Fluorinated poly（ethylene oxide） propyl-b-polydimethylsiloxane-b-propyl fluorinated poly（ethylene oxide） （FPEO-b-PDMS-b- FPEO） was synthesized by a free radical addition of carbon-hydrogen of polyether segments ...Fluorinated poly（ethylene oxide） propyl-b-polydimethylsiloxane-b-propyl fluorinated poly（ethylene oxide） （FPEO-b-PDMS-b- FPEO） was synthesized by a free radical addition of carbon-hydrogen of polyether segments of poly（ethylene oxide） propyl-b- polydimethylsiloxane-b-propyl poty（ethylene oxide） （PEO-b-PDMS-b-PEO） to hexafluoropropylene （HFP） using tert-butyl peroxypivalate as an initiator. In order to reduce the possibility of side reaction, the protection and deprotection via silylation were used for the end-hydroxyls in PEO-b-PDMS-b-PEO chain. The structure of Intermediates and FPEO-b-PDMS-b-FPEO was confirmed by means of Fourier transform infrared and 1H NMR spectroscopy. The effects of amount of initiator, reaction temperature and time on free radical addition were investigated in detail. 2009 Xing Yuan Zhang. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved.展开更多
With the blossom of DNA encoded library(DEL)and nucleic acid aptamer techniques,DNA-compatible reactions draw increasing attention in both the pharmaceutical industry and academia.In this regard,the incorporation of o...With the blossom of DNA encoded library(DEL)and nucleic acid aptamer techniques,DNA-compatible reactions draw increasing attention in both the pharmaceutical industry and academia.In this regard,the incorporation of organosulfur scaffolds on DNA via the Csp2-S bond exhibits advantages but remains underrepresented.Herein,we report a mild and efficient photoredox atom transfer radical addition(ATRA)to terminal and internal alkynes with thiosulfonates catalyzed by organic photocatalyst,furnishing a wide array of E-β-arylthiol-vinyl sulfones with excellent regio-and stereoselectivity.Mechanistic investigations demonstrate that sulfonyl radical likely served as the key intermediate in this transformation.Leveraging the broad functional group tolerance and the mild and biofriendly conditions,this protocol could be adapted to simultaneously install sulfones and sulfides on DNA.More importantly,a redox-responsive fluorescent probe(10-ethyl-2-sulfonate-acridone,ESAC)could be conveniently introduced on two commonly used aptamers(AS1411 and Sgc8c),allowing their subsequent imaging studies across a series of human tumor cell lines.Remarkably,the process of ESAC-aptamers entering the cells was captured by both confocal microscopy and flow cytometry techniques,whereby most of the ESAC-aptamers exhibited green fluorescence after their cellular uptake,with the small portion remaining in the outer membrane emitting blue fluorescence.展开更多
A simple one-pot reaction that serves to functionalize graphite nanosheets(graphene)and single-walled carbon nanotubes(SWNTs)with perfluorinated alkyl groups is reported.Free radical addition of 1-iodo-1H,1H,2H,2H-per...A simple one-pot reaction that serves to functionalize graphite nanosheets(graphene)and single-walled carbon nanotubes(SWNTs)with perfluorinated alkyl groups is reported.Free radical addition of 1-iodo-1H,1H,2H,2H-perfluorododecane to ortho-dichlorobenzene suspensions of the carbon nanomaterial is initiated by thermal decomposition of benzoyl peroxide.Similarly,UV photolysis of 1-iodo-perfluorodecane serves to functionalize the carbon materials.Perfluorododecyl-SWNTs,perfluorododecyl-graphene,and perfluorodecyl-graphene are characterized by infrared(IR)and Raman spectroscopy,X-ray photoelectron spectroscopy(XPS),thermogravimetric analysis(TGA),and atomic force microscopy(AFM).The products show enhanced dispersability in CHCl3 as compared to unfunctionalized starting materials.The advantage of this one-pot functionalization procedure lies in the use of pristine graphite as starting material thereby avoiding the use of harsh oxidizing conditions.展开更多
A new electrochemical strategy for the atom transfer radical addition(ATRA)of polychloroalkanes across olefins has been realized by the synergism of paired electrolysis and halogen bonding activation.Notably,readily a...A new electrochemical strategy for the atom transfer radical addition(ATRA)of polychloroalkanes across olefins has been realized by the synergism of paired electrolysis and halogen bonding activation.Notably,readily accessible 4,4-di-tert-butyl bipyridine(dtbpy),acting as a halogen bonding acceptor,shifted the reduction potential of C—Cl bonds positively by 110 mV.The decreased operating potential leads to a wide substrate scope and excellent functional group compatibility.A diverse array of terminal and internal alkenes such as(hetero)aryl olefins,unactive aliphatic olefins,and natural products and drugs-derived olefins were well compatible.展开更多
