The switchable cross-coupling of indoles and pyridotriazoles through carbene insertion at C_(2)-or C_(3)-positon has been developed in this paper.This highly site-selective C-H carbenoid functionalization is determine...The switchable cross-coupling of indoles and pyridotriazoles through carbene insertion at C_(2)-or C_(3)-positon has been developed in this paper.This highly site-selective C-H carbenoid functionalization is determined by both the Rh-catalyst species and auxiliary groups.[Cp∗RhCl_(2)]_(2) and coordinating pyrimidyl group direct the C-H carbenoid functionalization to occur at the C_(2)-position,while Rh2OAc4 and noncoordinating benzyl group lead the reaction to occur at the C_(3)-position of the indoles.This regioselective C−H functionalization strategy is of significant importance for the discovery of indole drugs.展开更多
The possibility to carry out Cu-catalyzed cross-couplings under ligandless conditions was studied. It was found that by using K3PO4 as the base, the cross-coupling could proceed successfully between aryl iodides and s...The possibility to carry out Cu-catalyzed cross-couplings under ligandless conditions was studied. It was found that by using K3PO4 as the base, the cross-coupling could proceed successfully between aryl iodides and several types of nucleophiles. Aryl bromides were completely inactive under the same reaction conditions.展开更多
The synergistic integration of metal catalysis with electrochemistry has emerged as a powerful tool for organic synthesis.However,in nickel-catalyzed electrochemical crosscoupling reactions,mismatches between external...The synergistic integration of metal catalysis with electrochemistry has emerged as a powerful tool for organic synthesis.However,in nickel-catalyzed electrochemical crosscoupling reactions,mismatches between external conditions and reaction rates often lead to side reactions such as catalyst deactivation,homocoupling,and protonation.Addressing this issue through the development of strategies is highly desirable.Herein,we report the successful merging of photochemistry with electrochemistry to facilitate nickel-catalyzed C−O cross-coupling reactions,providing a practical method for the synthesis of alkyl aryl ethers.Preliminary mechanistic studies suggest that this photoelectrochemical strategy effectively enhances the efficiency of nickelcatalyzed C−O cross-coupling reactions compared to traditional electrochemical methods by regenerating the active Ni^(Ⅰ) catalyst from the Ni^(Ⅱ) species through photochemistry.展开更多
Metal-catalyzed cross-electrophile couplings have become a valuable tool for carbon-carbon bond formation.This minireview provides a comprehensive overview of the recent developments in the topical field of cross-elec...Metal-catalyzed cross-electrophile couplings have become a valuable tool for carbon-carbon bond formation.This minireview provides a comprehensive overview of the recent developments in the topical field of cross-electrophile couplings,provides explanations of the current state-of-the-art,and highlights new opportunities arising in the emerging fields of photoredox catalysis and electrochemistry.展开更多
Highly efficient cross-couplings of diarylborinic acids with aryl tosylates and sulfamates are reported for construction of biaryls using a tri(4-methoxyphenyl)phosphine-supported nickel catalyst system: Ni[P(4-MeOC6H...Highly efficient cross-couplings of diarylborinic acids with aryl tosylates and sulfamates are reported for construction of biaryls using a tri(4-methoxyphenyl)phosphine-supported nickel catalyst system: Ni[P(4-MeOC6H4)3]2Cl2/2P(4-MeOC6H4)3 in the presence of K3PO4·3H2O in toluene. A variety of unsymmetrical biaryls could be obtained in good to excellent yields with1.5–3 mol% or 3–5 mol% catalyst loadings for aryl sulfamates and tosylates, respectively. In sharp contrast to the conventional nickel-catalyzed Suzuki coupling with arylboronic acids, arylsulfamates unexpectedly displayed a higher reactivity than the corresponding tosylates in coupling with diarylborinic acids catalyzed by the nickel/phosphine catalyst system.展开更多
