Lewis base-catalyzed annulations of allenoates have been one of the most powerful synthetic strategies for the synthesis of various valuable cycles,especially in the preparation of biologically active natural products...Lewis base-catalyzed annulations of allenoates have been one of the most powerful synthetic strategies for the synthesis of various valuable cycles,especially in the preparation of biologically active natural products and pharmaceuticals.Generally,the effective Lewis bases mainly include tertiary phosphine,NHC and tertiary amine catalysts,among those catalysis,tertiary amine Lewis bases have proven to be effective catalysts for a range of synthetic transformations.In the past decades,tremendous progress in-volving tertiary amines-promoted cycloaddition of allenoates has been made in the chemoselective con-struction of valuable motifs.This review describes a comprehensive and updated summary of tertiary amine Lewis base-promoted annulation reactions of allenoates.Diverse reactivities,chemoselectivties and detailed reaction mechanisms will be highlighted in this review.展开更多
A Lewis base catalyzed ring expansion of isatin with 2,2,2-trifluorodiazoethane(CF3 CHN2)is developed.It is characterized that the merge of tetramethylethylenediamine and CF3 CHN2 generates reactive triazene intermedi...A Lewis base catalyzed ring expansion of isatin with 2,2,2-trifluorodiazoethane(CF3 CHN2)is developed.It is characterized that the merge of tetramethylethylenediamine and CF3 CHN2 generates reactive triazene intermediates,which construct substituted 3-hydroxy-4-(trifluoromethyl)quinolinones with high efficiency.Synthetic application of the procedure is broadened by 3-trifluormethylpyrazole fused3-hydroxy-4-(trifluoromethyl)quinolinone synthesis.展开更多
Metal/nucleophilic Lewis base dual catalysis has been recognized as a reliable and promising strategy for finishing ideal organic synthesis over the past decades.The new strategy can usually achieve some chemical reac...Metal/nucleophilic Lewis base dual catalysis has been recognized as a reliable and promising strategy for finishing ideal organic synthesis over the past decades.The new strategy can usually achieve some chemical reactions that cannot be realized by the traditionally mono-catalytic system,dramatically expanding the synthetic utility of chemical transformations by leveraging additional activation modes.Thus considerable progress has been made in the synthesis of a wide range of heterocyclic and biologically active compounds by using the combination of diversely metal/nucleophilic Lewis base dual catalysts,including metal/phosphine,metal/N-heterocyclic carbene(NHC)and metal/tertiary amine dual catalysis systems.In this review,we describe a comprehensive and updated advance of metal/nucleophilic Lewis base dual catalytic annualtion reactions,meanwhile,the related mechanism and the application of these annulation strategies in natural product total synthesis will be highlighted in detail.展开更多
Heteroatom-doped carbon has been demonstrated to be one of the most promising non-noble metal catalysts with high catalytic activity and stability through the modification of the electronic and geometric structures.In...Heteroatom-doped carbon has been demonstrated to be one of the most promising non-noble metal catalysts with high catalytic activity and stability through the modification of the electronic and geometric structures.In this study,we develop a novel solvent method to prepare interconnected N,S co-doped three-dimensional（3D）carbon networks with tunable nanopores derived from an asso-ciated complex based on melamine and sodium dodecylbenzene sulfonate（SDBS）.After the intro-duction of silica templates and calcination,the catalyst exhibits 3D networks with interconnected 50-nm pores and partial graphitization.With the increase of the number of Lewis base sites caused by the N doping and change of the carbon charge and spin densities caused by the S doping,the designed N,S co-doped catalyst exhibits a similar electrochemical activity to that of the commercial 20-wt%Pt/C as an oxygen reduction reaction catalyst.In addition,in an aluminum-air battery,the proposed catalyst even outperforms the commercial 5-wt%Pt/C catalyst.Both interconnected porous structures and synergistic effects of N and S contribute to the superior catalytic perfor-mance.This study paves the way for the synthesis of various other N-doped and co-doped carbon materials as efficient catalysts in electrochemical energy applications.展开更多
Polyhedral boranes are a class of well-known boron molecular clusters widely used in energy;chemistry;medicine;and materials science because of their unique physical and chemical properties.Great efforts have been mad...Polyhedral boranes are a class of well-known boron molecular clusters widely used in energy;chemistry;medicine;and materials science because of their unique physical and chemical properties.Great efforts have been made in the past decades to find more effective synthetic methods for this important class of boron compounds.However;existing synthetic methods suffer from low efficiency and low selectivity.Herein;we report a facile one-pot synthesis of[(CH_(3))3S]_(2)B_(12)H_(12) with moderate yields at mild conditions.The mechanisms for the multi-step chemoselective synthesis of B_(12)H_(12)^(2-)without other by-products are elucidated based on theoretical results and our previous work.The Lewis base used in B–H bond condensation reaction;which acts as a hydrogen or to balance the newly generated polyhedral borane charges;is proposed and studied in detail.The current study has led to a more effective and selective synthetic method for B_(12)H_(12)^(2-) and has also implicated the syntheses of other new polyhedral boranes.展开更多