Different reaction conditions may cause different reaction paths for cleavage of the Se-Se bonds.Further reactions of(PhSe)2 with methylenecyclopropanes(MCPs)under different conditions lead to the construction of tota...Different reaction conditions may cause different reaction paths for cleavage of the Se-Se bonds.Further reactions of(PhSe)2 with methylenecyclopropanes(MCPs)under different conditions lead to the construction of totally different organic skeletons.Example described herein is typical for students to understand the cleavages of chemical bonds as well as the differences between free radical additions and electrophilic additions.展开更多
Radical addition of polyfluoroalkyl iodides to the C=C double bond of diethyl allylphos- phonate was carried out in CH_2Cl_2-H_2O two-phase medium in the presence of sodium dithionite to give dicthyl 3-polyfluoroalkyl...Radical addition of polyfluoroalkyl iodides to the C=C double bond of diethyl allylphos- phonate was carried out in CH_2Cl_2-H_2O two-phase medium in the presence of sodium dithionite to give dicthyl 3-polyfluoroalkyl-2-iodopropylphosphonates(3)in excellent yields.Compounds 3 were then converted to diethyl polyfluoroalkanephosphonates(4)by zinc-reduction,Thus a facile method for preparing polyfluoroalkanephosphonates is realized.展开更多
Sodium perfluoroalkanesulfinates [Cl(CF_2)n SO_2 Na (1), a, n=4; b, n=6; c, n=8] with the reduction potentials about 0.95-1.00V could be oxidized readily with various oxidizing agents such as Mn (OAc)_3·2H_2O, Ce...Sodium perfluoroalkanesulfinates [Cl(CF_2)n SO_2 Na (1), a, n=4; b, n=6; c, n=8] with the reduction potentials about 0.95-1.00V could be oxidized readily with various oxidizing agents such as Mn (OAc)_3·2H_2O, Ce(SO_4)_2, HgSO_4 and Co_2O_3 to generate perfluoroalkyl radicals which added to the olefins RCH=CHR′to give two kinds of adducts, namely RCH (R_f) CHXR′(3, X=H; 4, X=OAc), with good yields depending upon the solvent system used. Different oxidizing agents showed slight variation on the yields of the adducts. The reaction time could be greatly shortened at higher temperature. Thus, this reaction provides a new way for introducing a perfluoroalkyl group into olefinic compounds.展开更多
Chemical functionalization of graphene is a topic of paramount importance to broaden its applications in chemistry,physics,and biological science but remains a great challenge due to its low chemical activity and poor...Chemical functionalization of graphene is a topic of paramount importance to broaden its applications in chemistry,physics,and biological science but remains a great challenge due to its low chemical activity and poor dispersion.Here,we report a strategy for the photosynergetic electrochemical functionalization of graphene(EFG).By using chloride ion(Cl^(-))as the intercalation anions and co-reactants,the electrogenerated radicals confined in the expanded graphite layers enable efficient radical addition reaction,thus grasping crystallineperfect EFG.We found that the ultraviolet irradiation and applied voltage have increased the surface/interface concentration of Cl,thus boosting the functionalization of graphene.Theoretical calculation and experimental results verified the oxygen evolution reaction(OER)on EFG has been improved by regulating the doping of chlorine atoms.In addition,the reduced interlayer distance and enhanced electrostatic repulsion near the basal plane endow the fabricated EFG-based membrane with high salt retention.This work highlights a method for the in situ functionalization of graphene and the subsequent applications in OER and water desalination.展开更多
Alkenes difunctionalization reaction has been recognized as a highly important organic transformation.However,its application is significantly hindered by the reliance on homogeneous transition metal-assisted radical ...Alkenes difunctionalization reaction has been recognized as a highly important organic transformation.However,its application is significantly hindered by the reliance on homogeneous transition metal-assisted radical addition,as well as the need for additional oxidants.In this study,we report that azido-hydroxylation of alkenes can be efficiently achieved by a heterogeneous photoelectrochemical(PEC)oxidation on the BiVO_(4)photoanode,by using KN_(3)as the azido source in the presence of HCO_(3)^(-).A wide range of alkene substrates featuring diverse substituent groups can be effectively oxidized to the corresponding product with an impressive product selectivity.Electrochemical and electron paramagnetic resonance(EPR)experiments confirmed that the high performance is assigned to the interaction of hetero-radicals produced from the oxidation of N_(3)^(-)and