N-heterocyclic carbene-catalyzed enantioselective kinetic resolutions,dynamic kinetic resolutions,and desymmetrization reactions are systematically reviewed.The content is organized according to the activation modes i...N-heterocyclic carbene-catalyzed enantioselective kinetic resolutions,dynamic kinetic resolutions,and desymmetrization reactions are systematically reviewed.The content is organized according to the activation modes involved in these transformations.Future advances within this highly active research field are discussed from our perspectives on the topic.展开更多
Enones are widely explored in synthetic chemistry as fundamental building blocks for a wide range of reactions and exhibit intriguing biological activities that are pivotal for drug discovery.The development of synthe...Enones are widely explored in synthetic chemistry as fundamental building blocks for a wide range of reactions and exhibit intriguing biological activities that are pivotal for drug discovery.The development of synthetic strategies for highly efficient preparation of enones thereby receives intense attention,in particular through the transition metal-catalyzed coupling reactions.Here,we describe a carbene-catalyzed cross dehydrogenative coupling(CDC)reaction that enables effective assembly of simple aldehydes and alkenes to afford a diverse set of enone derivatives.Mechanistically,the in situ generated aryl radical is pivotal to“activate”the alkene by forming an allyl radical through intermolecular hydrogen atom transfer(HAT)pathway and thus forging the carbon-carbon bond formation with aldehyde as the acyl synthon.Notably,our method represents the first example on the enone synthesis through coupling of“non-functionalized”aldehydes and alkenes as coupling partners,and offers a distinct organocatalytic pathway to the transition metal-catalyzed coupling transformations.展开更多
Organoseleniums exhibit a diverse set of biological activities that are pivotal for drug discovery and are widely explored in synthetic chemistry and material science.While many transformations have been developed for...Organoseleniums exhibit a diverse set of biological activities that are pivotal for drug discovery and are widely explored in synthetic chemistry and material science.While many transformations have been developed for non-enantioselective C–Se bond formations,the catalyst-controlled stereoselective preparation of chiral organoseleniums continues to be of considerable challenge.In particular,there are limited studies on the enantioselective seleno-Michael addition reactions to access chiral selenium functional molecules.Here,we disclose a carbene-catalyzed highly enantioselective nucleophilic C–Se bond construction through formal[3+3]annulations between selenocarboxamides and bromoenals,affording seleno-thiazinone products with good yields and excellent enantioselectivities.The choice of a weak inorganic base was pivotal to suppressing the unproductive racemization and decomposition of the selenium products.Notably,the catalytically generated chiral selenium-containing heterocyclic products feature remarkable antimicrobial activities that could serve as promising lead scaffolds for further agrochemical development.展开更多
Silyl cobalt species are putative intermediates in cobalt-catalyzed transformations of hydrosilanes.However,their reactivity has remained poorly understood.Reported here is the investigation on four-coordinate disilyl...Silyl cobalt species are putative intermediates in cobalt-catalyzed transformations of hydrosilanes.However,their reactivity has remained poorly understood.Reported here is the investigation on four-coordinate disilyl Co(Ⅱ)complexes with N-hetereocyclic carbene ligation.The reactions of[(ICy)_(2)Co(vtms)](ICy=1,3-dicyclohexylimidazol-2-ylidene,vtms=vinyltrimethylsilane)with primary and secondary hydrosilanes(3 equiv.)furnish the four-coordinate disilyl complexes[trans-(ICy)_(2)Co(SiHRR')_(2)](SiHRR'=SiH_(2)Mes,1;SiH_(2)Ph,2;SiH_(2)Cy,3;SiHPh_(2),4;SiHEt_(2),5)in moderate to good yields.The structures of 1,2 and 4 were established by single-crystal X-ray diffraction.Solution magnetic susceptibility measurement and EPR spectroscopy indicate their low-spin nature(S=1/2).Reactivity studies on 4 led to the establishment of the conversions of 4 to the disilyl dihydride Co(Ⅲ)complex[K(THF)][(ICy)_(2)Co(H)_(2)(SiHPh_(2))_(2)]_n(6)and the fluorosilyl Co(Ⅱ)complex[(ICy)_(2)Co(THF)(SiFPh_(2))][BF_(4)](7)when 4 was treated with excess amount of K and AgBF_(4),respectively,in THF.These conversions hint at the high activity of low-valent and high-valent disilyl cobalt species[trans-(ICy)_(2)Co(SiHPh_(2))_(2)]^(1-)and[trans-(ICy)_(2)Co(SiHPh_(2))_(2)]^(2+).Complex 4 is reactive toward terminal alkynes,but inert toward alkenes and internal alkynes.The reactions of 4 with terminal alkynes CyC≡CH and Me_(3)SiC≡CH(3 equiv.)yield the Co(Ⅱ)complexes[(ICy)_(2)Co(C≡CCy)_(2)](8)and[(ICy)_(2)Co(C≡CSiMe_(3))((SiMe_(3))C=CH_(2))](9),respectively,along with H_(2)SiPh_(2)and alkynylsilanes RC≡CSiHPh_(2)(R=Cy,SiMe_(3)),whereas the reaction with 4-CF_(3)C_(6)H_(4)C≡CH(3 equiv.)produce[(ICy)_(2)Co(C≡CAr)((Ar)C=CH(SiHPh_(2))C=CHAr)](Ar=4-CF_(3)C_(6)H_(4))(10)and H_(2)SiPh_(2).These reactions are proposed to involveσ-bond metathesis reactions between alkyne C(sp)-H bonds and Co-Si bonds in 4.Complexes 6–10 have been characterized by NMR spectroscopy,X-ray diffraction study,and elemental analysis.展开更多
N-heterocyclic carbene-catalyzed reactions for the formation of aromatic compounds are reviewed.The reactions are subdivided into 4 types based on their activation modes.A brief summary on the achievements and the cha...N-heterocyclic carbene-catalyzed reactions for the formation of aromatic compounds are reviewed.The reactions are subdivided into 4 types based on their activation modes.A brief summary on the achievements and the challenges remaining in Nheterocyclic carbene(NHC)-catalyzed arene construction processes is provided at the end of this review.An outlook into the future research direction within this field is also given based on our own opinion and knowledge on the trends of the development of NHC organocatalysis.展开更多