Chiral carbonyl compounds frequently occur in natural products and pharmaceuticals. Additionally, they serve as important intermediates in organic synthesis. Transition metal-catalyzed asymmetric carbonylative cross-c...Chiral carbonyl compounds frequently occur in natural products and pharmaceuticals. Additionally, they serve as important intermediates in organic synthesis. Transition metal-catalyzed asymmetric carbonylative cross-coupling reactions are among the most straightforward and effective methods for synthesizing chiral carbonyl compounds, including esters, amides, and ketones. The advances in asymmetric carbonylative cross-coupling reactions using various O-, N-, C-, and S-containing nucleophiles or electrophiles over the past decade are summarized.展开更多
A chromium(II)-catalyzed reduction cross coupling reaction was reported.This reaction utilizes inexpensive and readily available chromium dichloride as a catalyst and 4,4'-di-tert-butyl-bipyridine as a ligand to a...A chromium(II)-catalyzed reduction cross coupling reaction was reported.This reaction utilizes inexpensive and readily available chromium dichloride as a catalyst and 4,4'-di-tert-butyl-bipyridine as a ligand to achieve reduction cross coupling between trifluoromethyl olefins and alkyl bromides under mild conditions,effectively synthesizing difluoroalkene derivatives.This reaction exhibits good substrate universality and is compatible with multiple important functional groups,providing a concise synthetic pathway for constructing conjugated difluoroalkenes containing allyl difluoromethylene structural units.Preliminary mechanistic experiments indicate that alkyl bromides first undergo a reduction process to generate corresponding alkyl radicals,followed by addition to trifluoromethyl olefins.After binding with Cr(II),they undergo aβ-fluorine elimination process to generate difluoroalkenes.展开更多
Selective defluorinative functionalization of trifluoromethylarenes(ArCF3)to obtain the pharmaceutically commonα,α-difluorobenzylic motif is an attractive and elegant synthetic route.Over the past decade,although C(...Selective defluorinative functionalization of trifluoromethylarenes(ArCF3)to obtain the pharmaceutically commonα,α-difluorobenzylic motif is an attractive and elegant synthetic route.Over the past decade,although C(sp^(3))-F bonds functionalization have been greatly developed,catalytic cross-coupling of trifluoromethylarenes with C-H of terminal alkynes remains a challenge.Here,we report an approach to achieve Sonogashira-type cross-coupling of trifluoromethylarenes with terminal alkynes C(sp)-H bonds via photoredox and Cu/L dual catalysis.Tridentate anionic ligand is pivotal to realize this C-H sp-sp^(3) cross-coupling.Moreover,this unique catalytic system is also suitable for cross-coupling of C(sp^(3))-F bonds with azoles C(sp^(2))-H bonds.A series of trifluoromethylarenes,terminal alkynes and azoles with various functional groups are compatible with this protocol affording a variety of defluoroalkynylation or defluoroazolation products.Preliminary mechanistic studies indicated that deprotonated BINOL involved as a photocatalyst to activate ArCF3 rather than a ligand to the metal.展开更多
In most Suzuki–Miyaura carbon-carbon cross-coupling reactions,the borabicyclo[3.3.1]nonane scaffold(9-BBN)only serves as an auxiliary facilitating the transmetalation step and thus is transformed into by-products.The...In most Suzuki–Miyaura carbon-carbon cross-coupling reactions,the borabicyclo[3.3.1]nonane scaffold(9-BBN)only serves as an auxiliary facilitating the transmetalation step and thus is transformed into by-products.There are rare examples where the 9-BBN derivatives serve as the potentially diverse C8 building blocks in cross-coupling reactions.Herein,we report a cobalt-catalyzed migratory carboncarbon cross-coupling reaction of the in situ formed 9-BBN ate complexes to afford diverse aryl-and alkyl-functionalized cyclooctenes.Preliminary mechanistic studies suggest the oxidation-induced cisbicyclo[3.3.0]oct-1-ylborane is the key intermediate in this migratory cross-coupling reaction,which promotes the development of other diverse migratory cross-coupling of borate complexes.