N-heterocyclic carbene(NHC)organocatalytic reactions that have been developed for asymmetric construction of axial and planar chirality are systematically summarized and discussed in this review.The challenges and lim...N-heterocyclic carbene(NHC)organocatalytic reactions that have been developed for asymmetric construction of axial and planar chirality are systematically summarized and discussed in this review.The challenges and limitations inherent to this highly reactive research field are highlighted towards the end of the review.Additionally,based on our understanding of the current advancements in NHC organocatalysis,we propose potential future directions for further exploration.展开更多
Metal-organic framework(MOF) is a class of inorganic-organic hybrid material assembled periodically with metal ions and organic ligands. MOFs have always been the focuses in a variety of frontier fields owing to the a...Metal-organic framework(MOF) is a class of inorganic-organic hybrid material assembled periodically with metal ions and organic ligands. MOFs have always been the focuses in a variety of frontier fields owing to the advantageous properties, such as large BET surface areas, tunable porosity and easyfunctionalized surface structure. Among the various application areas, catalysis is one of the earliest application fields of MOFs-based materials and is one of the fastest-growing topics. In this review, the main roles of MOFs in heterogeneous organocatalysis have been systematically summarized, including used as support materials(or hosts), independent catalysts, and sacrificial templates. Moreover, the application prospects of MOFs in photocatalysis and electrocatalysis frontiers were also mentioned.Finally, the key issues that should be conquered in future were briefly sketched in the final parts of each item. We hope our perspectives could be beneficial for the readers to better understand these topics and issues, and could also provide a direction for the future exploration of some novel types of MOFs-based nanocatalysts with stable structures and functions for heterogeneous catalysis.展开更多
Quaternary ammonium bases, such as aqueous （CH3）4NOH, were found to be an extraordinarily efficient cata-lyst for cyanosilylation of aldehydes. The addition reaction of trimethylsilyl cyanide （TMSCN） to equivalent...Quaternary ammonium bases, such as aqueous （CH3）4NOH, were found to be an extraordinarily efficient cata-lyst for cyanosilylation of aldehydes. The addition reaction of trimethylsilyl cyanide （TMSCN） to equivalent alde-hydes could proceed smoothly with turnover frequency （TOF） up to 3000000 h l and in near 100% yield under solvent-free conditions. These organic catalysts also tolerated various aldehydes including aromatic, aliphatic and a,fl-unsaturated aldehydes. This process perfectly conforms to the features of green chemistry： no waste regarding side-products and unconverted reactants, solvent-free, excellent catalytic activity, and no requirement for separa- tion.展开更多
Polyolefin-b-poly(ethylene oxide)(PEO)represents the most widely investigated amphiphilic block copolymers.So far,one-pot continuous synthesis of such hybrid block copolymers has only been fulfilled by anionic polymer...Polyolefin-b-poly(ethylene oxide)(PEO)represents the most widely investigated amphiphilic block copolymers.So far,one-pot continuous synthesis of such hybrid block copolymers has only been fulfilled by anionic polymerization through sequen-tial addition of vinyl monomers and ethylene oxide(EO).It still remains challenging to achieve altogether high block efficiency,high polymerization efficiency,and high molar mass for PEO.Here,we report a one-pot hybrid block copolymerization approach to polyisoprene/polystyrene(PI/PS)-b-PEO,in which PI/PS are formed by sBuLi-initiated anionic vinyl-addition polymerization,then in situ employed as macroinitiators for the anionic ring-opening polymerization(ROP)of EO aided by an organic Lewis pair.The cooperative(dual-ion-complexing)catalytic effect of organobase and triethylborane is proven,for thefirst time,effective for lithium alkoxide initiator system,allowing to achieve at room temperature high ROP activity(complete EO conversion and PEO of 3–64 kg/mol reached in 1–6 h),narrow molar mass distribution,controlled block lengths and composition.Density functional the-ory calculation shows that phosphazene bases are particularly effective,compared with N-heterocyclic bases,for complexing with Li+and enhancing the nucleophilicity of oxyanion.The rate of ROP is also affected by Li^(+)-induced aggregation of the chain-end ion pairs,which though can be offset by adequate catalyst loadings.The versatility of this approach is further demonstrated in the one-pot synthesis of tri-/tetrablock ter-/quaterpolymers constituted by PI,PS,PEO,and poly(propylene oxide).Of great interest,PS-b-PI-b-PEO triblock terpolymer with a specific com-position is found to form internally microphase-separated micellar aggregates when dispersed in water.展开更多
Phenolation is one of the effective strategies to synthesize lignin-based polyphenols,improve lignin’s properties,and extend its value-added applications in biological,medicinal and cosmetic fields.Herein,by taking t...Phenolation is one of the effective strategies to synthesize lignin-based polyphenols,improve lignin’s properties,and extend its value-added applications in biological,medicinal and cosmetic fields.Herein,by taking the structural feature advantage of lignin,an effective and green strategy was developed to molecularly engineer lignin into a robust lignin-3-(2-hydroxyphenyl)propionate ester(LPPE)derivative via a transesterification reaction between 3,4-dihydrocoumarin(DHC)and the aliphatic hydroxyls in lignin under organocatalysis.The strategy is optimized and the novel derivative was systematically characterized by ^(1)H,^(13)C and ^(31)P nuclear magnetic resonance(NMR)and Fourier transform infrared(FT-IR)spectroscopy.The findings indicated that the successful introduction of 3-(2-hydroxyphenyl)propionate groups using a OH groups/DHC/organic base mo-lar ratio of 1꞉1꞉0.3 at 120℃ for 6 h increased the content of phenolic hydroxyl groups from 1.7931 to 3.0179 mmol/g,and the LPPE exhibited excellent ultraviolet-absorbing and antioxidant per-formance with up to 90%free radical scavenging activity within 20 min using 5 mg/mL of LPPE.In addition,good biocompatibility and a high Sun protection factor(SPF)value of 40.9 were achieved at 5%(w)dosage of LPPE in the cream,indicating its significant application potential in sunscreen.展开更多
