5-(1-Menthyloxy)-2(5-H)-furanone is used as s chiral dipolarophile for thermal asymmetric 1,3-dipolar cycloaddition reaction with C-phenyl-N-phenyl nitrone to give the diastereomerically pure cycloaddition product.
An unexpected tricyclic compound 2,3,3a,4,5,9b-hexahydrophenylfuro[3.2-c] quinoline 4 and its aromatized product 6 were obtained when the cycloaddtion of imine 1 and substituted norbornene 2 was carried out in THF wit...An unexpected tricyclic compound 2,3,3a,4,5,9b-hexahydrophenylfuro[3.2-c] quinoline 4 and its aromatized product 6 were obtained when the cycloaddtion of imine 1 and substituted norbornene 2 was carried out in THF with a catalytic amount of boron trifluoride. The structures of the products were determined by spectral data and the mechanism of reaction was substantiated by the imitation reaction.展开更多
The 1.3-dipolar cycloaddition reaction of 2-trifluoromethyl- oxazolone and the activated carbon-carbon multiple bond was studied and gave a convenient way to synthesize 2-trifluoromethylpyrrole derivatives.
Lewis acid catalyzed cycloaddition reactions of N-arylideneaniline Ⅰ with 2,3-dihydrofuran Ⅱ gave a pair of epimers d1-2, 3, 3a, 4, 5, 9b-hexahydro-4-arylfuro [3,2-c]quinolines Ⅲ and Ⅲ) and a few of their correspo...Lewis acid catalyzed cycloaddition reactions of N-arylideneaniline Ⅰ with 2,3-dihydrofuran Ⅱ gave a pair of epimers d1-2, 3, 3a, 4, 5, 9b-hexahydro-4-arylfuro [3,2-c]quinolines Ⅲ and Ⅲ) and a few of their corresponding aromatized compounds Ⅳ.展开更多
The cycloaddition reactions between ketene or substituted ketenes and cyelopentadiene have been studied theoretically by means of the semiempirical AMI method.Three different substituted ketenes have been selected and...The cycloaddition reactions between ketene or substituted ketenes and cyelopentadiene have been studied theoretically by means of the semiempirical AMI method.Three different substituted ketenes have been selected and ten transition states,corresponding to different approach geometries have been located and characterized,The regioselectivity and stereoselectivity of the reactions are correctly predicted by the calculations and the reaction mechanisms are analyzed in terms of electronic and steric effects of the substitutents on the reacting ketene and cyc-lopentadiene.展开更多
Carbon dioxide (CO_(2)) is a principal greenhouse gas with a substantial impact on global climate change. The photocatalytic reduction of CO_(2) represents an economically viable and environmentally benign approach. T...Carbon dioxide (CO_(2)) is a principal greenhouse gas with a substantial impact on global climate change. The photocatalytic reduction of CO_(2) represents an economically viable and environmentally benign approach. This technique involves the catalysis of the reaction between CO_(2) and epoxides under photocatalytic conditions to yield cyclic carbonates. Notably, this process has garnered significant attention due to its high atomic efficiency and alignment with green chemistry principles. Increasingly, photocatalysts are employed to facilitate the synthesis of cyclic carbonates, demonstrating outstanding performance even under natural light. This review evaluates the current state of research on the photocatalytic cycloaddition of CO_(2) with epoxides, analyzes the reaction mechanism and key influencing factors, and provides a comparative summary of the photocatalysts developed in this domain. Additionally, this paper underscores the significance of the reaction devices. The paper explores reaction devices with potential applications for photocatalytic CO_(2) and epoxides and envisions future integrations of CO_(2) photocatalytic cycloaddition reactions with advanced reaction devices for practical applications in this area.展开更多
Given the widespread applications of fluorinated substances in pharmaceuticals,biology,and materials,the development of fluorine-containing building blocks remains an important topic in organic chemistry.In the repert...Given the widespread applications of fluorinated substances in pharmaceuticals,biology,and materials,the development of fluorine-containing building blocks remains an important topic in organic chemistry.In the repertoire of fluorinated diazo compounds,research on tri-and difluorodiazoethane is well-established,but the lack of synthetic methods has left studies related to monofluorodiazoethane as an unexplored territory.In our current work,the taming of the smallest monofluorodiazoethane reagent was realized using two phenylsulfonyl mask groups.This newly synthesized diazo reagent displayed intriguing reactivity patterns:the reaction with aryldiazonium salts gave monofluoromethyl tetrazoles,whereas its reactivity with alkynes and alkenes furnished monofluoromethyl isoxazoles and dihydro-isoxazoles.Furthermore,the removal of the masking groups provided access to a wide range of monofluoromethyl-functionalized heterocycles.展开更多
