A simple, efficient and low-cost methodology for the synthesis of α-aryl-α,β-unsaturated esters using paraformaldehyde as a source of carbon was developed. Factors that control reaction yields such as temperature, ...A simple, efficient and low-cost methodology for the synthesis of α-aryl-α,β-unsaturated esters using paraformaldehyde as a source of carbon was developed. Factors that control reaction yields such as temperature, concentration and reaction time were evaluated. A mechanism is proposed based on experimental structures of the intermediates.展开更多
Transition metal-catalyzed olefination of aryl C-H bond is a powerful tool for the synthesis of alkenes. While the Pd-catalyzed oxidative C-H olefination of arenes, also known as Fujiwara-Moritani reaction, has been e...Transition metal-catalyzed olefination of aryl C-H bond is a powerful tool for the synthesis of alkenes. While the Pd-catalyzed oxidative C-H olefination of arenes, also known as Fujiwara-Moritani reaction, has been established as one of the most efficient methods, the substrates are largely limited to terminal olefins with electron-withdrawing group(s). Herein, we report a synergistic silver-mediated and palladium-catalyzed non-directed C-H olefination of arenes with vinyl(pseudo)halides, which offers a complementary strategy to the typical Fujiwara-Moritani reaction. The reactions proceeded well for a variety of halogenated arenes, heteroarenes, and olefin substrates, providing an efficient access to various multi-substituted aryl olefins, including trisubstituted/tetrasubstituted olefins and several complex olefins derived from medicines or natural products. Mechanistic studies indicated a bimetallic Pd/Ag cooperation is operative in the catalysis, i.e., the reaction is initiated by aryl C-H bond cleavage via ligation with phosphine/Ag species, followed by transferring of the aryl moiety to a vinyl palladium intermediate,which is in turn formed by oxidative addition of vinyl(pseudo)halide to a Pd complex. This method enables the synthesis of a wide range of challenging multi-substituted vinyl products from simple arenes(directing-group free) in a streamlined and controllable fashion.展开更多
Four novel palladium（（Ⅱ）） complexes coordinated by phosphorus atoms from both 3,5-disubstituted-1H- 1,2,4-diazaphospholes in monodentate fashion were developed as efficient catalyst for the Mizoroki- Heck reactio...Four novel palladium（（Ⅱ）） complexes coordinated by phosphorus atoms from both 3,5-disubstituted-1H- 1,2,4-diazaphospholes in monodentate fashion were developed as efficient catalyst for the Mizoroki- Heck reaction of aryl halides with electron-deficient olefins. The coupling reaction of awl halide bearig different functional groups with olefin derivatives took place and the corresponding products were isolated in good to excellent yields under optimal conditions. The procedure exhibits good functional group tolerance and wide substrate scope. This Mizoroki-Heck reaction was further achieved using Pd（OAc）2 and 3,5-di-isopropyl-1H-1,2,4-diazaphospholes as combined catalyst, which provide the convenient and alternative method in organic synthesis展开更多
Photo[2+2]cycloaddition of olefins is a sought-after tool for making cyclobutanes,which are the building blocks for a wide range of biologically active molecules and natural products.However,the formation of cyclobuta...Photo[2+2]cycloaddition of olefins is a sought-after tool for making cyclobutanes,which are the building blocks for a wide range of biologically active molecules and natural products.However,the formation of cyclobutane derivatives from aryl terminal olefins is problematic due to their high redox potential,and high energy in the excited state,making visible-light-absorbing photocatalyst difficult to realize either electron or energy transfer to olefins during the photocyclic addition process.Herein,we report,for the first time,the aggregationinduced photo[2+2]cycloaddition of two olefins by visible-light catalysis in homogeneous solution.An array of control experiments and spectroscopic analyses reveal that the terminal olefins tend to aggregate to form excimers/exciplexes,which possess much lower energy than their monomeric forms,and enables triplet energy transfer from excited Ir(ppy)3*to supramolecular self-assembly feasible,leading to homo and cross[2+2]photodimerization of the olefins to fabricate cyclobutanes at ambient conditions in good to excellent yields.展开更多