High density of phenyl rings makes PAF-1 have robust structure and highly lipophilic pore, which make it very suitable for organocatalysis. However, there is no report about using PAF-1 as platform for enantioselectiv...High density of phenyl rings makes PAF-1 have robust structure and highly lipophilic pore, which make it very suitable for organocatalysis. However, there is no report about using PAF-1 as platform for enantioselective organocatalysis.In this paper, using PAF-1 as the platform, a chiral prolinamide catalytic site was introduced onto the framework of PAF-1 via a series of stepwise post-synthetic modifications,obtaining a novel PAF-supported chiral catalyst named PAF-1-NHPro. Then its enantioselective catalytic performance was studied by subjecting it to catalyze the model Aldol reaction between p-nitrobenzaldehyde and cyclohexanone.PAF-1-NHPro showed good diastereoselectivity and enantioselectivity with excellent and easy recyclability.展开更多
In recent years, a methodology merging photoredox catalysis with organocatalysis termed ＂photoredox organo- catalysis＂ has emerged to allow the direct, selective and efficient functionalization of the α/β-C of car...In recent years, a methodology merging photoredox catalysis with organocatalysis termed ＂photoredox organo- catalysis＂ has emerged to allow the direct, selective and efficient functionalization of the α/β-C of carbonyl com- pounds under mild reaction condition. In this review, photophysics background of photoredox catalysis is intro- duced, followed by a report on recent advances in direct α- and β-functionalization of carbonyls with photoredox organocatalysis methodology. With this different reaction modes, valuable synthetic targets including different a/fl-functionalized carbonyls are accessible.展开更多
The catalytic enantioselective electrophilic amination reaction has emerged as a highly efficient method for synthesizing diverse nitrogen-containing chiral molecules,with the development of various asymmetric catalys...The catalytic enantioselective electrophilic amination reaction has emerged as a highly efficient method for synthesizing diverse nitrogen-containing chiral molecules,with the development of various asymmetric catalysis systems.Chiral phosphoric acids(CPA)have been widely acknowledged as versatile chiral organocatalysts since it was first discovered in 2004,finding application in catalyzing diverse asymmetric reactions.A comprehensive overview of recent advances in CPA-catalyzed asymmetric electrophilic amination reactions using different N-electrophilic reagents,including azo reagents,aryldiazonium salts,and imine derivatives,is presented.Furthermore,insights into future developments in this field are offered.展开更多
A novel organocatalytic asymmetric approach to oxazoline derivatives that proceeds through Mannich/annulation reaction of N-acylimines with 3-chlorooxindoles is presented.This strategy provides an efficient and conven...A novel organocatalytic asymmetric approach to oxazoline derivatives that proceeds through Mannich/annulation reaction of N-acylimines with 3-chlorooxindoles is presented.This strategy provides an efficient and convenient method to access enantioenriched oxazolines such as valuable chiral S,Noxazoline ligand as well as Ferrox ligand in high yields with excellent enantio–and diastereroselectivity.Furthermore,the optically active oxazoline products can be converted to valuable 1,2-amino alcohols.More importantly,the synthetic utility of this transformation is demonstrated in the expeditious assembly of chiral Phox-type ligand,which shows excellent catalytic activities.展开更多
The alternating copolymer of CO_(2) with epoxide is a green plastic that can efficiently transform CO_(2) into valuable chemicals. Despite the significant advances made, the restricted practical application of CO_(2)-...The alternating copolymer of CO_(2) with epoxide is a green plastic that can efficiently transform CO_(2) into valuable chemicals. Despite the significant advances made, the restricted practical application of CO_(2)-sourced polycarbonates due to their lack of functionality has hindered field development. We successfully demonstrated the flame retardancy of poly(chloropropylene carbonate) (PCPC), a perfectly alternating copolymer of epichlorohydrin (ECH) and CO_(2). This was prepared at a 200-gram scale using a high-efficacy tetranuclear organoborane catalyst. PCPC’s excellent flame-retardant performance has been proven by both the vertical combustion test (UL94 V-0) and the limiting oxygen index (LOI) value (29.1%). The underlaid flame-retardant mechanism of PCPC was clearly elucidated. As a result, we confirmed that the generated cyclic carbonates and concurrently released flame-retardant chlorine radicals, hydrogen chloride, and CO_(2) during combustion render PCPC an excellent flame retardant. Furthermore, we investigated the practicability of PCPC as a halogen-rich polymeric flame retardant by blending it with commercial bisphenol A polycarbonate (BPA-PC). PCPC upgraded the flame retardancy rating of BPA polycarbonate from V-2 to V-0 even with a mere 1 wt% addition. It is our hope that this result will prove useful in future developments of advanced CO_(2)-sourced polymeric materials.展开更多
