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
The degradation mechanism of photocrosslinking products formed by cyclized polyisoprene-diazide system under the influence of the different alkyl benzene sulfonic acids was studied. The effects of alkyl chain length a...The degradation mechanism of photocrosslinking products formed by cyclized polyisoprene-diazide system under the influence of the different alkyl benzene sulfonic acids was studied. The effects of alkyl chain length and the concentration of alkyl benzene sulfonic acids on the rate of degradation reaction were discussed. It was found that in the initial stage of degradation, the cyclicity ratio and the average fused ring number did not change considerably, but the percentage of uncyclized parts content varied significantly. The suitable mechanism was supposed.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
A new gold self-relay catalytic annulation/nucleophilic substitution cascade of 1,3-enyne acetates with cyclic ether acetals is reported,enabling highly diastereoselective access to cyclic etherified cyclopentenones w...A new gold self-relay catalytic annulation/nucleophilic substitution cascade of 1,3-enyne acetates with cyclic ether acetals is reported,enabling highly diastereoselective access to cyclic etherified cyclopentenones with cyclic quaternary centers in moderate to good yields and>19∶1 dr.This catalysis enables the direct construction of two types of carboncyclic skeletons by adjusting the olefin types of 1,3-enyne acetates.When 1,3-enyne acetates bearing a cyclic alkene unit were used,5~6 fused bicarbocyclic products were diastereoselectively synthesized,whereas the reaction of acyclic 1,3-enyne acetates resulted in five-memebered carbocyclic framework.Notably,cyclic ether acetals are commonly used as protecting groups in traditional multistep organic syntheses,and in this reaction,such reagents serve as electrophilic cyclic ether precursors,achieving new uses for old reagents.The current method demonstrates good functional group compatibility,a broad substrate scope and high diastereoselectivity,providing a new synthetic strategy toward functionalized cyclopentenones.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
Houpolignols A-C(1-3),unprecedented oligomers of dearomatized obovatol with tetracyclo[9.3.1.0^(2,7).0^(9,14)]pentadecane(1 and 2)and 8,18-dioxapentacyclo[13.3.1.1^(5,9).0^(4,16).0^(13,20)]icosane(3)core structures,to...Houpolignols A-C(1-3),unprecedented oligomers of dearomatized obovatol with tetracyclo[9.3.1.0^(2,7).0^(9,14)]pentadecane(1 and 2)and 8,18-dioxapentacyclo[13.3.1.1^(5,9).0^(4,16).0^(13,20)]icosane(3)core structures,together with their biosynthetic congener houpolignol D(4),were isolated from the cortex of Magnolia officinalis var.biloba.Their structures were determined by spectroscopic analyses,Xray crystallography data,and quantum chemical calculations.Radical cascade cyclizations were proposed as crucial biosynthetic steps of 1-4.(±)-1 showed anti-nonalcoholic steatohepatitis(NASH)effect by promoting fatty acid beta-oxidation.展开更多
Lignans have been established as a privileged scaffold in drug discovery,particularly in anticancer and antioxidant properties.Concise and efficient construction of lignans and their derivatives in a single operation ...Lignans have been established as a privileged scaffold in drug discovery,particularly in anticancer and antioxidant properties.Concise and efficient construction of lignans and their derivatives in a single operation holds great medicinal significance for structure-activity relationship studies yet remains challenging.Drawing inspiration from the biosynthesis of lignans,we present a general,high-step-economy palladium-catalyzed reaction that converts simple chemical feedstocks into dehydrodibenzylbutyrolactone lignans through the in-situ construction and coupling of two phenylpropanoid molecules.The diversity of organoboronic acids and the editability of enyne provide a powerful platform for the rapid construction of lignan libraries,featuring 82 lignans analogs,collective syntheses of 10 distinct lignan skeletons,and 13 hybrid molecules combining pharmacophore fragments with drug and derivatives.The subtle combination of phosphine ligands with quinones for switching chemoselectivity is vital to the success of this protocol.展开更多
Benziodazole-triflate,as a novel heterocyclic hypervalent iodine(III)reagent,was prepared from the reaction of hypervalent chloroiodine(III)with silver triflate under mild conditions.The structure of this new reagent ...Benziodazole-triflate,as a novel heterocyclic hypervalent iodine(III)reagent,was prepared from the reaction of hypervalent chloroiodine(III)with silver triflate under mild conditions.The structure of this new reagent was elucidated by NMR spectroscopy and X-ray crystallography,and its reactions with diverseα-electron withdrawing group substituted carbonyl compounds were investigated.The results implied that benziodazole-triflate could be selectively used as both a 2-iodobenzamido-transfer reagent for the synthesis of oxazole compounds,and a triflate-transfer reagent for the triflation ofβ-keto-sulfones.Ionic mechanistic pathways,supported by density functional theory(DFT)calculations,were proposed to account for the divergent selectivities of the transformations.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 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
