The enantioselective construction of bis-heterocyclic frameworks containing pyrroline and indole motifs is achieved through a cooperative palladium-catalyzed tandem process.This methodology efficiently couples oxime e...The enantioselective construction of bis-heterocyclic frameworks containing pyrroline and indole motifs is achieved through a cooperative palladium-catalyzed tandem process.This methodology efficiently couples oxime esters and 2-alkynylanilines via a sequential Narasaka-Heck cyclization/Cacchi coupling reaction,providing direct access to complex chiral architectures in high yields with excellent enantioselectivity.The protocol demonstrates broad substrate scope and functional group tolerance.A diverse range of oxime esters,bearing both electron-donating and electron-withdrawing groups,as well as heterocyclic and polyarene substituents,undergo the transformation smoothly,delivering the desired products in 80%-96%yields and up to 98%ee.The reaction also accommodates various ortho-alkynylanilines with para-,meta-,and even sterically demanding ortho-substituents,yielding products with high stereocontrol.Preliminary mechanistic investigations reveal that the reaction is facilitated by a single palladium catalyst operating in synergy with two distinct supporting ligands.The system features two concurrent catalytic cycles:a Pd/Sadphos cycle that drives the enantioselective Narasaka-Heck cyclization of the oxime ester to form the pyrroline ring,and a Pd/Xantphos cycle that mediates the anti-aminopalladation(Cacchi reaction)of the 2-alkynylaniline to construct the indole core.A key transmetallation step between the alkyl-Pd(II)and alkenyl-Pd(II)intermediates from the respective cycles enables the coupling,followed by reductive elimination to furnish the final bis-heterocyclic product.The synthetic utility is highlighted by a gram-scale synthesis without erosion of yield or enantioselectivity,and the product could be readily derivatized to other valuable chiral nitrogen-containing scaffolds.This work establishes a streamlined and efficient route to enantioenriched bis-heterocycles,showcasing the power of single-metal,dual-ligand cooperative catalysis in complex molecule synthesis.展开更多
MgH2 is a promising and popular hydrogen storage material.In this work,the hydrogen desorption reactions of a single Pd atom adsorbed MgH2(110)surface are investigated by using first-principles density functional theo...MgH2 is a promising and popular hydrogen storage material.In this work,the hydrogen desorption reactions of a single Pd atom adsorbed MgH2(110)surface are investigated by using first-principles density functional theory calculations.We find that a single Pd atom adsorbed on the MgH2(110)surface can significantly lower the energy barrier of the hydrogen desorption reactions from 1.802 eV for pure MgH2(110)surface to 1.154 eV for Pd adsorbed MgH2(110)surface,indicating a strong Pd single-atom catalytic effect on the hydrogen desorption reactions.Furthermore,the Pd single-atom catalysis significantly reduces the hydrogen desorption temperature from 573K to 367K,which makes the hydrogen desorption reactions occur more easily and quickly on the MgH2(110)surface.We also discuss the microscopic process of the hydrogen desorption reactions through the reverse process of hydrogen spillover mechanism on the MgH2(110)surface.This study shows that Pd/MgH2 thin films can be used as good hydrogen storage materials in future experiments.展开更多
Tetracyclic coumarins are a class of important compounds with diverse and superior pharmacolog‐ical activities.However,a direct stereoselective method from simple and readily‐made coumarins derivatives remains chall...Tetracyclic coumarins are a class of important compounds with diverse and superior pharmacolog‐ical activities.However,a direct stereoselective method from simple and readily‐made coumarins derivatives remains challenging due to the inertness of coumarins as dienophiles.Herein,we de‐velop a decarboxylative asymmetric[4+2]cycloaddition of 3‐cyanocoumarins with vinyl benzoxa‐zinones,affording the coumarin‐derived condensed rings bearing three continuous stereocenters in high yields with excellent diastereoselectivities(>20/1 d.r.)and enantioselectivities(up to 99%ee).This direct enantioselective reaction was achieved by a Pd(0)/Cu(I)bimetallic catalytic system.The mechanism studies indicated that the synergistic activation effect,in which chiral Cu(I)as an availa‐ble Lewis acid catalyst activates 3‐cyanocoumarin and chiral Pd(0)complex activates benzoxazi‐none by the formation ofπ‐allyl‐palladium intermediate,plays an important role on the stereoselec‐tive control.The current work provides a new activation modes of Cu catalyst in the Pd/Cu bimetal‐lic catalytic system.展开更多