An N-heterocyclic carbene(NHC)catalyzed enantioselective cyclisation and trifluoromethylation of olefins with cinnamaldehydes via radical relay cross-coupling in the presence of Togni reagent is reported andδ-lactone...An N-heterocyclic carbene(NHC)catalyzed enantioselective cyclisation and trifluoromethylation of olefins with cinnamaldehydes via radical relay cross-coupling in the presence of Togni reagent is reported andδ-lactones tolerated with stereogenic centers atβ-andγ-positions are obtained in moderate to high yields and with high enantioselectivities.Further computational studies explain that the radical crosscoupling step is the key to determining the enantioselectivity.Energy analysis of key transition states and intermediates also provides a reasonable explanation for the difficulty of diastereoselective control.DFT calculations also reveal that the hydrogen-bonding interaction plays a vital role in the promotion of this chemistry.展开更多
The[2+2]photopolymerization of bisolefinic monomers is an important method for the synthesis of polymeric materials.However,these processes are usually carried out in solid states under the irradiation of high-energy ...The[2+2]photopolymerization of bisolefinic monomers is an important method for the synthesis of polymeric materials.However,these processes are usually carried out in solid states under the irradiation of high-energy UV light,while the corresponding[2+2]polymerization in solution has proved to be inefficient due to the lack of preassembly of the monomers.Herein,we demonstrate that the[2+2]polymerization of p-phenylenediacrylate monomers can be achieved in solution under visible light by employing energy transfer catalysis with 2,2'-methoxythioxanthone as a photocatalyst.Because no preassembly is required,this solution polymerization is applicable to p-phenylenediacrylate monomers with different ester groups,affording a series of cyclobutane-imbedded full-carbon chain polymers with high thermal stability,good solubility,and processibility.In addition,by virtue of the reversibility of the photo[2+2]cycloaddition,this[2+2]photopolymerization product can also undergo depolymerization to lower molecular weight polymers,suggesting the potential of this class of photopolymerization in the development of closed-loop chemical recyclable polymers.展开更多
The electrochemical CO_(2) reduction reaction(eCO_(2)RR),producing gaseous C_(2+)products such as ethylene(C_(2)H_(4)),represents a sustainable strategy to mitigate the greenhouse effect.Inspired by the promotion effe...The electrochemical CO_(2) reduction reaction(eCO_(2)RR),producing gaseous C_(2+)products such as ethylene(C_(2)H_(4)),represents a sustainable strategy to mitigate the greenhouse effect.Inspired by the promotion effect of the cyano group(-C≡N) for C-C coupling in organic chemistry,several cyano-containing organocatalysts have been found to be capable of directly converting CO_(2) into C_(2)H_(4) with-C≡N as the active center during the eCO_(2)RR.The selectivity of C_(2)H_(4) for the representative catalyst,metal-free dicyandiamide(DCD),reached 27.6 % after partial hydrogenation in KHCO_(3) solution.In addition,its selectivity can be further improved to 57.7 % when coupled with oriented Cu crystals.The experimental and computational results collectively reveal that charge redistribution between Cu{100} and DCD promotes the partial hydrogenation of the cyano group and lays the foundation for the reduced energy barrier for the CO_(2) reduction on-C≡N.This study breaks the limitations of traditional metal/metal oxide-based catalysts by using cyano-containing organocatalysts for direct C_(2+) product generation,expanding the eCO_(2)RR catalyst library.In addition,this research elucidates the role of charge redistribution and cyano group hydrogenation in lowering reaction barriers,providing fundamental guidance for the design of new organocatalysts.展开更多
The enamines, iminium ions, and oxazolidinones are thought to be the key intermediates in the proline-catalyzed reactions of aldehydes or ketones, but there is an extensive contro- versy about their roles. Here, the c...The enamines, iminium ions, and oxazolidinones are thought to be the key intermediates in the proline-catalyzed reactions of aldehydes or ketones, but there is an extensive contro- versy about their roles. Here, the corresponding transition states connecting any two of the three kinds of species are located at the wB97XD/6-311＋＋G＊＊ level of theory. The calcula- tions demonstrate that the oxazolidinones are the predominant species in both the gas phase and solvents; there exists tautomeric equilibrium among these species and the equilibriums are controlled by the employed solvents and temperature in the reaction. These results demonstrate that the concentration and role of the mentioned species are controlled by the employed solvent and temperature. A new reaction pathway is presented herein for the trans- formation between iminium ions and oxazolidinones through iminium ion-water complex and oxazolidinone-water complex. The calculations demonstrate that the rate-limiting step in proline-catalyzed Mannich reaction between acetaldehyde/keteones and N-Boc imines is the formation of the C-C bond rather than the intermediates tautomerization. These calculations rationalize the available experimental observations and can be valuable in optimizing the experimental conditions of asymmetric organic-catalyzed reactions of aldehydes or ketones.展开更多
This review summarizes the very recent advances in asymmetric reactions catalyzed by chiral phosphoric acids（CPAs）, a family of versatile catalysts that catalyze a broad range of reactions to afford diverse chiral m...This review summarizes the very recent advances in asymmetric reactions catalyzed by chiral phosphoric acids（CPAs）, a family of versatile catalysts that catalyze a broad range of reactions to afford diverse chiral molecules. In the past years, different kinds of chiral phosphoric acids have been designed and developed into a privileged class of catalysts in asymmetric synthesis. A number of remarkable achievements have been made by many groups around the world. Due to length limitation, this review only summarizes those works published from January 2016 to November 2017. Meanwhile, catalytic systems which combine metal catalysts and chiral phosphoric acids will not be discussed in this review.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