The binding behavior of pillar[5]arenes(P5 As)towards a series of olefin guests((E)-1,4-dichlo robut-2-ene(1 E),(Z)-1,4-dichlo robut-2-ene(1 Z),(E)-but-2-ene-1,4-diol(2 E),and(Z)-but-2-ene-1,4-diol(2 Z),as well as an ...The binding behavior of pillar[5]arenes(P5 As)towards a series of olefin guests((E)-1,4-dichlo robut-2-ene(1 E),(Z)-1,4-dichlo robut-2-ene(1 Z),(E)-but-2-ene-1,4-diol(2 E),and(Z)-but-2-ene-1,4-diol(2 Z),as well as an alkyne derivative 1,4-dichlorobut-2-yne(3))have been studied in organic solution.P5 As exhibit considerable selectivities for the trans-olefin isomers(1 E and 2 E)over their cis-isomers(1 Z and 2 Z).The cis/trans-selective interactions hold the potential of utilizing P5 As to separate olefin isomers.展开更多
Bis(4-fluorophenyl) substituted oxazole(2,5-Oxz) and C2(5)-C2'(5') linked bioxazole isomers(C2-C2'_BOxz,C2-C5'_BOxz and C5-C5'_BOxz) were concisely synthesized via palladium-catalyzed regioselectiv...Bis(4-fluorophenyl) substituted oxazole(2,5-Oxz) and C2(5)-C2'(5') linked bioxazole isomers(C2-C2'_BOxz,C2-C5'_BOxz and C5-C5'_BOxz) were concisely synthesized via palladium-catalyzed regioselective and sequential C-H arylation in 1-3 reaction steps along with 20%-83% of total yields from oxazole and4-bromofluorobenzene.The linking orientation plays a key role in the packing geometry and photophysical properties of C2-C2'_BOxz,C2-C5'_BOxz and C5-C5'_BOxz.These bioxazole isomers in solid state showed significant differences in photoluminescence quantum yields(PLQY)(0.33,0.25 and 0.04,respectively),delayed fluorescence properties and powder X-ray diffraction(PXRD) patterns,suggesting the divergence in intermolecular interactions.The theoretically calculated gradient isosurfaces and complexation energies indicate the existence of intense π-π interactions between molecular layers,which are in good agreement with the variation trend of optical properties.展开更多
Concise assembly of spirooxindoles is of great significance but a challenging task in modern organic synthesis.Described herein is an unusual base-promoted[4+2]spiroannulation of rarely used isatin-derivedβ-silylcarb...Concise assembly of spirooxindoles is of great significance but a challenging task in modern organic synthesis.Described herein is an unusual base-promoted[4+2]spiroannulation of rarely used isatin-derivedβ-silylcarbinols with o-halogen aromatic ketones,which enables rapid and modular synthesis of six-membered carbocyclic spirooxindoles in high yields with excellent functional group tolerance(>50 examples).Mechanistic experiments revealed that this reaction involved a Peterson olefination,Michael addition and intramolecular C(sp^(3))arylation cascade.The variegated synthetic derivatization of target products and successful construction of bioactive molecules further illustrate the synthetic potential in spirooxindole-related drug discovery.展开更多
Palladium-catalyzed Mizoroki-Heck reaction is a powerful and efficient method for construction of Csp2–Csp2 bonds.Herein,four palladium complexes(I—IV)with N,O-bidentate ligands(L1—L4)based on N-oxide units from cy...Palladium-catalyzed Mizoroki-Heck reaction is a powerful and efficient method for construction of Csp2–Csp2 bonds.Herein,four palladium complexes(I—IV)with N,O-bidentate ligands(L1—L4)based on N-oxide units from cyclic secondary amines were easily synthesized and successfully applied in Mizoroki-Heck reaction of aryl bromides with electron-deficient olefins.X-ray diffraction analyses indicated the palladium(II)atom of II took the distorted square planar geometry and was four-coordinated by nitrogen and oxygen atoms from two ligands(L2).Two free chloride ions were presented as counter anions in complex II.But the palladium(II)center of IV was coordinated by nitrogen and oxygen atoms from one ligand(L4)as well as two chlorine atoms,which exhibited the nearly square-planar geometry.The study on catalytic properties of palladium complexes revealed that complex II exhibited high activity superior to the other complexes.The coupling reactions of a series of aryl bromides and olefin derivatives proceeded in the presence of 2—5 mol%palladium complex II,giving the desired products in good to excellent yields.The advantages of this method such as good compatibility of functional groups,high yields,and short reaction times made it more attractive for constructing Csp2–Csp2 bonds in the synthesis of functional molecules and materials.展开更多
文摘A simple, efficient and low-cost methodology for the synthesis of α-aryl-α,β-unsaturated esters using paraformaldehyde as a source of carbon was developed. Factors that control reaction yields such as temperature, concentration and reaction time were evaluated. A mechanism is proposed based on experimental structures of the intermediates.