Substituted ureas hold considerable significance in both natural and synthetic chemicals.Pd-based homogenous catalyst has been used for the urea synthesis,however the aggregation of Pd(0)species leads to the deactivat...Substituted ureas hold considerable significance in both natural and synthetic chemicals.Pd-based homogenous catalyst has been used for the urea synthesis,however the aggregation of Pd(0)species leads to the deactivation of the catalyst even under mild conditions.Here,we present a photon-involved carbonylation of amines to synthesize ureas,achieving product yields of up to 99%,using Pd(OAc)2 and KI without losing the performance owing to the fast regeneration of Pd species under light irradiation.Reaction kinetics results and ultraviolet-visible absorption spectra indicate the regeneration of the Pd species is realized by the light irradiation(below 450 nm)which induces the oxidation reaction between HI and O_(2)to produce I_(2),so that the active species PdI_(2)is regenerated through the reaction between Pd(0)and the I_(2).展开更多
We report the unprecedent Pd(I)catalyzed ring-opening arylation of cyclopropyl-α-aminoamides.This protocol allows facile access to biologically important α-ketoamide-containing oligopeptides and even more challengin...We report the unprecedent Pd(I)catalyzed ring-opening arylation of cyclopropyl-α-aminoamides.This protocol allows facile access to biologically important α-ketoamide-containing oligopeptides and even more challenging peptide-natural product conjugates.Site selectivity was achieved by introduction of special unnatural amino acids,which also meets the requisite of bioorthogonal chemistry.Mechanism investigations reveals a distinct domino radical ring-opening process through Pd(I)catalysis.展开更多
Pd-catalyzed oxidative C-H/C-H coupling reaction is an emerging type of C-H acti- vation reaction, which attracts great interests because both reaction partners do not re- quire pre-functionalization. In the present s...Pd-catalyzed oxidative C-H/C-H coupling reaction is an emerging type of C-H acti- vation reaction, which attracts great interests because both reaction partners do not re- quire pre-functionalization. In the present study, we employed DFT methods to investigate the mechanism of Pd（OAc）2-catalyzed oxidative C-H/C-H coupling of pentafluoroben-zene with benzene. Four possible pathways were examined in the C-H activation part： path A benzene-pentafluorobenzene mechanism （C-H activation of benzene occurs before the C-H activation of pentafluorobenzene）, path B pentafluorobenzene-benzene mechanism （C-H activation of benzene occurs after the C-H activation of pentafluorobenzene）, path C benzene-pentafluorophenylsilver mechanism （C-H activation of benzene and subsequent transmetalation with pentafiuorophenyl silver complex）, path D pentafiuorophenylsilver- benzene mechanism （transmetalation with pentafluorophenyl silver complex and subsequent C-H activation of benzene）. Based on the calculations, the sequences of two C-H activation steps are found to be different in the oxidative couplings of same substrates （i. e. pentafiu- orobenzene and benzene） in different catalytic systems, where the additive Ag salts played a determinant role. In the absence of Ag salts, the energetically favored pathway is path B （i.e. the C-H activation of pentafluorobenzene takes place before the C-H cleavage of benzene）. In contrast, with the aid of Ag salts, the coordination of pentafluorophenylsilver to Pd center could occur easily with a subsequent C-H activation of benzene in the second step, and the second step significantly raises the whole reaction barrier. Alternatively, in the presence of Ag salts, the kinetically preferred mechanism is path C （i. e. the C-H activation of benzene takes place in the first step followed by transmetalation with pentafluorophenyl- silver complex）, which is similar to path A. The calculations are consistent with the H/D exchange experiment and kinetic isotope effects. Thus the present study not only offers a deeper understanding of oxidative C-H/C-H coupling reaction, but also provides helpful insights to further development of more efficient and selective oxidative C-H/C-H coupling reactions.展开更多
Nickel-and palladium-catalyzed cross-coupling reactions have attracted wide attentions,while ligandcontrolled selectivity in these reactions are still elusive,and calculations can help obtain possible catalytic cycles...Nickel-and palladium-catalyzed cross-coupling reactions have attracted wide attentions,while ligandcontrolled selectivity in these reactions are still elusive,and calculations can help obtain possible catalytic cycles to generate different products and provide insights into key factors of selectivity,which facilitates the development of new catalyst systems to control reaction selectivity.This review covers our efforts and some significant achievements from other groups on ligand-controlled reaction selectivity of coupling reactions,including introduction,computational methods,selectivity control by ligands in Niand Pd-catalyzed coupling reactions,as well as summary and future perspectives.展开更多
This report describes the oxidative cyclopalladation activation of a C≡C bond during the Pd-catalyzed hydroalkylation of alkynes and analyzes potential reaction pathways based on density functional theory calculation...This report describes the oxidative cyclopalladation activation of a C≡C bond during the Pd-catalyzed hydroalkylation of alkynes and analyzes potential reaction pathways based on density functional theory calculations. The more favorable pathway in-volves an oxidative cyclopalladation to generate a palladacyclopropene intermediate, which is rarely examined in Pd-catalyzed alkyne transformations. The reaction pathway proposed herein is kinetically favorable relative to the commonly proposed alkyne insertion mode. Furthermore, the Laplacians of the electron density, interaction region indicators, Mayer bond orders, and localized orbital bonding are evaluated to determine the reaction processes and characterize the key intermediates. Theoretical calculations indicate covalent bonding between a Pd(II) center and the two C-atoms in three-membered palladacycle species. Finally, electrostatic potential analysis reveals that the regioselectivity is governed by the charge distribution on the palladacycle moiety during the protonation step.展开更多