Well-defined polycarbonate diol was successfully synthesized through a strategy using a combination of organocatalyst and water.Such strategy was less developed in organocatalyzed polymerization and frequently regarde...Well-defined polycarbonate diol was successfully synthesized through a strategy using a combination of organocatalyst and water.Such strategy was less developed in organocatalyzed polymerization and frequently regarded as side reactions.Herein,one-component phosphonium borane Lewis pairs PB1-PB8 were successfully applied in the copolymerization of CO_(2) and cyclohexene oxide(CHO)to generate poly(CHO-alt-CO_(2))carbonate(PCHC).Parameters of linker length and counter anion effects on the catalyst activity were investigated.It was found that Lewis pair PB3 served as a dual initiator and catalyst in the copolymerization of CHO and CO_(2) with or without the presence of water.In contrast,Lewis pair PB8 can serve as a true catalyst for the preparation of well-definedα,ω-hydroxyl PCHC diols.This was achieved by introducing a labile CF3COO group as counter anion through anion exchange reaction while water molecules acted as chain transfer agents.The function of trifluoroacetate group in the polymerization process was investigated in detail and possible mechanism was proposed.Upon changing the amount of water and catalyst loading,PCHC diols with varied molecular weight(1.5 kg/mol to 7.5 kg/mol),low dispersities(D<1.2)and carbonate content(>99%)could be easily obtained.The low molecular weight PCHC diol was used as a bifunctional macroinitiator for the ring-opening polymerization of L-lactide(LLA)to afford ABA triblock copolymer in one-pot synthesis.展开更多
Enantioselective synthesis of functionalized fluorinated dihydropyrano[2,3-c]pyrazoles has been achieved via a diaminocyclohexane-thiourea catalyzed cascade Michael addition and Thorpe-Ziegler type cyclization in high...Enantioselective synthesis of functionalized fluorinated dihydropyrano[2,3-c]pyrazoles has been achieved via a diaminocyclohexane-thiourea catalyzed cascade Michael addition and Thorpe-Ziegler type cyclization in high yields （up to 98%） with moderate to good enantioselectivity （up to 90% ee）.展开更多
Selective oxidation with molecular oxygen as the sole oxidant under mild conditions is of crucialimportance for the long‐term sustainable exploitation of available feedstocks and the formation ofrequired intermediate...Selective oxidation with molecular oxygen as the sole oxidant under mild conditions is of crucialimportance for the long‐term sustainable exploitation of available feedstocks and the formation ofrequired intermediates for organic synthesis and industrial processes.Among the developed oxidationprotocols,innovative strategies using hydroxyimide organocatalysts in combination with metallicor metal‐free cocatalysts have attracted much attention because of the good activities andselectivities of such catalysts in the oxo functionalization of hydrocarbons.This method is based onthe reaction using N‐hydroxyphthalimide,which was first reported by Ishii’s group in the1990s.Although the important and wide‐ranging applications of such catalysts have been summarizedrecently,there are no reviews that focus solely on oxidation strategies using multi‐nitroxy organocatalysts,which have interesting properties and high reactivities.This review covers the concisesynthetic methods and mechanistic profiles of known multi‐nitroxy organocatalysts and summarizessignificant advances in their use in efficient aerobic oxidation.Based on a combination of experimentaland theoretical results,guidelines for the future rational design of multi‐nitroxy organocatalystsare proposed,and the properties of various model multi‐nitroxy organocatalysts are predicted.The present overview of the advantages,limitations,and potential applications of multi‐nitroxyorganocatalysts can provide useful tools for researchers in the field of selective oxidation.展开更多
An N-heterocyclic carbene(NHC)-catalyzed carbonyl nucleophilic substitution reaction between 1-cyclopropylcarbaldehydes and N-sulfonyl imines is developed for access to linearβ-aminoenone products.Theβ-aminoenones c...An N-heterocyclic carbene(NHC)-catalyzed carbonyl nucleophilic substitution reaction between 1-cyclopropylcarbaldehydes and N-sulfonyl imines is developed for access to linearβ-aminoenone products.Theβ-aminoenones containing cyclopropyl fragments can be afforded in moderate to excellent yields under mild conditions.The reaction features excellent trans-diastereoselectivities and the desired aminoenone products are all afforded as Z-isomers.展开更多
基金supported by the National Natural Science Foundation of China (22371057,32172459,32330087)the National Key Research and Development Program of China (2022YFD-1700300)+6 种基金the Science and Technology Department of Guizhou Province (Qiankehejichu-ZK (2021)Key033)the Frontiers Science Center for Asymmetric Synthesis and Medicinal Molecules,Department of Education,Guizhou Province (Qianjiaohe KY (2020)004)the Central Government Guides Local Science and Technology Development Fund Projects (Qiankehezhongyindi (2024)007, (2023)001)the Program of Major Scientific and Technological,Guizou Province (Qiankehechengguo (2024)zhongda007)the Program of Introducing Talents of Discipline to Universities of China (111 Program,D20023)at Guizhou Universitythe Yongjiang Plan for Innovation and Entrepreneurship Leading Talent Project in the City of Nanning (2021005)Guizhou University (China)。
文摘N-heterocyclic carbene(NHC)organocatalytic reactions that have been developed for asymmetric construction of axial and planar chirality are systematically summarized and discussed in this review.The challenges and limitations inherent to this highly reactive research field are highlighted towards the end of the review.Additionally,based on our understanding of the current advancements in NHC organocatalysis,we propose potential future directions for further exploration.
