field of chemistry.Overcoming the inherent low acidity of C-H bonds to activate the inert substrates is challenge...Mechanistic studies of the cleavage and transformation of unactivated C_(sp3)-H bonds are a significant field of chemistry.Overcoming the inherent low acidity of C-H bonds to activate the inert substrates is challenge under mild conditions.And their complex multi-step transformations may also hinder mechanistic understanding.Herein,we perform theoretical calculations and experimental studies to explore the C_(sp3)-H bonds activation and acylation mechanisms of toluene/thioether using the relatively weak base LDA.A synergistic"main and auxiliary"model was revealed involving dual lithium metal by LDA dimers,and the aryl dilithium species as an intermediate base can facilitate C_(sp3)-H activation.This model not only aids in understanding the acidity of unactivated C_(sp3)-H bonds and the nucleophilicity of their conjugate bases for their kinetic control through cooperative interactions,but also predicts unusual kinetic isotope effects(KIE)for newly designed 2-(methylthio)naphthalene that are experimentally validated.This research is expected to provide a crucial scenario for the cleavage and transformation of unactivated C_(sp3)-H bonds and the development of new functionalities for alkali metal reagents.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
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
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
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
Friedel-Crafts reaction and transition-metal catalysis represent primary methodologies for arene acylation;however,suffer from certain limitations,such as electronic effect-dependent reactivity,regioselectivity issues...Friedel-Crafts reaction and transition-metal catalysis represent primary methodologies for arene acylation;however,suffer from certain limitations,such as electronic effect-dependent reactivity,regioselectivity issues,the necessity of directing group,and relatively exceptionally limited exploration in meta-and para-acylations.N-heterocyclic carbene(NHC)catalysis has recently emerged as a promising alternative strategy for arene acylation,offering distinct regioselectivity profiles that are challenging to achieve through known methods.Herein,an NHC-mediated photo-catalytic para-selective C-H acylation of aryl alcohols is disclosed.The reaction employs a remote radical-induced temporary spiro cyclization strategy,proceeding via tandem radical dearomatization,radical acylation,rearomatization processes.Combined experimental and computational mechanistic studies support the proposed reaction pathway and observe an exclusive para-selectivity regardless of the nature of the substituents on the substrates.Despite the less satisfactory yields,the current method exhibits non-electronic nature-based reactivity and regioselectivity,enabling quick access to acylated arenes that are difficult or impossible for reported methods.展开更多
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
Highly toxic phosgene,diethyl chlorophosphate(DCP)and volatile acyl chlorides endanger our life and public security.To achieve facile sensing and discrimination of multiple target analytes,herein,we presented a single...Highly toxic phosgene,diethyl chlorophosphate(DCP)and volatile acyl chlorides endanger our life and public security.To achieve facile sensing and discrimination of multiple target analytes,herein,we presented a single fluorescent probe(BDP-CHD)for high-throughput screening of phosgene,DCP and volatile acyl chlorides.The probe underwent a covalent cascade reaction with phosgene to form boron dipyrromethene(BODIPY)with bright green fluorescence.By contrast,DCP,diphosgene and acyl chlorides can covalently assembled with the probe,giving rise to strong blue fluorescence.The probe has demonstrated high-throughput detection capability,high sensitivity,fast response(within 3 s)and parts per trillion(ppt)level detection limit.Furthermore,a portable platform based on BDP-CHD was constructed,which has achieved high-throughput discrimination of 16 analytes through linear discriminant analysis(LDA).Moreover,a smartphone adaptable RGB recognition pattern was established for the quantitative detection of multi-analytes.Therefore,this portable fluorescence sensing platform can serve as a versatile tool for rapid and high-throughput detection of toxic phosgene,DCP and volatile acyl chlorides.The proposed“one for more”strategy simplifies multi-target discrimination procedures and holds great promise for various sensing applications.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 support made of mussel-inspired polydopamine-coated magnetic iron oxide nanoparticles （PD-MNPs） was prepared and characterized. The widely used Aspetyillus niger lipase （ANL） was immobilized on the PD-MNPs （ANL...A support made of mussel-inspired polydopamine-coated magnetic iron oxide nanoparticles （PD-MNPs） was prepared and characterized. The widely used Aspetyillus niger lipase （ANL） was immobilized on the PD-MNPs （ANL@PD-MNPs） with a protein loading of 138 mg/g and an activity recovery of 83.6% under optimized conditions. For the immobilization, the pH and immobilization time were investigated. The pH and thermal and storage stability of the ANL@PD-MNPs significant- ly surpassed those of free ANL. The ANL@PD-MNPs had better solvent tolerance than free ANL. The secondary structure of free ANL and ANL@PD-MNPs was analyzed by infrared spectroscopy, A kinetic study demonstrated that the ANL@PD-MNPs had enhanced enzyme-substrate affinity and high catalytic efficiency. The ANL@PD-MNPs was applied as a biocatalyst for the regioselective acylation of dihydromyricetin （DMY） in DMSO and gave a conversion of 79.3%, which was higher than that of previous reports. The ANL@PD-MNPs retained over 55% of its initial activity after 10 cycles of reuse. The ANL@PD-MNPs were readily separated from the reaction system by a magnet. The PD-MNPs is an excellent support for ANL and the resulting ANL@PD-MNPs displayed good potential for the efficient synthesis of dihydromyricetin-3-acetate by enzymatic regioselective acylation.展开更多
