Highly dispersed palladium nanoparticles were synthesized in the presence of immobilized ionic liquid on mesoporous silica SBA-15.PdNPs(2.4 nm)_me-Im@SBA-15 catalyst was prepared by the reduction using NaBH_4 as the r...Highly dispersed palladium nanoparticles were synthesized in the presence of immobilized ionic liquid on mesoporous silica SBA-15.PdNPs(2.4 nm)_me-Im@SBA-15 catalyst was prepared by the reduction using NaBH_4 as the reducing agent with controlled feed rate and has been investigated as ligand-free catalyst for Suzuki–Miyaura cross-coupling reaction at room temperature in aqueous solution under air.PdNPs catalyst was also prepared in situ from PdCl4_me-Im@SBA-15 during the reaction and demonstrated high activity and stability towards nitrobenzene hydrogenation at high temperature. Both catalysts were reusable at least for four recycle processes without significant loss in activity with simple procedure. The catalysts were characterized by TEM, EXAFS, FTIR and XPS.展开更多
The use of thallium(I) hydroxide (TlOH) as a base is known to extremely accelerate the Suzuki-Miyaura cross-coupling reaction using organoboronic acid or organoboronic acid ester as a substrate. Here, we investigated ...The use of thallium(I) hydroxide (TlOH) as a base is known to extremely accelerate the Suzuki-Miyaura cross-coupling reaction using organoboronic acid or organoboronic acid ester as a substrate. Here, we investigated the effects of TlOH by comparing with other conventional bases such as KOH, K2CO3, and CsF for Pd0-mediated rapid cross-coupling reactions between CH3I and organoborane reagents, such as phenyl-, (Z)-4-benzyloxy-2-butenyl-, and benzylboronic acid pinacol esters under the conditions CH3I/borane/Pd0/base (1:40:1:3) in THF/H2O or DMF/H2O for 5 min with an aim to fabricate a PET tracer efficiently. Consequently, however, the use of TlOH was much less efficient than the other bases for the acceleration of cross-coupling reactions. Thus, it was reconfirmed that the milder and non-toxic conditions using K2CO3 or CsF so far developed by our group were most appropriate for the rapid C-methylations.展开更多
Phenolic compounds present in medicinal and edible plants such as flavonoids, chalcones, coumarins, quinones, and phenolic acids. The antioxidant potential of phenolic compounds shows potent activities for cancer prev...Phenolic compounds present in medicinal and edible plants such as flavonoids, chalcones, coumarins, quinones, and phenolic acids. The antioxidant potential of phenolic compounds shows potent activities for cancer prevention and its treatment. From a green chemistry point of view, cascade (tandem) reactions are ideal techniques in organic synthesis for building complex structures. Cascade techniques are sometimes observed in coupling reactions under mild conditions with a tolerance of multifunctional groups. It will be interesting to find a cascade type reaction to synthesize polyphenolic ethers. This research project achieves a new cross-coupling method for establishing polyphenolic ethers from mixed phenols and halides in the presence of palladium catalyst in moderate to good yields.展开更多
By the two-scale homogenization approach we justify a two-scale model of ion transport through a layered membrane, with flows being driven by a pressure gradient and an external electrical field. By up-scaling, the el...By the two-scale homogenization approach we justify a two-scale model of ion transport through a layered membrane, with flows being driven by a pressure gradient and an external electrical field. By up-scaling, the electroosmotic flow equations in horizontal thin slits separated by thin solid layers are approximated by a homogenized system of macroscale equations in the form of the Poisson equation for induced vertical electrical field and Onsager's reciprocity relations between global fluxes (hydrodynamic and electric) and forces (horizontal pressure gradient and external electrical field). In addition, the two-scale approach provides macroscopic mobility coefficients in the Onsager relations. On this way, the cross-coupling kinetic coefficient is obtained in a form which does involves the ζ -potential among the data provided the surface current is negligible.展开更多