A transition-metal-and oxidant-free amination/cyclization reaction to access 1,2,4-triazolo[1,5-a]pyridines was realized in water by using amino diphenylphosphinate as amino source.A broad array of readily accessible ...A transition-metal-and oxidant-free amination/cyclization reaction to access 1,2,4-triazolo[1,5-a]pyridines was realized in water by using amino diphenylphosphinate as amino source.A broad array of readily accessible N-(pyridyl)amides could be converted into the products featuring a diverse set of functional groups.The sustainable methodology was successfully applied to the late-stage functionalization of natural products and drugs.展开更多
A concise total synthesis of novel monoterpenoid indole alkaloid(-)-voacafricine A is described,which proceeded in 14 longest linear steps and 5.2%overall yield.Key transformations comprised of(a)an organocatalyticall...A concise total synthesis of novel monoterpenoid indole alkaloid(-)-voacafricine A is described,which proceeded in 14 longest linear steps and 5.2%overall yield.Key transformations comprised of(a)an organocatalytically asymmetric Pictet-Spengler cyclization/lactamization cascade reaction generating the key tetracyclic lactam skeleton;(b)asymmetricα-alkylation of carbonyl group induced by Evans'chiral auxiliary with excellent diastereoselectivity;(c)a highly efficient one-pot desulfurization/hydrogenation/debenzylation transformation using Raney Ni under hydrogen atmosphere;as well as(d)an intramolecular Vorbürggen reaction constructing the quaternary ammonium motif and the final cagelike skeleton.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
A formal[3+3]annulation of 3-aminopyrazoles with cinnamaldehydes or cinnamyl alcohols mediated by NH_(4)SCN has been developed.This protocol provides a practical route to construct 5-arylated pyrazolo[1,5-a]pyrimidine...A formal[3+3]annulation of 3-aminopyrazoles with cinnamaldehydes or cinnamyl alcohols mediated by NH_(4)SCN has been developed.This protocol provides a practical route to construct 5-arylated pyrazolo[1,5-a]pyrimidines with high functional group tolerance.The use of NH_(4)SCN as the cyanide anion surrogate allows the transient generation of cyanohydrin,which shifts the reactive center within cinnamaldehydes from formyl group to alkene group to realize an opposite regiocontrol comparing with previous reports.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
Tazobactam,β lactamase inhibitor, was synthesized from 6 aminopenicillanic acid through eleven steps, including diazotization, bromination, oxidation, chlorization, cyclization, deprotection and so on. The designed...Tazobactam,β lactamase inhibitor, was synthesized from 6 aminopenicillanic acid through eleven steps, including diazotization, bromination, oxidation, chlorization, cyclization, deprotection and so on. The designed route was examined, particularly the azide substitution and cyclization. In the latter reaction, vinyl acetic ester was employed in place of acetylene.展开更多
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.
文摘The degradation mechanism of photocrosslinking products formed by cyclized polyisoprene-diazide system under the influence of the different alkyl benzene sulfonic acids was studied. The effects of alkyl chain length and the concentration of alkyl benzene sulfonic acids on the rate of degradation reaction were discussed. It was found that in the initial stage of degradation, the cyclicity ratio and the average fused ring number did not change considerably, but the percentage of uncyclized parts content varied significantly. The suitable mechanism was supposed.
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A new gold self-relay catalytic annulation/nucleophilic substitution cascade of 1,3-enyne acetates with cyclic ether acetals is reported,enabling highly diastereoselective access to cyclic etherified cyclopentenones with cyclic quaternary centers in moderate to good yields and>19∶1 dr.This catalysis enables the direct construction of two types of carboncyclic skeletons by adjusting the olefin types of 1,3-enyne acetates.When 1,3-enyne acetates bearing a cyclic alkene unit were used,5~6 fused bicarbocyclic products were diastereoselectively synthesized,whereas the reaction of acyclic 1,3-enyne acetates resulted in five-memebered carbocyclic framework.Notably,cyclic ether acetals are commonly used as protecting groups in traditional multistep organic syntheses,and in this reaction,such reagents serve as electrophilic cyclic ether precursors,achieving new uses for old reagents.The current method demonstrates good functional group compatibility,a broad substrate scope and high diastereoselectivity,providing a new synthetic strategy toward functionalized cyclopentenones.
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 for this study is from the National Natural Science Foundation of China(No.32170406)the Social Development Special Projects-Key Research and Development Plan of Science and Technology Department of Yunnan Province(No.202303AC100025)the 111 Project from Ministry of Education of China and the State Administration of Foreign Export Affairs of China(No.B18056).
文摘Houpolignols A-C(1-3),unprecedented oligomers of dearomatized obovatol with tetracyclo[9.3.1.0^(2,7).0^(9,14)]pentadecane(1 and 2)and 8,18-dioxapentacyclo[13.3.1.1^(5,9).0^(4,16).0^(13,20)]icosane(3)core structures,together with their biosynthetic congener houpolignol D(4),were isolated from the cortex of Magnolia officinalis var.biloba.Their structures were determined by spectroscopic analyses,Xray crystallography data,and quantum chemical calculations.Radical cascade cyclizations were proposed as crucial biosynthetic steps of 1-4.(±)-1 showed anti-nonalcoholic steatohepatitis(NASH)effect by promoting fatty acid beta-oxidation.