Lewis base catalyzed and Brønsted acid controlled chemodivergent electrophilic selenofunctionalizations of alkynes were developed for the first time.Various selenium-containing tetrasubstituted alkenes were readi...Lewis base catalyzed and Brønsted acid controlled chemodivergent electrophilic selenofunctionalizations of alkynes were developed for the first time.Various selenium-containing tetrasubstituted alkenes were readily obtained in moderate to excellent yields with complete E/Z selectivities.As the substrates were 1-ethynyl naphthol derivatives,linear selenium-containing tetrasubstituted alkenes were produced via intermolecular oxygen nucleophilic attack in the absence of acid additive;in contrast,cyclic selenium-containing tetrasubstituted alkenes were generated through intramolecular carbon nucleophilic capture with the addition of Brønsted acid.展开更多
Tin-based perovskite solar cells(TPSCs)as the most promising candidate for lead-free PSCs have incurred extensive researches all over the world.However,the crystallization process of tin-based perovskite is too fast d...Tin-based perovskite solar cells(TPSCs)as the most promising candidate for lead-free PSCs have incurred extensive researches all over the world.However,the crystallization process of tin-based perovskite is too fast during the solution-deposited process,resulting in abundant pinholes and poor homogeneity that cause serious charge recombination in perovskite layer.Here,we employed theπ-conjugated Lewis base molecules with high electron density to systematically control the crystallization rate of FASnI3 perovskite by forming stable intermediate phase with the Sn-I frameworks,leading to a compact and uniform perovskite film with large increase in the carrier lifetime.Meanwhile,the introduction of theπ-conjugated systems also retards the permeation of moisture into perovskite crystal,which significantly suppresses the film degradation in air.These benefits contributed to a stabilizing power conversion efficiency(PCE)of 10.1%for the TPSCs and maintained over 90%of its initial PCE after 1000-h light soaking in air.Also,a steady-state efficiency of 9.2%was certified at the accredited test center.展开更多
In the recent decade, the development and application of organocatalysis for CO_2 transformation into useful chemicals have attracted much attention. Among these organocatalysts, Lewis base-CO_2 adducts(LB-CO_2) were ...In the recent decade, the development and application of organocatalysis for CO_2 transformation into useful chemicals have attracted much attention. Among these organocatalysts, Lewis base-CO_2 adducts(LB-CO_2) were found to be more efficient.The used Lewis base has great effect on the catalytic activity of its CO_2 adduct. This review reports the recent progress in LB-CO_2 adducts catalyzed the cyclization of CO_2 with epoxides or aziridines to afford cyclic carbonates or oxazolidinones,the carboxylation of CO_2 with propargylic alcohols to α-alkylidene cyclic carbonates, and the reduction of CO_2 to methanol,formamides and methylamines, with the focus on the catalytic mechanism.展开更多
It was found that, when the Baylis-Hillman reaction of arylaldehydes withmethyl vinyl ketone was carried out at below - 20℃ in the presence of boron (Ⅲ) tribromide ortitanium (Ⅳ) bromide using a catalytic amount of...It was found that, when the Baylis-Hillman reaction of arylaldehydes withmethyl vinyl ketone was carried out at below - 20℃ in the presence of boron (Ⅲ) tribromide ortitanium (Ⅳ) bromide using a catalytic amount of Lewis base such as amine, the brominated compoundsand the Baylis-Hillman adducts could be obtained as the major products in good yields for variousaryl aldehydes. But at room temperature, the elimination products were the major products. Inaddition, the palladium catalyzed allylic substitution reactions of the e-limination products werealso examined.展开更多
The first asymmetric decarboxylative[3+2]-cycloaddition of ethynyl indoloxazolidones with carboxylic acids has been developed under synergistic catalysis of copper and chiral Lewis base.This protocol provides a direct...The first asymmetric decarboxylative[3+2]-cycloaddition of ethynyl indoloxazolidones with carboxylic acids has been developed under synergistic catalysis of copper and chiral Lewis base.This protocol provides a direct and modular approach to biologically important pyrrolo[1,2-a]indoles bearing two vicinal stereogenic centers with excellent diastereo-and enantioselectivities(up to>20:1 dr and>99%ee).In addition,the utility of this methodology was demonstrated by scaled-up reaction and several synthetic transformations of the cycloadduct.展开更多
Carbon materials have shown remarkable usefulness in facilitating the performance of insulating sulfur cathode for lithium–sulfur batteries owing to their excellent conductivity and porous structure. However,the anxi...Carbon materials have shown remarkable usefulness in facilitating the performance of insulating sulfur cathode for lithium–sulfur batteries owing to their excellent conductivity and porous structure. However,the anxiety is the poor affinity toward polar polysulfides due to the intrinsic nonpolar surface of carbon.Herein, we report a direct pyrolysis of the mixture urea and boric acid to synthesize B/N–codoped hierarchically porous carbon nanosheets(B–N–CSs) as efficient sulfur host for lithium–sulfur battery. The graphene–like B–N–CSs provides high specific surface area and porous structure with abundant micropores(1.1 nm) and low–range mesopores(2.3 nm), thereby constraining the sulfur active materials within the pores. More importantly, the codoped B/N elements can further enhance the polysulfide confinement through strong Li–N and B–S interaction based on the Lewis acid–base theory. These structural superiorities significantly suppress the shuttle effect by both physical confinement and chemical interaction, and promote the redox kinetics of polysulfide conversion. When evaluated as the cathode host, the S/B–N–CSs composite displays the excellent performance with a high reversible capacity up to 772 m A h g–1 at 0.5 C and a low fading rate of ^0.09% per cycle averaged upon 500 cycles. In particular, remarkable stability with a high capacity retention of 87.1% can be realized when augmenting the sulfur loading in the cathode up to 4.6 mg cm^(-2).展开更多