Piezo-electric nano-positioning stages are being widely used in applications in which precision and accuracy in the order of nano, and high scanning speeds are paramount. This paper presents a Finite Element Analysis ...Piezo-electric nano-positioning stages are being widely used in applications in which precision and accuracy in the order of nano, and high scanning speeds are paramount. This paper presents a Finite Element Analysis (FEA) of the parallel piezo-flexural nano-positioning (PPNP) stages to investigate motion interference between their different axes. Cross-coupling is one of the significant contributors to undesirable runouts in the precision positioning of PPNP actuators. Using ABAQUS/CAE 2018 software, a 3D model of a PPNP stage was developed. The model consists of a central elastic body connected to a fixed frame through four flexural hinges. A cylindrical stack of multiple piezoelectric disks is placed between the moving central body and the fixed frame. Extensive simulations were carried out for three different friction coefficients in the piezoelectric disks’ contact surfaces, different frame materials, and different geometrical configurations of the stage and the hinges. As a result, it was observed that the primary root cause of the mechanical cross-coupling effect could be realized in the combination of the slip and rotation of the piezoelectric disks due to their frictional behavior with the stage moving in the tangential direction, concurrent with changes in the geometry of the stage.展开更多
The coupling reaction of aryl bromide and aryl boronic acid in water/DMF as solvent was studied using a palladium-complex as a catalyst in the presence of ultrasound at room temperature. The effect on the reaction of ...The coupling reaction of aryl bromide and aryl boronic acid in water/DMF as solvent was studied using a palladium-complex as a catalyst in the presence of ultrasound at room temperature. The effect on the reaction of a base and a solvent was also studied with and without ultrasound and was found to increase the speed of the reaction. In this regard, we propose reaction mechanisms that could explain the results obtained.展开更多
The selective coupling of alcohols is a fascinating yet challenging approach for upgrading alcohols. Herein, we accomplished the controlled production of β-disubstituted ketones or upgraded secondary alcohols via the...The selective coupling of alcohols is a fascinating yet challenging approach for upgrading alcohols. Herein, we accomplished the controlled production of β-disubstituted ketones or upgraded secondary alcohols via the Ir-catalyzed cross-coupling of secondary alcohols in excellent yields with broad substrate scopes. This selective control was achieved by using an in-situ generated monoNHC-Ir or a tris-NHC-Ir complex as the catalysts, respectively. Mechanistic studies revealed that the delicate balance between dehydrogenation and hydrogenation abilities of these bifunctional catalysts is crucial for achieving different selectivity. The tris-NHC-Ir complex effectively facilitated dehydrogenation of alcohols and hydrogenation of intermediates, leading to the desired upgraded secondary alcohols. Conversely, the high dehydrogenation ability of the mono-NHC-Ir complex promoted the conversion of formed secondary alcohols back to ketones.展开更多
The reductive cross-coupling between C(aryl)—O and Si—Cl bonds is of much importance as a valuable strategy for the construction of C(aryl)—Si bonds but has remained a great challenge.Herein,we report a reductive c...The reductive cross-coupling between C(aryl)—O and Si—Cl bonds is of much importance as a valuable strategy for the construction of C(aryl)—Si bonds but has remained a great challenge.Herein,we report a reductive cross-coupling of diaryl ethers and chlorosilanes via strong electrophilic C(aryl)—O and Si—Cl bonds cleavage by iron catalysis,which constitutes an efficient protocol for the synthesis of a range of functionalized arylsilanes.The combination of low cost FeCl2 as the precatalyst and iPrMgCl as the reductant shows high activity in the successive cleavage of unactivated C(aryl)—O bonds of diaryl ethers and strong electrophilic Si—Cl bonds of chlorosilanes,allowing their cross-coupling in a reductive fashion.The low-valent iron species generated in situ by reduction of FeCl2 with iPrMgCl was proposed,which prefers to initially cleavage the C(aryl)—O bond of diaryl ethers with the chelation help of an o-amide auxiliary.展开更多
The electrochemical utilization of electron-deficient methylarenes for radical-radical cross-couplings remains very rare.Enabled by an umpolung strategy,the unprecedented electrochemical cross-coupling of electron-def...The electrochemical utilization of electron-deficient methylarenes for radical-radical cross-couplings remains very rare.Enabled by an umpolung strategy,the unprecedented electrochemical cross-coupling of electron-deficient methylarenes with aldehydes was developed.The paired electrolysis simultaneously generated electron-deficient benzylic radicals and ketyl radicals at both electrodes,which then underwent radical recombination,governed by polarity matching and persistent-radical effect(PRE)to afford functionalized alcohols that are not easily accessible by other methods.This protocol features catalystand external redox agent-free conditions and a formal 100%atom economy.Mechanistic studies support the radical-radical cross-coupling pathway.展开更多
