High frequency(HF)transmission is an important communication techniques.However,conven-tional point-to-point transmission can be easily destroyed,which limits its utilization in practice.HF networking communication ...High frequency(HF)transmission is an important communication techniques.However,conven-tional point-to-point transmission can be easily destroyed,which limits its utilization in practice.HF networking communication has the capability against demolishment.The network structure is one of the key factors for HF networking communication.In this paper,a novel analysis method of the network connectedness based on the eigenvalue is derived,and a multi-layer distributed HF radio network structure is proposed.Both the theore-tical analysis and the computer simulation results verify that the application of the proposed network structure in the HF radio communication can improve the anti-demolishment ability of the HF network efficiently.展开更多
The development of stereodivergent synthetic methods to access all four stereoisomers of biologically importantα-fluoroγ-butyrolactones containing vicinal stereocenters is of great importance and poses a formidable ...The development of stereodivergent synthetic methods to access all four stereoisomers of biologically importantα-fluoroγ-butyrolactones containing vicinal stereocenters is of great importance and poses a formidable challenge owing to ring strain and steric hindrance.Herein,a novel asymmetric[3+2]annulation ofα-fluoroα-azaaryl acetates with vinylethylene carbonate was successfully developed through Cu/Ir-catalyzed cascade allylic alkylation/lactonization,affording a variety of enantioenrichedα-fluoroγ-butyrolactones bearing vicinal stereogenic centers with high reaction efficiency and excellent levels of both stereoselectivity and regioselectivity(up to 98%yield,generally>20:1 dr and>99%ee).Notably,all four stereoisomers of these pharmaceutically valuable molecules could be accessed individually via simple permutations of two enantiomeric catalysts.In addition,other azaaryl acetates bearingα-methyl,α-chlorine orα-phenyl group were tolerated well in this transformation.Reaction mechanistic investigations were conducted to explore the process of this bimetallic catalysis based on the results of reaction intermediates,isotopic labelling experiments,and kinetic studies.展开更多
Copper-catalyzed asymmetric 1,3-dipolar cycloaddition of azomethine ylides andβ-trifluoromethyl-substituted alkenyl heteroarenes was developed for the first time.A wide range of enantioenriched pyrrolidines containin...Copper-catalyzed asymmetric 1,3-dipolar cycloaddition of azomethine ylides andβ-trifluoromethyl-substituted alkenyl heteroarenes was developed for the first time.A wide range of enantioenriched pyrrolidines containing both heteroarenes and trifluoromethyl group with multiple stereogenic centers could be readily accessible by this method with good to high yields and excellent levels of both stereo-and regioselectivity(up to 99%yield,>20:1 rr,>20:1 dr,and up to 95%ee).Notably,substratecontrolled umpolung-type dipolar cycloaddition was also disclosed in this protocol to achieve regiodivergent synthesis withα-aryl substituted aldimine esters as the dipole precursors.Systematic DFT studies were conducted to explore the origin of the stereo-and regioselectivity of this 1,3-dipolar cycloaddition,and suggest that copper(Ⅱ)salt utilized in this catalytic system could be reduced in-situ to the active copper(Ⅰ)species and might be responsible for the observed high stereo-and regioselectivity.展开更多
Summaryof main observation and conclusion Herein,we developed an Ir/phase-transfer-catalysiscooperatively catalyzed asymmetric cascade allyla-tion/2-aza-Cope rearrangement of aldimine esters to prepare synthetically i...Summaryof main observation and conclusion Herein,we developed an Ir/phase-transfer-catalysiscooperatively catalyzed asymmetric cascade allyla-tion/2-aza-Cope rearrangement of aldimine esters to prepare synthetically important homoallylic amines in good yields with excellent enantioselectivi-ties.Compared with the bimetallic catalytic system to realize this transformation,the current cooperative Ir/tetrabutyl ammonium bromide catalytic system provides an alternative but more practical approach,which not only simplify the manipulation process but also increase the cost efficiency.展开更多
Azomethine ylides are useful intermediates for the rapid construction of chiral N-containing compounds.However,its synthetic potential has not been fully developed due to the limited reaction models.In combination wit...Azomethine ylides are useful intermediates for the rapid construction of chiral N-containing compounds.However,its synthetic potential has not been fully developed due to the limited reaction models.In combination with synergistic catalysis and azomethine ylide chemistry,we have developed several types of novel catalytic system including Cu/Pd,Cu/Ir and PTC/Ir catalysis;which can convert readily-available azomethine ylides to various high-valued molecules such as unnatural a-amino acids,homoallylic amines and N-heterocycles.Compared with the traditional mono-catalysis,the synergistic catalyst system exhibits enhanced catalytic efficiency and chiral induction ability in many cases.In addition,we have demonstrated that these strategies could be applied in the construction of bioactive compounds and natural products.展开更多