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 Pd-catalyzed Suzuki-Miyaura coupling reaction is a crucial tool for constructing C-C bonds.Currently,the organic solvents employed during reaction may cause serious environmental problems.Moreover,the low solubili...The Pd-catalyzed Suzuki-Miyaura coupling reaction is a crucial tool for constructing C-C bonds.Currently,the organic solvents employed during reaction may cause serious environmental problems.Moreover,the low solubility of inorganic bases in organic solvents leads to enormous mass transfer resistance.To address this issue,the Pickering droplets reactor stabilized by Pd/g-C_(3)N_(4)at substrate-water two-phase interface is reported.Benefiting from the hydrophobic conjugated framework and hydrophilic terminal groups,Pd/g-C_(3)N_(4)can configure stable Pickering emulsion without additional functionalization.The Pd loaded catalysts exhibits excellent performance(TOF=21852 h^(-1))for the Suzuki-Miyaura coupling reaction,which is deriving from unique electronic structure of g-C_(3)N_(4)and high interfacial area of emulsion.Moreover,there is no clear decrease in reactivity after six cycles(conversion>86%).In this study,the organic solvent was replaced by reaction substrate,and the high activity can be achieved for various halogenated aromatic hydrocarbons and their derivatives.展开更多
In order to improve the yield and reduce the cost in the synthesis of antitumor drug vismodegib the key intermediates are prepared and the Negishi reaction step is examined.The effects of different molar ratios of rea...In order to improve the yield and reduce the cost in the synthesis of antitumor drug vismodegib the key intermediates are prepared and the Negishi reaction step is examined.The effects of different molar ratios of reactants dosages of catalyst and time for refluxing are investigated by using single factor tests.The results demonstrate that when the molar ratios of 2-bromopyridine 2-chloro-N-4-chloro-3-iodophenyl -4-methylsulfonyl benzamide zinc chloride n-butyllithium and tetrakis triphenyl phosphine palladium are changed to 1.0∶0.5∶1.5∶1.1∶0.05 and the mixture is refluxed for 24 h the production yield is improved to 72%.This reaction condition significantly enhances the synthetic efficiency avoids consuming excessive raw materials/catalysts and meanwhile prevents a prolonged reaction time.The optimization of the proportion of reactants and the heating time is proved to be important for the efficiency and economy in cross-coupling reaction to synthesize vismodegib.展开更多
Synchronous reluctance motors(SynRM)are widely employed in industrial applications due to their high robustness,low cost,and absence of permanent magnets.In recent years,significant research efforts have focused on im...Synchronous reluctance motors(SynRM)are widely employed in industrial applications due to their high robustness,low cost,and absence of permanent magnets.In recent years,significant research efforts have focused on improving the controllability and efficiency of SynRM.Accurate rotor position information is essential for the controller to generate appropriate current and voltage references corresponding to the desired speed and load torque.Shaft-mounted position sensors are generally undesirable because of their high cost,sensitivity to harsh operating conditions,maintenance requirements,and reduced reliability in environments characterized by high vibration.Consequently,sensorless control techniques that estimate rotor position using measured stator currents and voltages have attracted increasing attention.However,magnetic saturation,parameter nonlinearities,and cross-coupling effects significantly degrade position estimation accuracy and may compromise the stability of sensorless SynRM drives.In this paper,a nonlinear SynRM model is developed using finite element analysis(FEA)to accurately capture magnetic saturation and cross-coupling effects,thereby providing a precise representation of the machine’s electromagnetic behavior under varying load and flux conditions.A series of magnetostatic FEA simulations is performed.To reduce computational complexity,only one motor pole is analyzed by applying anti-periodic boundary conditions along the domain sides and enforcing a zero magnetic vector potential on the external stator boundary.Nonlinear iron material properties are modeled using the appropriate B-H curve.The simulations are carried out by imposing d-and q-axis current components and computing the corresponding flux linkages and electromagnetic torque.Based on these results,both apparent and incremental inductances are extracted and incorporated into the control algorithm.An advanced fictitious flux linkage method combined with a phase-locked loop(PLL)is employed for accurate rotor position estimation.Simulation results confirm that the proposed sensorless control strategy ensures stable operation and high position estimation accuracy over the entire speed range.展开更多