HCO_(3)^(-).Transient spectroscopy dynamics experiments and density functional theory(DFT)analysis demonstrate that the addition order of two radical groups is attributed to their distinctive characteristics.The high reactivity of transient·N_(3)is preferentially added to the C=C double bond of alkene to form the carbon radical intermediate both kinetically and thermodynamically.The extended lifespan of persistent·CO_(3)^(-)can greatly increase the probability of paring the carbon radical intermediate,thus improving the selectivity of the azido-hydroxylation product.The present work provides a promising strategy for the difunctionalization of alkenes with the tandem addition of two radicals in the absence of homogeneous metal catalysis.展开更多
Three kinds of dialkylphosphinic acids(DAPAs),i.e.dihexylphophinic acid(DHPA),di-(2,4,4-trimethylpentyl) phosphinic acid(DTMPPA)and didecylphophinic acid(DDPA),were synthesized through free radical addition reaction.T...Three kinds of dialkylphosphinic acids(DAPAs),i.e.dihexylphophinic acid(DHPA),di-(2,4,4-trimethylpentyl) phosphinic acid(DTMPPA)and didecylphophinic acid(DDPA),were synthesized through free radical addition reaction.The influence of the types of initiator,reation time and reaction temperature on the yield of DAPAs were investigated.The products were characterized by NMR and MS.By using DHPA,DTMPPA and DDPA(10%in kerosene)as extractants,the extraction of Co2 +and Ni2 +in sulphate medium at different equilibrium pH values were measured.The results show that the maximum yield of DHPA, DTMPPA and DDPA can all be achieved at about 130℃under the initiation of di-tert-butyl peroxide(DTBP).All the extraction of cobalt with respect to DHPA,DDPA and DTMPPA precedes that of nickel.The difference in pH1/2 value(defined as the pH at which 50%metal extraction occurs)between cobalt and nickel increases in the following sequence from large to small:DHPA,DDPA and DTMPPA,which indicates that the separation ability for cobalt and nickel ascends from DHPA,DDPA to DTMPPA.展开更多
The synthesis of a thioether inserted, core-shell structured polymer from the scaffold of hyperbranched polyglycerol (PG) was described. PG was first allyl functionalized, and in the presence of AlBN, the allyl groups...The synthesis of a thioether inserted, core-shell structured polymer from the scaffold of hyperbranched polyglycerol (PG) was described. PG was first allyl functionalized, and in the presence of AlBN, the allyl groups further underwent radical addition to thiol compounds, thus thiol functional polyethylene oxide monomether (MPEO) were grafted onto PG. Similarly, 2-mercaptoethylammonium chloride was introduced onto PG via thiol addition, and the residual amino groups were further quaternized with decyl bromide, leading to an amphiphilic core-shell structure polymer. (c) 2007 De Cheng Wan. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved.展开更多
Unnatural amino acids(UAAs)have broad applications in pharmaceutical sciences and biological studies.Current synthetic methods for UAAs mainly rely on asymmetric catalysis and often require several steps.There is a la...Unnatural amino acids(UAAs)have broad applications in pharmaceutical sciences and biological studies.Current synthetic methods for UAAs mainly rely on asymmetric catalysis and often require several steps.There is a lack of direct and simple methods.To address this challenge,we designed the LADA(labeling-activation-desulfurization-addition)strategy:selective labeling and activation of cysteine residues,the photocatalytic desulfurization and the subsequent radical addition to alkenes.Although composed of two steps,it is one-pot synthesis and has advantages such as high functional group tolerance,biocompatible reaction condition,and retained stereochemistry.This highly efficient strategy was successfully applied in the direct synthesis of unnatural amino acids and modifications of peptides with more than 50 examples.展开更多
Nylon-6 has been modified by polyorganosiloxane. It was realized by radical addition of caprolactam to the vinyl group of silicone and anionic polymerization of the monomer in the presence of the silicone macromer. Th...Nylon-6 has been modified by polyorganosiloxane. It was realized by radical addition of caprolactam to the vinyl group of silicone and anionic polymerization of the monomer in the presence of the silicone macromer. The mechanical properties of the modified plastics are not far from that of the unmodified one whereas its frictional properties are significantly improved.展开更多
In this paper,we give definition and moduler representation of Kothe root for additive cate gories.Using these results,get inner representation of J-root and fully homomorph class of Jscmisimple additive categories.