Silica gel supported aluminium trichloride（SiO2-AlCl3） has been shown to be a mild,efficient,and chemoseiective heterogeneous Lewis acid catalyst for the acylation of aromatic compounds with acid chlorides.The catal...Silica gel supported aluminium trichloride（SiO2-AlCl3） has been shown to be a mild,efficient,and chemoseiective heterogeneous Lewis acid catalyst for the acylation of aromatic compounds with acid chlorides.The catalyst can be reused up to five times after simple washing with ether and is stable（as a bench top catalyst）.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
A series of monosubstituted troxerutin esters have been synthesized by enzyme-catalyzed regioselective acylation of troxerutin in nonaqueous medium.Using divinyl dicarboxylates(CH_2=CH-OOC-(CH_2)_n-COO-CH=CH_2,n = 2,3...A series of monosubstituted troxerutin esters have been synthesized by enzyme-catalyzed regioselective acylation of troxerutin in nonaqueous medium.Using divinyl dicarboxylates(CH_2=CH-OOC-(CH_2)_n-COO-CH=CH_2,n = 2,3,4,7,8,11) featuring different chain length as acyl donors and alkaline protease from Bacillus subtilis as catalyst,troxerutin was regioselective acylated at B ethoxyl group.The results indicated that the regioselectivity of the enzyme-catalyzed acylation was not affected by the chain length o...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
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.
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.
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 National Key Research and Development Program of China(No.2021YFA1500100)the National Natural Science Foundation of China(Nos.92156017 and 21890722)+1 种基金“Frontiers Science Center for New Organic Matter”,Nankai University(No.63181206)Haihe Laboratory of Sustainable Chemical Transformation of Tianjin(No.24HHWCSS00019)for generous financial support。
文摘Mechanistic studies of the cleavage and transformation of unactivated C_(sp3)-H bonds are a significant field of chemistry.Overcoming the inherent low acidity of C-H bonds to activate the inert substrates is challenge under mild conditions.And their complex multi-step transformations may also hinder mechanistic understanding.Herein,we perform theoretical calculations and experimental studies to explore the C_(sp3)-H bonds activation and acylation mechanisms of toluene/thioether using the relatively weak base LDA.A synergistic"main and auxiliary"model was revealed involving dual lithium metal by LDA dimers,and the aryl dilithium species as an intermediate base can facilitate C_(sp3)-H activation.This model not only aids in understanding the acidity of unactivated C_(sp3)-H bonds and the nucleophilicity of their conjugate bases for their kinetic control through cooperative interactions,but also predicts unusual kinetic isotope effects(KIE)for newly designed 2-(methylthio)naphthalene that are experimentally validated.This research is expected to provide a crucial scenario for the cleavage and transformation of unactivated C_(sp3)-H bonds and the development of new functionalities for alkali metal reagents.
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.
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.
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(22371058,21961006,32172459,22371057,22071036)National Key Research and Development Program of China(2022YFD1700300)+9 种基金National Natural Science Fund for Excellent Young Scientists Fund Program(Overseas),starting grant of Guizhou University[(2023)29]Science and Technology Department of Guizhou Province(Qiankehejichu-ZK[2024]Key009,Qiankehejichu-ZK[2021]Key033)Program of Introducing Talents of Discipline to Universities of China(111 Program,D20023)at Guizhou UniversityFrontiers Science Center for Asymmetric Synthesis and Medicinal Molecules,Department of Education,Guizhou Province[Qianjiaohe KY(2020)004]Guizhou University(China),Central Government Guides Local Science and Technology Development Fund Projects[Qiankehezhongyindi(2024)007]Singapore National Research Foundation under its NRF Investigatorship(NRFNRFI2016-06,U23A20201)Competitive Research Program(NRFCRP22-2019-0002),Ministry of Education,Singapore,under its MOE AcRF Tier 1 Award(RG7/20,RG70/21),MOE AcRF Tier 2(MOE2019-T22-117),and MOE AcRF Tier 3 Award(MOE2018-T3-1-003),a Chair Professorship GrantNanyang Technological Universitythe funding support from the Chinese University of Hong Kong(CUHK)under the Vice-Chancellor Early Career Professorship Scheme Research Startup Fund(Project Code 4933634)Research Startup Matching Support(Project Code 5501779)。
文摘Friedel-Crafts reaction and transition-metal catalysis represent primary methodologies for arene acylation;however,suffer from certain limitations,such as electronic effect-dependent reactivity,regioselectivity issues,the necessity of directing group,and relatively exceptionally limited exploration in meta-and para-acylations.N-heterocyclic carbene(NHC)catalysis has recently emerged as a promising alternative strategy for arene acylation,offering distinct regioselectivity profiles that are challenging to achieve through known methods.Herein,an NHC-mediated photo-catalytic para-selective C-H acylation of aryl alcohols is disclosed.The reaction employs a remote radical-induced temporary spiro cyclization strategy,proceeding via tandem radical dearomatization,radical acylation,rearomatization processes.Combined experimental and computational mechanistic studies support the proposed reaction pathway and observe an exclusive para-selectivity regardless of the nature of the substituents on the substrates.Despite the less satisfactory yields,the current method exhibits non-electronic nature-based reactivity and regioselectivity,enabling quick access to acylated arenes that are difficult or impossible for reported methods.