Sinomenine is a clinically available drug for the treatment of rheumatoid arthritis（RA）.In a continuous research aiming at discovery of sinomenine derivates with better bioactivity,a cross-coupling reaction of sinom...Sinomenine is a clinically available drug for the treatment of rheumatoid arthritis（RA）.In a continuous research aiming at discovery of sinomenine derivates with better bioactivity,a cross-coupling reaction of sinomenine and 1,2-dihydroxybenzene catalyzed by a fungus Coriolus unicolor afforded an unique C-C cross-coupled compound 2,together with（S）-disinomenine and （R）-disinomenine.The structure of 2 was elucidated by MS and NMR spectroscopy.Compound 2 was further assayed for the inhibitory activity on IL-6 overproduction in SW982 cells and exhibited a much more potent activity on IL-6（96%inhibition） compared with those of（S）-disinomenine and sinomenine（17%and 12%inhibition,respectively）.展开更多
A simple Cu（OAc）2 catalyzed Sonogashira coupling protocol is presented. It was found that the couplings of a variety of aryl halides with terminal alkynes were conducted smoothly to afford the corresponding desired ...A simple Cu（OAc）2 catalyzed Sonogashira coupling protocol is presented. It was found that the couplings of a variety of aryl halides with terminal alkynes were conducted smoothly to afford the corresponding desired products in moderate to excellent yields, using Cu（OAc）2 as the catalyst and Et3N as the solvent.展开更多
We describe a convenient method for the synthesis of 1,2-disubstituted acetylenes via a cross-coupling reaction of （bromoethynyl）benzene with Grignard reagents. The reaction of （bromoethynyl）benzene （1 mmol） wit...We describe a convenient method for the synthesis of 1,2-disubstituted acetylenes via a cross-coupling reaction of （bromoethynyl）benzene with Grignard reagents. The reaction of （bromoethynyl）benzene （1 mmol） with Grignard reagent （1.3 mmol） mediated by NiCl2 （4 mol%） and （p-CH3Ph）3P （8 mol%） in THF could produce 1,2-disubstituted acetylenes in good yields at room temperature.展开更多
Enamines, promoted by the samarium/samarium diiodide mixed reagent, were synthesized via the cross-coupling of thioamides and diarylketones in good yields.
Surface-enhanced Raman spectroscopy(SERS), a powerful surface vibrational spectroscopic technique, is ideally suited for in situ monitoring the chemical transformations occurred at surfaces and/or interfaces.For in si...Surface-enhanced Raman spectroscopy(SERS), a powerful surface vibrational spectroscopic technique, is ideally suited for in situ monitoring the chemical transformations occurred at surfaces and/or interfaces.For in situ SERS monitoring, a platform integrated both plasmonic and catalytic activity is a prerequisite. Here, we fabricate a bifunctional Au-Pd nanocoronal film for in situ SERS monitoring Suzuki-Miyaura cross-coupling reaction. This excellent bifunctional substrate leads to the coupling of high catalytic activity with a strong SERS effect at the center of two adjacent Au cores and shows fine reproducibility and stability of SERS signals. During investigating the Suzuki reaction with in situ SERS, we found two distinct catalytic kinetic processes resulted from two disparate catalytic sites on a Au-Pd nanocoronal. Comparing with conventional analytical techniques, this work provides a novel approach for studying Suzuki reactions at surfaces and/or interfaces with in situ SERS.展开更多
A nickel-catalyzed reductive cross-coupling reactions between polyfluoroarenes and alkyl electrophiles is reported to access substituted fluoroarenes through chelation-assisted C–F activation.Diverse primary and seco...A nickel-catalyzed reductive cross-coupling reactions between polyfluoroarenes and alkyl electrophiles is reported to access substituted fluoroarenes through chelation-assisted C–F activation.Diverse primary and secondary alkyl(pseudo)halides can be employed to couple with polyfluoroarenes,showing excellent regioselectivity.Furthermore,the nickel-catalyzed asymmetric cross-coupling of polyfluoroarenes with racemic alkyl halides is preliminarily explored.In addition,the practicability of the title transformation is also demonstrated by total synthesis of losmapimod and an analog as key steps.The developed method exhibits many advantages,including economic catalytic systems,commercially available alkyl electrophiles,and lack of sensitive organometallic reagents.展开更多
基金CAMS Innovation Fund for Medical Sciences(CIFMS)(Nos.2022-I2M-1-013,2022-I2M-1-014,2022-I2M-2-002).