基金supported by the National Natural Science Foundation of China(21706217)Scientific Research Fund of Chemical Synthesis and Pollution Control Key Laboratory of Sichuan Province(CSPC2015-1-2)+6 种基金Scientific Research Fund of China West normal University(15E009)Scientific Research Fund of Sichuan Provincial Education Department(17AZ0382,17TD0036)the Meritocracy Research Funds of China West normal University(17YC029)the Fundamental Research Funds of China West normal University(17C035)Scientific Research Fund of Science&Technology of Sichuan Province(2017JY0015)Youth Innovation Promotion Association of CAS(2015316)the National High Technology Research and Development Program of China(2015AA021107)
文摘Metal-organic framework(MOF) is a class of inorganic-organic hybrid material assembled periodically with metal ions and organic ligands. MOFs have always been the focuses in a variety of frontier fields owing to the advantageous properties, such as large BET surface areas, tunable porosity and easyfunctionalized surface structure. Among the various application areas, catalysis is one of the earliest application fields of MOFs-based materials and is one of the fastest-growing topics. In this review, the main roles of MOFs in heterogeneous organocatalysis have been systematically summarized, including used as support materials(or hosts), independent catalysts, and sacrificial templates. Moreover, the application prospects of MOFs in photocatalysis and electrocatalysis frontiers were also mentioned.Finally, the key issues that should be conquered in future were briefly sketched in the final parts of each item. We hope our perspectives could be beneficial for the readers to better understand these topics and issues, and could also provide a direction for the future exploration of some novel types of MOFs-based nanocatalysts with stable structures and functions for heterogeneous catalysis.
文摘Quaternary ammonium bases, such as aqueous （CH3）4NOH, were found to be an extraordinarily efficient cata-lyst for cyanosilylation of aldehydes. The addition reaction of trimethylsilyl cyanide （TMSCN） to equivalent alde-hydes could proceed smoothly with turnover frequency （TOF） up to 3000000 h l and in near 100% yield under solvent-free conditions. These organic catalysts also tolerated various aldehydes including aromatic, aliphatic and a,fl-unsaturated aldehydes. This process perfectly conforms to the features of green chemistry： no waste regarding side-products and unconverted reactants, solvent-free, excellent catalytic activity, and no requirement for separa- tion.
基金National Natural Science Foundation of China,Grant/Award Number:52022031Guangdong Provincial Key Laboratory of Luminescence from Molecular Aggregates,Grant/Award Number:2023B1212060003Hunan Provincial Natural Science Foundation of China,Grant/Award Number:2023JJ40620。
文摘Polyolefin-b-poly(ethylene oxide)(PEO)represents the most widely investigated amphiphilic block copolymers.So far,one-pot continuous synthesis of such hybrid block copolymers has only been fulfilled by anionic polymerization through sequen-tial addition of vinyl monomers and ethylene oxide(EO).It still remains challenging to achieve altogether high block efficiency,high polymerization efficiency,and high molar mass for PEO.Here,we report a one-pot hybrid block copolymerization approach to polyisoprene/polystyrene(PI/PS)-b-PEO,in which PI/PS are formed by sBuLi-initiated anionic vinyl-addition polymerization,then in situ employed as macroinitiators for the anionic ring-opening polymerization(ROP)of EO aided by an organic Lewis pair.The cooperative(dual-ion-complexing)catalytic effect of organobase and triethylborane is proven,for thefirst time,effective for lithium alkoxide initiator system,allowing to achieve at room temperature high ROP activity(complete EO conversion and PEO of 3–64 kg/mol reached in 1–6 h),narrow molar mass distribution,controlled block lengths and composition.Density functional the-ory calculation shows that phosphazene bases are particularly effective,compared with N-heterocyclic bases,for complexing with Li+and enhancing the nucleophilicity of oxyanion.The rate of ROP is also affected by Li^(+)-induced aggregation of the chain-end ion pairs,which though can be offset by adequate catalyst loadings.The versatility of this approach is further demonstrated in the one-pot synthesis of tri-/tetrablock ter-/quaterpolymers constituted by PI,PS,PEO,and poly(propylene oxide).Of great interest,PS-b-PI-b-PEO triblock terpolymer with a specific com-position is found to form internally microphase-separated micellar aggregates when dispersed in water.
基金supported by National Natural Science Foundation of China(No.22275041No.21774028,No.21574030)+4 种基金Science and Technology Department of Guizhou Province&Guizhou University Joint FundScience and Technology Department of Guizhou Province(Natural Science Key Fund ZK[2021]023Platform&Talents[2016]5652,[2017]5788,[2018]5781,and[2019]5607)Introduced Talent Research Project of Guizhou University([2022]16)LETSGrp2020042402 and Basic research project of Guizhou University([2023]01).