Palladium‐catalyzed asymmetric allylic alkylation(AAA)of vinyl benzoxazinanones has become an important strategy for the synthesis of chiral nitrogen‐containing heterocycle compounds.However,the asymmetric synthesis...Palladium‐catalyzed asymmetric allylic alkylation(AAA)of vinyl benzoxazinanones has become an important strategy for the synthesis of chiral nitrogen‐containing heterocycle compounds.However,the asymmetric synthesis of linear‐selective products has rarely been reported.The simultaneous control of regio‐,E/Z‐and enantioselectivities constitutes a major challenge and inhibits the advancement of this chemistry.Herein,we present a palladium‐catalyzed AAA of vinyl benzoxazinanones withα‐thiocyanato ketones,affording various chiral thiocyanates characterized with high linear‐,E‐and stereoselectivities.The reaction has a broad substrate scope and the chiral thiocyanates can be transformed to useful heterocycles.Experimental and computational studies suggest an inner‐sphere mechanism for AAA process,which results from the acidic and coordination effect of the nucleophilic substrates with palladium catalyst.展开更多
Direct alkylation with skipped enynes or cyclopropropylacetylenes represents an ideal process for the installation of pentadienyl group in terms of atom- and step-economy.The development of catalytic asymmetric versio...Direct alkylation with skipped enynes or cyclopropropylacetylenes represents an ideal process for the installation of pentadienyl group in terms of atom- and step-economy.The development of catalytic asymmetric versions has been frequently pursued and most of the successes have been achieved with enolizable aldehydes.We herein describe a synergistic chiral primary amine/Pd catalysis for asymmetric α-pentadienylation of β-ketocarbonyls and aldehydes with skipped enynes or cyclopropropylacetylenes.The reaction features the construction of acyclic all-carbon quaternary centers with high enantioselectivity,and good functional group tolerance and scalability.展开更多
Binaphthalene-core phosphepine compounds with axial chirality belong to an important class of organocatalysts and ligands used in catalytic asymmetric synthesis.However,the number and application of these compounds ha...Binaphthalene-core phosphepine compounds with axial chirality belong to an important class of organocatalysts and ligands used in catalytic asymmetric synthesis.However,the number and application of these compounds have been limited due to the lack of efficient synthetic methods currently available to researchers.Herein,a simple and efficient palladium-catalyzed C—P cross-coupling reaction of enantiopure(R)-1 with a variety of aryl and heteroaryl halides is reported.The reaction provides access to a series of chiral binaphthalene-core phosphepine compounds using Pd(OAc)2/dippf as a catalyst,which allows most products to be formed in moderate to high yields(40%~92%)with excellent ee values(90%~99%ee).展开更多
The cross-dimerization of terminal alkynes is the most straightforward and attractive approach to differently substituted 1,3-enynes,which are vital structural motifs in natural products,biologically active compounds,...The cross-dimerization of terminal alkynes is the most straightforward and attractive approach to differently substituted 1,3-enynes,which are vital structural motifs in natural products,biologically active compounds,and organic functional materials,etc.However,due to the inherent issues of the stereo-,regio-,and chemoselectivity,the strategy is less explored and remains problematic in substrate scope,selectivity,and screening of catalytic system,etc.Herein,a specific cross-dimerization of terminal alkynes is developed under Pd/TMEDA catalysis,which produces a series of gem-1,3-enynes(58 examples)in totally moderate to high yields with outstanding functional group tolerance.A cyclopalladium compound might be the key imtermediate,which performs anti-addition-carbometallation,and leads to the exclusive cross-selectivity.The unprecedented features of the reaction,such as anti-addition-carbometallation,easy control of selectivity,wide range of the donor alkynes,and very simple catalytic conditions,allow it not only a facile and functionally diverse synthesis of 1,3-enynes,but also a substantial progress for the textbook reaction.展开更多