Chiral phosphine-containing skeletons play a pivotal role in bioactive natural products, pharmaceuticals, chiral catalysts, and ligands. Despite considerable progress has been made in the synthesis of chiral phosphoru...Chiral phosphine-containing skeletons play a pivotal role in bioactive natural products, pharmaceuticals, chiral catalysts, and ligands. Despite considerable progress has been made in the synthesis of chiral phosphorus compounds, the development of facile and modular methods to access chiral allylic phosphorus compounds remains challenging due to the simultaneous control required for reactivity, enantioselectivity, and stereoselectivity. Herein, we present a general and modular platform to achieve the asymmetric reductive cross-coupling of α-bromophosphonates and vinyl bromides, enabling the synthesis of highly valuable chiral allylic phosphonate products with remarkable yields, enantioselectivities, and stereoselectivities.展开更多
Aldehydes are a kind of important synthons and reagents in organic synthesis.The efforts on transformations of aldehydes are highly rewarding and have always attracted considerable attention.Herein,a cross-coupling of...Aldehydes are a kind of important synthons and reagents in organic synthesis.The efforts on transformations of aldehydes are highly rewarding and have always attracted considerable attention.Herein,a cross-coupling of aldehydes withα-haloboronates has been achieved under dual nickel/photoredox catalysis system.Considering theα-haloboronates can be easily obtained from aldehydes with our deoxygenative difunctionalization of carbonyls(DODC)strategy,this protocol provides a formal deoxygenative cross-coupling of aldehydes to one-carbon-prolonged ketone products.The mild conditions enabled good functional group tolerance and broad substrate applicability.The application of this method was presented via a tunable synthesis of two ketones with very similar skeletons from two same aldehydes.展开更多
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 facile and elegant method for synthesis of novel N-aryl phenothiazine derivatives from 2-phenylindolizines and phenothiazines through direct electrochemical oxidation has been developed.This approach was performed s...A facile and elegant method for synthesis of novel N-aryl phenothiazine derivatives from 2-phenylindolizines and phenothiazines through direct electrochemical oxidation has been developed.This approach was performed smoothly at room temperature without external oxidant and catalyst.Cyclic voltammetry and in situ FTIR techniques were applied to analyze the cross-coupling process of phenothiazines and 2-phenylindolizines,which helped to select the appropriate reaction potential.Under the optimized conditions,a broad range of substrates were well tolerated,affording the desired products in moderate to excellent isolated yields(up to 91%)with high regioselectivity.Meanwhile,a plausible mechanism involving a radical pathway has been proposed.展开更多
Electrocatalytic dehydrogenative cross-coupling of various alcohols in aqueous electrolytes functionalizes alcohols to form structurally diverse long-carbon-chain chemicals.However,it remains challenging to achieve th...Electrocatalytic dehydrogenative cross-coupling of various alcohols in aqueous electrolytes functionalizes alcohols to form structurally diverse long-carbon-chain chemicals.However,it remains challenging to achieve the high selectivity because of the high reactivity of involved carbonyl intermediates and different oxidation rates for the alcohols.Herein,the synthesis ofα,β-unsaturated ketones from alcohols was realized by the electro-oxidation cross-coupling in aqueous solutions by a“salting-out”strategy to engineer the micro-environment at electrocatalytic reaction interfaces.Theoretical calculations and electrochemical measurements demonstrated that concentrated local intermediates could inhibit the over-oxidation of alcohols and accelerate the coupling reaction kinetics between the intermediates.This strategy can couple primary and secondary alcohols to formα,β-unsaturated carbonyl compounds with a selectivity of 87% and be easily scaled up to gram scales.This study provides an attractive strategy for broadening the diversity of organic products in electrocatalysis.展开更多