N-Heterocyclic carbene(NHC)-based cages have emerged as a prominent and dynamic research area within the research field of chemistry. Leveraging the distinctive electronic and steric properties of NHC ligands, the des...N-Heterocyclic carbene(NHC)-based cages have emerged as a prominent and dynamic research area within the research field of chemistry. Leveraging the distinctive electronic and steric properties of NHC ligands, the design, synthesis, and application of these corresponding cages have garnered substantial scholarly interest. In recent years, we have witnessed the successful fabrication of diverse NHC-based cages through a range of synthetic methodologies, which hold significant potential for applications in molecular recognition and catalysis. In this review, we delve into the foundational synthetic strategies that underlie the creation of NHC-based cages, employing approaches encompassing metal–NHC chelation, coordination assembly,and covalent bonding. Additionally, we compile the diverse applications of these cages within catalytic processes and molecular recognition. Lastly, we shed light on the current limitations of synthesis and outline future trends in the development of NHCbased cages.展开更多
Axially chiral biaryls represent the most important class of atropisomers,and they widely exist in natural products and biologically active molecules.They also constitute a unique scaffold for chiral ligands and catal...Axially chiral biaryls represent the most important class of atropisomers,and they widely exist in natural products and biologically active molecules.They also constitute a unique scaffold for chiral ligands and catalysts in organic synthesis.The development of synthetic methods to obtain such chiral compounds has received widespread attention,among which catalytically atroposelective ring-opening of configurationally labile compounds represents one of the most attractive strategies.Various substrates with strained cyclic structures,such as the renowned Bringmann's lactones,can undergo asymmetric transformation into stable atropisomers.Known advancement primarily relies on metal catalyst combined with well-designed chiral ligands,the approaches utilizing organocatalysis as a critical resolution strategy are notably scarce.In this study,we disclosed a N-heterocyclic carbene(NHC)-catalyzed asymmetric ring-opening reaction of biaryl lactams via direct atroposelective nucleophilic activation.The optimized bulky carbene catalyst ensures that the reaction can proceed under mild conditions,affording the desired product with good to excellent yields and atroposelectivity.展开更多
The highly efficient method has been developed for the synthesis of NHC·VOCl_(3) containing symmetrical or unsymmetrical Nheterocyclic carbene(NHC) ligands by the transmetallation reaction of NHC·AgCl with V...The highly efficient method has been developed for the synthesis of NHC·VOCl_(3) containing symmetrical or unsymmetrical Nheterocyclic carbene(NHC) ligands by the transmetallation reaction of NHC·AgCl with VOCl_(3).The total isolated yield of VOCl_(3)[1,3-(2,4,6-Me_(3)C_(6)H_(2))_(2)(NCH=)_(2)C:](V4') reached 86% by transmetallation reaction,which is much higher than that(48%) by direct coordination method.This methodology has also been used to synthesize the novel vanadium complexes containing unsymmetrical NHC ligands of VOCl_(3)[PhCH_(2)NCH=CHNR)C:](V5',R=2,4,6-Me_(3)C_(6)H_(2);V6',R=2,4-Me_(2)-6-Ph-C_(6)H_(2);V7',R=2,6-^(i)Pr_(2)-C_(6)H_(3)) with high yield,which could not be obtained by direct coordination method.The catalytic activity and copolymerization ability would be improved by introducing unsymmetrical NHC ligands due to their less steric bulky effect.The vanadium complex V5' containing unsymmetrical NHC ligand exhibits higher catalytic activity(3.7×10^(5)g_(copolymer)·mol^(-1) of V·h^(-1)) than that of V4' containing symmetrical NHC ligand.Moreover,the higher propylene incorporation ratio(45.6 mol%) in the copolymers of ethylene with propylene could be obtained by using V5' than that(39.9%) by using V4'.The results would provide a highly efficient strategy for the synthesis of early transition metal complexes containing versitile NHC ligands,affording the catalyst with both high catalytic activity and copolymerization ability for the synthesis of high performance polyolefin elastomers.展开更多
The fluoroalkyl fragment plays a vital role in various fields such as pharmaceuticals and materials science, and has a significant impact on human life not only on the present but also in the future. The insertion of ...The fluoroalkyl fragment plays a vital role in various fields such as pharmaceuticals and materials science, and has a significant impact on human life not only on the present but also in the future. The insertion of fluoroalkyl groups into the chemical skeletons can cause considerable alternations in the chemical, physical and biological properties of molecules, which has attracted numerous scientists from different fields. This review focuses on N-heterocyclic carbene(NHC)-catalyzed fluoroalkylation reactions, providing a detailed analysis and summary of the achievements in the past two decades. Many successful examples clearly indicate that NHCs can catalyze the tranformation of fluoroalkylation reagents with various electronic characteristics, whether electrophilic, nucleophilic, or radical precursors. Herein, the fluoroalkylation reactions are classified based on different catalytic modes of NHCs: Lewis base catalysis, Umploung catalysis, radical catalysis and others. Meanwhile, by refining and systematically studying the contribution of NHC catalysis in fluoroalkylation reactions, this review is expected to provide valuable insights and enlightenment for related fields.展开更多