文摘Phenolation is one of the effective strategies to synthesize lignin-based polyphenols,improve lignin’s properties,and extend its value-added applications in biological,medicinal and cosmetic fields.Herein,by taking the structural feature advantage of lignin,an effective and green strategy was developed to molecularly engineer lignin into a robust lignin-3-(2-hydroxyphenyl)propionate ester(LPPE)derivative via a transesterification reaction between 3,4-dihydrocoumarin(DHC)and the aliphatic hydroxyls in lignin under organocatalysis.The strategy is optimized and the novel derivative was systematically characterized by ^(1)H,^(13)C and ^(31)P nuclear magnetic resonance(NMR)and Fourier transform infrared(FT-IR)spectroscopy.The findings indicated that the successful introduction of 3-(2-hydroxyphenyl)propionate groups using a OH groups/DHC/organic base mo-lar ratio of 1꞉1꞉0.3 at 120℃ for 6 h increased the content of phenolic hydroxyl groups from 1.7931 to 3.0179 mmol/g,and the LPPE exhibited excellent ultraviolet-absorbing and antioxidant per-formance with up to 90%free radical scavenging activity within 20 min using 5 mg/mL of LPPE.In addition,good biocompatibility and a high Sun protection factor(SPF)value of 40.9 were achieved at 5%(w)dosage of LPPE in the cream,indicating its significant application potential in sunscreen.
基金supported by National Basic Research Program of China (2014CB931804)the National Natural Science Foundation of China (21302061 and 21531003)
文摘High density of phenyl rings makes PAF-1 have robust structure and highly lipophilic pore, which make it very suitable for organocatalysis. However, there is no report about using PAF-1 as platform for enantioselective organocatalysis.In this paper, using PAF-1 as the platform, a chiral prolinamide catalytic site was introduced onto the framework of PAF-1 via a series of stepwise post-synthetic modifications,obtaining a novel PAF-supported chiral catalyst named PAF-1-NHPro. Then its enantioselective catalytic performance was studied by subjecting it to catalyze the model Aldol reaction between p-nitrobenzaldehyde and cyclohexanone.PAF-1-NHPro showed good diastereoselectivity and enantioselectivity with excellent and easy recyclability.
文摘In recent years, a methodology merging photoredox catalysis with organocatalysis termed ＂photoredox organo- catalysis＂ has emerged to allow the direct, selective and efficient functionalization of the α/β-C of carbonyl com- pounds under mild reaction condition. In this review, photophysics background of photoredox catalysis is intro- duced, followed by a report on recent advances in direct α- and β-functionalization of carbonyls with photoredox organocatalysis methodology. With this different reaction modes, valuable synthetic targets including different a/fl-functionalized carbonyls are accessible.
文摘The catalytic enantioselective electrophilic amination reaction has emerged as a highly efficient method for synthesizing diverse nitrogen-containing chiral molecules,with the development of various asymmetric catalysis systems.Chiral phosphoric acids(CPA)have been widely acknowledged as versatile chiral organocatalysts since it was first discovered in 2004,finding application in catalyzing diverse asymmetric reactions.A comprehensive overview of recent advances in CPA-catalyzed asymmetric electrophilic amination reactions using different N-electrophilic reagents,including azo reagents,aryldiazonium salts,and imine derivatives,is presented.Furthermore,insights into future developments in this field are offered.
基金Qingdao Marine Science and Technology Center(No.2022QNLM030003–2)the Fundamental Research Funds for the Central Universities,Taishan Scholar Program of Shandong Province(No.tsqn202103152)+2 种基金National Natural Science Foundation of China(No.22201270)Natural Science Foundation of Shandong Province(No.ZR2021QB033)the National Key Research and Development Program of China(No.2022YFC2804400)for financial support。
文摘A novel organocatalytic asymmetric approach to oxazoline derivatives that proceeds through Mannich/annulation reaction of N-acylimines with 3-chlorooxindoles is presented.This strategy provides an efficient and convenient method to access enantioenriched oxazolines such as valuable chiral S,Noxazoline ligand as well as Ferrox ligand in high yields with excellent enantio–and diastereroselectivity.Furthermore,the optically active oxazoline products can be converted to valuable 1,2-amino alcohols.More importantly,the synthetic utility of this transformation is demonstrated in the expeditious assembly of chiral Phox-type ligand,which shows excellent catalytic activities.
基金supported by the National Science Fund for Distinguished Young Scholars(No.T2225004)National Natural Science Foundation of China(No.52373092)Shccig-Qinling Program.
