Following the conventional carbon allotropes of diamond and graphite,fullerene,carbon nanotubes(CNTs) and graphene as 0D,1D and 2D graphitic macromolecules have been discovered recently in succession,declaring the unl...Following the conventional carbon allotropes of diamond and graphite,fullerene,carbon nanotubes(CNTs) and graphene as 0D,1D and 2D graphitic macromolecules have been discovered recently in succession,declaring the unlimited potential of carbon-based nanomaterials and nanotechnology.Although CNTs exhibit significant potential applications in advanced materials and other fields due to their extraordinary mechanical strength and electrical/thermal conductivity properties,their low solubility,poor wettability and bad dispersibility in common solvents and solid matrices have limited their processing and applications.Thus,the attempt to achieve wettable/processable CNTs by functionalization has attracted increasing attention in both scientific and industrial communities.In recent years,azide chemistry has been demonstrated as a powerful means to covalently modify CNTs.It consists of two major approaches:click chemistry and nitrene chemistry,which both involve the usage of various azide compounds.The former one is based on highly reactive and stereospecifical Cu(I) catalyzed azide-alkyne cycloaddition reaction;the latter one is based on the electrophilic attack to unsaturated bonds of CNTs with nitrenes as reactive intermediates formed from thermolysis or photolysis of azides.In this mini-review paper,the azide chemistry to functionalize CNTs is highlighted and the corresponding functionalization routes to build CNT-based complex structures are also discussed.Besides,covalent functionalizations of other graphitic nanomaterials such as fullerence and graphene,via azide chemistry,are commented briefly.展开更多
α-Imino metal carbenes are versatile intermediates in organic synthesis,and have broad applications in the assembly of divergent N-heterocycles.However,the catalytic enantioselective desymmetrization based onα-imino...α-Imino metal carbenes are versatile intermediates in organic synthesis,and have broad applications in the assembly of divergent N-heterocycles.However,the catalytic enantioselective desymmetrization based onα-imino metal carbenes has not been developed to date.Herein,we disclose an enantioselective desymmetrizing C(sp^(2))-H functionalization of azide-ynamides viaα-imino copper carbenes,leading to the efficient assembly of divergent chiral indoloazepines in generally moderate to excellent yields with high enantioselectivities.Notably,this reaction represents the first enantioselective desymmetrization based onα-imino metal carbenes.Further synthetic transformations and biological tests show the potential utility of this method.Moreover,computational studies are employed to elucidate the reaction mechanism and the origin of enantioselectivity.展开更多
Nitrene transfer reactions are powerful tools in synthetic organic chemistry.In recent years,transitionmetal catalyzed nitrene transfer reactions with carbamates as the nitrene precursors have been widely pursued.Such...Nitrene transfer reactions are powerful tools in synthetic organic chemistry.In recent years,transitionmetal catalyzed nitrene transfer reactions with carbamates as the nitrene precursors have been widely pursued.Such species undergoes facile C-H amination,aziridination,and bifunctionalization of alkenes under the catalysis of different transition metals including Rh,Fe,Ru and others,enabling the efficient construction of various nitrogen-containing molecules.In this review,the recent developments in nitrene transfer reactions with carbamates via N-O bond cleavage were introduced based on different types of reaction,and the key mechanistic information and synthetic applications of the methodologies were discussed.展开更多
The palladium（o）-catalyzed nitrogen insertion into cyclic Si-Si bonds has been realized by using N-tosylhydrazones/diazo compounds as the nitrogen source. The palladium（Ⅱ） nitrene formation and subsequent migrato...The palladium（o）-catalyzed nitrogen insertion into cyclic Si-Si bonds has been realized by using N-tosylhydrazones/diazo compounds as the nitrogen source. The palladium（Ⅱ） nitrene formation and subsequent migratory insertion process are proposed as the key steps for this reaction.展开更多
A facile synthesis of various allyl sulfonamides based on imidation of allyl sulfides with chloramine-T and sub- sequent [2,3]-sigmatropic rearrangement has been achieved without metal catalysts. The reaction complete...A facile synthesis of various allyl sulfonamides based on imidation of allyl sulfides with chloramine-T and sub- sequent [2,3]-sigmatropic rearrangement has been achieved without metal catalysts. The reaction completes smoothly within 10 min, providing excellent yields in environment friendly solvent of alcohol. Functional groups such as bromine, hydroxyl, protected amido and aldehyde are tolerant under this condition.展开更多