AstereodivergentPd/Cucatalyst systemforasymmetric desymmetric alkylation of allylic geminal dicarboxylates has been developed,which was successfully applied to the asymmetric synthesis of β-hydroxycarbonylmotifs bear...AstereodivergentPd/Cucatalyst systemforasymmetric desymmetric alkylation of allylic geminal dicarboxylates has been developed,which was successfully applied to the asymmetric synthesis of β-hydroxycarbonylmotifs bearing a versatile carbon-carbon double bond in an enantio-and diastereodivergent manner.A wide scope of substrates including challenging alkylsubstituted,2-substituted,and3,3′-disubstitutedallylic species are compatible with this catalytic system,delivering the substituted products in high to excellent yieldsandwith excellent diastereo-(upto>20:1 dr)and enantioselectivities(up to>99%ee).Furthermore,the mechanism of this dual Pd/Cu catalytic system including:(1)the desymmetrization process ofgeminal dicarboxylates;(2)the origin of regioselectivity(branched or linear);(3)the enantio-and diastereoselectivity observed by changing the combinations of two chiral metal catalysts,have been carefully investigated by theoretical calculations.展开更多
We synthesized optically active 2-(8′-diphenylphosphino-1′-naphthyl)oxazoline ligands by palladium-catalyzed coupling reactions of (trimethylsilyl)diphenylphosphine with 2-(8′-bromo-1′-naphthyl)oxazolines, which, ...We synthesized optically active 2-(8′-diphenylphosphino-1′-naphthyl)oxazoline ligands by palladium-catalyzed coupling reactions of (trimethylsilyl)diphenylphosphine with 2-(8′-bromo-1′-naphthyl)oxazolines, which, in turn, were prepared from 8-bromo-1-naphthoyl chloride by the reaction with natural optical active amino alcohols. Pd-Catalyzed allylic alkylation reaction induced by these chiral ligands gave the allylic substituted products in high yields and moderate ee values.展开更多
Main observation and conclusion A highly enantioselective 2,3-allenylation of acyclic and cyclicα-imino carboxylates via a synergistic bimetallic Pd/Cu catalysis with the same commercially available(R,Rp)-iPr-FOXAP(a...Main observation and conclusion A highly enantioselective 2,3-allenylation of acyclic and cyclicα-imino carboxylates via a synergistic bimetallic Pd/Cu catalysis with the same commercially available(R,Rp)-iPr-FOXAP(also as Phosferrox,(R,R)-[2-(4’-i-propyloxazolin-2’-yl)ferrocenyl]diphenyl phosphine)ligand for both metals affording optically active 2,3-butadienylα-amino acid derivatives in high to excellent yields with excellent enantioselectivities has been developed.展开更多
A series of 3-acyl-substituted isoindolinone derivatives were synthesized in a one-pot manner via the reaction of o-bromobenzaldehydes,isocyanides,and carboxylic acids in the presence of palladium catalyst and base. T...A series of 3-acyl-substituted isoindolinone derivatives were synthesized in a one-pot manner via the reaction of o-bromobenzaldehydes,isocyanides,and carboxylic acids in the presence of palladium catalyst and base. The reaction employing easily available starting materials features simple operation and high efficiency. The mechanistic study showed that the reaction might undergo 1) Pd-catalyzed [3+2] cyclization of o-bromobenzaldehyde with isocyanide and the re-insertion of another molecule of isocyanide,2) addition of carboxylic acid to in situ formed ketenimine followed by a rearrangement relay to give 3,3-diacyl-substituted isoindolinone derivative. Further transformations of the obtained products through decarbonylation could also be realized.展开更多
Comprehensive Summary 2,3-Allenyl amines have shown wide applicability in biomedical and synthetic applications.Due to their enormous potential for applications,researchers have been dedicated to the development of me...Comprehensive Summary 2,3-Allenyl amines have shown wide applicability in biomedical and synthetic applications.Due to their enormous potential for applications,researchers have been dedicated to the development of methods for synthesizing 2,3-allenyl amines.Herein,a palladium-catalyzed three-component reaction of 2-alkynyl-1,4-diol dicarbonates,organoboronic acids,and nitrogen nucleophiles forming 2,3-allenyl amines with excellent regio-and chemo-selectivity has been developed.Substrate compatibility and synthetic applications have been demonstrated.Control experiments supported a mechanism involving 1,2,3-triene-Pd species and methylene-π-allyl palladium species.展开更多
We have summarized the developments and advancements of allyl-(aza)allyl coupling reactions in the past years.Since the first report in 1980,Pd-catalyzed allyl-allyl couplings have not drawn chemists'much attentio...We have summarized the developments and advancements of allyl-(aza)allyl coupling reactions in the past years.Since the first report in 1980,Pd-catalyzed allyl-allyl couplings have not drawn chemists'much attention for almost 20 years.Not until the last two decades,transition-metal-catalyzed allyl-(aza)allyl transformations have been retrieved vital interest and significantly developed in many respects,including metal-catalyst,ligand development,mechanistic understanding,substrate scope,and applications in the preparation of complex functional molecules.This review is organized according to the transition metals used in allyl-allyl coupling reactions including our own work.Besides,transition-metal-free,allyl-azaallyl cross-couplings and applications in the total synthesis of natural products and drugs have also been included.展开更多
基金support of National Key R&D Program of China(No.2021YFFO701600)NSFC(22271053,22031004,21921003)Shanghai Municipal Education Commission(20212308).
