Humans and animals can be exposed to Dioxins and Furans through ingestion of fatty food, skin contact, and breathing contaminated air. Resulting health problems include skin disease, immune problems, and cancers. Mana...Humans and animals can be exposed to Dioxins and Furans through ingestion of fatty food, skin contact, and breathing contaminated air. Resulting health problems include skin disease, immune problems, and cancers. Managing the release of these chemicals is therefore important. The Stockholm Convention on Persistent Organic Pollutants requires parties to adopt measures that reduce sources of these chemicals. Sierra Leone developed its National Implementation Plan (NIP) in 2008, in compliance with this requirement. However, no known further steps have been taken, particularly at community level. In 2013, the UNDP’s GEF/SGP funded a pilot project to manage the release of Dioxins and Furans from two dumpsites in Freetown, Sierra Leone. This work was sponsored with funds from that project. The work sought to delineate the exposure of communities within and around the Bormeh-Kingtom dumpsite (Kingtom, Kolleh town, Ascension town, Crab town, and Congo town) to the chemicals. The study considered sources of exposure, relative quantities generated per year, and the routes of exposure. This exposure study is a first step in managing the release from those sources. Enumerators deployed at the dumpsite every day, 7:00 AM to 6:00 PM, for three months, quantifying and recording source materials. The amount of source materials dumped per day informed calculation of Dioxin/Furan releases in grams toxicity equivalence per year. The results revealed a release of 128.914 g TEQ/year in air and residue. This implies that the communities are at high risk of inhalation and dermal exposure. Livestock, mainly pigs, are also exposed as they feed on the waste deposited in the dumpsite. Humans in turn feed on the livestock, a recipe for biomagnification. The project team has been working on developing Best Management Practices to suppress the release of the chemicals.展开更多
Intermolecular addition-cyclization of 1, 3-dicarbonyl compounds with arylbromo- allenes in K2CO3 mediated condition afforded 2, 3, 4-trisubstituted furans in good yield.
The authors have studied the Diels-Alder reactions between furan derivatives and maleimide derivatives in an ionic liquid and have found that higher reactivity can be obtained in a protic ionic liquid [Mim]Tf2N than i...The authors have studied the Diels-Alder reactions between furan derivatives and maleimide derivatives in an ionic liquid and have found that higher reactivity can be obtained in a protic ionic liquid [Mim]Tf2N than in the conventional organic solvent. Furthermore, in the Diels-Alder reactions of 2- and 2,5-alkylfurans with N-alkylma- leimide, the reactivity increases by extending the alkyl chain length of N-alkylmaleimide. In addition, it was demon- strated that endo-selectivity increases when 2,5-disubstituted furans are used. These results will be explained by comparing the stability of the Diels-Alder adduct with that of the products obtained from the reactions of 2-substituted furans and 2,5-disubstituted furans.展开更多
This paper describes the development of an integrated approach for the preparation of diverse furan derivatives from acetylenic alcohols by gold and palladium catalyzed π-activation chemistry.Notably,this new method ...This paper describes the development of an integrated approach for the preparation of diverse furan derivatives from acetylenic alcohols by gold and palladium catalyzed π-activation chemistry.Notably,this new method was found to be amenable to cyclooctyl-containing substrates,which represents a significant extension to this methodology compared with our previous reports.Furthermore,this newly developed method allowed for the direct construction of cyclooctyl furans from their synthetic precursors under Sonogashira conditions.Experimental results revealed that palladium played two major functions in these reactions,including（1） an essential catalyst in the cross-coupling reaction of the substrates;and（2）facilitating the cyclization of the acetylenic alcohol intermediates through a typical π-activation process.The scope of this chemistry was highlighted by the one-pot synthesis of 3-iodofuran,which provided an opportunity for further functionalization（via coupling methods）.Finally,the AuBr3 protocol was also elaborated to domino cyclization/C-H activation reactions,as well as the cyclization of acyclic precursors.Taken together,the results of this study demonstrate that gold and palladium catalysts can be used to complement each other in cyclization reactions.展开更多