Radical-involved allylation reactions have emerged as a powerful platform for construction of carbon-carbon and carbonheteroatom bonds, facilitating the strategic incorporation of diverse allyl moieties. Nevertheless,...Radical-involved allylation reactions have emerged as a powerful platform for construction of carbon-carbon and carbonheteroatom bonds, facilitating the strategic incorporation of diverse allyl moieties. Nevertheless, this burgeoning field still faces ongoing challenges, including limitations of radical precursors and coupling partners, and difficulties in achieving enantiocontrol. Herein, we report for the first time a highly enantioselective radical allylation involving β-keto esters with vinyl cyclopropanes utilizing a synergistic dual photoredox/nickel catalysis under visible light irradiation. The mild and redox-neutral catalytic protocol demonstrates an extensive substrate compatibility and good functional tolerance, providing access to enantioenriched β-keto esters featuring quaternary α-stereocenter with good yields and high enantioselectivities. Preliminary mechanistic studies have uncovered that the success of the reaction hinges on the dual roles of nickel catalyst, including in situ formation of photoredox sensitive substrate/Ni complex and the ensuing asymmetric radical addition step.展开更多
The functionalization of alkenes is a practical and important approach to access high value-added compounds.We herein realized the combination of energy transfer(EnT)and hydrogen atom transfer(HAT)process for the in s...The functionalization of alkenes is a practical and important approach to access high value-added compounds.We herein realized the combination of energy transfer(EnT)and hydrogen atom transfer(HAT)process for the in situ giving acyl azolium ions from the acyl electrophiles and N-heterocyclic carbenes(NHCs)catalysts under light irradiation,and developed three-component radical relay-type alkylacylation of readily available alkenes promoted by the cooperative NHC-photo cocatalysis to access structurally diversified alkylacylation products.The unique strategy for the NHC catalyst-bound acyl azoliums working as the intermolecular HAT reagent with the En T process was revealed.This protocol was also utilized to enable the late-stage functionalization of some important drugs and bioactive molecules.It featured readily bifunctionalization of alkenes,a wide range of alkenes and acyl imidazoles,mild reaction conditions,excellent selectivity,as well as broad functional group compatibility.Scale-up synthesis and a list of derivatization reactions displayed the potential synthetic application.Control experimental investigations and computational studies support that it involved the photoexcitation of in situ forming acyl azolium ions via En T process to access triplet diradical species with facile intersystem crossing,and acted as HAT reagents to undergo intermolecular HAT process,and then engaged in the following radical addition/radical-radical cross-coupling reaction with NHCs-linked radicals,resulting in alkylacylation products promoted by cooperative NHC and photocatalysis.展开更多
Unnatural amino acids(UAAs)are important building blocks in organic synthesis and drug discovery.They are also frequently integrated into peptides or proteins for biological studies.However,the direct and simplified s...Unnatural amino acids(UAAs)are important building blocks in organic synthesis and drug discovery.They are also frequently integrated into peptides or proteins for biological studies.However,the direct and simplified synthesis of UAAs remains a great challenge.At the same time,vast known peptide modifications are based on carbon-heteroatom bonds.There are no general methods for peptide modifications via the construction of C–C bonds.To address this challenge,herein we propose the LADA strategy,which is composed of two steps:the selective labeling and activation of cysteine residues,the desulfurization to generate carbon-centered radical and the radical addition to alkenes to build C–C bond.This one-pot protocol has obvious advantages such as good functional group tolerance,biocompatible reaction conditions,and retained stereochemistry.This strategy was successfully utilized for the synthesis of unnatural amino acids and direct modifications of peptides.展开更多
基金supports from the National Natural Science Foundation of China(No.50273035)and Hefei Ketian Chemical Industry Co.,Ltd.