The stacking of multiple defect-rich grain boundaries(GBs)along the long transportation path(~3μm)of charge carriers in printable mesoscopic perovskite solar cells(p-MPSCs)impedes their power conversion efficiency(PC...The stacking of multiple defect-rich grain boundaries(GBs)along the long transportation path(~3μm)of charge carriers in printable mesoscopic perovskite solar cells(p-MPSCs)impedes their power conversion efficiency(PCE).Organic Lewis bases are widely utilized for defect passivation at GBs,but how their passivation efficiency affects energy loss remains unclear.Here we employed triphenylphosphine(TPP)and triphenylphosphine oxide(TPPO)as the model passivators in p-MPSCs.TPPO has a more negatively charged center than TPP,which enables its stronger coordination with one of the most common and detrimental defects at the GBs—undercoordinated lead.When added into the perovskite with the same ratio,TPPO passivates defects more significantly and thus less TPPO remaining inactive compared with TPP.Inactive organic passivators accumulated at the GBs could impose barriers to charge carrier transportation.Indeed,TPPO improves the device performance more significantly with a champion PCE of 20.54%achieved.Besides,the TPPO devices demonstrate excellent stability with 95%of initial PCE remaining after 600 h of maximum power point tracking at(55±5)℃.展开更多
Rechargeable magnesium batteries(RMBs)are considered the promising candidates for post lithium-ion batteries due to the abundant storage,high capacity,and dendrite-rare characteristic of Mg anode.However,the lack of p...Rechargeable magnesium batteries(RMBs)are considered the promising candidates for post lithium-ion batteries due to the abundant storage,high capacity,and dendrite-rare characteristic of Mg anode.However,the lack of practical electrolytes impedes the development and application of RMBs.Here,through a one-step reaction of LiCl congenital-containing Knochel–Hauser base TMPL(2,2,6,6-tetrame thylpiperidinylmagnesium chloride lithium chloride complex)with Lewis acid AlCl_(3),we successfully synthesized an efficient amino-magnesium halide TMPLA electrolyte.Raman and mass spectroscopy identified that the electrolyte comprises the typical di-nuclear copolymer[Mg_(2)Cl_(3)·6THF]+cation group and[(TMP)2AlCl_(2)]-anion group,further supported by the results of density functional theory calculations(DFT)and the Molecular dynamics(MD)simulations.The TMPLA electrolyte exhibits promising electrochemical performance,including available anodic stability(>2.65 V vs.SS),high ionic conductivity(6.05mS cm^(-1)),and low overpotential(<0.1 V)as well as appropriate Coulombic efficiency(97.3%)for Mg plating/stripping.Both the insertion Mo6S8cathode and conversion Cu S cathode delivered a desirable electrochemical performance with high capacity and good cycling stability based on the TMPLA electrolyte.In particular,when compatible with low cost and easily synthesized Cu S,the Cu S||Mg cell displayed an extremely high discharge capacity of 458.8 mAh g^(-1)for the first cycle and stabilized at 170.2 mAh g^(-1)with high Coulombic efficiency(99.1%)after 50 cycles at 0.05 C.Our work proposes an efficient electrolyte with impressive compatibility with Mg anode and insertion/conversion cathode for practical RMBs and provides a more profound knowledge of the Lewis acid–base reaction mechanisms.展开更多
The scope of stereochemistry recognition usually occurs near the chiral scaffold of a ligand or catalyst.Remote stereocontrol,which can surpass the limits of stereorecognition of remote prochiral centers,has long been...The scope of stereochemistry recognition usually occurs near the chiral scaffold of a ligand or catalyst.Remote stereocontrol,which can surpass the limits of stereorecognition of remote prochiral centers,has long been a challenging object of great interest in asymmetric catalysis.The current work realized the remote stereocontrol of 1,7-zwitterion intermediates formed from Huang's o-amino aryl MBH carbonates.With simple and easily accessibleβ-ICD as the bifunctional catalyst,multifunctionalized tetrahydroquinoline derivatives could be synthesized via(4+2)cycloadditions with excellent enantioselectivity and diastereoselectivity under mild conditions.The strategy possesses broad substrate scope,and three types of electron-deficient enones are successfully applied.Mechanistic studies disclosed the Lewis base-catalyzed reaction pathway,and H-bonding between the catalyst and enones is crucial for long-range stereocontrol.Scale-up reaction and transformations of the tetrahydroquinoline products demonstrated the potential of this strategy.展开更多
In a recent article in Nature Energy,Zhang and He from Soochow University,Ozin from the University of Toronto,and their colleagues reported on a partially substituted perovskite that facilitates the efficient photocat...In a recent article in Nature Energy,Zhang and He from Soochow University,Ozin from the University of Toronto,and their colleagues reported on a partially substituted perovskite that facilitates the efficient photocatalytic dehydrogenation of ethane[1].This material represents another prototypical example of surface frustrated Lewis pairs(SFLPs)in heterogeneous photocatalysis.The concept of SFLPs is based on the original idea of‘frustrated Lewis pairs’(FLPs)—sterically hindered Lewis acids and bases that cannot form the classical adducts[2].While FLPs are wellestablished in homogeneous catalysis,their surface counterparts,SFLPs,have found important applications in heterogeneous catalysis using solid-state materials[3].SFLP-based catalysts often consist of(bi)metallic oxyhydroxide/oxides/hydroxides,such as In_(2)O_(3)-x(OH)y,CoGeO_(2)-x(OH)y,BixIn2-xO3,ZnSn(OH)6,Cu_(2)O/CeO_(2),modified CeO_(2),and MOFs[4‒7].More recently,materials like wurtzite-structured GaN,ZnO,and AlP have also been identified as exceptions.SFLPs are known to activate small molecules such as CO_(2),H2,alkenes,dienes,and alkynes,and have gained particular CO_(2) reduction[4‒9].However,the application of SFLPs in C−H activation of ethane via photocatalysis has been less explored.Therefore,this work opens new possibilities for utilizing SFLPs in catalysis beyond CO_(2) hydrogenation[10,11].展开更多