文摘The alternating copolymer of CO_(2) with epoxide is a green plastic that can efficiently transform CO_(2) into valuable chemicals. Despite the significant advances made, the restricted practical application of CO_(2)-sourced polycarbonates due to their lack of functionality has hindered field development. We successfully demonstrated the flame retardancy of poly(chloropropylene carbonate) (PCPC), a perfectly alternating copolymer of epichlorohydrin (ECH) and CO_(2). This was prepared at a 200-gram scale using a high-efficacy tetranuclear organoborane catalyst. PCPC’s excellent flame-retardant performance has been proven by both the vertical combustion test (UL94 V-0) and the limiting oxygen index (LOI) value (29.1%). The underlaid flame-retardant mechanism of PCPC was clearly elucidated. As a result, we confirmed that the generated cyclic carbonates and concurrently released flame-retardant chlorine radicals, hydrogen chloride, and CO_(2) during combustion render PCPC an excellent flame retardant. Furthermore, we investigated the practicability of PCPC as a halogen-rich polymeric flame retardant by blending it with commercial bisphenol A polycarbonate (BPA-PC). PCPC upgraded the flame retardancy rating of BPA polycarbonate from V-2 to V-0 even with a mere 1 wt% addition. It is our hope that this result will prove useful in future developments of advanced CO_(2)-sourced polymeric materials.
基金financial supports for this work are provided by the National Natural Science Foundation of China(Nos.21871160,21672121,22071130)。
文摘An N-heterocyclic carbene(NHC)catalyzed enantioselective cyclisation and trifluoromethylation of olefins with cinnamaldehydes via radical relay cross-coupling in the presence of Togni reagent is reported andδ-lactones tolerated with stereogenic centers atβ-andγ-positions are obtained in moderate to high yields and with high enantioselectivities.Further computational studies explain that the radical crosscoupling step is the key to determining the enantioselectivity.Energy analysis of key transition states and intermediates also provides a reasonable explanation for the difficulty of diastereoselective control.DFT calculations also reveal that the hydrogen-bonding interaction plays a vital role in the promotion of this chemistry.
基金financially supported by the National Natural Science Foundation of China(Nos.22371240 and 22361132535)Xiamen University for the financial support。
文摘The[2+2]photopolymerization of bisolefinic monomers is an important method for the synthesis of polymeric materials.However,these processes are usually carried out in solid states under the irradiation of high-energy UV light,while the corresponding[2+2]polymerization in solution has proved to be inefficient due to the lack of preassembly of the monomers.Herein,we demonstrate that the[2+2]polymerization of p-phenylenediacrylate monomers can be achieved in solution under visible light by employing energy transfer catalysis with 2,2'-methoxythioxanthone as a photocatalyst.Because no preassembly is required,this solution polymerization is applicable to p-phenylenediacrylate monomers with different ester groups,affording a series of cyclobutane-imbedded full-carbon chain polymers with high thermal stability,good solubility,and processibility.In addition,by virtue of the reversibility of the photo[2+2]cycloaddition,this[2+2]photopolymerization product can also undergo depolymerization to lower molecular weight polymers,suggesting the potential of this class of photopolymerization in the development of closed-loop chemical recyclable polymers.
基金financial support provided by the National Natural Science Foundation of China (52472304)。
文摘The electrochemical CO_(2) reduction reaction(eCO_(2)RR),producing gaseous C_(2+)products such as ethylene(C_(2)H_(4)),represents a sustainable strategy to mitigate the greenhouse effect.Inspired by the promotion effect of the cyano group(-C≡N) for C-C coupling in organic chemistry,several cyano-containing organocatalysts have been found to be capable of directly converting CO_(2) into C_(2)H_(4) with-C≡N as the active center during the eCO_(2)RR.The selectivity of C_(2)H_(4) for the representative catalyst,metal-free dicyandiamide(DCD),reached 27.6 % after partial hydrogenation in KHCO_(3) solution.In addition,its selectivity can be further improved to 57.7 % when coupled with oriented Cu crystals.The experimental and computational results collectively reveal that charge redistribution between Cu{100} and DCD promotes the partial hydrogenation of the cyano group and lays the foundation for the reduced energy barrier for the CO_(2) reduction on-C≡N.This study breaks the limitations of traditional metal/metal oxide-based catalysts by using cyano-containing organocatalysts for direct C_(2+) product generation,expanding the eCO_(2)RR catalyst library.In addition,this research elucidates the role of charge redistribution and cyano group hydrogenation in lowering reaction barriers,providing fundamental guidance for the design of new organocatalysts.
文摘The enamines, iminium ions, and oxazolidinones are thought to be the key intermediates in the proline-catalyzed reactions of aldehydes or ketones, but there is an extensive contro- versy about their roles. Here, the corresponding transition states connecting any two of the three kinds of species are located at the wB97XD/6-311＋＋G＊＊ level of theory. The calcula- tions demonstrate that the oxazolidinones are the predominant species in both the gas phase and solvents; there exists tautomeric equilibrium among these species and the equilibriums are controlled by the employed solvents and temperature in the reaction. These results demonstrate that the concentration and role of the mentioned species are controlled by the employed solvent and temperature. A new reaction pathway is presented herein for the trans- formation between iminium ions and oxazolidinones through iminium ion-water complex and oxazolidinone-water complex. The calculations demonstrate that the rate-limiting step in proline-catalyzed Mannich reaction between acetaldehyde/keteones and N-Boc imines is the formation of the C-C bond rather than the intermediates tautomerization. These calculations rationalize the available experimental observations and can be valuable in optimizing the experimental conditions of asymmetric organic-catalyzed reactions of aldehydes or ketones.