An efficiently catalytic method toward the synthesis of indolin-2-ones featuring an allylic derived C_(3)-quaternary stereocenter via an intramolecular Heck cyclization/Suzuki coupling of N-substituted-N-(2-bromopheny...An efficiently catalytic method toward the synthesis of indolin-2-ones featuring an allylic derived C_(3)-quaternary stereocenter via an intramolecular Heck cyclization/Suzuki coupling of N-substituted-N-(2-bromophenyl)acrylamides and organoboron reagents was successfully developed by using a 1,3-bis(2,6-diisopropylphenyl)acenaphthoimidazol-2-ylidene(AnIPr)-ligated oxazoline palladacycle.It enabled a very broad substrate scope tolerating different functional groups,electronic properties and steric bulkiness.Notably,it revealed a great potential to build diverse heterocycle-fused indoline alkaloids via the same intermediate 3-allyl-1,3-dimethylindolin-2-one.展开更多
We report herein an unprecedented N-heterocyclic carbene-catalyzed formal[3+3]annulation of ynals with N-Ts indolin-3-ones under the oxidation condition affording the functionalized pyrano[3,2-b]indol-2-ones.The alkyn...We report herein an unprecedented N-heterocyclic carbene-catalyzed formal[3+3]annulation of ynals with N-Ts indolin-3-ones under the oxidation condition affording the functionalized pyrano[3,2-b]indol-2-ones.The alkynyl acylazoliums via the combination of a carbene with ynals in the presence of oxidate proved to be the important intermediates for the success of this transformation.This method features a broad substrate scope and mild conditions,including axially chiral skeletons with suitable substitutions.展开更多
Transition-metal-catalyzed asymmetric alkylation of aldehydes represents a straightforward strategy for the synthesis of chiral secondary alcohols.However,efficient methods using organoborons as coupling reagents are ...Transition-metal-catalyzed asymmetric alkylation of aldehydes represents a straightforward strategy for the synthesis of chiral secondary alcohols.However,efficient methods using organoborons as coupling reagents are rare.Herein,we report a highly enantioselective nickel-catalyzed alkylation reaction of aldehydes,using readily available alkylborons as nucleophiles.A wide variety of chiral secondary alcohols were prepared from commercially available aldehydes with high yields.The key to the excellent enantioselectivity and chemoselectivity was the employment of a bulky C2-symmetric chiral NHC ligand.This protocol features excellent enantiocontrol,mild conditions,and good functional group compatibility.展开更多
While N-heterocyclic carbene(NHC)catalyzed electron-pair-transfer processes have been developed into an important tool for synthetically important bond formations during the past decades,the corresponding radical reac...While N-heterocyclic carbene(NHC)catalyzed electron-pair-transfer processes have been developed into an important tool for synthetically important bond formations during the past decades,the corresponding radical reactions via NHC catalysis have only received growing attention in the past six years.Taking into account the advantages NHC-catalyzed radical reactions might bring,such as creating new activation modes that were previously unobtainable,it is worthwhile to provide a conceptual understanding of this emerging area.Therefore,herein we give an overview of NHC-catalyzed radical reactions via different synthetic techniques.展开更多
Comprehensive Summary Poly-NHC-based organometallic assemblies 3-PF6,3-SbF6 and 3-OTf were obtained and verified by NMR spectroscopy,ESI mass spectrometry and single-crystal X-ray diffraction analyses.Controllable str...Comprehensive Summary Poly-NHC-based organometallic assemblies 3-PF6,3-SbF6 and 3-OTf were obtained and verified by NMR spectroscopy,ESI mass spectrometry and single-crystal X-ray diffraction analyses.Controllable structural interconversion was observed between the poly-NHC-based organometallic assemblies and their self-aggregated dimers in solution affected by concentration,solvent and metal ion.1H NMR spectra of assembly 3-PF6 in CD3CN at different concentrations demonstrated controllable structural interconversion,and 19F NMR spectrum of assembly 3-PF6 at high concentration further evidenced the presence of the free hexafluorophosphate anion and encapsulated hexafluorophosphate anion for its two sets of signals.In addition,single-crystal X-ray diffraction analysis provided clear evidence that in the solid state,two assemblies 3-PF6 were vertically stuck,forming a self-aggregated dimer with an encapsulated hexafluorophosphate anion.Investigating the reversible structural interconversion is beneficial for revealing the intrinsic nature on the atom level and paving the way to design the stimuli-responsive functional system.展开更多
The N-heterocyclic carbene(NHC)-catalyzed reactions involving two-electron reaction pathway have been well-established.However,the development of NHC-catalyzed radical reactions is still in its infancy in terms of rea...The N-heterocyclic carbene(NHC)-catalyzed reactions involving two-electron reaction pathway have been well-established.However,the development of NHC-catalyzed radical reactions is still in its infancy in terms of reaction types and enantioselectivity.In the past decade,several elegant NHC-catalyzed radical reactions have been developed,including NHC-catalyzed oxidation of aldehydes to esters,reductive coupling reactions using Breslow intermediate as SET reductant and NHC-catalyzed reactions via radical homoenolates,dienoaltes and trienolates.This review summarizes the recent advances in NHC-catalyzed reactions involving radical intermediates.展开更多