文摘Fluorinated poly（ethylene oxide） propyl-b-polydimethylsiloxane-b-propyl fluorinated poly（ethylene oxide） （FPEO-b-PDMS-b- FPEO） was synthesized by a free radical addition of carbon-hydrogen of polyether segments of poly（ethylene oxide） propyl-b- polydimethylsiloxane-b-propyl poty（ethylene oxide） （PEO-b-PDMS-b-PEO） to hexafluoropropylene （HFP） using tert-butyl peroxypivalate as an initiator. In order to reduce the possibility of side reaction, the protection and deprotection via silylation were used for the end-hydroxyls in PEO-b-PDMS-b-PEO chain. The structure of Intermediates and FPEO-b-PDMS-b-FPEO was confirmed by means of Fourier transform infrared and 1H NMR spectroscopy. The effects of amount of initiator, reaction temperature and time on free radical addition were investigated in detail. 2009 Xing Yuan Zhang. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved.
基金the following institutions for their financial support:T.J.thanks Guangdong Basic and Applied Basic Research Foundation,China(grant nos.2021B1515120046 and 2022B1515120075)the Science and Technology Innovation Commission of Shenzhen Municipality,China(grant nos.JCYJ20220818101404010 and 20220815113214003)+4 种基金High-Level of Special Funds,China(grant no.G03050K003)the National Natural Science Foundation of China(grant no.22078263)the National Key R&D Program of China(grant no.2022YFC2106100)the Hunan Provincial Science Foundation for Distinguished Young Scholars,China(grant no.2022JJ10005)the Key Science and Technology project of Hunan Province,China(grant no.2021SK1020).
文摘With the blossom of DNA encoded library(DEL)and nucleic acid aptamer techniques,DNA-compatible reactions draw increasing attention in both the pharmaceutical industry and academia.In this regard,the incorporation of organosulfur scaffolds on DNA via the Csp2-S bond exhibits advantages but remains underrepresented.Herein,we report a mild and efficient photoredox atom transfer radical addition(ATRA)to terminal and internal alkynes with thiosulfonates catalyzed by organic photocatalyst,furnishing a wide array of E-β-arylthiol-vinyl sulfones with excellent regio-and stereoselectivity.Mechanistic investigations demonstrate that sulfonyl radical likely served as the key intermediate in this transformation.Leveraging the broad functional group tolerance and the mild and biofriendly conditions,this protocol could be adapted to simultaneously install sulfones and sulfides on DNA.More importantly,a redox-responsive fluorescent probe(10-ethyl-2-sulfonate-acridone,ESAC)could be conveniently introduced on two commonly used aptamers(AS1411 and Sgc8c),allowing their subsequent imaging studies across a series of human tumor cell lines.Remarkably,the process of ESAC-aptamers entering the cells was captured by both confocal microscopy and flow cytometry techniques,whereby most of the ESAC-aptamers exhibited green fluorescence after their cellular uptake,with the small portion remaining in the outer membrane emitting blue fluorescence.
文摘A simple one-pot reaction that serves to functionalize graphite nanosheets(graphene)and single-walled carbon nanotubes(SWNTs)with perfluorinated alkyl groups is reported.Free radical addition of 1-iodo-1H,1H,2H,2H-perfluorododecane to ortho-dichlorobenzene suspensions of the carbon nanomaterial is initiated by thermal decomposition of benzoyl peroxide.Similarly,UV photolysis of 1-iodo-perfluorodecane serves to functionalize the carbon materials.Perfluorododecyl-SWNTs,perfluorododecyl-graphene,and perfluorodecyl-graphene are characterized by infrared(IR)and Raman spectroscopy,X-ray photoelectron spectroscopy(XPS),thermogravimetric analysis(TGA),and atomic force microscopy(AFM).The products show enhanced dispersability in CHCl3 as compared to unfunctionalized starting materials.The advantage of this one-pot functionalization procedure lies in the use of pristine graphite as starting material thereby avoiding the use of harsh oxidizing conditions.