A cooperative Pd/Cu-catalyzed three-component cross-coupling reaction of alkynes,B_(2)Pin_(2) and alkene-tethered aryl halides is reported.This reaction proceeds under mild conditions and shows broad sub-strate scope,...A cooperative Pd/Cu-catalyzed three-component cross-coupling reaction of alkynes,B_(2)Pin_(2) and alkene-tethered aryl halides is reported.This reaction proceeds under mild conditions and shows broad sub-strate scope,providing a variety of heterocycles containing tetrasubstituted alkenylboronate moieties in synthetically useful yields with excellent chemoselectivity and regioselectivity.This transformation fea-tures the catalytic generation ofβ-borylalkenylcopper intermediates and their use in Pd-catalyzed Heck cyclization/cross-couplings.An enantioselective cascade cyclization/cross-coupling process has also been developed for the synthesis of enantiomerically enriched oxindole bearing a tetrasubstituted alkenyl-boronate moiety.展开更多
A radical decarboxylative C(sp^(3))–C(sp^(3))cross-coupling of NHPI esters and cyclopropanols was developed by combining photocatalysis and copper catalysis,which presents the efficient access toβ-benzyl ketones in ...A radical decarboxylative C(sp^(3))–C(sp^(3))cross-coupling of NHPI esters and cyclopropanols was developed by combining photocatalysis and copper catalysis,which presents the efficient access toβ-benzyl ketones in excellent yields.Terpyridin-4′-one used as the ligand is vital for the reaction,which could facilitate the capture of benzylic radicals by alkyl-copper species generated from copper-catalyzed ring-opening of cyclopropanols.The reaction exhibited broad substrate scope and wide functional group compatibility,providing an alternative approach for C(sp^(3))–C(sp^(3))bond formation.展开更多
Chloroalkanes are important building blocks in the synthesis,but their use in redox chemistry is limited by their negative reduction potentials.Electrosynthesis can precisely control the reaction energy just by adjust...Chloroalkanes are important building blocks in the synthesis,but their use in redox chemistry is limited by their negative reduction potentials.Electrosynthesis can precisely control the reaction energy just by adjusting the current or voltage to achieve the selectivity of regulation.In this study,the consecutively paired electrolyticmediated controllable radical cross-coupling of thiophenols with dichloromethane was developed to deliver the dithioacetals,sulfides,and sulfoxides in the absence of electrochemical mediator conditions.It features broad substrate scope,simple operation,gram-scale synthesis,and is eco-friendly.Mechanistic studies reveal that this electrochemical reaction is radical-induced cross-coupling of thiophenols with dichloromethane.展开更多
Tetrasubstituted olefins are significant scaffolds as they are prevalent in many biologically active compounds and versatile building blocks for organic synthesis. Herein, we report an electrochemical oxidative Csp^3...Tetrasubstituted olefins are significant scaffolds as they are prevalent in many biologically active compounds and versatile building blocks for organic synthesis. Herein, we report an electrochemical oxidative Csp^3—H/S—H cross-coupling reaction, in which various tetrasubstituted olefins were prepared under base-free, transition metal-free, and oxidants-free reaction conditions.展开更多
The asymmetric reductive arylation and alkenylation of benzylic chloride under photoredox/nickel dual catalysis using chiral bimidazoline(Bilm)ligand is reported to access 1,1-diaryl alkanes and aryl allylic compounds...The asymmetric reductive arylation and alkenylation of benzylic chloride under photoredox/nickel dual catalysis using chiral bimidazoline(Bilm)ligand is reported to access 1,1-diaryl alkanes and aryl allylic compounds with good yield as well as stereo-and enantioselectivities.This protocol uses more commercially available and less expensive C(sp^(2))-Br as the electrophile coupling partner.A primary result using alkenyl chloride and alkyl chloride is also reported.Various functional groups are tolerated and the applications of this method are investigated by late-stage functionalization and gram-scale reaction.展开更多
We investigate motion synchronization of dual-cylinder pneumatic servo systems and develop an adaptive robust synchronization controller. The proposed controller incorporates the cross-coupling technology into the int...We investigate motion synchronization of dual-cylinder pneumatic servo systems and develop an adaptive robust synchronization controller. The proposed controller incorporates the cross-coupling technology into the integrated direct/indirect adaptive robust control(DIARC) architecture by feeding back the coupled position errors, which are formed by the trajectory tracking errors of two cylinders and the synchronization error between them. The controller employs an online recursive least squares estimation algorithm to obtain accurate estimates of model parameters for reducing the extent of parametric uncertainties, and uses a robust control law to attenuate the effects of parameter estimation errors, unmodeled dynamics, and disturbances. Therefore, asymptotic convergence to zero of both trajectory tracking and synchronization errors can be guaranteed. Experimental results verify the effectiveness of the proposed controller.展开更多