Herein,we present a method for the homogeneous hydrogenation of nitroarenes to produce anilines using low catalyst loading(1 mo%)of copper N-heterocyclic carbene complexes as the catalyst and ammonia borane as the sou...Herein,we present a method for the homogeneous hydrogenation of nitroarenes to produce anilines using low catalyst loading(1 mo%)of copper N-heterocyclic carbene complexes as the catalyst and ammonia borane as the source of hydrogen.A wide range of nitroarenes,featuring diverse functional groups,were selectively transformed into their corresponding primary aromatic amines with high yields.This process can be readily scaled up and exhibits compatibility with various sensitive functional groups,including halogen,trifluoromethyl,aminomethyl,alkenyl,cyano,ester,amide,and hydroxyl.Notably,this catalytic methodology finds application in the synthesis of essential drug compounds.Mechanistic investigations suggest that the in-situ-generated Cu-H species may serve as active intermediates,with reduction pathways involving species such as azobenzene,1,2-diphenylhydrazine,nitrosobenzene,and N-phenylhydroxylamine.展开更多
While nickel(II)complexes have been widely used as catalysts for carbon-carbon coupling reactions,the exploration of their photophysical and photochemical properties is still in the infancy.Here,a series of square-pla...While nickel(II)complexes have been widely used as catalysts for carbon-carbon coupling reactions,the exploration of their photophysical and photochemical properties is still in the infancy.Here,a series of square-planar Ni(II)complexes[(diNHC)NiX2]bearing chelating benzimidazole-based bis(N-heterocyclic carbene)ligands and varying anionic coligands(1,X=Cl;2,X=Br;3,X=I)are synthesized and structurally characterized.In solid state,both 1 and 2 exhibit orange-red photoluminescence under ambient conditions.The photophysical and electrochemical measurements along with density functional theory(DFT)calculations reveal that the low-energy emissions can be attributed to singlet excited states with ligand-to-ligand charge-transfer(LLCT)character.This work suggests that strong-field N-heterocyclic carbene ligands play a crucial role to achieve the luminescence of Ni(II)complexes.展开更多
A pentagonal-prismatic cylinder[Ag5(L)2](PF6)5 obtained from the pentaphenylpyrrole-bridged pentaimidazolium salt H5-L(PF6)5 and AgI ions was determined by X-ray diffraction analyses.The target organometallic cylinder...A pentagonal-prismatic cylinder[Ag5(L)2](PF6)5 obtained from the pentaphenylpyrrole-bridged pentaimidazolium salt H5-L(PF6)5 and AgI ions was determined by X-ray diffraction analyses.The target organometallic cylinder not only exhibited enhanced fluorescence emission in dilute solution at room temperature but also showed an improved phosphorescence ratio compared with the free precursor and maintained a long lifetime(1.39 s)in the solid state at 77 K.Furthermore,the experimental results and DFT calculations confirmed that the formation of the organometallic cylinder promoted intersystem crossing.Meanwhile,the frontier orbitals of[Ag5(L)2](PF6)5 showed the main contribution of building block PPP as the luminescence source of[Ag5(L)2](PF6)5 by a modest heavy-atom effect.These results provide a strategy for constructing enhanced phosphorescent emission and long lifetime organometallic supramolecular phosphorescent materials.展开更多
In this study,firstly,3-bromopropanenitrile(2a),ethyl bromoacetate(2b),and 2-bromoethan-1-amine(2c)were added to 5,6-dimethylbenzimidazole(1)and symmetrically-connected N-heterocyclic carbenes(NHC)[(3a-3c)]were synthe...In this study,firstly,3-bromopropanenitrile(2a),ethyl bromoacetate(2b),and 2-bromoethan-1-amine(2c)were added to 5,6-dimethylbenzimidazole(1)and symmetrically-connected N-heterocyclic carbenes(NHC)[(3a-3c)]were synthesized.Then,the NHC precursor compounds were reacted with PdCl2 and Pd(Ⅱ)-NHC complexes[(4a—4c)]were obtained.The synthesized NHC precursors(3a-3c)and Pd(Ⅱ)-NHC complexes(4a—4c)were characterized by different spectroscopic methods.The antibacterial activities of these products were measured against bacteria and fungus with the disc diffusion method.Pd(Ⅱ)-NHC complexes had higher antibacterial activity than the NHC precursors.The synthesized compounds showed antimicrobial activity with different properties from each other.In vitro biological activities of salts and metal complexes on selected bacteria were determined by the broth dilution method based on Clinical and Laboratory Standards Institute guidelines.1,3-Bis-(2-hydroxyethyl)imidazolinium bromide and 3-(2-ethoxy-2-oxoethyl)-1-(3-aminopropyl)-^(1)H-imidazole-3-ium bromide had activity against Escherichia coli.展开更多
Developing discrete radical organometallic nanocages is essential for fabricating functional materials.In this study,we construct a series of poly-NHC-based(NHC=N-heterocyclic carbene)organometallic nanocages 3a-3c wi...Developing discrete radical organometallic nanocages is essential for fabricating functional materials.In this study,we construct a series of poly-NHC-based(NHC=N-heterocyclic carbene)organometallic nanocages 3a-3c with different sizes by employing redox-active bis(triarylamine)derivatives with differentπ-conjugated spacers as building blocks.The varied sizes of nanocages 3a-3c modulate the distance of the redox-active centers and reversibly convert them to radical nanocages 3a^(2+)-3c^(2+)through chemical and electrochemical oxidation.Radical nanocages 3a^(2+)-3c^(2+)display clear bond and angle alteration and retention of their three-dimensional topologies.This work not only merely proves that these nanocages are excellent stimulus-responsive materials but also opens a door to the rational design of novel radical organometallic nanocages.展开更多
基金supported by the National Natural Science Foundation of China (21961006,32172459,22371057)Science and Technology Department of Guizhou Province (Qiankehejichu-ZK[2021]Key033)+1 种基金Program of Introducing Talents of Discipline to Universities of China (111 Program,D20023) at Guizhou UniversityFrontiers Science Center for Asymmetric Synthesis and Medicinal Molecules,Department of Education,Guizhou Province (Qianjiaohe KY (2020)004),Guizhou University (China)。
文摘N-heterocyclic carbene-catalyzed enantioselective kinetic resolutions,dynamic kinetic resolutions,and desymmetrization reactions are systematically reviewed.The content is organized according to the activation modes involved in these transformations.Future advances within this highly active research field are discussed from our perspectives on the topic.