基金Financial support from the National Natural Science Foundation of China (No. 21772046)the Recruitment Program of Global Experts(1000 Talents Plan)+1 种基金the Natural Science Foundation of Fujian Province(No. 2016J01064)Program of Innovative Research Team of Huaqiao University (No. Z14X0047)are gratefully acknowledged
文摘This review summarizes the very recent advances in asymmetric reactions catalyzed by chiral phosphoric acids（CPAs）, a family of versatile catalysts that catalyze a broad range of reactions to afford diverse chiral molecules. In the past years, different kinds of chiral phosphoric acids have been designed and developed into a privileged class of catalysts in asymmetric synthesis. A number of remarkable achievements have been made by many groups around the world. Due to length limitation, this review only summarizes those works published from January 2016 to November 2017. Meanwhile, catalytic systems which combine metal catalysts and chiral phosphoric acids will not be discussed in this review.
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financially supported by the National Key R&D Program of China(No.2021YFA1501600)the National Natural Science Foundation of China(Nos.22175105 and 22031005)。
文摘Well-defined polycarbonate diol was successfully synthesized through a strategy using a combination of organocatalyst and water.Such strategy was less developed in organocatalyzed polymerization and frequently regarded as side reactions.Herein,one-component phosphonium borane Lewis pairs PB1-PB8 were successfully applied in the copolymerization of CO_(2) and cyclohexene oxide(CHO)to generate poly(CHO-alt-CO_(2))carbonate(PCHC).Parameters of linker length and counter anion effects on the catalyst activity were investigated.It was found that Lewis pair PB3 served as a dual initiator and catalyst in the copolymerization of CHO and CO_(2) with or without the presence of water.In contrast,Lewis pair PB8 can serve as a true catalyst for the preparation of well-definedα,ω-hydroxyl PCHC diols.This was achieved by introducing a labile CF3COO group as counter anion through anion exchange reaction while water molecules acted as chain transfer agents.The function of trifluoroacetate group in the polymerization process was investigated in detail and possible mechanism was proposed.Upon changing the amount of water and catalyst loading,PCHC diols with varied molecular weight(1.5 kg/mol to 7.5 kg/mol),low dispersities(D<1.2)and carbonate content(>99%)could be easily obtained.The low molecular weight PCHC diol was used as a bifunctional macroinitiator for the ring-opening polymerization of L-lactide(LLA)to afford ABA triblock copolymer in one-pot synthesis.
基金supported by National Basic Research Program of China(973 Program,No.2010CB833200)the National Natural Science Foundation of China(Nos.21032006,203900502,20532040,21290180)Science and Technology Commission of Shanghai Municipality(No.11XD1406400)
文摘Enantioselective synthesis of functionalized fluorinated dihydropyrano[2,3-c]pyrazoles has been achieved via a diaminocyclohexane-thiourea catalyzed cascade Michael addition and Thorpe-Ziegler type cyclization in high yields （up to 98%） with moderate to good enantioselectivity （up to 90% ee）.
基金supported by the China Postdoctoral Science Foundation (2014M551746)~~
文摘Selective oxidation with molecular oxygen as the sole oxidant under mild conditions is of crucialimportance for the long‐term sustainable exploitation of available feedstocks and the formation ofrequired intermediates for organic synthesis and industrial processes.Among the developed oxidationprotocols,innovative strategies using hydroxyimide organocatalysts in combination with metallicor metal‐free cocatalysts have attracted much attention because of the good activities andselectivities of such catalysts in the oxo functionalization of hydrocarbons.This method is based onthe reaction using N‐hydroxyphthalimide,which was first reported by Ishii’s group in the1990s.Although the important and wide‐ranging applications of such catalysts have been summarizedrecently,there are no reviews that focus solely on oxidation strategies using multi‐nitroxy organocatalysts,which have interesting properties and high reactivities.This review covers the concisesynthetic methods and mechanistic profiles of known multi‐nitroxy organocatalysts and summarizessignificant advances in their use in efficient aerobic oxidation.Based on a combination of experimentaland theoretical results,guidelines for the future rational design of multi‐nitroxy organocatalystsare proposed,and the properties of various model multi‐nitroxy organocatalysts are predicted.The present overview of the advantages,limitations,and potential applications of multi‐nitroxyorganocatalysts can provide useful tools for researchers in the field of selective oxidation.
基金the financial support from the National Natural Science Foundation of China(Nos.21772029,32172459,21961006,22001173)The 10 Talent Plan(Shicengci)of Guizhou Province(No.[2016]5649)+4 种基金the Science and Technology Department of Guizhou Province(Nos.[2019]1020,Qiankehejichu-ZK[2021]Key033)the Program of Introducing Talents of Discipline to Universities of China(111 Program,No.D20023)at Guizhou UniversityFrontiers Science Center for Asymmetric Synthesis and Medicinal Molecules,Department of Education,Guizhou Province[No.Qianjiaohe KY(2020)004]the Guizhou Province First-Class Disciplines Project(No.GNYL(2017)008)Guizhou University(China)。
文摘An N-heterocyclic carbene(NHC)-catalyzed carbonyl nucleophilic substitution reaction between 1-cyclopropylcarbaldehydes and N-sulfonyl imines is developed for access to linearβ-aminoenone products.Theβ-aminoenones containing cyclopropyl fragments can be afforded in moderate to excellent yields under mild conditions.The reaction features excellent trans-diastereoselectivities and the desired aminoenone products are all afforded as Z-isomers.