A transition-metal-free strategy for the synthesis of tetrasubstituted furans is reported.Promoted by boron trifluo-ride diethyl etherate,the reaction of alkynyl sulfoxides with ynamides/ynol ethers proceeded via a ca...A transition-metal-free strategy for the synthesis of tetrasubstituted furans is reported.Promoted by boron trifluo-ride diethyl etherate,the reaction of alkynyl sulfoxides with ynamides/ynol ethers proceeded via a cascade process including cross-coupling of the two reactants,[3,3]-sulfonium rearrangement,and 5-exo-dig heterocyclization,leading to tetrasubstituted furan products.The resultant α-alkylthio groups can be used for further functionalization,such as to introduce other alkyl/aryl groups.展开更多
A simple and highly efficient catalytic system for the selective aerobic oxidative ring-opening of substituted furans has been achieved using Fe(NO_(3))_(3)·9H_(2)O as a catalyst and air as an oxidant under mild ...A simple and highly efficient catalytic system for the selective aerobic oxidative ring-opening of substituted furans has been achieved using Fe(NO_(3))_(3)·9H_(2)O as a catalyst and air as an oxidant under mild conditions.A series of(Z)-1,4-enediones were obtained in good yields(up to 97%)with excellent stereoselectivity(up to>20:1 Z/E ratio).The present synthetic method exhibits perfect atom economy,wide substrate scope,and highly functionalized products allowing diverse transformations.展开更多
In pharmaceutical chemistry,five-membered aromatic heterocycles occupy a pivotal position due to their distinctive structural motifs that significantly enhance drug-like properties,including metabolic stability,solubi...In pharmaceutical chemistry,five-membered aromatic heterocycles occupy a pivotal position due to their distinctive structural motifs that significantly enhance drug-like properties,including metabolic stability,solubility,and target selectivity.These privileged structures,characterized by unique physicochemical properties and diverse biological activities,serve as fundamental building blocks for numerous clinically approved drugs.Among these heterocycles,pyrrole stands out as a privileged structural motif that is widely distributed in natural products and bioactive molecules[1,2].展开更多
Main observation and conclusion The reaction of 2-alkynylanisoles/sulfides with SOCl_(2) and DMSO was conducted to conveniently furnish the biologically interesting 3-(methylthio)-benzo[b]furans/thiophenes via intramo...Main observation and conclusion The reaction of 2-alkynylanisoles/sulfides with SOCl_(2) and DMSO was conducted to conveniently furnish the biologically interesting 3-(methylthio)-benzo[b]furans/thiophenes via intramolecular cyclization.DMSO acts as a solvent as well as a sulfur source and can also be replaced with DMSO-d_(6),enabling the incorporation of the SCD3 moiety of DMSO-d_(6) to the 3-position of the heterocyclic frameworks.展开更多
Furans bearing alkynyl substituents are highly useful in organic synthesis.However,the methodologies to access these important furan derivatives are rather limited.We herein report an efficient synthesis of alkynylate...Furans bearing alkynyl substituents are highly useful in organic synthesis.However,the methodologies to access these important furan derivatives are rather limited.We herein report an efficient synthesis of alkynylated furan derivatives based on Pd-catalyzed oxidative cross-coupling reaction between allenyl ketones and terminal alkynes.This novel synthesis of alkynylated furans with wide substrate scope is operationally simple and tolerates various functional groups.Mechanistically,the formation of the palladium carbene through cycloisomerization and the subsequent alkynyl migratory insertion are proposed as the key steps in the transformation.The reaction reported in this paper further demonstrates the generality of the carbene-based cross coupling.展开更多
The mechanisms of gold（I）-catalyzed cycloaddition of 1-（1-alkynyl） cyclopropyl ketones with nucleophiles have been investi- gated using density functional theory calculations at the B3LYP/6-31G （d, p） level of t...The mechanisms of gold（I）-catalyzed cycloaddition of 1-（1-alkynyl） cyclopropyl ketones with nucleophiles have been investi- gated using density functional theory calculations at the B3LYP/6-31G （d, p） level of theory. A polarizable continuum model （PCM） has been established in order to evaluate the effects of solvents on the reactions. The results of the calculations indicate that the first step of the catalytic cycle is the cyclization of the carbonyl oxygen onto the triple bond which forms a new and stable resonance structure of an oxonium ion and a carbocation intermediate. The subsequent ring expansion step results in the formation of the final product and regeneration of the catalyst. Furthermore, the regioselectivity and effect of substituents has been discussed, including an analysis of energy, bond length, and natural bond orbital （NBO） charge distributions in the rate-determining step. Our computational results are consistent with earlier experimental observations.展开更多