基金the financial support from the Institute for Quantum Chemical Exploration(IQCE)
文摘Highly dispersed palladium nanoparticles were synthesized in the presence of immobilized ionic liquid on mesoporous silica SBA-15.PdNPs(2.4 nm)_me-Im@SBA-15 catalyst was prepared by the reduction using NaBH_4 as the reducing agent with controlled feed rate and has been investigated as ligand-free catalyst for Suzuki–Miyaura cross-coupling reaction at room temperature in aqueous solution under air.PdNPs catalyst was also prepared in situ from PdCl4_me-Im@SBA-15 during the reaction and demonstrated high activity and stability towards nitrobenzene hydrogenation at high temperature. Both catalysts were reusable at least for four recycle processes without significant loss in activity with simple procedure. The catalysts were characterized by TEM, EXAFS, FTIR and XPS.
文摘The use of thallium(I) hydroxide (TlOH) as a base is known to extremely accelerate the Suzuki-Miyaura cross-coupling reaction using organoboronic acid or organoboronic acid ester as a substrate. Here, we investigated the effects of TlOH by comparing with other conventional bases such as KOH, K2CO3, and CsF for Pd0-mediated rapid cross-coupling reactions between CH3I and organoborane reagents, such as phenyl-, (Z)-4-benzyloxy-2-butenyl-, and benzylboronic acid pinacol esters under the conditions CH3I/borane/Pd0/base (1:40:1:3) in THF/H2O or DMF/H2O for 5 min with an aim to fabricate a PET tracer efficiently. Consequently, however, the use of TlOH was much less efficient than the other bases for the acceleration of cross-coupling reactions. Thus, it was reconfirmed that the milder and non-toxic conditions using K2CO3 or CsF so far developed by our group were most appropriate for the rapid C-methylations.
文摘Phenolic compounds present in medicinal and edible plants such as flavonoids, chalcones, coumarins, quinones, and phenolic acids. The antioxidant potential of phenolic compounds shows potent activities for cancer prevention and its treatment. From a green chemistry point of view, cascade (tandem) reactions are ideal techniques in organic synthesis for building complex structures. Cascade techniques are sometimes observed in coupling reactions under mild conditions with a tolerance of multifunctional groups. It will be interesting to find a cascade type reaction to synthesize polyphenolic ethers. This research project achieves a new cross-coupling method for establishing polyphenolic ethers from mixed phenols and halides in the presence of palladium catalyst in moderate to good yields.
文摘By the two-scale homogenization approach we justify a two-scale model of ion transport through a layered membrane, with flows being driven by a pressure gradient and an external electrical field. By up-scaling, the electroosmotic flow equations in horizontal thin slits separated by thin solid layers are approximated by a homogenized system of macroscale equations in the form of the Poisson equation for induced vertical electrical field and Onsager's reciprocity relations between global fluxes (hydrodynamic and electric) and forces (horizontal pressure gradient and external electrical field). In addition, the two-scale approach provides macroscopic mobility coefficients in the Onsager relations. On this way, the cross-coupling kinetic coefficient is obtained in a form which does involves the ζ -potential among the data provided the surface current is negligible.
文摘Piezo-electric nano-positioning stages are being widely used in applications in which precision and accuracy in the order of nano, and high scanning speeds are paramount. This paper presents a Finite Element Analysis (FEA) of the parallel piezo-flexural nano-positioning (PPNP) stages to investigate motion interference between their different axes. Cross-coupling is one of the significant contributors to undesirable runouts in the precision positioning of PPNP actuators. Using ABAQUS/CAE 2018 software, a 3D model of a PPNP stage was developed. The model consists of a central elastic body connected to a fixed frame through four flexural hinges. A cylindrical stack of multiple piezoelectric disks is placed between the moving central body and the fixed frame. Extensive simulations were carried out for three different friction coefficients in the piezoelectric disks’ contact surfaces, different frame materials, and different geometrical configurations of the stage and the hinges. As a result, it was observed that the primary root cause of the mechanical cross-coupling effect could be realized in the combination of the slip and rotation of the piezoelectric disks due to their frictional behavior with the stage moving in the tangential direction, concurrent with changes in the geometry of the stage.