Three isomorphic polytungstates,CsgK_(18)H_(10){[Sm_(2)(H_(2)O)_(4)W_(4)O_(10)(AsW_(9)0_(33))3]_(2)(N(CH_(2)PO_(3))_(2))}:46.5H_(2)O(1),CS_(10)K_(9)H_(18){[Eu_(2)(H_(2)O)_(4)W_(4)O_(10)(AsW_(9)0_(33))_(3)]_(2)(N(CH_(2...Three isomorphic polytungstates,CsgK_(18)H_(10){[Sm_(2)(H_(2)O)_(4)W_(4)O_(10)(AsW_(9)0_(33))3]_(2)(N(CH_(2)PO_(3))_(2))}:46.5H_(2)O(1),CS_(10)K_(9)H_(18){[Eu_(2)(H_(2)O)_(4)W_(4)O_(10)(AsW_(9)0_(33))_(3)]_(2)(N(CH_(2)PO_(3))_(2))}.41.5H_(2)O(2),Cs_(10)K_(9)H_(18){[Gd_(2)(H_(2)O)_(4)W_(4)O_(10)(AsW_(9)O_(33))_(3)]_(2)(N(CH_(2)PO_(3))_(2))}:46H_(2)O(_(3)),have been successfully synthesized and characterized by routine methods,and demonstrated excellent catalytic activities in Knoevenagel condensation reaction as heterogeneous catalysts.Notably,catalyst 1 achieved higher reaction activity than catalysts 2 and 3,where a satisfactory reaction yield(95%)and high TON value(6380)could be obtained at moderate reaction condition.In addition,in the scale-up experiment,with the help of catalyst 1,7.8g benzaldehyde and 5.7g ethyl cyanoacetate could transform into corresponding condensation product with a satisfactory yield(83%)and impressive TON value(13.883).展开更多
Phenols,in stead of con venti onal alcoholic compounds,are used to in itiate ring-openi ng polymerizati on(ROP)of ethyle neoxide and propyle ne oxide in bulk at room temperature in cooperati on with the recently preva...Phenols,in stead of con venti onal alcoholic compounds,are used to in itiate ring-openi ng polymerizati on(ROP)of ethyle neoxide and propyle ne oxide in bulk at room temperature in cooperati on with the recently prevaili ng bicompone nt metal-free catalyst comprising an organobase and triethylborane.Experimental and DFT calculation results both point out that due to the lower nucleophilicity of the initiating(phe no late)species than the propagating(alcoholate)species,chai n initiat ion is distinctly slower tha n propagation and the difference becomes eve n larger as the acidity of the phe nolic in itiator increases.Nevertheless,we 11-defi ned polyethers with expected molar mass,low dispersity,and high end-group fidelity are afforded substa ntiating that the ROP is living/c on trolled in spite of the slow initiation.Evolution of product composition indicates that the reaction on alcoholates(i.e.,propagation)is effectively inhib-ited by the unreacted phenols during the initiation step because of the adequately large acidity differenee,which is key to the success of the slow-initiation living/controlled polymerization.The acidity difference betwee n phe nol and alcohol also facilitates the fulfill-ment of highly selective phenolysis of epoxides,a"1+1"type addition reaction between phenol and epoxide(in excess)rather than the"1+n"type ROP reaction,by use of a milder organobase and decreased Lewis acid/base ratio.展开更多
The cycloaddition reaction of CO_(2)with epoxide not only effectively reduces the concentration of CO_(2)in the atmosphere,but also has excellent industrial application value and up to 100%atom utilization,but there a...The cycloaddition reaction of CO_(2)with epoxide not only effectively reduces the concentration of CO_(2)in the atmosphere,but also has excellent industrial application value and up to 100%atom utilization,but there are difficulties in separation and recovery of traditional homogeneous catalysts,harsh reaction conditions of traditional heterogeneous catalysts,and activation of CO_(2)molecules.In this paper,an easily synthesized heterogeneous catalyst CeNCl/C was used to catalyze the cycloaddition reaction of CO_(2)with styrene oxide,with a high yield of 92.7%,a high selectivity of 96.7%,a turnover numbers(TON)value of 349,and a good stability demonstrated in six cycle tests(equivalent to 216 h of testing).Through comprehensive studies,it was shown that CeNCl/C contains Lewis acid-base centers as active centers,which can effectively reduce the energy barrier required for ring opening of the reaction substrate,enhance the adsorption and activation of CO_(2),and promote the formation of intermediates,which led to the acquisition of excellent catalytic activity.展开更多
Since the introduction of the concept of frustrated Lewis pair by Stephan in 2006,the frustrated Lewis pair(FLP)chemistry has evolved into a rich and fruitful research area which is largely responsible for the renaiss...Since the introduction of the concept of frustrated Lewis pair by Stephan in 2006,the frustrated Lewis pair(FLP)chemistry has evolved into a rich and fruitful research area which is largely responsible for the renaissance of main group chemistry in recent years.Among many applications of FLP,design of catalytic systems based on the concept of FLP,pioneered by Stephan,Chen and others,provides a powerful arsenal that has been applied to organic synthesis and polymerization.This article will highlight key advances in the development of FLP related catalysis.展开更多
Developing method for strong Si–F σ bond activation is a very important tool in organosilicon transformation chemistry, only few examples of Si–F bond activation are precedent in the literature. Herein, we develope...Developing method for strong Si–F σ bond activation is a very important tool in organosilicon transformation chemistry, only few examples of Si–F bond activation are precedent in the literature. Herein, we developed a new and efficient method to activate strong Si–F bond by transition-metal-free Si–F/Si–H cross coupling reaction catalyzed with 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) catalytic system under mild conditions. Various disiloxanes bearing tolerated functional groups were successfully synthesized in moderate to excellent yields from fluorosilanes and hydrosilanes. Moreover, H_(2)O was found to be the oxygen donor in this catalytic system. Density functional theory calculations were performed to verify the mechanism of DBU promoted Si–F/Si–H cross-coupling reactions.展开更多
基金the National Natural Science Foundation of China(No.21702189)Key Scientific and Technological Project of Henan Province(No.202102310004)Zhengzhou University(No.JC21253007)of China for financial support.