A magnetic nano-supported Cu(I)catalyst was prepared and showed high activity for cyclization of ene-yne-ketone to synthesize furans.The catalyst was easily recovered from the reaction by using external magnets and re...A magnetic nano-supported Cu(I)catalyst was prepared and showed high activity for cyclization of ene-yne-ketone to synthesize furans.The catalyst was easily recovered from the reaction by using external magnets and reused 8 times without significant loss of its catalytic activity.展开更多
C-H functionalization of allenes is an available strategy to construct heterocyclic compounds.Herein we propose a sus-tainable electrocatalytic C-H activation for the synthesis of novel highly functionalized tetrasubs...C-H functionalization of allenes is an available strategy to construct heterocyclic compounds.Herein we propose a sus-tainable electrocatalytic C-H activation for the synthesis of novel highly functionalized tetrasubstituted furans,which is accomplished by intermolecular cyclization of allenes and 1,3-dicarbonyl compounds.展开更多
o-Carboryne （1,2-dehydro-o-carborane） is a very useful synthon for the synthesis of a variety of carborane-functionalized molecules. Diels-Alder reaction of o-carboryne with furans gave a series of carborane-fused o...o-Carboryne （1,2-dehydro-o-carborane） is a very useful synthon for the synthesis of a variety of carborane-functionalized molecules. Diels-Alder reaction of o-carboryne with furans gave a series of carborane-fused oxanorbornenes in moderate to high yields using 1-OTf-1,2-C_2B_10H_11 as carboryne precursor. The resultant cycloadducts can undergo hydrogenation, cyclic oxidation, bromination, [4＋2]/[2＋2] cycloaddition and nucleophilic ring opening reaction to afford a variety of highly functionalized carboranes that may find applications as useful basic units in medicine and materials science.展开更多
We present here a facile and practical procedure for the synthesis of tetrasubstituted furans from alkynes catalyzed by palladium acetate together with cupric acetate in acetic acid,using atmospheric oxygen as a termi...We present here a facile and practical procedure for the synthesis of tetrasubstituted furans from alkynes catalyzed by palladium acetate together with cupric acetate in acetic acid,using atmospheric oxygen as a terminal oxidant.Various internal aromatic alkynes afforded the target furans in satisfactory yield.展开更多
Correction for‘Electrochemically-mediated C-H functionalization of allenes and 1,3-dicarbonyl compounds to construct tetrasubstituted furans’by Mu-Xue He et al.,Org.Chem.Front.,2022,DOI:10.1039/d1qo01458g.One of the...Correction for‘Electrochemically-mediated C-H functionalization of allenes and 1,3-dicarbonyl compounds to construct tetrasubstituted furans’by Mu-Xue He et al.,Org.Chem.Front.,2022,DOI:10.1039/d1qo01458g.One of the author names(Hai-Tao Tang)was spelled incorrectly in the published article;the corrected version is shown here.The Royal Society of Chemistry apologises for these errors and any consequent inconvenience to authors and readers.展开更多
A[3+2]cyclization reaction of acylacetonitriles and hydroxyacetone was developed by using Sc(OTf)_(3)as a catalyst to synthesize some furan derivatives.Bifunctional C2-based acetals,such asα-bromoacetaldehyde acetal,...A[3+2]cyclization reaction of acylacetonitriles and hydroxyacetone was developed by using Sc(OTf)_(3)as a catalyst to synthesize some furan derivatives.Bifunctional C2-based acetals,such asα-bromoacetaldehyde acetal,1,4-dithiane-2,5-diol and glycolaldehyde diethyl acetal,also reacted readily as alternative counterpart reagents to acylacetonitriles.The established reactions can be used to synthesize a well-known fungicide,fenfuram.Antifungal activity investigation against four common plant funguses indicated that some of the obtained furan products furnish general and high biological activities.展开更多
The evaluation of toxicity related to polychlorinated dibenzo-p-dioxins and furans(PCDD/Fs)and dioxin-like polychlorinated biphenyls(DL-PCBs)is crucial for a comprehensive risk assessment in real-world exposure scenar...The evaluation of toxicity related to polychlorinated dibenzo-p-dioxins and furans(PCDD/Fs)and dioxin-like polychlorinated biphenyls(DL-PCBs)is crucial for a comprehensive risk assessment in real-world exposure scenarios.This study employed a controlled feeding experiment to investigate the metabolic effects of dioxin-like compounds(DLCs)on laying hens via feed exposure.Diets enriched with two concentrations(1.17 and 5.13 pg toxic equivalents(TEQ)/g dry weight(dw))were administered over 14 days,followed by 28 days of clean feed.Metabolomics analyses of blood samples revealed significant metabolic variations between PCDD/Fs and DL-PCBs exposed groups and controls,reflecting the induced metabolic disruption.Distinct changes were observed in sphingosine,palmitoleic acid,linoleate,linolenic acid,taurocholic acid,indole acrylic acid,and dibutyl phthalate levels,implying possible connections between PCDD/Fs and DL-PCBs toxic effects and energy-neuronal imbalances,along with lipid accumulation and anomalous amino acid metabolism,impacting taurine metabolism.Moreover,we identified three differential endogenous metabolites—L-tryptophan,indole-3-acetaldehyde,and indole acrylic acid—as potential ligands for the aryl hydrocarbon receptor(AhR),suggesting their role inmediating PCDD/Fs and DL-PCBs toxicity.This comprehensive investigation provides novel insights into the metabolic alterations induced by PCDD/Fs and DL-PCBs in laying hens,thereby enhancing our ability to assess risks associated with their exposure in human populations.展开更多