基金Financial support was provided by the State Key Laboratory of Pulp and Paper Engineering(No.2022PY01)the National Natural Science Foundation of China(Nos.22231002 and 21871095)the Key-Area Research and Development Program of Guangdong Province(No.2020B010188001)。
文摘Lignans have been established as a privileged scaffold in drug discovery,particularly in anticancer and antioxidant properties.Concise and efficient construction of lignans and their derivatives in a single operation holds great medicinal significance for structure-activity relationship studies yet remains challenging.Drawing inspiration from the biosynthesis of lignans,we present a general,high-step-economy palladium-catalyzed reaction that converts simple chemical feedstocks into dehydrodibenzylbutyrolactone lignans through the in-situ construction and coupling of two phenylpropanoid molecules.The diversity of organoboronic acids and the editability of enyne provide a powerful platform for the rapid construction of lignan libraries,featuring 82 lignans analogs,collective syntheses of 10 distinct lignan skeletons,and 13 hybrid molecules combining pharmacophore fragments with drug and derivatives.The subtle combination of phosphine ligands with quinones for switching chemoselectivity is vital to the success of this protocol.
基金the National Natural Science Foundation of China(Nos.22071175,22071116)Tianjin Graduate Research and Innovation Project(No.2021YJSB196)and for financial supports。
文摘Benziodazole-triflate,as a novel heterocyclic hypervalent iodine(III)reagent,was prepared from the reaction of hypervalent chloroiodine(III)with silver triflate under mild conditions.The structure of this new reagent was elucidated by NMR spectroscopy and X-ray crystallography,and its reactions with diverseα-electron withdrawing group substituted carbonyl compounds were investigated.The results implied that benziodazole-triflate could be selectively used as both a 2-iodobenzamido-transfer reagent for the synthesis of oxazole compounds,and a triflate-transfer reagent for the triflation ofβ-keto-sulfones.Ionic mechanistic pathways,supported by density functional theory(DFT)calculations,were proposed to account for the divergent selectivities of the transformations.
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financial support from the National Natural Science Foundation of China(No.82003585)the Program for Science&Technology Innovation Talents in Universities of Henan Province(No.24HASTIT069)+5 种基金the Technical Innovation Team of Henan Normal University(No.2022TD03)the Special Project for Fundamental Research in University of Henan Province(No.23ZX009)the Henan Science and Technology Program(No.232102310364)the Key Project of Henan Educational Committee(No.22A150041)Excellent Youth Foundation of Henan Scientific Committee(No.222300420012)the Young Core Instructor Training Program of Xinyang Agriculture and Forestry University(2023)。
文摘A transition-metal-and oxidant-free amination/cyclization reaction to access 1,2,4-triazolo[1,5-a]pyridines was realized in water by using amino diphenylphosphinate as amino source.A broad array of readily accessible N-(pyridyl)amides could be converted into the products featuring a diverse set of functional groups.The sustainable methodology was successfully applied to the late-stage functionalization of natural products and drugs.
基金supported by Beijing Key Laboratory of Active Substance Discovery and Druggability Evaluation,CAMS Innovation Fund for Medical Sciences(CIFMS,No.2022-I2M-3–002)。
文摘A concise total synthesis of novel monoterpenoid indole alkaloid(-)-voacafricine A is described,which proceeded in 14 longest linear steps and 5.2%overall yield.Key transformations comprised of(a)an organocatalytically asymmetric Pictet-Spengler cyclization/lactamization cascade reaction generating the key tetracyclic lactam skeleton;(b)asymmetricα-alkylation of carbonyl group induced by Evans'chiral auxiliary with excellent diastereoselectivity;(c)a highly efficient one-pot desulfurization/hydrogenation/debenzylation transformation using Raney Ni under hydrogen atmosphere;as well as(d)an intramolecular Vorbürggen reaction constructing the quaternary ammonium motif and the final cagelike skeleton.
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.
文摘A formal[3+3]annulation of 3-aminopyrazoles with cinnamaldehydes or cinnamyl alcohols mediated by NH_(4)SCN has been developed.This protocol provides a practical route to construct 5-arylated pyrazolo[1,5-a]pyrimidines with high functional group tolerance.The use of NH_(4)SCN as the cyanide anion surrogate allows the transient generation of cyanohydrin,which shifts the reactive center within cinnamaldehydes from formyl group to alkene group to realize an opposite regiocontrol comparing with previous reports.
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.
文摘Tazobactam,β lactamase inhibitor, was synthesized from 6 aminopenicillanic acid through eleven steps, including diazotization, bromination, oxidation, chlorization, cyclization, deprotection and so on. The designed route was examined, particularly the azide substitution and cyclization. In the latter reaction, vinyl acetic ester was employed in place of acetylene.