The isomerizations of singlet and triplet silyl nitrene are studied using ab initio method ofquantum chemistry.The singlet transition state has been optimized.The mechanism proposed here is thatthe triplet species tra...The isomerizations of singlet and triplet silyl nitrene are studied using ab initio method ofquantum chemistry.The singlet transition state has been optimized.The mechanism proposed here is thatthe triplet species transforms first to singlet one through intersystem crossing and then the isomerization re-action takes place.The difference of energies between the triplet and singlet species has been obtained.Theactive barrier and the reaction energy have been calculated.The relative structure data of reactants,transi-tion state and products are given.展开更多
C-H amination by iron-imido/nitrene species has attracted increasing research interest in recent years because of its potential use in economical and environmentally benign syntheses of amino compounds.With the aim of...C-H amination by iron-imido/nitrene species has attracted increasing research interest in recent years because of its potential use in economical and environmentally benign syntheses of amino compounds.With the aim of providing a comprehensive overview of this field,which is of interest to both the synthetic organic and inorganic communities,this paper reviews the status quo of C-H amination chemistry by iron-imido/nitrene intermediates,as well as by well-defined iron-imido/nitrene compounds,with special emphasis on their structure/reactivity correlations.Achievements,problems,and perspectives in this growing field are discussed.展开更多
Main observation and conclusion A redox-neutral Fe-catalyzed intramolecular C-H amidation of N-benzoyloxyureas is described.This methodology employs a simple iron complex in situ generated from Fe(OTf)2 and bipyridine...Main observation and conclusion A redox-neutral Fe-catalyzed intramolecular C-H amidation of N-benzoyloxyureas is described.This methodology employs a simple iron complex in situ generated from Fe(OTf)2 and bipyridine as the catalyst and N-benzoyloxyureas as the nitrene precursors without using exogenous oxidants.An array of cyclic ureas were synthesized via aliphatic C(sp^(3))-H amidation in excellent yields.In addition,this catalytic system is also amenable to aryl C(sp^(2))-H nitrene insertion to provide benzimidazolones in moderate yields.展开更多
Chiral β-amino alcohols are important building blocks for the synthesis of drugs, natural products, chiral auxiliaries, chiral ligands and chiral organocatalysts. The catalytic asymmetric β-amination of alcohols off...Chiral β-amino alcohols are important building blocks for the synthesis of drugs, natural products, chiral auxiliaries, chiral ligands and chiral organocatalysts. The catalytic asymmetric β-amination of alcohols offers a direct strategy to access this class of molecules. Herein, we report a general intramolecular C(sp^(3))–H nitrene insertion method for the synthesis of chiral oxazolidin-2-ones as precursors of chiral β-amino alcohols. Specifically, the ring-closing C(sp^(3))–H amination of N-benzoyloxycarbamates with 2 mol% of a chiral ruthenium catalyst provides cyclic carbamates in up to 99% yield and with up to 99% ee.The method is applicable to benzylic, allylic, and propargylic C–H bonds and can even be applied to completely non-activated C(sp^(3))–H bonds, although with somewhat reduced yields and stereoselectivities. The obtained cyclic carbamates can subsequently be hydrolyzed to obtain chiral β-amino alcohols. The method is very practical as the catalyst can be easily synthesized on a gram scale and can be recycled after the reaction for further use. The synthetic value of the new method is demonstrated with the asymmetric synthesis of a chiral oxazolidin-2-one as intermediate for the synthesis of the natural product aurantioclavine and chiral β-amino alcohols that are intermediates for the synthesis of chiral amino acids, indane-derived chiral Box-ligands, and the natural products dihydrohamacanthin A and dragmacidin A.展开更多
Density functional theory(DFT) calculations are performed to investigate recent experimentally studied ring-closing sulfoxide imidation catalyzed by Fe(Ⅱ)-phthalocyanine(FeⅡPc). Our results reveal that the ground st...Density functional theory(DFT) calculations are performed to investigate recent experimentally studied ring-closing sulfoxide imidation catalyzed by Fe(Ⅱ)-phthalocyanine(FeⅡPc). Our results reveal that the ground state of iron phthalocyanine nitrene intermediate(PcFeNR, R =(CH_(2))_(3)(SO)Ph), which is believed to mediate the intramolecular imitation, is triplet state featuring a diradical structure. The formation of Pc Fe NR is the result of a denitrification process with a calculated high-barrier of 23.4 kcal/mol which is in good agreement with the experimentally observed high reaction temperature of 100 ℃. The generated Pc Fe NR undergoes a low-barrier intramolecular nucleophilic attack by proximal nitrogen atom on the sulfur accomplishing the cyclization of sulfoxide. This study provides theoretical insights into the mechanism-based design of useful catalysts for nitrene transfer reactions.展开更多