基金supported by the National Key R&D Program of China(2021YFA1500100)the National Natural Science Foundation of China(21821002,92256303,22171278)+1 种基金Shanghai Science and Technology Committee(23ZR1482400)the Natural Science Foundation of Ningbo(2023J034)。
文摘Transition metal-catalyzed olefination of aryl C-H bond is a powerful tool for the synthesis of alkenes. While the Pd-catalyzed oxidative C-H olefination of arenes, also known as Fujiwara-Moritani reaction, has been established as one of the most efficient methods, the substrates are largely limited to terminal olefins with electron-withdrawing group(s). Herein, we report a synergistic silver-mediated and palladium-catalyzed non-directed C-H olefination of arenes with vinyl(pseudo)halides, which offers a complementary strategy to the typical Fujiwara-Moritani reaction. The reactions proceeded well for a variety of halogenated arenes, heteroarenes, and olefin substrates, providing an efficient access to various multi-substituted aryl olefins, including trisubstituted/tetrasubstituted olefins and several complex olefins derived from medicines or natural products. Mechanistic studies indicated a bimetallic Pd/Ag cooperation is operative in the catalysis, i.e., the reaction is initiated by aryl C-H bond cleavage via ligation with phosphine/Ag species, followed by transferring of the aryl moiety to a vinyl palladium intermediate,which is in turn formed by oxidative addition of vinyl(pseudo)halide to a Pd complex. This method enables the synthesis of a wide range of challenging multi-substituted vinyl products from simple arenes(directing-group free) in a streamlined and controllable fashion.
基金Financial support from Scientific and Technological Innovation Programs of Higher Education Institutions in Shanxi(No. 2015157)Teaching Reform Project of Shanxi Normal University(No. SD2014JGKT-52)Undergraduate Training Programs for Innovation and Entrepreneurship of Modern College of Arts and Sciences, Shanxi Normal University(No. WL2015CXCY-YJ-26)
文摘Four novel palladium（（Ⅱ）） complexes coordinated by phosphorus atoms from both 3,5-disubstituted-1H- 1,2,4-diazaphospholes in monodentate fashion were developed as efficient catalyst for the Mizoroki- Heck reaction of aryl halides with electron-deficient olefins. The coupling reaction of awl halide bearig different functional groups with olefin derivatives took place and the corresponding products were isolated in good to excellent yields under optimal conditions. The procedure exhibits good functional group tolerance and wide substrate scope. This Mizoroki-Heck reaction was further achieved using Pd（OAc）2 and 3,5-di-isopropyl-1H-1,2,4-diazaphospholes as combined catalyst, which provide the convenient and alternative method in organic synthesis
基金This work was supported financially by the Ministry of Science and Technology of China(2017YFA0206903)the National Natural Science Foundation of China(21861132004)+1 种基金the Strategic Priority Research Program of the Chinese Academy of Sciences(XDB17000000)the Key Research Program of Frontier Sciences of the Chinese Academy of Sciences(QYZDY-SSW-JSC029),and K.C.Wong Education Foundation.
文摘Photo[2+2]cycloaddition of olefins is a sought-after tool for making cyclobutanes,which are the building blocks for a wide range of biologically active molecules and natural products.However,the formation of cyclobutane derivatives from aryl terminal olefins is problematic due to their high redox potential,and high energy in the excited state,making visible-light-absorbing photocatalyst difficult to realize either electron or energy transfer to olefins during the photocyclic addition process.Herein,we report,for the first time,the aggregationinduced photo[2+2]cycloaddition of two olefins by visible-light catalysis in homogeneous solution.An array of control experiments and spectroscopic analyses reveal that the terminal olefins tend to aggregate to form excimers/exciplexes,which possess much lower energy than their monomeric forms,and enables triplet energy transfer from excited Ir(ppy)3*to supramolecular self-assembly feasible,leading to homo and cross[2+2]photodimerization of the olefins to fabricate cyclobutanes at ambient conditions in good to excellent yields.