基金funding supports from the National Natural Science Foundation of China(Nos.21732002,22061007,22071036,and 22207022)Frontiers Science Center for Asymmetric Synthesis and Medicinal Molecules,National Natural Science Fund for Excellent Young Scientists Fund Program(Overseas),the starting grant of Guizhou University[No.(2022)47)]+10 种基金Department of Education,Guizhou Province[Qianjiaohe KY No.(2020)004]The 10 Talent Plan(Shicengci)of Guizhou Province(No.[2016]5649)Science and Technology Department of Guizhou Province(Nos.[Qiankehe-jichu-ZK[2022]zhongdian024],[2018]2802,[2019]1020,QKHJC-ZK[2022]-455)Department of Education of Guizhou Province(No.QJJ(2022)205)Program of Introducing Talents of Discipline to Universities of China(111 Program,No.D20023)at Guizhou UniversitySingapore National Research Foundation under its NRF Investigatorship(No.NRF-NRFI2016–06)Competitive Research Program(No.NRF-CRP22–2019–0002)Ministry of Education,Singapore,under its MOE Ac RF Tier 1 Award(Nos.RG7/20,RG70/21)MOE AcRF Tier 2(No.MOE2019-T2–2–117)MOE AcRF Tier 3 Award(No.MOE2018-T3–1–003)a Chair Professorship Grant,and Nanyang Technological University。
文摘Enones are widely explored in synthetic chemistry as fundamental building blocks for a wide range of reactions and exhibit intriguing biological activities that are pivotal for drug discovery.The development of synthetic strategies for highly efficient preparation of enones thereby receives intense attention,in particular through the transition metal-catalyzed coupling reactions.Here,we describe a carbene-catalyzed cross dehydrogenative coupling(CDC)reaction that enables effective assembly of simple aldehydes and alkenes to afford a diverse set of enone derivatives.Mechanistically,the in situ generated aryl radical is pivotal to“activate”the alkene by forming an allyl radical through intermolecular hydrogen atom transfer(HAT)pathway and thus forging the carbon-carbon bond formation with aldehyde as the acyl synthon.Notably,our method represents the first example on the enone synthesis through coupling of“non-functionalized”aldehydes and alkenes as coupling partners,and offers a distinct organocatalytic pathway to the transition metal-catalyzed coupling transformations.
基金supported by the National Natural Science Foundation of China(21732002,22061007,22071036,22207022)the Frontiers Science Center for Asymmetric Synthesis and Medicinal Molecules+6 种基金the National Natural Science Fund for Excellent Young Scientists Fund Program(Overseas)-YQHWthe starting grant of Guizhou University((2022)47))the Department of Education,Guizhou Province(Qianjiaohe KY number(2020)004)the Department of Education of Guizhou Province(QJJ(2022)205)the 10 Talent Plan(Shicengci)of Guizhou Province([2016]5649)the Science and Technology Department of Guizhou Province(Qiankehe-jichu-ZK[2024]-030,zhongdian024,[2018]2802,[2019]1020,QKHJC-ZK[2022]-455)the Program of Introducing Talents of Discipline to Universities of China(111 Program,D20023)at Guizhou University。
文摘Organoseleniums exhibit a diverse set of biological activities that are pivotal for drug discovery and are widely explored in synthetic chemistry and material science.While many transformations have been developed for non-enantioselective C–Se bond formations,the catalyst-controlled stereoselective preparation of chiral organoseleniums continues to be of considerable challenge.In particular,there are limited studies on the enantioselective seleno-Michael addition reactions to access chiral selenium functional molecules.Here,we disclose a carbene-catalyzed highly enantioselective nucleophilic C–Se bond construction through formal[3+3]annulations between selenocarboxamides and bromoenals,affording seleno-thiazinone products with good yields and excellent enantioselectivities.The choice of a weak inorganic base was pivotal to suppressing the unproductive racemization and decomposition of the selenium products.Notably,the catalytically generated chiral selenium-containing heterocyclic products feature remarkable antimicrobial activities that could serve as promising lead scaffolds for further agrochemical development.
基金supported by the National Key Research and Development Program of the Ministry of Science and Technology of China(No.2021YFA1500203)Natural Science Foundation of China(Nos.22231010,22061160464,21821002,and 22201290)Shanghai Sailing Program(No.22YF1458200)。
文摘Silyl cobalt species are putative intermediates in cobalt-catalyzed transformations of hydrosilanes.However,their reactivity has remained poorly understood.Reported here is the investigation on four-coordinate disilyl Co(Ⅱ)complexes with N-hetereocyclic carbene ligation.The reactions of[(ICy)_(2)Co(vtms)](ICy=1,3-dicyclohexylimidazol-2-ylidene,vtms=vinyltrimethylsilane)with primary and secondary hydrosilanes(3 equiv.)furnish the four-coordinate disilyl complexes[trans-(ICy)_(2)Co(SiHRR')_(2)](SiHRR'=SiH_(2)Mes,1;SiH_(2)Ph,2;SiH_(2)Cy,3;SiHPh_(2),4;SiHEt_(2),5)in moderate to good yields.The structures of 1,2 and 4 were established by single-crystal X-ray diffraction.Solution magnetic susceptibility measurement and EPR spectroscopy indicate their low-spin nature(S=1/2).Reactivity studies on 4 led to the establishment of the conversions of 4 to the disilyl dihydride Co(Ⅲ)complex[K(THF)][(ICy)_(2)Co(H)_(2)(SiHPh_(2))_(2)]_n(6)and the fluorosilyl Co(Ⅱ)complex[(ICy)_(2)Co(THF)(SiFPh_(2))][BF_(4)](7)when 4 was treated with excess amount of K and AgBF_(4),respectively,in THF.These conversions hint at the high activity of low-valent and high-valent disilyl cobalt species[trans-(ICy)_(2)Co(SiHPh_(2))_(2)]^(1-)and[trans-(ICy)_(2)Co(SiHPh_(2))_(2)]^(2+).Complex 4 is reactive toward terminal alkynes,but inert toward alkenes and internal alkynes.The reactions of 4 with terminal alkynes CyC≡CH and Me_(3)SiC≡CH(3 equiv.)yield the Co(Ⅱ)complexes[(ICy)_(2)Co(C≡CCy)_(2)](8)and[(ICy)_(2)Co(C≡CSiMe_(3))((SiMe_(3))C=CH_(2))](9),respectively,along with H_(2)SiPh_(2)and alkynylsilanes RC≡CSiHPh_(2)(R=Cy,SiMe_(3)),whereas the reaction with 4-CF_(3)C_(6)H_(4)C≡CH(3 equiv.)produce[(ICy)_(2)Co(C≡CAr)((Ar)C=CH(SiHPh_(2))C=CHAr)](Ar=4-CF_(3)C_(6)H_(4))(10)and H_(2)SiPh_(2).These reactions are proposed to involveσ-bond metathesis reactions between alkyne C(sp)-H bonds and Co-Si bonds in 4.Complexes 6–10 have been characterized by NMR spectroscopy,X-ray diffraction study,and elemental analysis.