基金financially supported by the National Natural Science Foundation of China (No.50773038,and No.20974093)National Basic Research Program of China (973 Program) (No.2007CB936000)+3 种基金the Fundamental Research Funds for the Central Universities (2009QNA4040)Qianjiang Talent Foundation of Zhejiang Province (2010R10021)the Foundation for the Author of National Excellent Doctoral Disser-tation of China (No.200527)China Postdoctoral Science Foundation (No.20100471707)
文摘Following the conventional carbon allotropes of diamond and graphite,fullerene,carbon nanotubes(CNTs) and graphene as 0D,1D and 2D graphitic macromolecules have been discovered recently in succession,declaring the unlimited potential of carbon-based nanomaterials and nanotechnology.Although CNTs exhibit significant potential applications in advanced materials and other fields due to their extraordinary mechanical strength and electrical/thermal conductivity properties,their low solubility,poor wettability and bad dispersibility in common solvents and solid matrices have limited their processing and applications.Thus,the attempt to achieve wettable/processable CNTs by functionalization has attracted increasing attention in both scientific and industrial communities.In recent years,azide chemistry has been demonstrated as a powerful means to covalently modify CNTs.It consists of two major approaches:click chemistry and nitrene chemistry,which both involve the usage of various azide compounds.The former one is based on highly reactive and stereospecifical Cu(I) catalyzed azide-alkyne cycloaddition reaction;the latter one is based on the electrophilic attack to unsaturated bonds of CNTs with nitrenes as reactive intermediates formed from thermolysis or photolysis of azides.In this mini-review paper,the azide chemistry to functionalize CNTs is highlighted and the corresponding functionalization routes to build CNT-based complex structures are also discussed.Besides,covalent functionalizations of other graphitic nanomaterials such as fullerence and graphene,via azide chemistry,are commented briefly.
基金supported by the National Natural Science Foundation of China(22331004,22125108 and 22121001)the National Fund for Fostering Talents of Basic Science NFFTBS(J1310024)。
文摘α-Imino metal carbenes are versatile intermediates in organic synthesis,and have broad applications in the assembly of divergent N-heterocycles.However,the catalytic enantioselective desymmetrization based onα-imino metal carbenes has not been developed to date.Herein,we disclose an enantioselective desymmetrizing C(sp^(2))-H functionalization of azide-ynamides viaα-imino copper carbenes,leading to the efficient assembly of divergent chiral indoloazepines in generally moderate to excellent yields with high enantioselectivities.Notably,this reaction represents the first enantioselective desymmetrization based onα-imino metal carbenes.Further synthetic transformations and biological tests show the potential utility of this method.Moreover,computational studies are employed to elucidate the reaction mechanism and the origin of enantioselectivity.
基金the financial support provided by the National Natural Science Foundation of China(Nos.21572163 and 21873074)the Wenzhou Science&Technology Bureau(No.G20210032)。
文摘Nitrene transfer reactions are powerful tools in synthetic organic chemistry.In recent years,transitionmetal catalyzed nitrene transfer reactions with carbamates as the nitrene precursors have been widely pursued.Such species undergoes facile C-H amination,aziridination,and bifunctionalization of alkenes under the catalysis of different transition metals including Rh,Fe,Ru and others,enabling the efficient construction of various nitrogen-containing molecules.In this review,the recent developments in nitrene transfer reactions with carbamates via N-O bond cleavage were introduced based on different types of reaction,and the key mechanistic information and synthetic applications of the methodologies were discussed.
基金The project is supported by the National Basic Research Pro- gram of China （973 Program, No. 2015CB856600） and the Natio- anal Natural Science Foundation of China （Grant 21332002, 21472004）.
文摘The palladium（o）-catalyzed nitrogen insertion into cyclic Si-Si bonds has been realized by using N-tosylhydrazones/diazo compounds as the nitrogen source. The palladium（Ⅱ） nitrene formation and subsequent migratory insertion process are proposed as the key steps for this reaction.
文摘A facile synthesis of various allyl sulfonamides based on imidation of allyl sulfides with chloramine-T and sub- sequent [2,3]-sigmatropic rearrangement has been achieved without metal catalysts. The reaction completes smoothly within 10 min, providing excellent yields in environment friendly solvent of alcohol. Functional groups such as bromine, hydroxyl, protected amido and aldehyde are tolerant under this condition.