文摘The switchable cross-coupling of indoles and pyridotriazoles through carbene insertion at C_(2)-or C_(3)-positon has been developed in this paper.This highly site-selective C-H carbenoid functionalization is determined by both the Rh-catalyst species and auxiliary groups.[Cp∗RhCl_(2)]_(2) and coordinating pyrimidyl group direct the C-H carbenoid functionalization to occur at the C_(2)-position,while Rh2OAc4 and noncoordinating benzyl group lead the reaction to occur at the C_(3)-position of the indoles.This regioselective C−H functionalization strategy is of significant importance for the discovery of indole drugs.
文摘The possibility to carry out Cu-catalyzed cross-couplings under ligandless conditions was studied. It was found that by using K3PO4 as the base, the cross-coupling could proceed successfully between aryl iodides and several types of nucleophiles. Aryl bromides were completely inactive under the same reaction conditions.
基金supported by National Key R&D Program of China(2021YFA1500100)NSF of China(21821002,22101294,22425111,22361142834)+2 种基金S&TCSM of Shanghai(21ZR1476500)the Strategic Priority Research Program of the Chinese Academy of Sciences(XDB0610000)Natural Science Foundation of Ningbo Municipality(2023J035).
文摘The synergistic integration of metal catalysis with electrochemistry has emerged as a powerful tool for organic synthesis.However,in nickel-catalyzed electrochemical crosscoupling reactions,mismatches between external conditions and reaction rates often lead to side reactions such as catalyst deactivation,homocoupling,and protonation.Addressing this issue through the development of strategies is highly desirable.Herein,we report the successful merging of photochemistry with electrochemistry to facilitate nickel-catalyzed C−O cross-coupling reactions,providing a practical method for the synthesis of alkyl aryl ethers.Preliminary mechanistic studies suggest that this photoelectrochemical strategy effectively enhances the efficiency of nickelcatalyzed C−O cross-coupling reactions compared to traditional electrochemical methods by regenerating the active Ni^(Ⅰ) catalyst from the Ni^(Ⅱ) species through photochemistry.
基金This research was made possible as a result of a generous grant from National Natural Science Foundation of China Foundation(grant no.22001248)supported by the King Abdullah University of Science and Technology(KAUST),Saudi Arabia,Office of Sponsored Research(URF/1/4405).
文摘Metal-catalyzed cross-electrophile couplings have become a valuable tool for carbon-carbon bond formation.This minireview provides a comprehensive overview of the recent developments in the topical field of cross-electrophile couplings,provides explanations of the current state-of-the-art,and highlights new opportunities arising in the emerging fields of photoredox catalysis and electrochemistry.
基金This work was supported by the National Natural Science Foundation of China(20972049).
文摘Highly efficient cross-couplings of diarylborinic acids with aryl tosylates and sulfamates are reported for construction of biaryls using a tri(4-methoxyphenyl)phosphine-supported nickel catalyst system: Ni[P(4-MeOC6H4)3]2Cl2/2P(4-MeOC6H4)3 in the presence of K3PO4·3H2O in toluene. A variety of unsymmetrical biaryls could be obtained in good to excellent yields with1.5–3 mol% or 3–5 mol% catalyst loadings for aryl sulfamates and tosylates, respectively. In sharp contrast to the conventional nickel-catalyzed Suzuki coupling with arylboronic acids, arylsulfamates unexpectedly displayed a higher reactivity than the corresponding tosylates in coupling with diarylborinic acids catalyzed by the nickel/phosphine catalyst system.