文摘The enantioselective construction of bis-heterocyclic frameworks containing pyrroline and indole motifs is achieved through a cooperative palladium-catalyzed tandem process.This methodology efficiently couples oxime esters and 2-alkynylanilines via a sequential Narasaka-Heck cyclization/Cacchi coupling reaction,providing direct access to complex chiral architectures in high yields with excellent enantioselectivity.The protocol demonstrates broad substrate scope and functional group tolerance.A diverse range of oxime esters,bearing both electron-donating and electron-withdrawing groups,as well as heterocyclic and polyarene substituents,undergo the transformation smoothly,delivering the desired products in 80%-96%yields and up to 98%ee.The reaction also accommodates various ortho-alkynylanilines with para-,meta-,and even sterically demanding ortho-substituents,yielding products with high stereocontrol.Preliminary mechanistic investigations reveal that the reaction is facilitated by a single palladium catalyst operating in synergy with two distinct supporting ligands.The system features two concurrent catalytic cycles:a Pd/Sadphos cycle that drives the enantioselective Narasaka-Heck cyclization of the oxime ester to form the pyrroline ring,and a Pd/Xantphos cycle that mediates the anti-aminopalladation(Cacchi reaction)of the 2-alkynylaniline to construct the indole core.A key transmetallation step between the alkyl-Pd(II)and alkenyl-Pd(II)intermediates from the respective cycles enables the coupling,followed by reductive elimination to furnish the final bis-heterocyclic product.The synthetic utility is highlighted by a gram-scale synthesis without erosion of yield or enantioselectivity,and the product could be readily derivatized to other valuable chiral nitrogen-containing scaffolds.This work establishes a streamlined and efficient route to enantioenriched bis-heterocycles,showcasing the power of single-metal,dual-ligand cooperative catalysis in complex molecule synthesis.
基金supported by the National Key Basic Research Program(No.2011CB921404)National Natural Science Foundation of China(No.21421063,No.91021004,No.21233007,No.21803066)+2 种基金Strategic Priority Research Program of Chinese Academy of Sciences(No.XDC01000000)Research Start-Up Grants(No.KY2340000094)from University of Science and Technology of Chinathe Chinese Academy of Sciences Pioneer Hundred Talents Program
文摘MgH2 is a promising and popular hydrogen storage material.In this work,the hydrogen desorption reactions of a single Pd atom adsorbed MgH2(110)surface are investigated by using first-principles density functional theory calculations.We find that a single Pd atom adsorbed on the MgH2(110)surface can significantly lower the energy barrier of the hydrogen desorption reactions from 1.802 eV for pure MgH2(110)surface to 1.154 eV for Pd adsorbed MgH2(110)surface,indicating a strong Pd single-atom catalytic effect on the hydrogen desorption reactions.Furthermore,the Pd single-atom catalysis significantly reduces the hydrogen desorption temperature from 573K to 367K,which makes the hydrogen desorption reactions occur more easily and quickly on the MgH2(110)surface.We also discuss the microscopic process of the hydrogen desorption reactions through the reverse process of hydrogen spillover mechanism on the MgH2(110)surface.This study shows that Pd/MgH2 thin films can be used as good hydrogen storage materials in future experiments.
文摘Tetracyclic coumarins are a class of important compounds with diverse and superior pharmacolog‐ical activities.However,a direct stereoselective method from simple and readily‐made coumarins derivatives remains challenging due to the inertness of coumarins as dienophiles.Herein,we de‐velop a decarboxylative asymmetric[4+2]cycloaddition of 3‐cyanocoumarins with vinyl benzoxa‐zinones,affording the coumarin‐derived condensed rings bearing three continuous stereocenters in high yields with excellent diastereoselectivities(>20/1 d.r.)and enantioselectivities(up to 99%ee).This direct enantioselective reaction was achieved by a Pd(0)/Cu(I)bimetallic catalytic system.The mechanism studies indicated that the synergistic activation effect,in which chiral Cu(I)as an availa‐ble Lewis acid catalyst activates 3‐cyanocoumarin and chiral Pd(0)complex activates benzoxazi‐none by the formation ofπ‐allyl‐palladium intermediate,plays an important role on the stereoselec‐tive control.The current work provides a new activation modes of Cu catalyst in the Pd/Cu bimetal‐lic catalytic system.