Primary diamines play an important role in the chemical industry,where they are widely used as raw materials for the manufacture of pharmaceuticals and polymers.Currently,primary diamines are mainly derived from petro...Primary diamines play an important role in the chemical industry,where they are widely used as raw materials for the manufacture of pharmaceuticals and polymers.Currently,primary diamines are mainly derived from petroleum,while harsh or toxic conditions are often needed.Biomass is abundant and renewable,which serves as a promising alternative raw material to produce primary diamines.This review primarily focuses on the synthesis of 2,5-bis(aminomethyl)furan(BAMF),a bio-based diamine with potential as a biomonomer for polyamides and polyureas.Specifically,this review emphasizes the synthesis of BAMF fromthree biomass-derived alcohols and aldehydes,namely 5-hydroxymethylfurfural(HMF),2,5-bis(hydroxymethyl)furan(BHMF),and 2,5-diformylfuran(DFF).These are the key substrates to get BAMF and could be readily obtained from carbohydrates.Even though great effort has been put into the synthesis of BAMF,it remains a tough problem to obtain BAMF with a high yield at a low cost due to the inevitable side reactions,such as unwanted hydrogenation reactions and condensation reactions.Many strategies have been proposed to solve this problem,such as the hydrogen-borrowing strategy and stepwise reductive amination strategy.Herein,we will summarize the key advancements in this area,and discuss the challenges that need to be responded in the future,hoping to provide an insight into the design and development of a more efficient system for the production of biomass-derived diamines.展开更多
An efficient and novel approach is proposed for oxidative arylation of bio-based furfuryl alcohol(FA)to aryl furans(AFs),a versatile monomer of photoelectric materials,in the presence of UiO-67-Pd(F)with phenanthrolin...An efficient and novel approach is proposed for oxidative arylation of bio-based furfuryl alcohol(FA)to aryl furans(AFs),a versatile monomer of photoelectric materials,in the presence of UiO-67-Pd(F)with phenanthroline/bipyridine,and poly-F substituted phenyl ligands as the mixture linkers.The results of control experiments and theoretical calculations reveal that the–F on the phenyl linkers efficiently tunes the electron-deficient nature of Pd through the Zr_(6) clusters bridges,which favors the adsorption and activation of the furan ring.Furthermore,the conjugation of different nitrogen-containing ligands facilitates Pd coordination for the Heck-type insertion and subsequent electrophilic palladation,respectively.As a result,the oxidative arylation of FA derivatives is substantially enhanced because of these electronic and steric synergistic effects.Under the optimized conditions,72.2%FA conversion and 74.8%mono aryl furan(MAF)selectivity are shown in the Heck-type insertion.Meanwhile,85.3%of MAF is converted,affording 74.8%selectivity of final product(AFs)in the subsequent electrophilic palladation reaction.This process efficiency is remarkably higher than that with homogeneous catalysts.In addition,furan-benzene polymer obtained from the halogen-free synthesis catalyzed by UiO-67-Pd(F)show significantly better properties than that from conventional Suzuki coupling method.Therefore,the present work provides a new insight for useful AFs synthesis by oxidative arylation of bio-furan via rational tunning the metal center micro-environment of heterogeneous catalyst.展开更多
Since the 2010 s, the authorities of Guangdong province and local governments have enhanced law enforcement and environmental regulations to abolish open burning, acid washing, and other uncontrolled e-waste recycling...Since the 2010 s, the authorities of Guangdong province and local governments have enhanced law enforcement and environmental regulations to abolish open burning, acid washing, and other uncontrolled e-waste recycling activities. In this study, ambient air and indoor dust near different kinds of e-waste recycling processes were collected in Guiyu and Qingyuan to investigate the pollution status of particles and polychlorinated dibenzo-pdioxins and furans（PCDD/Fs） after stricter environmental regulations. PM_（2.5） and PCDD/Fs both showed significantly reduced levels in the two regions compared with the documented data. The congener distribution and principal component analysis results also confirmed the significant differences between the current PCDD/Fs pollution characterizations and the historical ones. The estimated total intake doses via air inhalation and dust ingestion of children in the recycling region of Guiyu ranged from 10 to 32 pg TEQ/（kg·day）, which far exceeded the tolerable daily intake（TDI） limit（1–4 pg TEQ/（kg·day）. Although the measurements showed a significant reduction of the release of PCDD/Fs, the pollution status was still considered severe in Guiyu town after stricter regulations were implemented.展开更多