文摘Chiral carbonyl compounds frequently occur in natural products and pharmaceuticals. Additionally, they serve as important intermediates in organic synthesis. Transition metal-catalyzed asymmetric carbonylative cross-coupling reactions are among the most straightforward and effective methods for synthesizing chiral carbonyl compounds, including esters, amides, and ketones. The advances in asymmetric carbonylative cross-coupling reactions using various O-, N-, C-, and S-containing nucleophiles or electrophiles over the past decade are summarized.
文摘A chromium(II)-catalyzed reduction cross coupling reaction was reported.This reaction utilizes inexpensive and readily available chromium dichloride as a catalyst and 4,4'-di-tert-butyl-bipyridine as a ligand to achieve reduction cross coupling between trifluoromethyl olefins and alkyl bromides under mild conditions,effectively synthesizing difluoroalkene derivatives.This reaction exhibits good substrate universality and is compatible with multiple important functional groups,providing a concise synthetic pathway for constructing conjugated difluoroalkenes containing allyl difluoromethylene structural units.Preliminary mechanistic experiments indicate that alkyl bromides first undergo a reduction process to generate corresponding alkyl radicals,followed by addition to trifluoromethyl olefins.After binding with Cr(II),they undergo aβ-fluorine elimination process to generate difluoroalkenes.
基金support of this work by the National Natural Science Foundation of China(Nos.22371307,21971267)the program for Guangdong Introducing Innovative and Entrepreneurial Teams(No.2017ZT07C069).
文摘Selective defluorinative functionalization of trifluoromethylarenes(ArCF3)to obtain the pharmaceutically commonα,α-difluorobenzylic motif is an attractive and elegant synthetic route.Over the past decade,although C(sp^(3))-F bonds functionalization have been greatly developed,catalytic cross-coupling of trifluoromethylarenes with C-H of terminal alkynes remains a challenge.Here,we report an approach to achieve Sonogashira-type cross-coupling of trifluoromethylarenes with terminal alkynes C(sp)-H bonds via photoredox and Cu/L dual catalysis.Tridentate anionic ligand is pivotal to realize this C-H sp-sp^(3) cross-coupling.Moreover,this unique catalytic system is also suitable for cross-coupling of C(sp^(3))-F bonds with azoles C(sp^(2))-H bonds.A series of trifluoromethylarenes,terminal alkynes and azoles with various functional groups are compatible with this protocol affording a variety of defluoroalkynylation or defluoroazolation products.Preliminary mechanistic studies indicated that deprotonated BINOL involved as a photocatalyst to activate ArCF3 rather than a ligand to the metal.
基金supported by the National Natural Science Foundation of China(No.22171046)the Hundred-Talent Project of Fujian(No.50021113)Fuzhou University(No.0480-00489503)。
文摘In most Suzuki–Miyaura carbon-carbon cross-coupling reactions,the borabicyclo[3.3.1]nonane scaffold(9-BBN)only serves as an auxiliary facilitating the transmetalation step and thus is transformed into by-products.There are rare examples where the 9-BBN derivatives serve as the potentially diverse C8 building blocks in cross-coupling reactions.Herein,we report a cobalt-catalyzed migratory carboncarbon cross-coupling reaction of the in situ formed 9-BBN ate complexes to afford diverse aryl-and alkyl-functionalized cyclooctenes.Preliminary mechanistic studies suggest the oxidation-induced cisbicyclo[3.3.0]oct-1-ylborane is the key intermediate in this migratory cross-coupling reaction,which promotes the development of other diverse migratory cross-coupling of borate complexes.
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the National Natural Science Foundation of China(22178243).