文摘Substituted ureas hold considerable significance in both natural and synthetic chemicals.Pd-based homogenous catalyst has been used for the urea synthesis,however the aggregation of Pd(0)species leads to the deactivation of the catalyst even under mild conditions.Here,we present a photon-involved carbonylation of amines to synthesize ureas,achieving product yields of up to 99%,using Pd(OAc)2 and KI without losing the performance owing to the fast regeneration of Pd species under light irradiation.Reaction kinetics results and ultraviolet-visible absorption spectra indicate the regeneration of the Pd species is realized by the light irradiation(below 450 nm)which induces the oxidation reaction between HI and O_(2)to produce I_(2),so that the active species PdI_(2)is regenerated through the reaction between Pd(0)and the I_(2).
基金support from the University Nursing Program for Young Scholars with Creative Talents in Heilongjiang Province(No.UNPYSCT-2017124)。
文摘We report the unprecedent Pd(I)catalyzed ring-opening arylation of cyclopropyl-α-aminoamides.This protocol allows facile access to biologically important α-ketoamide-containing oligopeptides and even more challenging peptide-natural product conjugates.Site selectivity was achieved by introduction of special unnatural amino acids,which also meets the requisite of bioorthogonal chemistry.Mechanism investigations reveals a distinct domino radical ring-opening process through Pd(I)catalysis.
文摘Pd-catalyzed oxidative C-H/C-H coupling reaction is an emerging type of C-H acti- vation reaction, which attracts great interests because both reaction partners do not re- quire pre-functionalization. In the present study, we employed DFT methods to investigate the mechanism of Pd（OAc）2-catalyzed oxidative C-H/C-H coupling of pentafluoroben-zene with benzene. Four possible pathways were examined in the C-H activation part： path A benzene-pentafluorobenzene mechanism （C-H activation of benzene occurs before the C-H activation of pentafluorobenzene）, path B pentafluorobenzene-benzene mechanism （C-H activation of benzene occurs after the C-H activation of pentafluorobenzene）, path C benzene-pentafluorophenylsilver mechanism （C-H activation of benzene and subsequent transmetalation with pentafiuorophenyl silver complex）, path D pentafiuorophenylsilver- benzene mechanism （transmetalation with pentafluorophenyl silver complex and subsequent C-H activation of benzene）. Based on the calculations, the sequences of two C-H activation steps are found to be different in the oxidative couplings of same substrates （i. e. pentafiu- orobenzene and benzene） in different catalytic systems, where the additive Ag salts played a determinant role. In the absence of Ag salts, the energetically favored pathway is path B （i.e. the C-H activation of pentafluorobenzene takes place before the C-H cleavage of benzene）. In contrast, with the aid of Ag salts, the coordination of pentafluorophenylsilver to Pd center could occur easily with a subsequent C-H activation of benzene in the second step, and the second step significantly raises the whole reaction barrier. Alternatively, in the presence of Ag salts, the kinetically preferred mechanism is path C （i. e. the C-H activation of benzene takes place in the first step followed by transmetalation with pentafluorophenyl- silver complex）, which is similar to path A. The calculations are consistent with the H/D exchange experiment and kinetic isotope effects. Thus the present study not only offers a deeper understanding of oxidative C-H/C-H coupling reaction, but also provides helpful insights to further development of more efficient and selective oxidative C-H/C-H coupling reactions.
基金supported by the National Natural Science Foundation of China(No.21203166)Visiting Scholars Project of Zhejiang Education Department(No.FX2017023).
文摘Nickel-and palladium-catalyzed cross-coupling reactions have attracted wide attentions,while ligandcontrolled selectivity in these reactions are still elusive,and calculations can help obtain possible catalytic cycles to generate different products and provide insights into key factors of selectivity,which facilitates the development of new catalyst systems to control reaction selectivity.This review covers our efforts and some significant achievements from other groups on ligand-controlled reaction selectivity of coupling reactions,including introduction,computational methods,selectivity control by ligands in Niand Pd-catalyzed coupling reactions,as well as summary and future perspectives.