A novel approach to stereodivergent synthesis of carbocyclicα-quaternary amino acid derivatives,bearing two contiguous stereocenters,is proposed through sequential dual Cu/Ir-catalyzed asymmetric allylation and ring-...A novel approach to stereodivergent synthesis of carbocyclicα-quaternary amino acid derivatives,bearing two contiguous stereocenters,is proposed through sequential dual Cu/Ir-catalyzed asymmetric allylation and ring-closing metathesis.A variety of five and six-membered carbocyclicα-quaternary amino acid derivatives could be readily achieved in good to high yields with exclusive regioselectivities,excellent diastereoselectivities(13:1->20:1 dr)and enantioselectivities(generally>99%ee).Of particular note is that the current protocol is also a versatile synthetic tool for the stereodivergent construction of the challenging seven and eight-membered carbocyclicα-amino acid derivatives.All four stereoisomers of these important molecules could be precisely synthesized through the permutation of chiral Cu/Ir catalytic system.The power of this strategy has been demonstrated for the facile access to some biologically active chiral molecules,such as spiro-hydantoins.展开更多
We report an unprecedented Pd-catalyzed asymmetric allylic alkylation of 1-(indol-2-yl)cyclobutanols followed by anα-iminol rearrangement.High yields with excellent chemo-,regio-,diastereo-,and enantioselectivities h...We report an unprecedented Pd-catalyzed asymmetric allylic alkylation of 1-(indol-2-yl)cyclobutanols followed by anα-iminol rearrangement.High yields with excellent chemo-,regio-,diastereo-,and enantioselectivities have been realized,affording a wide range of enantioenriched 2-spirocyclicindolines bearing two contiguous stereocenters.The facial selectivity of the ensuing rearrangement is controlled by the subtle difference of the substituents on the all-carbon quaternary stereogenic center formed in the allylic alkylation step.Nonactivated racemic terminal allylic alcohols are utilized as efficient electrophiles via kinetic resolution pathways for the first time in Pd-catalyzed asymmetric allylic alkylation.The role of Et3B additive is pivotal to activating allylic alcohols toward the formation of π-allylpalladium species and suppressing N/O allylic alkylation of indole with enhanced C3-nucleophilicity.Electrospray ionization high-resolution mass spectrometry(ESIHRMS)experiments provided strong evidence for the existence of the key nucleophilic boron anionic species,which fully accounts for the essential role of the Et_(3)B additive.The study of the mechanism indicates that the real catalytically active species is an electronic π-cinnamyl-palladium complex coordinated by two phosphoramidite ligands,which is consistent with the observed nonlinear effect and control experiments and is further confirmed by X-ray structure analysis.展开更多
Cu-catalyzed endo-selective asymmetric 1,3-dipolar cycloaddition of azomethine ylides with ethenesulfonyl fluorides(ESFs) was successfully developed, this protocol provided an efficient and facile method to a wide ran...Cu-catalyzed endo-selective asymmetric 1,3-dipolar cycloaddition of azomethine ylides with ethenesulfonyl fluorides(ESFs) was successfully developed, this protocol provided an efficient and facile method to a wide range of chiral pyrrolidine-3-sulfonyl fluorides with good to excellent results(up to 87% yield,>20:1 dr, 94% ee). Some other chiral sulfonyl derivatives, such as sulfonamide and sulfonate, were easily accessible through simple transformations with high yields, which demonstrated that the cycloaddition products could be synthetically useful in the sulfur(VI) fluoride exchange(Su FEx) chemistry.展开更多
A series of structurally novel multifunctional chiral aminophosphine catalysts were developed through a concise synthetic strategy from easily available starting materials.The highly enantioselective intermolecular cr...A series of structurally novel multifunctional chiral aminophosphine catalysts were developed through a concise synthetic strategy from easily available starting materials.The highly enantioselective intermolecular cross Rauhut-Currier reactions of vinyl ketones with 3-acyl acrylates and 2-ene-1,4-diones catalyzed by(S,S)-5a were well realized,generating a wide range of the structurally important chiral multicarbonyl products in good to excellent yields with high stereocontrol(up to 97%yield,99%ee).In addition,a series of 31P NMR experiments were carried out to further investigate the catalytic process.展开更多
Since the discovery of left-handed G-quadruplex(L-G4)structure formed by natural DNA,there has been a growing interest in its potential functions.This study utilised it to catalyse enantioselective Diels-Alder reactio...Since the discovery of left-handed G-quadruplex(L-G4)structure formed by natural DNA,there has been a growing interest in its potential functions.This study utilised it to catalyse enantioselective Diels-Alder reactions,considering its different optical rotation compared to an ordinary G4.It was determined that when L-G4 was used with a combination of copper(Ⅱ)ions,there was a good enantioselectivity(-52%ee)without further addition of ligands.When further consideration was given by adding G4 ligands,G4 was further stabilised,even obtaining a better enantioselectivity(up to-80%ee).Moreover,when using ligands that have regulatory effects on G4,the ee value can be adjusted.In this work,a minimal left-handed G4 was reported.A follow-up study was also con ducted,which recovers that the minimal left-handed G4 remains its catalytic effect and enantioselectivity,but is not so effective as the former case.This indicates that a complete G4 structure is relatively conducive to chiral catalysis.展开更多