文摘Humans and animals can be exposed to Dioxins and Furans through ingestion of fatty food, skin contact, and breathing contaminated air. Resulting health problems include skin disease, immune problems, and cancers. Managing the release of these chemicals is therefore important. The Stockholm Convention on Persistent Organic Pollutants requires parties to adopt measures that reduce sources of these chemicals. Sierra Leone developed its National Implementation Plan (NIP) in 2008, in compliance with this requirement. However, no known further steps have been taken, particularly at community level. In 2013, the UNDP’s GEF/SGP funded a pilot project to manage the release of Dioxins and Furans from two dumpsites in Freetown, Sierra Leone. This work was sponsored with funds from that project. The work sought to delineate the exposure of communities within and around the Bormeh-Kingtom dumpsite (Kingtom, Kolleh town, Ascension town, Crab town, and Congo town) to the chemicals. The study considered sources of exposure, relative quantities generated per year, and the routes of exposure. This exposure study is a first step in managing the release from those sources. Enumerators deployed at the dumpsite every day, 7:00 AM to 6:00 PM, for three months, quantifying and recording source materials. The amount of source materials dumped per day informed calculation of Dioxin/Furan releases in grams toxicity equivalence per year. The results revealed a release of 128.914 g TEQ/year in air and residue. This implies that the communities are at high risk of inhalation and dermal exposure. Livestock, mainly pigs, are also exposed as they feed on the waste deposited in the dumpsite. Humans in turn feed on the livestock, a recipe for biomagnification. The project team has been working on developing Best Management Practices to suppress the release of the chemicals.
基金We are grateful to the National Natural Science Foundation of China(No.20472072,20332060).
文摘Intermolecular addition-cyclization of 1, 3-dicarbonyl compounds with arylbromo- allenes in K2CO3 mediated condition afforded 2, 3, 4-trisubstituted furans in good yield.
文摘The authors have studied the Diels-Alder reactions between furan derivatives and maleimide derivatives in an ionic liquid and have found that higher reactivity can be obtained in a protic ionic liquid [Mim]Tf2N than in the conventional organic solvent. Furthermore, in the Diels-Alder reactions of 2- and 2,5-alkylfurans with N-alkylma- leimide, the reactivity increases by extending the alkyl chain length of N-alkylmaleimide. In addition, it was demon- strated that endo-selectivity increases when 2,5-disubstituted furans are used. These results will be explained by comparing the stability of the Diels-Alder adduct with that of the products obtained from the reactions of 2-substituted furans and 2,5-disubstituted furans.
基金supported by the Department of Science and Technology(INSPIRE Faculty Program),India~~
文摘This paper describes the development of an integrated approach for the preparation of diverse furan derivatives from acetylenic alcohols by gold and palladium catalyzed π-activation chemistry.Notably,this new method was found to be amenable to cyclooctyl-containing substrates,which represents a significant extension to this methodology compared with our previous reports.Furthermore,this newly developed method allowed for the direct construction of cyclooctyl furans from their synthetic precursors under Sonogashira conditions.Experimental results revealed that palladium played two major functions in these reactions,including（1） an essential catalyst in the cross-coupling reaction of the substrates;and（2）facilitating the cyclization of the acetylenic alcohol intermediates through a typical π-activation process.The scope of this chemistry was highlighted by the one-pot synthesis of 3-iodofuran,which provided an opportunity for further functionalization（via coupling methods）.Finally,the AuBr3 protocol was also elaborated to domino cyclization/C-H activation reactions,as well as the cyclization of acyclic precursors.Taken together,the results of this study demonstrate that gold and palladium catalysts can be used to complement each other in cyclization reactions.