基金the National Natural Science Foundation of China(21871019,21901263,22171015)Beijing Municipal Education Committee Project(KZ202110005003,KM202110005006)Beijing Natural Science Foundation(2222003).
文摘A new electrochemical strategy for the atom transfer radical addition(ATRA)of polychloroalkanes across olefins has been realized by the synergism of paired electrolysis and halogen bonding activation.Notably,readily accessible 4,4-di-tert-butyl bipyridine(dtbpy),acting as a halogen bonding acceptor,shifted the reduction potential of C—Cl bonds positively by 110 mV.The decreased operating potential leads to a wide substrate scope and excellent functional group compatibility.A diverse array of terminal and internal alkenes such as(hetero)aryl olefins,unactive aliphatic olefins,and natural products and drugs-derived olefins were well compatible.
文摘Different reaction conditions may cause different reaction paths for cleavage of the Se-Se bonds.Further reactions of(PhSe)2 with methylenecyclopropanes(MCPs)under different conditions lead to the construction of totally different organic skeletons.Example described herein is typical for students to understand the cleavages of chemical bonds as well as the differences between free radical additions and electrophilic additions.
文摘Radical addition of polyfluoroalkyl iodides to the C=C double bond of diethyl allylphos- phonate was carried out in CH_2Cl_2-H_2O two-phase medium in the presence of sodium dithionite to give dicthyl 3-polyfluoroalkyl-2-iodopropylphosphonates(3)in excellent yields.Compounds 3 were then converted to diethyl polyfluoroalkanephosphonates(4)by zinc-reduction,Thus a facile method for preparing polyfluoroalkanephosphonates is realized.
文摘Sodium perfluoroalkanesulfinates [Cl(CF_2)n SO_2 Na (1), a, n=4; b, n=6; c, n=8] with the reduction potentials about 0.95-1.00V could be oxidized readily with various oxidizing agents such as Mn (OAc)_3·2H_2O, Ce(SO_4)_2, HgSO_4 and Co_2O_3 to generate perfluoroalkyl radicals which added to the olefins RCH=CHR′to give two kinds of adducts, namely RCH (R_f) CHXR′(3, X=H; 4, X=OAc), with good yields depending upon the solvent system used. Different oxidizing agents showed slight variation on the yields of the adducts. The reaction time could be greatly shortened at higher temperature. Thus, this reaction provides a new way for introducing a perfluoroalkyl group into olefinic compounds.
基金supported by the Natural Science Foundation of Guangxi Province(2021GXNSFBA220077,GUIKE AD23026050)National Natural Science Foundation of China(22102035 and 22162006)Innovation Project of Guangxi Graduate Education(XYCBZ2024021).
文摘Chemical functionalization of graphene is a topic of paramount importance to broaden its applications in chemistry,physics,and biological science but remains a great challenge due to its low chemical activity and poor dispersion.Here,we report a strategy for the photosynergetic electrochemical functionalization of graphene(EFG).By using chloride ion(Cl^(-))as the intercalation anions and co-reactants,the electrogenerated radicals confined in the expanded graphite layers enable efficient radical addition reaction,thus grasping crystallineperfect EFG.We found that the ultraviolet irradiation and applied voltage have increased the surface/interface concentration of Cl,thus boosting the functionalization of graphene.Theoretical calculation and experimental results verified the oxygen evolution reaction(OER)on EFG has been improved by regulating the doping of chlorine atoms.In addition,the reduced interlayer distance and enhanced electrostatic repulsion near the basal plane endow the fabricated EFG-based membrane with high salt retention.This work highlights a method for the in situ functionalization of graphene and the subsequent applications in OER and water desalination.