Sequential Ir-catalyzed asymmetric allylation/2-aza-Cope rearrangement of arylidene aminomalonates with allylic carbonates was successfully developed,and a variety of enantioenriched homoallylic amine derivatives were...Sequential Ir-catalyzed asymmetric allylation/2-aza-Cope rearrangement of arylidene aminomalonates with allylic carbonates was successfully developed,and a variety of enantioenriched homoallylic amine derivatives were obtained in high yields with good chirality transfer and excellent E/Z-geometry control(up to 99%yield,96%ee).Compared with previous dual catalytic system established for this transformation,the current mono metal catalytic system provides a simpler and more practical protocol employing the readily available starting materials.展开更多
基金supported by the Key Laboratory Project of National Defense Fund under Grant No. 51434090104JB0202the Advance Research Project of National Defense Science and Technology Fund under Grant No. 51406020205JB0204
文摘High frequency(HF)transmission is an important communication techniques.However,conven-tional point-to-point transmission can be easily destroyed,which limits its utilization in practice.HF networking communication has the capability against demolishment.The network structure is one of the key factors for HF networking communication.In this paper,a novel analysis method of the network connectedness based on the eigenvalue is derived,and a multi-layer distributed HF radio network structure is proposed.Both the theore-tical analysis and the computer simulation results verify that the application of the proposed network structure in the HF radio communication can improve the anti-demolishment ability of the HF network efficiently.
基金We are grateful for financial support from the National Key R&D Program of China(2023YFA1506700)National Natural Science Foundation of China(22071186,22071187,22101216,22271226,and 22371216)+3 种基金Natural Science Foundation of Hubei Province(2020CFA036,2021CFA069)Natural Science Foundation of Jiangsu Province(BK20190213)China Postdoctoral Science Foundation(2021M702514)National Youth Talent Support Program,and Fundamental Research Funds for the Central Universities(2042022kf1180).
文摘The development of stereodivergent synthetic methods to access all four stereoisomers of biologically importantα-fluoroγ-butyrolactones containing vicinal stereocenters is of great importance and poses a formidable challenge owing to ring strain and steric hindrance.Herein,a novel asymmetric[3+2]annulation ofα-fluoroα-azaaryl acetates with vinylethylene carbonate was successfully developed through Cu/Ir-catalyzed cascade allylic alkylation/lactonization,affording a variety of enantioenrichedα-fluoroγ-butyrolactones bearing vicinal stereogenic centers with high reaction efficiency and excellent levels of both stereoselectivity and regioselectivity(up to 98%yield,generally>20:1 dr and>99%ee).Notably,all four stereoisomers of these pharmaceutically valuable molecules could be accessed individually via simple permutations of two enantiomeric catalysts.In addition,other azaaryl acetates bearingα-methyl,α-chlorine orα-phenyl group were tolerated well in this transformation.Reaction mechanistic investigations were conducted to explore the process of this bimetallic catalysis based on the results of reaction intermediates,isotopic labelling experiments,and kinetic studies.
基金supported by the National Natural Science Foundation of China(22071186,22071187,22073067,22101216,22271226,21933003,22193020,22193023)the National Youth Talent Support Program+3 种基金the Natural Science Foundation of Hubei Province(2020CFA0362021CFA069)the Fundamental Research Funds for the Central Universities(2042022kf1180,2042022kf1040)the Shenzhen Nobel Prize Scientists Laboratory Project(C17783101)the Guangdong Provincial Key Laboratory of Catalytic Chemistry(2020B121201002)。
文摘Copper-catalyzed asymmetric 1,3-dipolar cycloaddition of azomethine ylides andβ-trifluoromethyl-substituted alkenyl heteroarenes was developed for the first time.A wide range of enantioenriched pyrrolidines containing both heteroarenes and trifluoromethyl group with multiple stereogenic centers could be readily accessible by this method with good to high yields and excellent levels of both stereo-and regioselectivity(up to 99%yield,>20:1 rr,>20:1 dr,and up to 95%ee).Notably,substratecontrolled umpolung-type dipolar cycloaddition was also disclosed in this protocol to achieve regiodivergent synthesis withα-aryl substituted aldimine esters as the dipole precursors.Systematic DFT studies were conducted to explore the origin of the stereo-and regioselectivity of this 1,3-dipolar cycloaddition,and suggest that copper(Ⅱ)salt utilized in this catalytic system could be reduced in-situ to the active copper(Ⅰ)species and might be responsible for the observed high stereo-and regioselectivity.