文摘A transition-metal-free strategy for the synthesis of tetrasubstituted furans is reported.Promoted by boron trifluo-ride diethyl etherate,the reaction of alkynyl sulfoxides with ynamides/ynol ethers proceeded via a cascade process including cross-coupling of the two reactants,[3,3]-sulfonium rearrangement,and 5-exo-dig heterocyclization,leading to tetrasubstituted furan products.The resultant α-alkylthio groups can be used for further functionalization,such as to introduce other alkyl/aryl groups.
基金supported by the Leading Innovative and Entrepreneur Team Introduction Program of Zhejiang(No.2022R01007)a Start-up Research Grant from Zhejiang Normal University,the National Key Research and Development Program of China(No.2021YFA0804900)+1 种基金the NSFC(No.21971062)Shanghai Frontiers Science Center of Optogenetic Techniques for Cell Metabolism.
文摘A simple and highly efficient catalytic system for the selective aerobic oxidative ring-opening of substituted furans has been achieved using Fe(NO_(3))_(3)·9H_(2)O as a catalyst and air as an oxidant under mild conditions.A series of(Z)-1,4-enediones were obtained in good yields(up to 97%)with excellent stereoselectivity(up to>20:1 Z/E ratio).The present synthetic method exhibits perfect atom economy,wide substrate scope,and highly functionalized products allowing diverse transformations.
基金supported by the National Key R&D Program of China(2023YFA1507203 and 2024YFA1509700)the National Natural Science Foundation of China(92256301,22271113,and 22471089).
文摘In pharmaceutical chemistry,five-membered aromatic heterocycles occupy a pivotal position due to their distinctive structural motifs that significantly enhance drug-like properties,including metabolic stability,solubility,and target selectivity.These privileged structures,characterized by unique physicochemical properties and diverse biological activities,serve as fundamental building blocks for numerous clinically approved drugs.Among these heterocycles,pyrrole stands out as a privileged structural motif that is widely distributed in natural products and bioactive molecules[1,2].
基金We acknowledge the National Natural Science Foundation of China(No.21472136)for financial support.
文摘Main observation and conclusion The reaction of 2-alkynylanisoles/sulfides with SOCl_(2) and DMSO was conducted to conveniently furnish the biologically interesting 3-(methylthio)-benzo[b]furans/thiophenes via intramolecular cyclization.DMSO acts as a solvent as well as a sulfur source and can also be replaced with DMSO-d_(6),enabling the incorporation of the SCD3 moiety of DMSO-d_(6) to the 3-position of the heterocyclic frameworks.
基金supported by NSFC(22371008),BNLMSLaboratory for Synthetic Chemistry and Chemical Biology of Health@InnoHK of ITC,HKSAR.
文摘Furans bearing alkynyl substituents are highly useful in organic synthesis.However,the methodologies to access these important furan derivatives are rather limited.We herein report an efficient synthesis of alkynylated furan derivatives based on Pd-catalyzed oxidative cross-coupling reaction between allenyl ketones and terminal alkynes.This novel synthesis of alkynylated furans with wide substrate scope is operationally simple and tolerates various functional groups.Mechanistically,the formation of the palladium carbene through cycloisomerization and the subsequent alkynyl migratory insertion are proposed as the key steps in the transformation.The reaction reported in this paper further demonstrates the generality of the carbene-based cross coupling.
基金supported by the Natural Science Foundation of Gansu Province (10710RJZA114)
文摘The mechanisms of gold（I）-catalyzed cycloaddition of 1-（1-alkynyl） cyclopropyl ketones with nucleophiles have been investi- gated using density functional theory calculations at the B3LYP/6-31G （d, p） level of theory. A polarizable continuum model （PCM） has been established in order to evaluate the effects of solvents on the reactions. The results of the calculations indicate that the first step of the catalytic cycle is the cyclization of the carbonyl oxygen onto the triple bond which forms a new and stable resonance structure of an oxonium ion and a carbocation intermediate. The subsequent ring expansion step results in the formation of the final product and regeneration of the catalyst. Furthermore, the regioselectivity and effect of substituents has been discussed, including an analysis of energy, bond length, and natural bond orbital （NBO） charge distributions in the rate-determining step. Our computational results are consistent with earlier experimental observations.
基金supported by the Natural Science Foundation of Guangdong Province(No.10151022501000033).
文摘A magnetic nano-supported Cu(I)catalyst was prepared and showed high activity for cyclization of ene-yne-ketone to synthesize furans.The catalyst was easily recovered from the reaction by using external magnets and reused 8 times without significant loss of its catalytic activity.
基金This work was supported by National Natural Science Foundation of China(22161008,21861006,22061003)Guangxi Natural Science Foundation of China(2021GXNSFFA220005)the Chunhui Program(GX2019001).