文摘The Pd-catalyzed Suzuki-Miyaura coupling reaction is a crucial tool for constructing C-C bonds.Currently,the organic solvents employed during reaction may cause serious environmental problems.Moreover,the low solubility of inorganic bases in organic solvents leads to enormous mass transfer resistance.To address this issue,the Pickering droplets reactor stabilized by Pd/g-C_(3)N_(4)at substrate-water two-phase interface is reported.Benefiting from the hydrophobic conjugated framework and hydrophilic terminal groups,Pd/g-C_(3)N_(4)can configure stable Pickering emulsion without additional functionalization.The Pd loaded catalysts exhibits excellent performance(TOF=21852 h^(-1))for the Suzuki-Miyaura coupling reaction,which is deriving from unique electronic structure of g-C_(3)N_(4)and high interfacial area of emulsion.Moreover,there is no clear decrease in reactivity after six cycles(conversion>86%).In this study,the organic solvent was replaced by reaction substrate,and the high activity can be achieved for various halogenated aromatic hydrocarbons and their derivatives.
基金The National Basic Research Program of China(973Program)(No.2011CB933503)China Postdoctoral Science Foundation(No.2013M541592)
文摘In order to improve the yield and reduce the cost in the synthesis of antitumor drug vismodegib the key intermediates are prepared and the Negishi reaction step is examined.The effects of different molar ratios of reactants dosages of catalyst and time for refluxing are investigated by using single factor tests.The results demonstrate that when the molar ratios of 2-bromopyridine 2-chloro-N-4-chloro-3-iodophenyl -4-methylsulfonyl benzamide zinc chloride n-butyllithium and tetrakis triphenyl phosphine palladium are changed to 1.0∶0.5∶1.5∶1.1∶0.05 and the mixture is refluxed for 24 h the production yield is improved to 72%.This reaction condition significantly enhances the synthetic efficiency avoids consuming excessive raw materials/catalysts and meanwhile prevents a prolonged reaction time.The optimization of the proportion of reactants and the heating time is proved to be important for the efficiency and economy in cross-coupling reaction to synthesize vismodegib.
文摘Synchronous reluctance motors(SynRM)are widely employed in industrial applications due to their high robustness,low cost,and absence of permanent magnets.In recent years,significant research efforts have focused on improving the controllability and efficiency of SynRM.Accurate rotor position information is essential for the controller to generate appropriate current and voltage references corresponding to the desired speed and load torque.Shaft-mounted position sensors are generally undesirable because of their high cost,sensitivity to harsh operating conditions,maintenance requirements,and reduced reliability in environments characterized by high vibration.Consequently,sensorless control techniques that estimate rotor position using measured stator currents and voltages have attracted increasing attention.However,magnetic saturation,parameter nonlinearities,and cross-coupling effects significantly degrade position estimation accuracy and may compromise the stability of sensorless SynRM drives.In this paper,a nonlinear SynRM model is developed using finite element analysis(FEA)to accurately capture magnetic saturation and cross-coupling effects,thereby providing a precise representation of the machine’s electromagnetic behavior under varying load and flux conditions.A series of magnetostatic FEA simulations is performed.To reduce computational complexity,only one motor pole is analyzed by applying anti-periodic boundary conditions along the domain sides and enforcing a zero magnetic vector potential on the external stator boundary.Nonlinear iron material properties are modeled using the appropriate B-H curve.The simulations are carried out by imposing d-and q-axis current components and computing the corresponding flux linkages and electromagnetic torque.Based on these results,both apparent and incremental inductances are extracted and incorporated into the control algorithm.An advanced fictitious flux linkage method combined with a phase-locked loop(PLL)is employed for accurate rotor position estimation.Simulation results confirm that the proposed sensorless control strategy ensures stable operation and high position estimation accuracy over the entire speed range.
基金supported by National Natural Science Foundation of China(Nos20872060,20936002 and 31100080)the Fundamental Research Funds for Central University(No1082020502)
文摘Sinomenine is a clinically available drug for the treatment of rheumatoid arthritis（RA）.In a continuous research aiming at discovery of sinomenine derivates with better bioactivity,a cross-coupling reaction of sinomenine and 1,2-dihydroxybenzene catalyzed by a fungus Coriolus unicolor afforded an unique C-C cross-coupled compound 2,together with（S）-disinomenine and （R）-disinomenine.The structure of 2 was elucidated by MS and NMR spectroscopy.Compound 2 was further assayed for the inhibitory activity on IL-6 overproduction in SW982 cells and exhibited a much more potent activity on IL-6（96%inhibition） compared with those of（S）-disinomenine and sinomenine（17%and 12%inhibition,respectively）.