基金This work was supported by NSFC(Nos.21525207,21772147)China Postdoctoral Science Foundation funded project(No.2017M620331).The Program of Introducing Talents of Discipline to Universities of China(111 Program)is also appreciated.We thank Prof.Shu-Li You at Shanghai Institute of Organic Chemistry(SIOC)for generously providing ligand THQPhos.
文摘Summaryof main observation and conclusion Herein,we developed an Ir/phase-transfer-catalysiscooperatively catalyzed asymmetric cascade allyla-tion/2-aza-Cope rearrangement of aldimine esters to prepare synthetically important homoallylic amines in good yields with excellent enantioselectivi-ties.Compared with the bimetallic catalytic system to realize this transformation,the current cooperative Ir/tetrabutyl ammonium bromide catalytic system provides an alternative but more practical approach,which not only simplify the manipulation process but also increase the cost efficiency.
基金C.J.W.thanks the NSFC(Grants 21772147,21525207,21372180,21172176,20972117,20702039)for financial supportthe Program of Introducing Talents of Discipline to Universities of China(111 Project)is also appreciated.
文摘Azomethine ylides are useful intermediates for the rapid construction of chiral N-containing compounds.However,its synthetic potential has not been fully developed due to the limited reaction models.In combination with synergistic catalysis and azomethine ylide chemistry,we have developed several types of novel catalytic system including Cu/Pd,Cu/Ir and PTC/Ir catalysis;which can convert readily-available azomethine ylides to various high-valued molecules such as unnatural a-amino acids,homoallylic amines and N-heterocycles.Compared with the traditional mono-catalysis,the synergistic catalyst system exhibits enhanced catalytic efficiency and chiral induction ability in many cases.In addition,we have demonstrated that these strategies could be applied in the construction of bioactive compounds and natural products.
基金We are grateful for financial support from the National Natural Science Foundation of China(Grant Nos.21772147,22071186,22071187)the Natural Science Foundation of Hubei Province(Grant Nos.2020CFA036,2021CFA069)the Natural Science Foundation of Jiangsu Province(Grant No.BK20190213).
文摘A novel approach to stereodivergent synthesis of carbocyclicα-quaternary amino acid derivatives,bearing two contiguous stereocenters,is proposed through sequential dual Cu/Ir-catalyzed asymmetric allylation and ring-closing metathesis.A variety of five and six-membered carbocyclicα-quaternary amino acid derivatives could be readily achieved in good to high yields with exclusive regioselectivities,excellent diastereoselectivities(13:1->20:1 dr)and enantioselectivities(generally>99%ee).Of particular note is that the current protocol is also a versatile synthetic tool for the stereodivergent construction of the challenging seven and eight-membered carbocyclicα-amino acid derivatives.All four stereoisomers of these important molecules could be precisely synthesized through the permutation of chiral Cu/Ir catalytic system.The power of this strategy has been demonstrated for the facile access to some biologically active chiral molecules,such as spiro-hydantoins.
基金supported by the NSFC(nos.21525207,21772147,and 220711186)the Huibei Province Natural Science Foundation(no.2020CFA036)+1 种基金Support by the Fundamental Research Funds for the Central Universitiesthe Program of Introducing Talents of Discipline to Universities of China(111 Program)is also appreciated.