文摘C-H functionalization of allenes is an available strategy to construct heterocyclic compounds.Herein we propose a sus-tainable electrocatalytic C-H activation for the synthesis of novel highly functionalized tetrasubstituted furans,which is accomplished by intermolecular cyclization of allenes and 1,3-dicarbonyl compounds.
文摘o-Carboryne （1,2-dehydro-o-carborane） is a very useful synthon for the synthesis of a variety of carborane-functionalized molecules. Diels-Alder reaction of o-carboryne with furans gave a series of carborane-fused oxanorbornenes in moderate to high yields using 1-OTf-1,2-C_2B_10H_11 as carboryne precursor. The resultant cycloadducts can undergo hydrogenation, cyclic oxidation, bromination, [4＋2]/[2＋2] cycloaddition and nucleophilic ring opening reaction to afford a variety of highly functionalized carboranes that may find applications as useful basic units in medicine and materials science.
基金We thank Scientific and Technological Project of Zhanjiang City(No.2012C3106024)Guangdong Medical College(No.M2010006)for financial support.
文摘We present here a facile and practical procedure for the synthesis of tetrasubstituted furans from alkynes catalyzed by palladium acetate together with cupric acetate in acetic acid,using atmospheric oxygen as a terminal oxidant.Various internal aromatic alkynes afforded the target furans in satisfactory yield.
文摘Correction for‘Electrochemically-mediated C-H functionalization of allenes and 1,3-dicarbonyl compounds to construct tetrasubstituted furans’by Mu-Xue He et al.,Org.Chem.Front.,2022,DOI:10.1039/d1qo01458g.One of the author names(Hai-Tao Tang)was spelled incorrectly in the published article;the corrected version is shown here.The Royal Society of Chemistry apologises for these errors and any consequent inconvenience to authors and readers.
基金The authors thank the financial support of the Natural Science Foundation of Hubei Province(No.2020CFB717)the Youth Science Foundation of Hubei Academy of Agricultural Sciences(No.2021NKYJJ17)+2 种基金also gratefully acknowledge the partial support from the Program for Leading Talents of Hubei Academy of Agricultural Sciences(No.L2018031)Hubei Biopesticide Engineering Research Centre(Nos.HBERC-RC-202104 and HBERC-RC-202002)Gu thanks the National Natural Science Foundation of China of China(No.22072049).
文摘A[3+2]cyclization reaction of acylacetonitriles and hydroxyacetone was developed by using Sc(OTf)_(3)as a catalyst to synthesize some furan derivatives.Bifunctional C2-based acetals,such asα-bromoacetaldehyde acetal,1,4-dithiane-2,5-diol and glycolaldehyde diethyl acetal,also reacted readily as alternative counterpart reagents to acylacetonitriles.The established reactions can be used to synthesize a well-known fungicide,fenfuram.Antifungal activity investigation against four common plant funguses indicated that some of the obtained furan products furnish general and high biological activities.
基金supported by the National Key Research and Development Program of China (Nos.2018YFA0901101,2018YFA0901103,and 2017YFC1600301)the National Natural Science Foundation of China (Nos.22076216,21976201,and 21836004).
文摘The evaluation of toxicity related to polychlorinated dibenzo-p-dioxins and furans(PCDD/Fs)and dioxin-like polychlorinated biphenyls(DL-PCBs)is crucial for a comprehensive risk assessment in real-world exposure scenarios.This study employed a controlled feeding experiment to investigate the metabolic effects of dioxin-like compounds(DLCs)on laying hens via feed exposure.Diets enriched with two concentrations(1.17 and 5.13 pg toxic equivalents(TEQ)/g dry weight(dw))were administered over 14 days,followed by 28 days of clean feed.Metabolomics analyses of blood samples revealed significant metabolic variations between PCDD/Fs and DL-PCBs exposed groups and controls,reflecting the induced metabolic disruption.Distinct changes were observed in sphingosine,palmitoleic acid,linoleate,linolenic acid,taurocholic acid,indole acrylic acid,and dibutyl phthalate levels,implying possible connections between PCDD/Fs and DL-PCBs toxic effects and energy-neuronal imbalances,along with lipid accumulation and anomalous amino acid metabolism,impacting taurine metabolism.Moreover,we identified three differential endogenous metabolites—L-tryptophan,indole-3-acetaldehyde,and indole acrylic acid—as potential ligands for the aryl hydrocarbon receptor(AhR),suggesting their role inmediating PCDD/Fs and DL-PCBs toxicity.This comprehensive investigation provides novel insights into the metabolic alterations induced by PCDD/Fs and DL-PCBs in laying hens,thereby enhancing our ability to assess risks associated with their exposure in human populations.