文摘Lewis base-catalyzed annulations of allenoates have been one of the most powerful synthetic strategies for the synthesis of various valuable cycles,especially in the preparation of biologically active natural products and pharmaceuticals.Generally,the effective Lewis bases mainly include tertiary phosphine,NHC and tertiary amine catalysts,among those catalysis,tertiary amine Lewis bases have proven to be effective catalysts for a range of synthetic transformations.In the past decades,tremendous progress in-volving tertiary amines-promoted cycloaddition of allenoates has been made in the chemoselective con-struction of valuable motifs.This review describes a comprehensive and updated summary of tertiary amine Lewis base-promoted annulation reactions of allenoates.Diverse reactivities,chemoselectivties and detailed reaction mechanisms will be highlighted in this review.
基金financial support from the National Natural Science Foundation of China(No.81602977)the CAMS Innovation Fund for Medical Sciences(Nos.2019-RC-HL-010,2017-I2M-1013)+1 种基金the Science and Technology Development Project of Jilin Province of China(No.20190304050YY)China Association of Chinese Medicine(No.2017QNRC001)。
文摘A Lewis base catalyzed ring expansion of isatin with 2,2,2-trifluorodiazoethane(CF3 CHN2)is developed.It is characterized that the merge of tetramethylethylenediamine and CF3 CHN2 generates reactive triazene intermediates,which construct substituted 3-hydroxy-4-(trifluoromethyl)quinolinones with high efficiency.Synthetic application of the procedure is broadened by 3-trifluormethylpyrazole fused3-hydroxy-4-(trifluoromethyl)quinolinone synthesis.
基金the National Natural Science Foundation of China(No.21702189)the Key Scientific and Technological Project of Henan Province(No.202102310004)+1 种基金Science and Technology Research and Development Plan Joint Fund(cultivation of superior disciplines)Project(No.222301420042)Zhengzhou University(No.JC21253007)of China for financial support of this research.
文摘Metal/nucleophilic Lewis base dual catalysis has been recognized as a reliable and promising strategy for finishing ideal organic synthesis over the past decades.The new strategy can usually achieve some chemical reactions that cannot be realized by the traditionally mono-catalytic system,dramatically expanding the synthetic utility of chemical transformations by leveraging additional activation modes.Thus considerable progress has been made in the synthesis of a wide range of heterocyclic and biologically active compounds by using the combination of diversely metal/nucleophilic Lewis base dual catalysts,including metal/phosphine,metal/N-heterocyclic carbene(NHC)and metal/tertiary amine dual catalysis systems.In this review,we describe a comprehensive and updated advance of metal/nucleophilic Lewis base dual catalytic annualtion reactions,meanwhile,the related mechanism and the application of these annulation strategies in natural product total synthesis will be highlighted in detail.
基金supported by the National Natural Science Foundation of China (51674297)the Natural Science Foundation of Hunan Province (2016JJ2137)the Fundamental Research Funds for the Central Universities of Central South University (2015cx001)~~
文摘Heteroatom-doped carbon has been demonstrated to be one of the most promising non-noble metal catalysts with high catalytic activity and stability through the modification of the electronic and geometric structures.In this study,we develop a novel solvent method to prepare interconnected N,S co-doped three-dimensional（3D）carbon networks with tunable nanopores derived from an asso-ciated complex based on melamine and sodium dodecylbenzene sulfonate（SDBS）.After the intro-duction of silica templates and calcination,the catalyst exhibits 3D networks with interconnected 50-nm pores and partial graphitization.With the increase of the number of Lewis base sites caused by the N doping and change of the carbon charge and spin densities caused by the S doping,the designed N,S co-doped catalyst exhibits a similar electrochemical activity to that of the commercial 20-wt%Pt/C as an oxygen reduction reaction catalyst.In addition,in an aluminum-air battery,the proposed catalyst even outperforms the commercial 5-wt%Pt/C catalyst.Both interconnected porous structures and synergistic effects of N and S contribute to the superior catalytic perfor-mance.This study paves the way for the synthesis of various other N-doped and co-doped carbon materials as efficient catalysts in electrochemical energy applications.
基金supported by the National Natural Science Foundation of China(22171246,U1804253 to X.Chen,and 21773214 to D.Wei)L.S.Wang wishes to thank the US National Science Foundation for support under grant CHE-2403841.
文摘Polyhedral boranes are a class of well-known boron molecular clusters widely used in energy;chemistry;medicine;and materials science because of their unique physical and chemical properties.Great efforts have been made in the past decades to find more effective synthetic methods for this important class of boron compounds.However;existing synthetic methods suffer from low efficiency and low selectivity.Herein;we report a facile one-pot synthesis of[(CH_(3))3S]_(2)B_(12)H_(12) with moderate yields at mild conditions.The mechanisms for the multi-step chemoselective synthesis of B_(12)H_(12)^(2-)without other by-products are elucidated based on theoretical results and our previous work.The Lewis base used in B–H bond condensation reaction;which acts as a hydrogen or to balance the newly generated polyhedral borane charges;is proposed and studied in detail.The current study has led to a more effective and selective synthetic method for B_(12)H_(12)^(2-) and has also implicated the syntheses of other new polyhedral boranes.
基金the National Natural Science Foundation of China(Nos.22071149,21871178)the Natural Science Foundation of Shanghai(23ZR1428200)the Program for Professor of Special Appointment(Eastern Scholar)at Shanghai Institutions of Higher Learning for financial support.
文摘Lewis base catalyzed and Brønsted acid controlled chemodivergent electrophilic selenofunctionalizations of alkynes were developed for the first time.Various selenium-containing tetrasubstituted alkenes were readily obtained in moderate to excellent yields with complete E/Z selectivities.As the substrates were 1-ethynyl naphthol derivatives,linear selenium-containing tetrasubstituted alkenes were produced via intermolecular oxygen nucleophilic attack in the absence of acid additive;in contrast,cyclic selenium-containing tetrasubstituted alkenes were generated through intramolecular carbon nucleophilic capture with the addition of Brønsted acid.