基金the National Natural Science Foundation of China(Nos.21772118 and 21971192)。
文摘The binding behavior of pillar[5]arenes(P5 As)towards a series of olefin guests((E)-1,4-dichlo robut-2-ene(1 E),(Z)-1,4-dichlo robut-2-ene(1 Z),(E)-but-2-ene-1,4-diol(2 E),and(Z)-but-2-ene-1,4-diol(2 Z),as well as an alkyne derivative 1,4-dichlorobut-2-yne(3))have been studied in organic solution.P5 As exhibit considerable selectivities for the trans-olefin isomers(1 E and 2 E)over their cis-isomers(1 Z and 2 Z).The cis/trans-selective interactions hold the potential of utilizing P5 As to separate olefin isomers.
基金the financial support from the National Natural Science Foundation of China(Nos.21801028,11704050,61505015)Scientific Research Project of the Education Department of Sichuan Province(No.2018Z099)Project of Science and Technology Department of Sichuan Province(No.2017FZ0085)。
文摘Bis(4-fluorophenyl) substituted oxazole(2,5-Oxz) and C2(5)-C2'(5') linked bioxazole isomers(C2-C2'_BOxz,C2-C5'_BOxz and C5-C5'_BOxz) were concisely synthesized via palladium-catalyzed regioselective and sequential C-H arylation in 1-3 reaction steps along with 20%-83% of total yields from oxazole and4-bromofluorobenzene.The linking orientation plays a key role in the packing geometry and photophysical properties of C2-C2'_BOxz,C2-C5'_BOxz and C5-C5'_BOxz.These bioxazole isomers in solid state showed significant differences in photoluminescence quantum yields(PLQY)(0.33,0.25 and 0.04,respectively),delayed fluorescence properties and powder X-ray diffraction(PXRD) patterns,suggesting the divergence in intermolecular interactions.The theoretically calculated gradient isosurfaces and complexation energies indicate the existence of intense π-π interactions between molecular layers,which are in good agreement with the variation trend of optical properties.
基金financial support of National Natural Science Foundation of China(21901193,22271314 and 22377097)the innovation foundation of Key Laboratory of Green Chemical Engineering Process of Ministry of Education(GCX2023002).
文摘Concise assembly of spirooxindoles is of great significance but a challenging task in modern organic synthesis.Described herein is an unusual base-promoted[4+2]spiroannulation of rarely used isatin-derivedβ-silylcarbinols with o-halogen aromatic ketones,which enables rapid and modular synthesis of six-membered carbocyclic spirooxindoles in high yields with excellent functional group tolerance(>50 examples).Mechanistic experiments revealed that this reaction involved a Peterson olefination,Michael addition and intramolecular C(sp^(3))arylation cascade.The variegated synthetic derivatization of target products and successful construction of bioactive molecules further illustrate the synthetic potential in spirooxindole-related drug discovery.
基金the Natural Science Foundation of Shanxi Province(No.201901D111276)Innovative Program of Graduate Education in Shanxi Province(No.2023KY464)for financial support ofthis work.
文摘Palladium-catalyzed Mizoroki-Heck reaction is a powerful and efficient method for construction of Csp2–Csp2 bonds.Herein,four palladium complexes(I—IV)with N,O-bidentate ligands(L1—L4)based on N-oxide units from cyclic secondary amines were easily synthesized and successfully applied in Mizoroki-Heck reaction of aryl bromides with electron-deficient olefins.X-ray diffraction analyses indicated the palladium(II)atom of II took the distorted square planar geometry and was four-coordinated by nitrogen and oxygen atoms from two ligands(L2).Two free chloride ions were presented as counter anions in complex II.But the palladium(II)center of IV was coordinated by nitrogen and oxygen atoms from one ligand(L4)as well as two chlorine atoms,which exhibited the nearly square-planar geometry.The study on catalytic properties of palladium complexes revealed that complex II exhibited high activity superior to the other complexes.The coupling reactions of a series of aryl bromides and olefin derivatives proceeded in the presence of 2—5 mol%palladium complex II,giving the desired products in good to excellent yields.The advantages of this method such as good compatibility of functional groups,high yields,and short reaction times made it more attractive for constructing Csp2–Csp2 bonds in the synthesis of functional molecules and materials.