基金financially supported by China Scholarship Council,Science and Technology Project of the State Administration for Market Regulation(2022MK111)the Fundamental Research Funds for the Central Universities.
文摘Primary diamines play an important role in the chemical industry,where they are widely used as raw materials for the manufacture of pharmaceuticals and polymers.Currently,primary diamines are mainly derived from petroleum,while harsh or toxic conditions are often needed.Biomass is abundant and renewable,which serves as a promising alternative raw material to produce primary diamines.This review primarily focuses on the synthesis of 2,5-bis(aminomethyl)furan(BAMF),a bio-based diamine with potential as a biomonomer for polyamides and polyureas.Specifically,this review emphasizes the synthesis of BAMF fromthree biomass-derived alcohols and aldehydes,namely 5-hydroxymethylfurfural(HMF),2,5-bis(hydroxymethyl)furan(BHMF),and 2,5-diformylfuran(DFF).These are the key substrates to get BAMF and could be readily obtained from carbohydrates.Even though great effort has been put into the synthesis of BAMF,it remains a tough problem to obtain BAMF with a high yield at a low cost due to the inevitable side reactions,such as unwanted hydrogenation reactions and condensation reactions.Many strategies have been proposed to solve this problem,such as the hydrogen-borrowing strategy and stepwise reductive amination strategy.Herein,we will summarize the key advancements in this area,and discuss the challenges that need to be responded in the future,hoping to provide an insight into the design and development of a more efficient system for the production of biomass-derived diamines.
文摘An efficient and novel approach is proposed for oxidative arylation of bio-based furfuryl alcohol(FA)to aryl furans(AFs),a versatile monomer of photoelectric materials,in the presence of UiO-67-Pd(F)with phenanthroline/bipyridine,and poly-F substituted phenyl ligands as the mixture linkers.The results of control experiments and theoretical calculations reveal that the–F on the phenyl linkers efficiently tunes the electron-deficient nature of Pd through the Zr_(6) clusters bridges,which favors the adsorption and activation of the furan ring.Furthermore,the conjugation of different nitrogen-containing ligands facilitates Pd coordination for the Heck-type insertion and subsequent electrophilic palladation,respectively.As a result,the oxidative arylation of FA derivatives is substantially enhanced because of these electronic and steric synergistic effects.Under the optimized conditions,72.2%FA conversion and 74.8%mono aryl furan(MAF)selectivity are shown in the Heck-type insertion.Meanwhile,85.3%of MAF is converted,affording 74.8%selectivity of final product(AFs)in the subsequent electrophilic palladation reaction.This process efficiency is remarkably higher than that with homogeneous catalysts.In addition,furan-benzene polymer obtained from the halogen-free synthesis catalyzed by UiO-67-Pd(F)show significantly better properties than that from conventional Suzuki coupling method.Therefore,the present work provides a new insight for useful AFs synthesis by oxidative arylation of bio-furan via rational tunning the metal center micro-environment of heterogeneous catalyst.
基金supported by the National Natural Science Foundation of China(No.91543202)the Ministry of Environmental Protection of the People's Republic of China(Nos.201409022,201409080 and 201509063)South China Institute of Environmental Science(No.PM-zx021-201510-015)
文摘Since the 2010 s, the authorities of Guangdong province and local governments have enhanced law enforcement and environmental regulations to abolish open burning, acid washing, and other uncontrolled e-waste recycling activities. In this study, ambient air and indoor dust near different kinds of e-waste recycling processes were collected in Guiyu and Qingyuan to investigate the pollution status of particles and polychlorinated dibenzo-pdioxins and furans（PCDD/Fs） after stricter environmental regulations. PM_（2.5） and PCDD/Fs both showed significantly reduced levels in the two regions compared with the documented data. The congener distribution and principal component analysis results also confirmed the significant differences between the current PCDD/Fs pollution characterizations and the historical ones. The estimated total intake doses via air inhalation and dust ingestion of children in the recycling region of Guiyu ranged from 10 to 32 pg TEQ/（kg·day）, which far exceeded the tolerable daily intake（TDI） limit（1–4 pg TEQ/（kg·day）. Although the measurements showed a significant reduction of the release of PCDD/Fs, the pollution status was still considered severe in Guiyu town after stricter regulations were implemented.