基金supported by the National Natural Science Foundation of China(11574199,11674219,11834011)the Program for Professor of Special Appointment(Eastern Scholar)at Shanghai Institutions of Higher Learning+1 种基金National Institute for Materials Science was supported by the New Energy and Industrial Technology Development Organization(NEDO,Japan)the KAKEHI Grant of Japan(18H02078)
文摘Tin-based perovskite solar cells(TPSCs)as the most promising candidate for lead-free PSCs have incurred extensive researches all over the world.However,the crystallization process of tin-based perovskite is too fast during the solution-deposited process,resulting in abundant pinholes and poor homogeneity that cause serious charge recombination in perovskite layer.Here,we employed theπ-conjugated Lewis base molecules with high electron density to systematically control the crystallization rate of FASnI3 perovskite by forming stable intermediate phase with the Sn-I frameworks,leading to a compact and uniform perovskite film with large increase in the carrier lifetime.Meanwhile,the introduction of theπ-conjugated systems also retards the permeation of moisture into perovskite crystal,which significantly suppresses the film degradation in air.These benefits contributed to a stabilizing power conversion efficiency(PCE)of 10.1%for the TPSCs and maintained over 90%of its initial PCE after 1000-h light soaking in air.Also,a steady-state efficiency of 9.2%was certified at the accredited test center.
基金supported by the National Natural Science Foundation of China(21402021)the Program for Changjiang Scholars and Innovative Research Team in University(IRT13008)
文摘In the recent decade, the development and application of organocatalysis for CO_2 transformation into useful chemicals have attracted much attention. Among these organocatalysts, Lewis base-CO_2 adducts(LB-CO_2) were found to be more efficient.The used Lewis base has great effect on the catalytic activity of its CO_2 adduct. This review reports the recent progress in LB-CO_2 adducts catalyzed the cyclization of CO_2 with epoxides or aziridines to afford cyclic carbonates or oxazolidinones,the carboxylation of CO_2 with propargylic alcohols to α-alkylidene cyclic carbonates, and the reduction of CO_2 to methanol,formamides and methylamines, with the focus on the catalytic mechanism.
文摘It was found that, when the Baylis-Hillman reaction of arylaldehydes withmethyl vinyl ketone was carried out at below - 20℃ in the presence of boron (Ⅲ) tribromide ortitanium (Ⅳ) bromide using a catalytic amount of Lewis base such as amine, the brominated compoundsand the Baylis-Hillman adducts could be obtained as the major products in good yields for variousaryl aldehydes. But at room temperature, the elimination products were the major products. Inaddition, the palladium catalyzed allylic substitution reactions of the e-limination products werealso examined.
基金This work is supported by the National Natural Science Foundation of China(Nos.21901072 and 21772038).
文摘The first asymmetric decarboxylative[3+2]-cycloaddition of ethynyl indoloxazolidones with carboxylic acids has been developed under synergistic catalysis of copper and chiral Lewis base.This protocol provides a direct and modular approach to biologically important pyrrolo[1,2-a]indoles bearing two vicinal stereogenic centers with excellent diastereo-and enantioselectivities(up to>20:1 dr and>99%ee).In addition,the utility of this methodology was demonstrated by scaled-up reaction and several synthetic transformations of the cycloadduct.
基金financial support of the National Natural Science Foundation of China (Grant No. 21263016, 21363015, 51662029, 21863006)the Youth Science Foundation of Jiangxi Province (Grant No. 20192BAB216001)the Key Laboratory of Jiangxi Province for Environment and Energy Catalysis (20181BCD40004)。
文摘Carbon materials have shown remarkable usefulness in facilitating the performance of insulating sulfur cathode for lithium–sulfur batteries owing to their excellent conductivity and porous structure. However,the anxiety is the poor affinity toward polar polysulfides due to the intrinsic nonpolar surface of carbon.Herein, we report a direct pyrolysis of the mixture urea and boric acid to synthesize B/N–codoped hierarchically porous carbon nanosheets(B–N–CSs) as efficient sulfur host for lithium–sulfur battery. The graphene–like B–N–CSs provides high specific surface area and porous structure with abundant micropores(1.1 nm) and low–range mesopores(2.3 nm), thereby constraining the sulfur active materials within the pores. More importantly, the codoped B/N elements can further enhance the polysulfide confinement through strong Li–N and B–S interaction based on the Lewis acid–base theory. These structural superiorities significantly suppress the shuttle effect by both physical confinement and chemical interaction, and promote the redox kinetics of polysulfide conversion. When evaluated as the cathode host, the S/B–N–CSs composite displays the excellent performance with a high reversible capacity up to 772 m A h g–1 at 0.5 C and a low fading rate of ^0.09% per cycle averaged upon 500 cycles. In particular, remarkable stability with a high capacity retention of 87.1% can be realized when augmenting the sulfur loading in the cathode up to 4.6 mg cm^(-2).
基金financial support from the National Natural Science Foundation of China(Grant numbers 22439001,52172198,51902117)the China Postdoctoral Science Foundation(Grant number BX20240123)the Fundamental Research Funds for the Central Universities(Grant number HUST:2024JYCXJJ043)。
文摘The stacking of multiple defect-rich grain boundaries(GBs)along the long transportation path(~3μm)of charge carriers in printable mesoscopic perovskite solar cells(p-MPSCs)impedes their power conversion efficiency(PCE).Organic Lewis bases are widely utilized for defect passivation at GBs,but how their passivation efficiency affects energy loss remains unclear.Here we employed triphenylphosphine(TPP)and triphenylphosphine oxide(TPPO)as the model passivators in p-MPSCs.TPPO has a more negatively charged center than TPP,which enables its stronger coordination with one of the most common and detrimental defects at the GBs—undercoordinated lead.When added into the perovskite with the same ratio,TPPO passivates defects more significantly and thus less TPPO remaining inactive compared with TPP.Inactive organic passivators accumulated at the GBs could impose barriers to charge carrier transportation.Indeed,TPPO improves the device performance more significantly with a champion PCE of 20.54%achieved.Besides,the TPPO devices demonstrate excellent stability with 95%of initial PCE remaining after 600 h of maximum power point tracking at(55±5)℃.