文摘The coupling reaction of aryl bromide and aryl boronic acid in water/DMF as solvent was studied using a palladium-complex as a catalyst in the presence of ultrasound at room temperature. The effect on the reaction of a base and a solvent was also studied with and without ultrasound and was found to increase the speed of the reaction. In this regard, we propose reaction mechanisms that could explain the results obtained.
基金supported by the National Natural Science Foundation of China(22271060)the Department of Chemistry at Fudan University。
文摘The selective coupling of alcohols is a fascinating yet challenging approach for upgrading alcohols. Herein, we accomplished the controlled production of β-disubstituted ketones or upgraded secondary alcohols via the Ir-catalyzed cross-coupling of secondary alcohols in excellent yields with broad substrate scopes. This selective control was achieved by using an in-situ generated monoNHC-Ir or a tris-NHC-Ir complex as the catalysts, respectively. Mechanistic studies revealed that the delicate balance between dehydrogenation and hydrogenation abilities of these bifunctional catalysts is crucial for achieving different selectivity. The tris-NHC-Ir complex effectively facilitated dehydrogenation of alcohols and hydrogenation of intermediates, leading to the desired upgraded secondary alcohols. Conversely, the high dehydrogenation ability of the mono-NHC-Ir complex promoted the conversion of formed secondary alcohols back to ketones.
基金financial support from the National Natural Science Foundation of China(21901206)Postdoctoral Science Foundation of China(2022M712589)+2 种基金General key R&D Projects in Shaanxi Province(2023-YBGY-321)Natural Science Foundation of Chongqing(CSTB2022NSCQ-MSX0826)Fundamental Research Funds for the Central Universities and the Haihe Laboratory of Sustainable Chemical Transformation.
文摘The reductive cross-coupling between C(aryl)—O and Si—Cl bonds is of much importance as a valuable strategy for the construction of C(aryl)—Si bonds but has remained a great challenge.Herein,we report a reductive cross-coupling of diaryl ethers and chlorosilanes via strong electrophilic C(aryl)—O and Si—Cl bonds cleavage by iron catalysis,which constitutes an efficient protocol for the synthesis of a range of functionalized arylsilanes.The combination of low cost FeCl2 as the precatalyst and iPrMgCl as the reductant shows high activity in the successive cleavage of unactivated C(aryl)—O bonds of diaryl ethers and strong electrophilic Si—Cl bonds of chlorosilanes,allowing their cross-coupling in a reductive fashion.The low-valent iron species generated in situ by reduction of FeCl2 with iPrMgCl was proposed,which prefers to initially cleavage the C(aryl)—O bond of diaryl ethers with the chelation help of an o-amide auxiliary.
基金the National Natural Science Foundation of China(grant nos.22271009 and 22171015)Beijing Natural Science Foundation(grant no.2222003)Beijing Municipal Education Committee Project(grant nos.KZ202110005003 and KM202110005006).
文摘The electrochemical utilization of electron-deficient methylarenes for radical-radical cross-couplings remains very rare.Enabled by an umpolung strategy,the unprecedented electrochemical cross-coupling of electron-deficient methylarenes with aldehydes was developed.The paired electrolysis simultaneously generated electron-deficient benzylic radicals and ketyl radicals at both electrodes,which then underwent radical recombination,governed by polarity matching and persistent-radical effect(PRE)to afford functionalized alcohols that are not easily accessible by other methods.This protocol features catalystand external redox agent-free conditions and a formal 100%atom economy.Mechanistic studies support the radical-radical cross-coupling pathway.