基金supported by the National Natural Science Foundation of China(22136005,22188102,22321004)the Strategic Priority Research Program of the Chinese Academy of Sciences(XDB36000000)。
文摘Alkenes difunctionalization reaction has been recognized as a highly important organic transformation.However,its application is significantly hindered by the reliance on homogeneous transition metal-assisted radical addition,as well as the need for additional oxidants.In this study,we report that azido-hydroxylation of alkenes can be efficiently achieved by a heterogeneous photoelectrochemical(PEC)oxidation on the BiVO_(4)photoanode,by using KN_(3)as the azido source in the presence of HCO_(3)^(-).A wide range of alkene substrates featuring diverse substituent groups can be effectively oxidized to the corresponding product with an impressive product selectivity.Electrochemical and electron paramagnetic resonance(EPR)experiments confirmed that the high performance is assigned to the interaction of hetero-radicals produced from the oxidation of N_(3)^(-)and HCO_(3)^(-).Transient spectroscopy dynamics experiments and density functional theory(DFT)analysis demonstrate that the addition order of two radical groups is attributed to their distinctive characteristics.The high reactivity of transient·N_(3)is preferentially added to the C=C double bond of alkene to form the carbon radical intermediate both kinetically and thermodynamically.The extended lifespan of persistent·CO_(3)^(-)can greatly increase the probability of paring the carbon radical intermediate,thus improving the selectivity of the azido-hydroxylation product.The present work provides a promising strategy for the difunctionalization of alkenes with the tandem addition of two radicals in the absence of homogeneous metal catalysis.
基金Projects(2007CB613506)supported by the National Basic Research Program of ChinaProjects(50674060,50734005)supported by the National Natural Science Foundation of China
文摘Three kinds of dialkylphosphinic acids(DAPAs),i.e.dihexylphophinic acid(DHPA),di-(2,4,4-trimethylpentyl) phosphinic acid(DTMPPA)and didecylphophinic acid(DDPA),were synthesized through free radical addition reaction.The influence of the types of initiator,reation time and reaction temperature on the yield of DAPAs were investigated.The products were characterized by NMR and MS.By using DHPA,DTMPPA and DDPA(10%in kerosene)as extractants,the extraction of Co2 +and Ni2 +in sulphate medium at different equilibrium pH values were measured.The results show that the maximum yield of DHPA, DTMPPA and DDPA can all be achieved at about 130℃under the initiation of di-tert-butyl peroxide(DTBP).All the extraction of cobalt with respect to DHPA,DDPA and DTMPPA precedes that of nickel.The difference in pH1/2 value(defined as the pH at which 50%metal extraction occurs)between cobalt and nickel increases in the following sequence from large to small:DHPA,DDPA and DTMPPA,which indicates that the separation ability for cobalt and nickel ascends from DHPA,DDPA to DTMPPA.
文摘The synthesis of a thioether inserted, core-shell structured polymer from the scaffold of hyperbranched polyglycerol (PG) was described. PG was first allyl functionalized, and in the presence of AlBN, the allyl groups further underwent radical addition to thiol compounds, thus thiol functional polyethylene oxide monomether (MPEO) were grafted onto PG. Similarly, 2-mercaptoethylammonium chloride was introduced onto PG via thiol addition, and the residual amino groups were further quaternized with decyl bromide, leading to an amphiphilic core-shell structure polymer. (c) 2007 De Cheng Wan. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved.
文摘Unnatural amino acids(UAAs)have broad applications in pharmaceutical sciences and biological studies.Current synthetic methods for UAAs mainly rely on asymmetric catalysis and often require several steps.There is a lack of direct and simple methods.To address this challenge,we designed the LADA(labeling-activation-desulfurization-addition)strategy:selective labeling and activation of cysteine residues,the photocatalytic desulfurization and the subsequent radical addition to alkenes.Although composed of two steps,it is one-pot synthesis and has advantages such as high functional group tolerance,biocompatible reaction condition,and retained stereochemistry.This highly efficient strategy was successfully applied in the direct synthesis of unnatural amino acids and modifications of peptides with more than 50 examples.