基金financial support from the National Natural Science Foundation of China(Nos.21975159,2157316)the Shanghai Aerospace Science and Technology Innovation Fund(No.SAST2018-117)the Oceanic Interdisciplinary Program of Shanghai Jiao Tong University(No.WH410260401/006)。
文摘Rechargeable magnesium batteries(RMBs)are considered the promising candidates for post lithium-ion batteries due to the abundant storage,high capacity,and dendrite-rare characteristic of Mg anode.However,the lack of practical electrolytes impedes the development and application of RMBs.Here,through a one-step reaction of LiCl congenital-containing Knochel–Hauser base TMPL(2,2,6,6-tetrame thylpiperidinylmagnesium chloride lithium chloride complex)with Lewis acid AlCl_(3),we successfully synthesized an efficient amino-magnesium halide TMPLA electrolyte.Raman and mass spectroscopy identified that the electrolyte comprises the typical di-nuclear copolymer[Mg_(2)Cl_(3)·6THF]+cation group and[(TMP)2AlCl_(2)]-anion group,further supported by the results of density functional theory calculations(DFT)and the Molecular dynamics(MD)simulations.The TMPLA electrolyte exhibits promising electrochemical performance,including available anodic stability(>2.65 V vs.SS),high ionic conductivity(6.05mS cm^(-1)),and low overpotential(<0.1 V)as well as appropriate Coulombic efficiency(97.3%)for Mg plating/stripping.Both the insertion Mo6S8cathode and conversion Cu S cathode delivered a desirable electrochemical performance with high capacity and good cycling stability based on the TMPLA electrolyte.In particular,when compatible with low cost and easily synthesized Cu S,the Cu S||Mg cell displayed an extremely high discharge capacity of 458.8 mAh g^(-1)for the first cycle and stabilized at 170.2 mAh g^(-1)with high Coulombic efficiency(99.1%)after 50 cycles at 0.05 C.Our work proposes an efficient electrolyte with impressive compatibility with Mg anode and insertion/conversion cathode for practical RMBs and provides a more profound knowledge of the Lewis acid–base reaction mechanisms.
基金the National Natural Science Foundation of China(Nos.82073997 and 22001024)the Science&Technology Department of Sichuan Province(Nos.2021YFS0044 and 2021YJ0402)+1 种基金Innovation Team and Talents Cultivation Program of National Administration of Traditional Chinese Medicine(No.ZYYCXTD-D-202209)Xinglin Scholar Research Promotion Project of Chengdu University of TCM.
文摘The scope of stereochemistry recognition usually occurs near the chiral scaffold of a ligand or catalyst.Remote stereocontrol,which can surpass the limits of stereorecognition of remote prochiral centers,has long been a challenging object of great interest in asymmetric catalysis.The current work realized the remote stereocontrol of 1,7-zwitterion intermediates formed from Huang's o-amino aryl MBH carbonates.With simple and easily accessibleβ-ICD as the bifunctional catalyst,multifunctionalized tetrahydroquinoline derivatives could be synthesized via(4+2)cycloadditions with excellent enantioselectivity and diastereoselectivity under mild conditions.The strategy possesses broad substrate scope,and three types of electron-deficient enones are successfully applied.Mechanistic studies disclosed the Lewis base-catalyzed reaction pathway,and H-bonding between the catalyst and enones is crucial for long-range stereocontrol.Scale-up reaction and transformations of the tetrahydroquinoline products demonstrated the potential of this strategy.
基金supported by the National Key R&D Program of China(Grant No.2021YFF0502000)the National Natural Science Foundation of China(Grant No.52372233)the China Postdoctoral Science Foundation(No.2024M762820).
文摘In a recent article in Nature Energy,Zhang and He from Soochow University,Ozin from the University of Toronto,and their colleagues reported on a partially substituted perovskite that facilitates the efficient photocatalytic dehydrogenation of ethane[1].This material represents another prototypical example of surface frustrated Lewis pairs(SFLPs)in heterogeneous photocatalysis.The concept of SFLPs is based on the original idea of‘frustrated Lewis pairs’(FLPs)—sterically hindered Lewis acids and bases that cannot form the classical adducts[2].While FLPs are wellestablished in homogeneous catalysis,their surface counterparts,SFLPs,have found important applications in heterogeneous catalysis using solid-state materials[3].SFLP-based catalysts often consist of(bi)metallic oxyhydroxide/oxides/hydroxides,such as In_(2)O_(3)-x(OH)y,CoGeO_(2)-x(OH)y,BixIn2-xO3,ZnSn(OH)6,Cu_(2)O/CeO_(2),modified CeO_(2),and MOFs[4‒7].More recently,materials like wurtzite-structured GaN,ZnO,and AlP have also been identified as exceptions.SFLPs are known to activate small molecules such as CO_(2),H2,alkenes,dienes,and alkynes,and have gained particular CO_(2) reduction[4‒9].However,the application of SFLPs in C−H activation of ethane via photocatalysis has been less explored.Therefore,this work opens new possibilities for utilizing SFLPs in catalysis beyond CO_(2) hydrogenation[10,11].
基金support from the National Science Foundation of China(Nos.21620102002,91422302,21371048,91222102 and 21573056).