基金supported by the National Natural Science Foundation of China (22071183)the Science and Technology Commission of Shanghai Municipality (19DZ2271500)。
文摘Chiral phosphine-containing skeletons play a pivotal role in bioactive natural products, pharmaceuticals, chiral catalysts, and ligands. Despite considerable progress has been made in the synthesis of chiral phosphorus compounds, the development of facile and modular methods to access chiral allylic phosphorus compounds remains challenging due to the simultaneous control required for reactivity, enantioselectivity, and stereoselectivity. Herein, we present a general and modular platform to achieve the asymmetric reductive cross-coupling of α-bromophosphonates and vinyl bromides, enabling the synthesis of highly valuable chiral allylic phosphonate products with remarkable yields, enantioselectivities, and stereoselectivities.
基金the National Natural Science Foundation of China(Grant No.22071183)for financial support.
文摘Aldehydes are a kind of important synthons and reagents in organic synthesis.The efforts on transformations of aldehydes are highly rewarding and have always attracted considerable attention.Herein,a cross-coupling of aldehydes withα-haloboronates has been achieved under dual nickel/photoredox catalysis system.Considering theα-haloboronates can be easily obtained from aldehydes with our deoxygenative difunctionalization of carbonyls(DODC)strategy,this protocol provides a formal deoxygenative cross-coupling of aldehydes to one-carbon-prolonged ketone products.The mild conditions enabled good functional group tolerance and broad substrate applicability.The application of this method was presented via a tunable synthesis of two ketones with very similar skeletons from two same aldehydes.
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 generous financial support of the National Natural Science Foundations of China(Nos.22178321,21773211 and 21776260)。
文摘A facile and elegant method for synthesis of novel N-aryl phenothiazine derivatives from 2-phenylindolizines and phenothiazines through direct electrochemical oxidation has been developed.This approach was performed smoothly at room temperature without external oxidant and catalyst.Cyclic voltammetry and in situ FTIR techniques were applied to analyze the cross-coupling process of phenothiazines and 2-phenylindolizines,which helped to select the appropriate reaction potential.Under the optimized conditions,a broad range of substrates were well tolerated,affording the desired products in moderate to excellent isolated yields(up to 91%)with high regioselectivity.Meanwhile,a plausible mechanism involving a radical pathway has been proposed.
基金supported by the National Key R&D Program of China(2020YFA0710000)the National Natural Science Foundation of China(22122901)+2 种基金the Provincial Natural Science Foundation of Hunan(2021JJ0008,2021JJ20024,2021RC3054)the Provincial Natural Science Foundation of Hunan(2022JJ40043)Hunan Provincial Innovation Foundation For Postgraduate(CX20220386)。
文摘Electrocatalytic dehydrogenative cross-coupling of various alcohols in aqueous electrolytes functionalizes alcohols to form structurally diverse long-carbon-chain chemicals.However,it remains challenging to achieve the high selectivity because of the high reactivity of involved carbonyl intermediates and different oxidation rates for the alcohols.Herein,the synthesis ofα,β-unsaturated ketones from alcohols was realized by the electro-oxidation cross-coupling in aqueous solutions by a“salting-out”strategy to engineer the micro-environment at electrocatalytic reaction interfaces.Theoretical calculations and electrochemical measurements demonstrated that concentrated local intermediates could inhibit the over-oxidation of alcohols and accelerate the coupling reaction kinetics between the intermediates.This strategy can couple primary and secondary alcohols to formα,β-unsaturated carbonyl compounds with a selectivity of 87% and be easily scaled up to gram scales.This study provides an attractive strategy for broadening the diversity of organic products in electrocatalysis.
基金financial support from the National Natural Science Foundation of China(No.22171215)the Excellent Youth Foundation of Hubei Scientific Committee(No.2022CFA092)the GuangDong Basic and Applied Basic Research Foundation(No.2022A1515110113).
文摘A cooperative Pd/Cu-catalyzed three-component cross-coupling reaction of alkynes,B_(2)Pin_(2) and alkene-tethered aryl halides is reported.This reaction proceeds under mild conditions and shows broad sub-strate scope,providing a variety of heterocycles containing tetrasubstituted alkenylboronate moieties in synthetically useful yields with excellent chemoselectivity and regioselectivity.This transformation fea-tures the catalytic generation ofβ-borylalkenylcopper intermediates and their use in Pd-catalyzed Heck cyclization/cross-couplings.An enantioselective cascade cyclization/cross-coupling process has also been developed for the synthesis of enantiomerically enriched oxindole bearing a tetrasubstituted alkenyl-boronate moiety.