文摘We report an unprecedented Pd-catalyzed asymmetric allylic alkylation of 1-(indol-2-yl)cyclobutanols followed by anα-iminol rearrangement.High yields with excellent chemo-,regio-,diastereo-,and enantioselectivities have been realized,affording a wide range of enantioenriched 2-spirocyclicindolines bearing two contiguous stereocenters.The facial selectivity of the ensuing rearrangement is controlled by the subtle difference of the substituents on the all-carbon quaternary stereogenic center formed in the allylic alkylation step.Nonactivated racemic terminal allylic alcohols are utilized as efficient electrophiles via kinetic resolution pathways for the first time in Pd-catalyzed asymmetric allylic alkylation.The role of Et3B additive is pivotal to activating allylic alcohols toward the formation of π-allylpalladium species and suppressing N/O allylic alkylation of indole with enhanced C3-nucleophilicity.Electrospray ionization high-resolution mass spectrometry(ESIHRMS)experiments provided strong evidence for the existence of the key nucleophilic boron anionic species,which fully accounts for the essential role of the Et_(3)B additive.The study of the mechanism indicates that the real catalytically active species is an electronic π-cinnamyl-palladium complex coordinated by two phosphoramidite ligands,which is consistent with the observed nonlinear effect and control experiments and is further confirmed by X-ray structure analysis.
基金the financial support from the National Natural Science Foundation of China (Nos. 21772147, 22071186, 22071187)Natural Science Foundation of Hubei Province (No. 2020CFA036)+1 种基金Natural Science Foundation of Jiangsu Province (No. SKB2019041078)The Program of Introducing Talents of Discipline to Universities of China (111 Project) is also appreciated。
文摘Cu-catalyzed endo-selective asymmetric 1,3-dipolar cycloaddition of azomethine ylides with ethenesulfonyl fluorides(ESFs) was successfully developed, this protocol provided an efficient and facile method to a wide range of chiral pyrrolidine-3-sulfonyl fluorides with good to excellent results(up to 87% yield,>20:1 dr, 94% ee). Some other chiral sulfonyl derivatives, such as sulfonamide and sulfonate, were easily accessible through simple transformations with high yields, which demonstrated that the cycloaddition products could be synthetically useful in the sulfur(VI) fluoride exchange(Su FEx) chemistry.
基金support from the National Natural Science Foundation of China(Grant Nos.22071186,22071187)the Natural Science Foundation of Hubei Province(Grant Nos.2020CFA036,2021CFA069)+1 种基金the Natural Science Foundation of Jiangsu Province(Grant No.BK20190213)the Fundamental Research Funds for the Central Universities(Grant No.2042022kf1180).
文摘A series of structurally novel multifunctional chiral aminophosphine catalysts were developed through a concise synthetic strategy from easily available starting materials.The highly enantioselective intermolecular cross Rauhut-Currier reactions of vinyl ketones with 3-acyl acrylates and 2-ene-1,4-diones catalyzed by(S,S)-5a were well realized,generating a wide range of the structurally important chiral multicarbonyl products in good to excellent yields with high stereocontrol(up to 97%yield,99%ee).In addition,a series of 31P NMR experiments were carried out to further investigate the catalytic process.
基金This work was supported by the National Natural Science Foundation of China(Nos.21432008,91753201,and 21721005).
文摘Since the discovery of left-handed G-quadruplex(L-G4)structure formed by natural DNA,there has been a growing interest in its potential functions.This study utilised it to catalyse enantioselective Diels-Alder reactions,considering its different optical rotation compared to an ordinary G4.It was determined that when L-G4 was used with a combination of copper(Ⅱ)ions,there was a good enantioselectivity(-52%ee)without further addition of ligands.When further consideration was given by adding G4 ligands,G4 was further stabilised,even obtaining a better enantioselectivity(up to-80%ee).Moreover,when using ligands that have regulatory effects on G4,the ee value can be adjusted.In this work,a minimal left-handed G4 was reported.A follow-up study was also con ducted,which recovers that the minimal left-handed G4 remains its catalytic effect and enantioselectivity,but is not so effective as the former case.This indicates that a complete G4 structure is relatively conducive to chiral catalysis.
基金We are grateful for financial support from the National Natural Science Foundation of China(Grant Nos.21525207,21772147to C.J.W.)Natural Science Foundation of Jiangsu Province(Grant No.SKB2019041078 to X.Q.D.)+2 种基金Wuhan Morning Light Plan ofYouth Science and Technology(Grant No.2017050304010307 to X.Q.D.)Postdoctoral Innovative Talent Support Program of china(BX20190253 to C.s.).We thank Prof.Shu-Li You at SloC forgenerously providing(R,R)-THQ-PhosThe Program of Introducing Talents of Discipline to Universities of China(111 Project)is alsoappreciated.
文摘Sequential Ir-catalyzed asymmetric allylation/2-aza-Cope rearrangement of arylidene aminomalonates with allylic carbonates was successfully developed,and a variety of enantioenriched homoallylic amine derivatives were obtained in high yields with good chirality transfer and excellent E/Z-geometry control(up to 99%yield,96%ee).Compared with previous dual catalytic system established for this transformation,the current mono metal catalytic system provides a simpler and more practical protocol employing the readily available starting materials.