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the financial support of the National Natural Science Foundation of China(No.22168009)。
文摘Highly toxic phosgene,diethyl chlorophosphate(DCP)and volatile acyl chlorides endanger our life and public security.To achieve facile sensing and discrimination of multiple target analytes,herein,we presented a single fluorescent probe(BDP-CHD)for high-throughput screening of phosgene,DCP and volatile acyl chlorides.The probe underwent a covalent cascade reaction with phosgene to form boron dipyrromethene(BODIPY)with bright green fluorescence.By contrast,DCP,diphosgene and acyl chlorides can covalently assembled with the probe,giving rise to strong blue fluorescence.The probe has demonstrated high-throughput detection capability,high sensitivity,fast response(within 3 s)and parts per trillion(ppt)level detection limit.Furthermore,a portable platform based on BDP-CHD was constructed,which has achieved high-throughput discrimination of 16 analytes through linear discriminant analysis(LDA).Moreover,a smartphone adaptable RGB recognition pattern was established for the quantitative detection of multi-analytes.Therefore,this portable fluorescence sensing platform can serve as a versatile tool for rapid and high-throughput detection of toxic phosgene,DCP and volatile acyl chlorides.The proposed“one for more”strategy simplifies multi-target discrimination procedures and holds great promise for various sensing applications.
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 the National Natural Science Foundation of China(21336002,21222606,21376096)the Key Program of Guangdong Natural Science Foundation(S2013020013049)+1 种基金the Fundamental Research Funds for the Chinese Universities(2015PT002,2015ZP009)the Program of State Key Laboratory of Pulp and Paper Engineering(2015C04)~~
文摘A support made of mussel-inspired polydopamine-coated magnetic iron oxide nanoparticles （PD-MNPs） was prepared and characterized. The widely used Aspetyillus niger lipase （ANL） was immobilized on the PD-MNPs （ANL@PD-MNPs） with a protein loading of 138 mg/g and an activity recovery of 83.6% under optimized conditions. For the immobilization, the pH and immobilization time were investigated. The pH and thermal and storage stability of the ANL@PD-MNPs significant- ly surpassed those of free ANL. The ANL@PD-MNPs had better solvent tolerance than free ANL. The secondary structure of free ANL and ANL@PD-MNPs was analyzed by infrared spectroscopy, A kinetic study demonstrated that the ANL@PD-MNPs had enhanced enzyme-substrate affinity and high catalytic efficiency. The ANL@PD-MNPs was applied as a biocatalyst for the regioselective acylation of dihydromyricetin （DMY） in DMSO and gave a conversion of 79.3%, which was higher than that of previous reports. The ANL@PD-MNPs retained over 55% of its initial activity after 10 cycles of reuse. The ANL@PD-MNPs were readily separated from the reaction system by a magnet. The PD-MNPs is an excellent support for ANL and the resulting ANL@PD-MNPs displayed good potential for the efficient synthesis of dihydromyricetin-3-acetate by enzymatic regioselective acylation.
文摘Silica gel supported aluminium trichloride（SiO2-AlCl3） has been shown to be a mild,efficient,and chemoseiective heterogeneous Lewis acid catalyst for the acylation of aromatic compounds with acid chlorides.The catalyst can be reused up to five times after simple washing with ether and is stable（as a bench top catalyst）.
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...
基金the Science and Technology hall of Henan Province(No.072300420070No.82102330014)China,for financially supported to this work.
文摘A series of monosubstituted troxerutin esters have been synthesized by enzyme-catalyzed regioselective acylation of troxerutin in nonaqueous medium.Using divinyl dicarboxylates(CH_2=CH-OOC-(CH_2)_n-COO-CH=CH_2,n = 2,3,4,7,8,11) featuring different chain length as acyl donors and alkaline protease from Bacillus subtilis as catalyst,troxerutin was regioselective acylated at B ethoxyl group.The results indicated that the regioselectivity of the enzyme-catalyzed acylation was not affected by the chain length o...
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.