基金the National Natural Science Foundation of China
文摘The isomerizations of singlet and triplet silyl nitrene are studied using ab initio method ofquantum chemistry.The singlet transition state has been optimized.The mechanism proposed here is thatthe triplet species transforms first to singlet one through intersystem crossing and then the isomerization re-action takes place.The difference of energies between the triplet and singlet species has been obtained.Theactive barrier and the reaction energy have been calculated.The relative structure data of reactants,transi-tion state and products are given.
基金supported by the National Basic Research Program of China(2011CB808705)the National Natural Science Foundation of China(21002114 and 20872168)
文摘C-H amination by iron-imido/nitrene species has attracted increasing research interest in recent years because of its potential use in economical and environmentally benign syntheses of amino compounds.With the aim of providing a comprehensive overview of this field,which is of interest to both the synthetic organic and inorganic communities,this paper reviews the status quo of C-H amination chemistry by iron-imido/nitrene intermediates,as well as by well-defined iron-imido/nitrene compounds,with special emphasis on their structure/reactivity correlations.Achievements,problems,and perspectives in this growing field are discussed.
基金the financial support from NSFC(Nos.21971198 and 21772148)Large-scale Instrument and Equipment Sharing Foundation of Wuhan University and the Natural Science Foundation of Hubei Province(Grant No.2020CFA036)。
文摘Main observation and conclusion A redox-neutral Fe-catalyzed intramolecular C-H amidation of N-benzoyloxyureas is described.This methodology employs a simple iron complex in situ generated from Fe(OTf)2 and bipyridine as the catalyst and N-benzoyloxyureas as the nitrene precursors without using exogenous oxidants.An array of cyclic ureas were synthesized via aliphatic C(sp^(3))-H amidation in excellent yields.In addition,this catalytic system is also amenable to aryl C(sp^(2))-H nitrene insertion to provide benzimidazolones in moderate yields.
基金supported by the Deutsche Forschungsgemeinschaft(ME 1805/15-1)。
文摘Chiral β-amino alcohols are important building blocks for the synthesis of drugs, natural products, chiral auxiliaries, chiral ligands and chiral organocatalysts. The catalytic asymmetric β-amination of alcohols offers a direct strategy to access this class of molecules. Herein, we report a general intramolecular C(sp^(3))–H nitrene insertion method for the synthesis of chiral oxazolidin-2-ones as precursors of chiral β-amino alcohols. Specifically, the ring-closing C(sp^(3))–H amination of N-benzoyloxycarbamates with 2 mol% of a chiral ruthenium catalyst provides cyclic carbamates in up to 99% yield and with up to 99% ee.The method is applicable to benzylic, allylic, and propargylic C–H bonds and can even be applied to completely non-activated C(sp^(3))–H bonds, although with somewhat reduced yields and stereoselectivities. The obtained cyclic carbamates can subsequently be hydrolyzed to obtain chiral β-amino alcohols. The method is very practical as the catalyst can be easily synthesized on a gram scale and can be recycled after the reaction for further use. The synthetic value of the new method is demonstrated with the asymmetric synthesis of a chiral oxazolidin-2-one as intermediate for the synthesis of the natural product aurantioclavine and chiral β-amino alcohols that are intermediates for the synthesis of chiral amino acids, indane-derived chiral Box-ligands, and the natural products dihydrohamacanthin A and dragmacidin A.
基金Supported by the NSFC (21933009)the Strategic Priority Research Program of the Chinese Academy of Sciences (XDB20000000)。
文摘Density functional theory(DFT) calculations are performed to investigate recent experimentally studied ring-closing sulfoxide imidation catalyzed by Fe(Ⅱ)-phthalocyanine(FeⅡPc). Our results reveal that the ground state of iron phthalocyanine nitrene intermediate(PcFeNR, R =(CH_(2))_(3)(SO)Ph), which is believed to mediate the intramolecular imitation, is triplet state featuring a diradical structure. The formation of Pc Fe NR is the result of a denitrification process with a calculated high-barrier of 23.4 kcal/mol which is in good agreement with the experimentally observed high reaction temperature of 100 ℃. The generated Pc Fe NR undergoes a low-barrier intramolecular nucleophilic attack by proximal nitrogen atom on the sulfur accomplishing the cyclization of sulfoxide. This study provides theoretical insights into the mechanism-based design of useful catalysts for nitrene transfer reactions.