文摘N-heterocyclic carbene-catalyzed reactions for the formation of aromatic compounds are reviewed.The reactions are subdivided into 4 types based on their activation modes.A brief summary on the achievements and the challenges remaining in Nheterocyclic carbene(NHC)-catalyzed arene construction processes is provided at the end of this review.An outlook into the future research direction within this field is also given based on our own opinion and knowledge on the trends of the development of NHC organocatalysis.
基金supported by the National Natural Science Foundation of China (22271060)the Department of Chemistry at Fudan University。
文摘N-Heterocyclic carbene(NHC)-based cages have emerged as a prominent and dynamic research area within the research field of chemistry. Leveraging the distinctive electronic and steric properties of NHC ligands, the design, synthesis, and application of these corresponding cages have garnered substantial scholarly interest. In recent years, we have witnessed the successful fabrication of diverse NHC-based cages through a range of synthetic methodologies, which hold significant potential for applications in molecular recognition and catalysis. In this review, we delve into the foundational synthetic strategies that underlie the creation of NHC-based cages, employing approaches encompassing metal–NHC chelation, coordination assembly,and covalent bonding. Additionally, we compile the diverse applications of these cages within catalytic processes and molecular recognition. Lastly, we shed light on the current limitations of synthesis and outline future trends in the development of NHCbased cages.
基金the Natural Science Foundation of Jiangsu Province(BK20221309)the National Natural Science Foundation of China(21602105).
文摘Axially chiral biaryls represent the most important class of atropisomers,and they widely exist in natural products and biologically active molecules.They also constitute a unique scaffold for chiral ligands and catalysts in organic synthesis.The development of synthetic methods to obtain such chiral compounds has received widespread attention,among which catalytically atroposelective ring-opening of configurationally labile compounds represents one of the most attractive strategies.Various substrates with strained cyclic structures,such as the renowned Bringmann's lactones,can undergo asymmetric transformation into stable atropisomers.Known advancement primarily relies on metal catalyst combined with well-designed chiral ligands,the approaches utilizing organocatalysis as a critical resolution strategy are notably scarce.In this study,we disclosed a N-heterocyclic carbene(NHC)-catalyzed asymmetric ring-opening reaction of biaryl lactams via direct atroposelective nucleophilic activation.The optimized bulky carbene catalyst ensures that the reaction can proceed under mild conditions,affording the desired product with good to excellent yields and atroposelectivity.
基金financially supported by the National Natural Science Foundation of China (Nos.21774006 and 21634002)。
文摘The highly efficient method has been developed for the synthesis of NHC·VOCl_(3) containing symmetrical or unsymmetrical Nheterocyclic carbene(NHC) ligands by the transmetallation reaction of NHC·AgCl with VOCl_(3).The total isolated yield of VOCl_(3)[1,3-(2,4,6-Me_(3)C_(6)H_(2))_(2)(NCH=)_(2)C:](V4') reached 86% by transmetallation reaction,which is much higher than that(48%) by direct coordination method.This methodology has also been used to synthesize the novel vanadium complexes containing unsymmetrical NHC ligands of VOCl_(3)[PhCH_(2)NCH=CHNR)C:](V5',R=2,4,6-Me_(3)C_(6)H_(2);V6',R=2,4-Me_(2)-6-Ph-C_(6)H_(2);V7',R=2,6-^(i)Pr_(2)-C_(6)H_(3)) with high yield,which could not be obtained by direct coordination method.The catalytic activity and copolymerization ability would be improved by introducing unsymmetrical NHC ligands due to their less steric bulky effect.The vanadium complex V5' containing unsymmetrical NHC ligand exhibits higher catalytic activity(3.7×10^(5)g_(copolymer)·mol^(-1) of V·h^(-1)) than that of V4' containing symmetrical NHC ligand.Moreover,the higher propylene incorporation ratio(45.6 mol%) in the copolymers of ethylene with propylene could be obtained by using V5' than that(39.9%) by using V4'.The results would provide a highly efficient strategy for the synthesis of early transition metal complexes containing versitile NHC ligands,affording the catalyst with both high catalytic activity and copolymerization ability for the synthesis of high performance polyolefin elastomers.
基金supported by the National Natural Science Foundation of China (21871160, 21672121, 22071130)the Bayer Investigator Fellowthe Fellowship of Tsinghua-Peking Center for Life Sciences (CLS)。
文摘The fluoroalkyl fragment plays a vital role in various fields such as pharmaceuticals and materials science, and has a significant impact on human life not only on the present but also in the future. The insertion of fluoroalkyl groups into the chemical skeletons can cause considerable alternations in the chemical, physical and biological properties of molecules, which has attracted numerous scientists from different fields. This review focuses on N-heterocyclic carbene(NHC)-catalyzed fluoroalkylation reactions, providing a detailed analysis and summary of the achievements in the past two decades. Many successful examples clearly indicate that NHCs can catalyze the tranformation of fluoroalkylation reagents with various electronic characteristics, whether electrophilic, nucleophilic, or radical precursors. Herein, the fluoroalkylation reactions are classified based on different catalytic modes of NHCs: Lewis base catalysis, Umploung catalysis, radical catalysis and others. Meanwhile, by refining and systematically studying the contribution of NHC catalysis in fluoroalkylation reactions, this review is expected to provide valuable insights and enlightenment for related fields.