基金supported by the National Natural Science Foundation of China(Nos.22003006,21822303,22103008,22271034)Project supported by graduate research and innovation foundation of Chongqing,China(No.CYB20045)a project(No.2018CDXZ0002)supported by the Fundamental Research Funds for the Central Universities(Chongqing University)。
文摘This report describes the oxidative cyclopalladation activation of a C≡C bond during the Pd-catalyzed hydroalkylation of alkynes and analyzes potential reaction pathways based on density functional theory calculations. The more favorable pathway in-volves an oxidative cyclopalladation to generate a palladacyclopropene intermediate, which is rarely examined in Pd-catalyzed alkyne transformations. The reaction pathway proposed herein is kinetically favorable relative to the commonly proposed alkyne insertion mode. Furthermore, the Laplacians of the electron density, interaction region indicators, Mayer bond orders, and localized orbital bonding are evaluated to determine the reaction processes and characterize the key intermediates. Theoretical calculations indicate covalent bonding between a Pd(II) center and the two C-atoms in three-membered palladacycle species. Finally, electrostatic potential analysis reveals that the regioselectivity is governed by the charge distribution on the palladacycle moiety during the protonation step.
文摘Palladium‐catalyzed asymmetric allylic alkylation(AAA)of vinyl benzoxazinanones has become an important strategy for the synthesis of chiral nitrogen‐containing heterocycle compounds.However,the asymmetric synthesis of linear‐selective products has rarely been reported.The simultaneous control of regio‐,E/Z‐and enantioselectivities constitutes a major challenge and inhibits the advancement of this chemistry.Herein,we present a palladium‐catalyzed AAA of vinyl benzoxazinanones withα‐thiocyanato ketones,affording various chiral thiocyanates characterized with high linear‐,E‐and stereoselectivities.The reaction has a broad substrate scope and the chiral thiocyanates can be transformed to useful heterocycles.Experimental and computational studies suggest an inner‐sphere mechanism for AAA process,which results from the acidic and coordination effect of the nucleophilic substrates with palladium catalyst.
基金the Natural Science Foundation of China(21861132003 and 22031006)Tsinghua University Initiative Scientific Research Program for financial support.
文摘Direct alkylation with skipped enynes or cyclopropropylacetylenes represents an ideal process for the installation of pentadienyl group in terms of atom- and step-economy.The development of catalytic asymmetric versions has been frequently pursued and most of the successes have been achieved with enolizable aldehydes.We herein describe a synergistic chiral primary amine/Pd catalysis for asymmetric α-pentadienylation of β-ketocarbonyls and aldehydes with skipped enynes or cyclopropropylacetylenes.The reaction features the construction of acyclic all-carbon quaternary centers with high enantioselectivity,and good functional group tolerance and scalability.
文摘Binaphthalene-core phosphepine compounds with axial chirality belong to an important class of organocatalysts and ligands used in catalytic asymmetric synthesis.However,the number and application of these compounds have been limited due to the lack of efficient synthetic methods currently available to researchers.Herein,a simple and efficient palladium-catalyzed C—P cross-coupling reaction of enantiopure(R)-1 with a variety of aryl and heteroaryl halides is reported.The reaction provides access to a series of chiral binaphthalene-core phosphepine compounds using Pd(OAc)2/dippf as a catalyst,which allows most products to be formed in moderate to high yields(40%~92%)with excellent ee values(90%~99%ee).
基金supported by the National Natural Science Foundation of China(21878072,21706058,22102062,21725602)the Hunan Provincial Natural Science Foundation of China(2020JJ2011)the China Postdoctoral Science Foundation(2019M662774).
文摘The cross-dimerization of terminal alkynes is the most straightforward and attractive approach to differently substituted 1,3-enynes,which are vital structural motifs in natural products,biologically active compounds,and organic functional materials,etc.However,due to the inherent issues of the stereo-,regio-,and chemoselectivity,the strategy is less explored and remains problematic in substrate scope,selectivity,and screening of catalytic system,etc.Herein,a specific cross-dimerization of terminal alkynes is developed under Pd/TMEDA catalysis,which produces a series of gem-1,3-enynes(58 examples)in totally moderate to high yields with outstanding functional group tolerance.A cyclopalladium compound might be the key imtermediate,which performs anti-addition-carbometallation,and leads to the exclusive cross-selectivity.The unprecedented features of the reaction,such as anti-addition-carbometallation,easy control of selectivity,wide range of the donor alkynes,and very simple catalytic conditions,allow it not only a facile and functionally diverse synthesis of 1,3-enynes,but also a substantial progress for the textbook reaction.
基金supported by the National Natural Science Foundation of China(nos.21620102003,21831005,21901158,and 21991112)the Shanghai Sailing Program(no.19YF1421900)+3 种基金Shanghai Municipal Education Commission(no.201701070002E00030)National Key R&D Program of China(no.2018YFE0126800)the Science and Technology Commission of Shanghai Municipality(no.19JC1430100)Zhiyuan Scholar Program(no.ZIRC2020-04).