文摘Three isomorphic polytungstates,CsgK_(18)H_(10){[Sm_(2)(H_(2)O)_(4)W_(4)O_(10)(AsW_(9)0_(33))3]_(2)(N(CH_(2)PO_(3))_(2))}:46.5H_(2)O(1),CS_(10)K_(9)H_(18){[Eu_(2)(H_(2)O)_(4)W_(4)O_(10)(AsW_(9)0_(33))_(3)]_(2)(N(CH_(2)PO_(3))_(2))}.41.5H_(2)O(2),Cs_(10)K_(9)H_(18){[Gd_(2)(H_(2)O)_(4)W_(4)O_(10)(AsW_(9)O_(33))_(3)]_(2)(N(CH_(2)PO_(3))_(2))}:46H_(2)O(_(3)),have been successfully synthesized and characterized by routine methods,and demonstrated excellent catalytic activities in Knoevenagel condensation reaction as heterogeneous catalysts.Notably,catalyst 1 achieved higher reaction activity than catalysts 2 and 3,where a satisfactory reaction yield(95%)and high TON value(6380)could be obtained at moderate reaction condition.In addition,in the scale-up experiment,with the help of catalyst 1,7.8g benzaldehyde and 5.7g ethyl cyanoacetate could transform into corresponding condensation product with a satisfactory yield(83%)and impressive TON value(13.883).
基金support of the National Natural Science Founda-tion of China(Nos.52022031,21734004,21971075)the Fund of Guangdong Provincial Key Laboratory of Luminescenee from Molecular Aggregates(No.2019B030301003)is acknowledged.
文摘Phenols,in stead of con venti onal alcoholic compounds,are used to in itiate ring-openi ng polymerizati on(ROP)of ethyle neoxide and propyle ne oxide in bulk at room temperature in cooperati on with the recently prevaili ng bicompone nt metal-free catalyst comprising an organobase and triethylborane.Experimental and DFT calculation results both point out that due to the lower nucleophilicity of the initiating(phe no late)species than the propagating(alcoholate)species,chai n initiat ion is distinctly slower tha n propagation and the difference becomes eve n larger as the acidity of the phe nolic in itiator increases.Nevertheless,we 11-defi ned polyethers with expected molar mass,low dispersity,and high end-group fidelity are afforded substa ntiating that the ROP is living/c on trolled in spite of the slow initiation.Evolution of product composition indicates that the reaction on alcoholates(i.e.,propagation)is effectively inhib-ited by the unreacted phenols during the initiation step because of the adequately large acidity differenee,which is key to the success of the slow-initiation living/controlled polymerization.The acidity difference betwee n phe nol and alcohol also facilitates the fulfill-ment of highly selective phenolysis of epoxides,a"1+1"type addition reaction between phenol and epoxide(in excess)rather than the"1+n"type ROP reaction,by use of a milder organobase and decreased Lewis acid/base ratio.
基金supported by the financial aid from the National Key Research and Development Program of China(No.2021YFB3500700)the National Natural Science Foundation of China(Nos.22020102003,22025506,22271274 and U23A20140)+2 种基金Jilin Province Science and Technology Development Plan Project(No.20230101022JC)Hunan Province High-tech Industry Science and Technology Innovation Leading Plan(No.2022GK4021)funding from National Natural Science Foundation of China Outstanding Youth Science Foundation of China(Overseas).
文摘The cycloaddition reaction of CO_(2)with epoxide not only effectively reduces the concentration of CO_(2)in the atmosphere,but also has excellent industrial application value and up to 100%atom utilization,but there are difficulties in separation and recovery of traditional homogeneous catalysts,harsh reaction conditions of traditional heterogeneous catalysts,and activation of CO_(2)molecules.In this paper,an easily synthesized heterogeneous catalyst CeNCl/C was used to catalyze the cycloaddition reaction of CO_(2)with styrene oxide,with a high yield of 92.7%,a high selectivity of 96.7%,a turnover numbers(TON)value of 349,and a good stability demonstrated in six cycle tests(equivalent to 216 h of testing).Through comprehensive studies,it was shown that CeNCl/C contains Lewis acid-base centers as active centers,which can effectively reduce the energy barrier required for ring opening of the reaction substrate,enhance the adsorption and activation of CO_(2),and promote the formation of intermediates,which led to the acquisition of excellent catalytic activity.
基金the National Natural Science Foundation of China(21672039,21871051,22071027)Shanghai Science and Technology Committee(19DZ2270100)is gratefully acknowledged.
文摘Since the introduction of the concept of frustrated Lewis pair by Stephan in 2006,the frustrated Lewis pair(FLP)chemistry has evolved into a rich and fruitful research area which is largely responsible for the renaissance of main group chemistry in recent years.Among many applications of FLP,design of catalytic systems based on the concept of FLP,pioneered by Stephan,Chen and others,provides a powerful arsenal that has been applied to organic synthesis and polymerization.This article will highlight key advances in the development of FLP related catalysis.
基金the support of the Foundation of Department of Education of Guangdong Province(Nos.2021ZDZX2045,2024KTSCX040)the Wuyi University Innovation and Entrepreneurship Project(2023CX07,S202411349118)+1 种基金the National Natural Science Foundation of China(22163007)Guizhou Provincial Key Technology R&D Program(ZZSG[2024]002).
文摘Developing method for strong Si–F σ bond activation is a very important tool in organosilicon transformation chemistry, only few examples of Si–F bond activation are precedent in the literature. Herein, we developed a new and efficient method to activate strong Si–F bond by transition-metal-free Si–F/Si–H cross coupling reaction catalyzed with 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) catalytic system under mild conditions. Various disiloxanes bearing tolerated functional groups were successfully synthesized in moderate to excellent yields from fluorosilanes and hydrosilanes. Moreover, H_(2)O was found to be the oxygen donor in this catalytic system. Density functional theory calculations were performed to verify the mechanism of DBU promoted Si–F/Si–H cross-coupling reactions.