基金National Natural Science Foundation of China(No.22101133)Natural Science Foundation of Jiangsu Province(No.BK20200768)and Nanjing Forestry University are greatly acknowledged.
文摘An efficiently catalytic method toward the synthesis of indolin-2-ones featuring an allylic derived C_(3)-quaternary stereocenter via an intramolecular Heck cyclization/Suzuki coupling of N-substituted-N-(2-bromophenyl)acrylamides and organoboron reagents was successfully developed by using a 1,3-bis(2,6-diisopropylphenyl)acenaphthoimidazol-2-ylidene(AnIPr)-ligated oxazoline palladacycle.It enabled a very broad substrate scope tolerating different functional groups,electronic properties and steric bulkiness.Notably,it revealed a great potential to build diverse heterocycle-fused indoline alkaloids via the same intermediate 3-allyl-1,3-dimethylindolin-2-one.
基金We thank the financial support from the Program for Young Talents of Shaanxi Province(5113200043)the Fundamental Research Funds for the Central Universities.
文摘We report herein an unprecedented N-heterocyclic carbene-catalyzed formal[3+3]annulation of ynals with N-Ts indolin-3-ones under the oxidation condition affording the functionalized pyrano[3,2-b]indol-2-ones.The alkynyl acylazoliums via the combination of a carbene with ynals in the presence of oxidate proved to be the important intermediates for the success of this transformation.This method features a broad substrate scope and mild conditions,including axially chiral skeletons with suitable substitutions.
基金supported by the National Key R&D Program of China(2022YFA1503702,2021YFF0701600)the National Natural Science Foundation of China(22325110,92256303,21821002,22171280)+2 种基金the Strategic Priority Research Program of the Chinese Academy of Sciences(XDB0610000)the Program of Shanghai Academic Research Leader(22XD1424900)the CAS Youth Interdisciplinary Team(JCTD-2021-11)and the Ningbo Natural Science Foundation(2022J017).
文摘Transition-metal-catalyzed asymmetric alkylation of aldehydes represents a straightforward strategy for the synthesis of chiral secondary alcohols.However,efficient methods using organoborons as coupling reagents are rare.Herein,we report a highly enantioselective nickel-catalyzed alkylation reaction of aldehydes,using readily available alkylborons as nucleophiles.A wide variety of chiral secondary alcohols were prepared from commercially available aldehydes with high yields.The key to the excellent enantioselectivity and chemoselectivity was the employment of a bulky C2-symmetric chiral NHC ligand.This protocol features excellent enantiocontrol,mild conditions,and good functional group compatibility.
文摘While N-heterocyclic carbene(NHC)catalyzed electron-pair-transfer processes have been developed into an important tool for synthetically important bond formations during the past decades,the corresponding radical reactions via NHC catalysis have only received growing attention in the past six years.Taking into account the advantages NHC-catalyzed radical reactions might bring,such as creating new activation modes that were previously unobtainable,it is worthwhile to provide a conceptual understanding of this emerging area.Therefore,herein we give an overview of NHC-catalyzed radical reactions via different synthetic techniques.
基金supported by the National Natural Science Fund for Distinguished Young Scholars of China(No.22025107)Shaanxi Fundamental Science Research Project for Chemistry&Biology(No.22JHZ003)。
文摘Comprehensive Summary Poly-NHC-based organometallic assemblies 3-PF6,3-SbF6 and 3-OTf were obtained and verified by NMR spectroscopy,ESI mass spectrometry and single-crystal X-ray diffraction analyses.Controllable structural interconversion was observed between the poly-NHC-based organometallic assemblies and their self-aggregated dimers in solution affected by concentration,solvent and metal ion.1H NMR spectra of assembly 3-PF6 in CD3CN at different concentrations demonstrated controllable structural interconversion,and 19F NMR spectrum of assembly 3-PF6 at high concentration further evidenced the presence of the free hexafluorophosphate anion and encapsulated hexafluorophosphate anion for its two sets of signals.In addition,single-crystal X-ray diffraction analysis provided clear evidence that in the solid state,two assemblies 3-PF6 were vertically stuck,forming a self-aggregated dimer with an encapsulated hexafluorophosphate anion.Investigating the reversible structural interconversion is beneficial for revealing the intrinsic nature on the atom level and paving the way to design the stimuli-responsive functional system.
基金the financial support from the National Natural Science Foundation of China (Nos.21672216,21831008)the Beijing National Laboratory for Molecular Sciences (No. BNLMS-CXXM-202003)。
文摘The N-heterocyclic carbene(NHC)-catalyzed reactions involving two-electron reaction pathway have been well-established.However,the development of NHC-catalyzed radical reactions is still in its infancy in terms of reaction types and enantioselectivity.In the past decade,several elegant NHC-catalyzed radical reactions have been developed,including NHC-catalyzed oxidation of aldehydes to esters,reductive coupling reactions using Breslow intermediate as SET reductant and NHC-catalyzed reactions via radical homoenolates,dienoaltes and trienolates.This review summarizes the recent advances in NHC-catalyzed reactions involving radical intermediates.