文摘AstereodivergentPd/Cucatalyst systemforasymmetric desymmetric alkylation of allylic geminal dicarboxylates has been developed,which was successfully applied to the asymmetric synthesis of β-hydroxycarbonylmotifs bearing a versatile carbon-carbon double bond in an enantio-and diastereodivergent manner.A wide scope of substrates including challenging alkylsubstituted,2-substituted,and3,3′-disubstitutedallylic species are compatible with this catalytic system,delivering the substituted products in high to excellent yieldsandwith excellent diastereo-(upto>20:1 dr)and enantioselectivities(up to>99%ee).Furthermore,the mechanism of this dual Pd/Cu catalytic system including:(1)the desymmetrization process ofgeminal dicarboxylates;(2)the origin of regioselectivity(branched or linear);(3)the enantio-and diastereoselectivity observed by changing the combinations of two chiral metal catalysts,have been carefully investigated by theoretical calculations.
文摘We synthesized optically active 2-(8′-diphenylphosphino-1′-naphthyl)oxazoline ligands by palladium-catalyzed coupling reactions of (trimethylsilyl)diphenylphosphine with 2-(8′-bromo-1′-naphthyl)oxazolines, which, in turn, were prepared from 8-bromo-1-naphthoyl chloride by the reaction with natural optical active amino alcohols. Pd-Catalyzed allylic alkylation reaction induced by these chiral ligands gave the allylic substituted products in high yields and moderate ee values.
基金Financial support from the National Natural Science Foundation of China(Grant No.21690063 to S.M.,and Grant No.21901158 to X.H.)is greatly appreciated.We thank Mr.Huanan Wang in this group for reproducing the results of(R)-3'd,(Rm-3and(R)-17k,presented in Tables 2,3,and 4,respectively.
文摘Main observation and conclusion A highly enantioselective 2,3-allenylation of acyclic and cyclicα-imino carboxylates via a synergistic bimetallic Pd/Cu catalysis with the same commercially available(R,Rp)-iPr-FOXAP(also as Phosferrox,(R,R)-[2-(4’-i-propyloxazolin-2’-yl)ferrocenyl]diphenyl phosphine)ligand for both metals affording optically active 2,3-butadienylα-amino acid derivatives in high to excellent yields with excellent enantioselectivities has been developed.
基金the National Natural Science Foundation of China(Nos.21772138 and 21672157)the Natural Science Foundation of Jiangsu Province(BK20221356)PAPD。
文摘A series of 3-acyl-substituted isoindolinone derivatives were synthesized in a one-pot manner via the reaction of o-bromobenzaldehydes,isocyanides,and carboxylic acids in the presence of palladium catalyst and base. The reaction employing easily available starting materials features simple operation and high efficiency. The mechanistic study showed that the reaction might undergo 1) Pd-catalyzed [3+2] cyclization of o-bromobenzaldehyde with isocyanide and the re-insertion of another molecule of isocyanide,2) addition of carboxylic acid to in situ formed ketenimine followed by a rearrangement relay to give 3,3-diacyl-substituted isoindolinone derivative. Further transformations of the obtained products through decarbonylation could also be realized.
基金National Natural Science Foundation of China(No.21988101)is greatly appreciated.
文摘Comprehensive Summary 2,3-Allenyl amines have shown wide applicability in biomedical and synthetic applications.Due to their enormous potential for applications,researchers have been dedicated to the development of methods for synthesizing 2,3-allenyl amines.Herein,a palladium-catalyzed three-component reaction of 2-alkynyl-1,4-diol dicarbonates,organoboronic acids,and nitrogen nucleophiles forming 2,3-allenyl amines with excellent regio-and chemo-selectivity has been developed.Substrate compatibility and synthetic applications have been demonstrated.Control experiments supported a mechanism involving 1,2,3-triene-Pd species and methylene-π-allyl palladium species.
基金supported by the National Natural Science Foundation of China(No.22201300)the Fundamental Research Funds for the Central Universities,and the Research Funds of Renmin University of China(No.21XNLG04).
文摘We have summarized the developments and advancements of allyl-(aza)allyl coupling reactions in the past years.Since the first report in 1980,Pd-catalyzed allyl-allyl couplings have not drawn chemists'much attention for almost 20 years.Not until the last two decades,transition-metal-catalyzed allyl-(aza)allyl transformations have been retrieved vital interest and significantly developed in many respects,including metal-catalyst,ligand development,mechanistic understanding,substrate scope,and applications in the preparation of complex functional molecules.This review is organized according to the transition metals used in allyl-allyl coupling reactions including our own work.Besides,transition-metal-free,allyl-azaallyl cross-couplings and applications in the total synthesis of natural products and drugs have also been included.