文摘Nylon-6 has been modified by polyorganosiloxane. It was realized by radical addition of caprolactam to the vinyl group of silicone and anionic polymerization of the monomer in the presence of the silicone macromer. The mechanical properties of the modified plastics are not far from that of the unmodified one whereas its frictional properties are significantly improved.
文摘In this paper,we give definition and moduler representation of Kothe root for additive cate gories.Using these results,get inner representation of J-root and fully homomorph class of Jscmisimple additive categories.
基金the National Natural Science Foundation of China (22171099, and 92256301)the National Key R&D Program of China (2023YFA1507203 and 2022YFA1506100)+3 种基金the Open Research Fund of School of Chemistry and Chemical Engineeringthe Fundamental Research Funds for the Central Universities of China (CCNU24JCPT016)Henan Normal University (2021YB02)the Double-Thousand Talents Plan of Jiangxi Province (jxsq2023102004)。
文摘Radical-involved allylation reactions have emerged as a powerful platform for construction of carbon-carbon and carbonheteroatom bonds, facilitating the strategic incorporation of diverse allyl moieties. Nevertheless, this burgeoning field still faces ongoing challenges, including limitations of radical precursors and coupling partners, and difficulties in achieving enantiocontrol. Herein, we report for the first time a highly enantioselective radical allylation involving β-keto esters with vinyl cyclopropanes utilizing a synergistic dual photoredox/nickel catalysis under visible light irradiation. The mild and redox-neutral catalytic protocol demonstrates an extensive substrate compatibility and good functional tolerance, providing access to enantioenriched β-keto esters featuring quaternary α-stereocenter with good yields and high enantioselectivities. Preliminary mechanistic studies have uncovered that the success of the reaction hinges on the dual roles of nickel catalyst, including in situ formation of photoredox sensitive substrate/Ni complex and the ensuing asymmetric radical addition step.
基金supported by the Fundamental Research Funds for the Central Universities(2042025kf0032)the National Natural Science Foundation of China(22271226,22171134,22071186,22071187)+1 种基金the National Key R&D Program of China(2023YFA1506700)the National Youth Talent Support Program。
文摘The functionalization of alkenes is a practical and important approach to access high value-added compounds.We herein realized the combination of energy transfer(EnT)and hydrogen atom transfer(HAT)process for the in situ giving acyl azolium ions from the acyl electrophiles and N-heterocyclic carbenes(NHCs)catalysts under light irradiation,and developed three-component radical relay-type alkylacylation of readily available alkenes promoted by the cooperative NHC-photo cocatalysis to access structurally diversified alkylacylation products.The unique strategy for the NHC catalyst-bound acyl azoliums working as the intermolecular HAT reagent with the En T process was revealed.This protocol was also utilized to enable the late-stage functionalization of some important drugs and bioactive molecules.It featured readily bifunctionalization of alkenes,a wide range of alkenes and acyl imidazoles,mild reaction conditions,excellent selectivity,as well as broad functional group compatibility.Scale-up synthesis and a list of derivatization reactions displayed the potential synthetic application.Control experimental investigations and computational studies support that it involved the photoexcitation of in situ forming acyl azolium ions via En T process to access triplet diradical species with facile intersystem crossing,and acted as HAT reagents to undergo intermolecular HAT process,and then engaged in the following radical addition/radical-radical cross-coupling reaction with NHCs-linked radicals,resulting in alkylacylation products promoted by cooperative NHC and photocatalysis.
基金supported by the Shanghai Jiao Tong University(WF220417003 to Z.S.)。
文摘Unnatural amino acids(UAAs)are important building blocks in organic synthesis and drug discovery.They are also frequently integrated into peptides or proteins for biological studies.However,the direct and simplified synthesis of UAAs remains a great challenge.At the same time,vast known peptide modifications are based on carbon-heteroatom bonds.There are no general methods for peptide modifications via the construction of C–C bonds.To address this challenge,herein we propose the LADA strategy,which is composed of two steps:the selective labeling and activation of cysteine residues,the desulfurization to generate carbon-centered radical and the radical addition to alkenes to build C–C bond.This one-pot protocol has obvious advantages such as good functional group tolerance,biocompatible reaction conditions,and retained stereochemistry.This strategy was successfully utilized for the synthesis of unnatural amino acids and direct modifications of peptides.