基金supported by the National Key R&D Program of China(2021YFA1500100)the National Natural Science Foundation of China(91956202,92256301,21821002,21971255)+1 种基金the Science and Technology Commission of Shanghai Municipality(20JC1417000,21520780100)the International Partnership Program(121731KYSB20190016)of the Chinese Academy of Sciences。
文摘A radical decarboxylative C(sp^(3))–C(sp^(3))cross-coupling of NHPI esters and cyclopropanols was developed by combining photocatalysis and copper catalysis,which presents the efficient access toβ-benzyl ketones in excellent yields.Terpyridin-4′-one used as the ligand is vital for the reaction,which could facilitate the capture of benzylic radicals by alkyl-copper species generated from copper-catalyzed ring-opening of cyclopropanols.The reaction exhibited broad substrate scope and wide functional group compatibility,providing an alternative approach for C(sp^(3))–C(sp^(3))bond formation.
基金This work is supported by the National Natural Science Foundation of China(No.21902083)the Natural Science Foundation of Shandong Province(No.ZR2020QB130)This work is also supported by the Talent Program Foundation of Qufu Normal University(Nos.6132 and 6125).
文摘Chloroalkanes are important building blocks in the synthesis,but their use in redox chemistry is limited by their negative reduction potentials.Electrosynthesis can precisely control the reaction energy just by adjusting the current or voltage to achieve the selectivity of regulation.In this study,the consecutively paired electrolyticmediated controllable radical cross-coupling of thiophenols with dichloromethane was developed to deliver the dithioacetals,sulfides,and sulfoxides in the absence of electrochemical mediator conditions.It features broad substrate scope,simple operation,gram-scale synthesis,and is eco-friendly.Mechanistic studies reveal that this electrochemical reaction is radical-induced cross-coupling of thiophenols with dichloromethane.
基金the National Natural Science Foundation of China (Nos.21562026,21762025,21702027)the Natural Science Foundation of Jiangxi Province (No.20161BAB203085) for financial support.
文摘Tetrasubstituted olefins are significant scaffolds as they are prevalent in many biologically active compounds and versatile building blocks for organic synthesis. Herein, we report an electrochemical oxidative Csp^3—H/S—H cross-coupling reaction, in which various tetrasubstituted olefins were prepared under base-free, transition metal-free, and oxidants-free reaction conditions.
基金Financial support was provided by the Zhejang Provincial Natural Science Foundation of China(No.LR19B020001)NSFC(Nos.21922107 and 21772171)+1 种基金the National Key R&D Program of China(Nos.2021YFA1500200 and 2021YFF0701603)the Center of Chemistry for Frontier Technologies.
文摘The asymmetric reductive arylation and alkenylation of benzylic chloride under photoredox/nickel dual catalysis using chiral bimidazoline(Bilm)ligand is reported to access 1,1-diaryl alkanes and aryl allylic compounds with good yield as well as stereo-and enantioselectivities.This protocol uses more commercially available and less expensive C(sp^(2))-Br as the electrophile coupling partner.A primary result using alkenyl chloride and alkyl chloride is also reported.Various functional groups are tolerated and the applications of this method are investigated by late-stage functionalization and gram-scale reaction.
基金supported by the Fundamental Research Funds for the Central Universities,China(No.2014QNA40)the Natural Science Foundation of Jiangsu Province,China(No.BK20140188)
文摘We investigate motion synchronization of dual-cylinder pneumatic servo systems and develop an adaptive robust synchronization controller. The proposed controller incorporates the cross-coupling technology into the integrated direct/indirect adaptive robust control(DIARC) architecture by feeding back the coupled position errors, which are formed by the trajectory tracking errors of two cylinders and the synchronization error between them. The controller employs an online recursive least squares estimation algorithm to obtain accurate estimates of model parameters for reducing the extent of parametric uncertainties, and uses a robust control law to attenuate the effects of parameter estimation errors, unmodeled dynamics, and disturbances. Therefore, asymptotic convergence to zero of both trajectory tracking and synchronization errors can be guaranteed. Experimental results verify the effectiveness of the proposed controller.