文摘A simple Cu（OAc）2 catalyzed Sonogashira coupling protocol is presented. It was found that the couplings of a variety of aryl halides with terminal alkynes were conducted smoothly to afford the corresponding desired products in moderate to excellent yields, using Cu（OAc）2 as the catalyst and Et3N as the solvent.
基金financially supported by the Fundamental Research Funds for the Central Universities,Southwest University for Nationalities (No.12NZYTH03)the Natural Science Foundation of Southwest University for Nationalities (No.381010)+1 种基金the Project of Postgraduate Degree Construction,Southwest University for Nationalities (No.2013XWD-S0703)the State Administration of Foreign Experts Affairs project (No.2012-10)
文摘We describe a convenient method for the synthesis of 1,2-disubstituted acetylenes via a cross-coupling reaction of （bromoethynyl）benzene with Grignard reagents. The reaction of （bromoethynyl）benzene （1 mmol） with Grignard reagent （1.3 mmol） mediated by NiCl2 （4 mol%） and （p-CH3Ph）3P （8 mol%） in THF could produce 1,2-disubstituted acetylenes in good yields at room temperature.
基金the National Natural Science Foundation of China(Project No.20072033)Specialized Research Fund for the Doctoral Program of Higher Education of China.
文摘Enamines, promoted by the samarium/samarium diiodide mixed reagent, were synthesized via the cross-coupling of thioamides and diarylketones in good yields.
基金the financial support from the National Natural Science Foundation of China (No. 22022406)the Natural Science Foundation of Tianjin (Nos. 20JCJQJC00110 and 20JCYBJC00590)+1 种基金the 111 project (No. B12015)the Haihe Laboratory of Sustainable Chemical Transformations。
文摘Surface-enhanced Raman spectroscopy(SERS), a powerful surface vibrational spectroscopic technique, is ideally suited for in situ monitoring the chemical transformations occurred at surfaces and/or interfaces.For in situ SERS monitoring, a platform integrated both plasmonic and catalytic activity is a prerequisite. Here, we fabricate a bifunctional Au-Pd nanocoronal film for in situ SERS monitoring Suzuki-Miyaura cross-coupling reaction. This excellent bifunctional substrate leads to the coupling of high catalytic activity with a strong SERS effect at the center of two adjacent Au cores and shows fine reproducibility and stability of SERS signals. During investigating the Suzuki reaction with in situ SERS, we found two distinct catalytic kinetic processes resulted from two disparate catalytic sites on a Au-Pd nanocoronal. Comparing with conventional analytical techniques, this work provides a novel approach for studying Suzuki reactions at surfaces and/or interfaces with in situ SERS.
基金the National Natural Science Foundation of China (Nos. 22025104, 21972064 and 21901111)the National Natural Science Foundation of Jiangsu Province (No. BK20170632)+2 种基金the Excellent Youth Foundation of Jiangsu Scientific Committee (No. BK20180007)the “Innovation & Entrepreneurship Talents Plan” of Jiangsu Provincethe Fundamental Research Funds for the Central Universities for their financial support
文摘A nickel-catalyzed reductive cross-coupling reactions between polyfluoroarenes and alkyl electrophiles is reported to access substituted fluoroarenes through chelation-assisted C–F activation.Diverse primary and secondary alkyl(pseudo)halides can be employed to couple with polyfluoroarenes,showing excellent regioselectivity.Furthermore,the nickel-catalyzed asymmetric cross-coupling of polyfluoroarenes with racemic alkyl halides is preliminarily explored.In addition,the practicability of the title transformation is also demonstrated by total synthesis of losmapimod and an analog as key steps.The developed method exhibits many advantages,including economic catalytic systems,commercially available alkyl electrophiles,and lack of sensitive organometallic reagents.