基金financial support from the National Natural Science Foundation of China(22061041)Key Project of Science&Technology of Shaanxi Province(2023-YBGY-430)+5 种基金Project of Science&Technology Bureau of Yulin City(CXY-2022-185)Doctoral Research Foundation of Yan'an University(YDBK2019-60)the Training Program of Innovation and Entrepreneurship for Undergraduates of Yan'an University(D2022077)Research Program of Yan'an University(YDY2020-61)the Youth Innovation Team Project of Shaanxi Provincial Education Department(No.23JP193)National Science Foundation of Shaanxi Province(S2023-JC-QN-0079).
文摘Herein,we present a method for the homogeneous hydrogenation of nitroarenes to produce anilines using low catalyst loading(1 mo%)of copper N-heterocyclic carbene complexes as the catalyst and ammonia borane as the source of hydrogen.A wide range of nitroarenes,featuring diverse functional groups,were selectively transformed into their corresponding primary aromatic amines with high yields.This process can be readily scaled up and exhibits compatibility with various sensitive functional groups,including halogen,trifluoromethyl,aminomethyl,alkenyl,cyano,ester,amide,and hydroxyl.Notably,this catalytic methodology finds application in the synthesis of essential drug compounds.Mechanistic investigations suggest that the in-situ-generated Cu-H species may serve as active intermediates,with reduction pathways involving species such as azobenzene,1,2-diphenylhydrazine,nitrosobenzene,and N-phenylhydroxylamine.
基金the Natural Science Foundation of China(No.22175191)Y.C.thanks the financial support from CAS-Croucher Funding Scheme for Joint Laboratories and Beijing Municipal Science&Technology Commission(No.Z211100007921020).
文摘While nickel(II)complexes have been widely used as catalysts for carbon-carbon coupling reactions,the exploration of their photophysical and photochemical properties is still in the infancy.Here,a series of square-planar Ni(II)complexes[(diNHC)NiX2]bearing chelating benzimidazole-based bis(N-heterocyclic carbene)ligands and varying anionic coligands(1,X=Cl;2,X=Br;3,X=I)are synthesized and structurally characterized.In solid state,both 1 and 2 exhibit orange-red photoluminescence under ambient conditions.The photophysical and electrochemical measurements along with density functional theory(DFT)calculations reveal that the low-energy emissions can be attributed to singlet excited states with ligand-to-ligand charge-transfer(LLCT)character.This work suggests that strong-field N-heterocyclic carbene ligands play a crucial role to achieve the luminescence of Ni(II)complexes.
基金supported by the National Natural Science Foundation of China(22025107)the National Youth Top-notch Talent Support Program of China,Xi'an Key Laboratory of Functional Supramolecular Structure and Materialsthe FM&EM International Joint Laboratory of Northwest University.
文摘A pentagonal-prismatic cylinder[Ag5(L)2](PF6)5 obtained from the pentaphenylpyrrole-bridged pentaimidazolium salt H5-L(PF6)5 and AgI ions was determined by X-ray diffraction analyses.The target organometallic cylinder not only exhibited enhanced fluorescence emission in dilute solution at room temperature but also showed an improved phosphorescence ratio compared with the free precursor and maintained a long lifetime(1.39 s)in the solid state at 77 K.Furthermore,the experimental results and DFT calculations confirmed that the formation of the organometallic cylinder promoted intersystem crossing.Meanwhile,the frontier orbitals of[Ag5(L)2](PF6)5 showed the main contribution of building block PPP as the luminescence source of[Ag5(L)2](PF6)5 by a modest heavy-atom effect.These results provide a strategy for constructing enhanced phosphorescent emission and long lifetime organometallic supramolecular phosphorescent materials.
基金supported by the Trakya University Research Fund(No.TUBAP-2014-106)。
文摘In this study,firstly,3-bromopropanenitrile(2a),ethyl bromoacetate(2b),and 2-bromoethan-1-amine(2c)were added to 5,6-dimethylbenzimidazole(1)and symmetrically-connected N-heterocyclic carbenes(NHC)[(3a-3c)]were synthesized.Then,the NHC precursor compounds were reacted with PdCl2 and Pd(Ⅱ)-NHC complexes[(4a—4c)]were obtained.The synthesized NHC precursors(3a-3c)and Pd(Ⅱ)-NHC complexes(4a—4c)were characterized by different spectroscopic methods.The antibacterial activities of these products were measured against bacteria and fungus with the disc diffusion method.Pd(Ⅱ)-NHC complexes had higher antibacterial activity than the NHC precursors.The synthesized compounds showed antimicrobial activity with different properties from each other.In vitro biological activities of salts and metal complexes on selected bacteria were determined by the broth dilution method based on Clinical and Laboratory Standards Institute guidelines.1,3-Bis-(2-hydroxyethyl)imidazolinium bromide and 3-(2-ethoxy-2-oxoethyl)-1-(3-aminopropyl)-^(1)H-imidazole-3-ium bromide had activity against Escherichia coli.
基金The authors gratefully acknowledge financial support from the National Natural Science Fund for Distinguished Young Scholars of China(No.22025107)the National Youth Top-notch Talent Support Program of China,Xi'an Key Laboratory of Functional Supramolecular Structure and Materials,and the FM&EM International Joint Laboratory of Northwest University.
文摘Developing discrete radical organometallic nanocages is essential for fabricating functional materials.In this study,we construct a series of poly-NHC-based(NHC=N-heterocyclic carbene)organometallic nanocages 3a-3c with different sizes by employing redox-active bis(triarylamine)derivatives with differentπ-conjugated spacers as building blocks.The varied sizes of nanocages 3a-3c modulate the distance of the redox-active centers and reversibly convert them to radical nanocages 3a^(2+)-3c^(2+)through chemical and electrochemical oxidation.Radical nanocages 3a^(2+)-3c^(2+)display clear bond and angle alteration and retention of their three-dimensional topologies.This work not only merely proves that these nanocages are excellent stimulus-responsive materials but also opens a door to the rational design of novel radical organometallic nanocages.