Among the many strategies for CO_(2)resource utilization,the synthetic technology of cyclic carbonates with 100%atom economy through CO_(2)and epoxide is one of the most industrially viable routes,but its efficiency h...Among the many strategies for CO_(2)resource utilization,the synthetic technology of cyclic carbonates with 100%atom economy through CO_(2)and epoxide is one of the most industrially viable routes,but its efficiency has been severely hampered by the lack of highly active catalytic sites.Moreover,due to the intrinsic thermodynamic stability and kinetic inertia of CO_(2)and the higher energy barrier of the ring-opening reaction of epoxides,the heterogeneous catalytic conversion of CO_(2)highly depends on harsh operating conditions,high temperatures and pressures,and the incorporation of cocatalysts.The devel-opment of efficient heterogeneous catalysts for CO_(2)conversion under cocatalyst-free and mild conditions has always been a challenge.Herein,we have proposed a synergetic strategy of facet and vacancy engi-neering for the construction of highly efficient heterogeneous catalyst BiO1-x Br1-y-(010)for CO_(2)cycload-dition,where introducing the OVs-BrVs pairs into typical(010)facets BiOBr with simultaneous surface Lewis acid sites Bi^(3+)and nucleophilic sites Br^(−).By combining theoretical calculations and a series of systematic experiments,such as CO_(2)temperature-programmed desorption,electron paramagnetic res-onance and fluorescence probe analysis experiments,the introduced OVs-BrVs pair can not only form Bi^(3+)-Bi^(3-x)+dual active sites on the surface,which activate PO and CO_(2)respectively to reduce the energy barrier of CO_(2)insertion,but also activate Br^(−)near BrVs to enhance their nucleophilic attacking ability and reduce the energy barrier of epoxides ring-opening.As a result,the BiO1-x Br1-y-(010)with abundant surface OVs-BrVs pairs showed a high cyclic carbonates conversion of 99%with 100%selectivity un-der cocatalyst-free and mild conditions,far surpassing most heterogeneous catalytic systems.This work provides a completely new strategy to construct high-performance heterogeneous CO_(2)cycloaddition cata-lysts through a simple facet and vacancy engineering strategy to overcome the harsh operating conditions limitation and the use of cocatalysts.展开更多
The mechanism of a cycloaddition reaction between singlet dichloromethylene germylene and ethylene has been investigated with B3LYP/6-31G＊ method, including geometry optimization and vibrational analysis for the invo...The mechanism of a cycloaddition reaction between singlet dichloromethylene germylene and ethylene has been investigated with B3LYP/6-31G＊ method, including geometry optimization and vibrational analysis for the involved stationary points on the potential energy surface. Energies for the involved conformations were calculated by CCSD（T）//B3LYP/6-31G＊ method. On the basis of the surface energy profile obtained with CCSD（T）// B3LYP/6-31G＊ method for the cycloaddition reaction between singlet dichloromethylene germylene and ethylene, it can be predicted that the dominant reaction pathway is that an intermediate INT1 is firstly formed between the two reactants through a barrier-free exothermic reaction of 61.7 kJ/mol, and the intermediate INT1 then isomerizes to an active four-membered ring product P2.1 via a transition state TS2, an intermediate INT2 and a transition state TS2.1, in which energy barriers are 57.7 and 42.2 kJ/mol, respectively.展开更多
Mechanism of the cycloadditional formaldehyde has been investigated reaction between singlet with MP2/6-31G^＊ method, dichloro-germylidene and including geometry optimization, vibrational analysis and energies for t...Mechanism of the cycloadditional formaldehyde has been investigated reaction between singlet with MP2/6-31G^＊ method, dichloro-germylidene and including geometry optimization, vibrational analysis and energies for the involved stationary points on the potential energy surface. From the potential energy profile, we predict that the cyeloaddition reaction between singlet dichloro-germylidene and formaldehyde has two competitive dominant reaction pathways, going with the formation of two side products （INT3 and INT4）, simultaneously. Both of the two competitive reactions consist of two steps, two reactants firstly form a three-membered ring intermediate INT1 and a twisted four-membered ring intermediate INT2, respectively, both of which are barrier-free exothermic reactions of 41.5 and 72.3 kJ/mol; then INT1 isomerizes to a four-membered ring product P1 via transition state TS1, and INT2 isomerizes to a chlorine-traasfer product P2 via transition state TS2, with the barriers of 2.9 and 0.3 kJ/mol, respectively. Simultaneously, P1 and INT2 further react with formaldehyde to form INT3 and INT4, respectively, which are also barrier-free exothermic reaction of 74.9 and 88.1 kJ/mol.展开更多
The base mediated cycloaddition reactions of 4-dimethylamino-l-phenacylpyridinium bromides with two mo- lecular 3-phenaeylideneoxindoles in methylene dichloride afforded functionalized dispirocyclopentyl-3,3＇-bisoxin...The base mediated cycloaddition reactions of 4-dimethylamino-l-phenacylpyridinium bromides with two mo- lecular 3-phenaeylideneoxindoles in methylene dichloride afforded functionalized dispirocyclopentyl-3,3＇-bisoxin- doles in good yields and with high diastereoselectivity. The similar cycloaddition reactions of 1-（N,N-dialkylcarba- moylmethyl） and 1-cyanomethyl 4-dimethylamino-pyridinium bromide in refluxing ethanol in the presence of triethylamine a/so resulted in dispirocyclopentyl-3,3＇-bisoxindoles with high diastereoselectivity. The stereochemis- try of dispirocyclopentyl-3,3＇-bisoxindoles was elucidated on the basis of ^1H NMR data and single crystal struc- tures.展开更多
Syntheses of 4 novel chiral azetidin 2 one derivatives, which were characterized by 1H NMR, IR, specific rotation and elemental analysis, through Staudinger cycloaddition reaction of Schiff base of benzaldehyd...Syntheses of 4 novel chiral azetidin 2 one derivatives, which were characterized by 1H NMR, IR, specific rotation and elemental analysis, through Staudinger cycloaddition reaction of Schiff base of benzaldehyde with chlorine substitution at different position in benzene ring, were described. For the first time, this type of 3 S ,4 R configuration azetidin 2 one mono^crystals with many chiral centers [(3 S ,4 R ) 3 hydroxy N [( S ) (1 phenyl)ethyl ] 4 (2′ chlorophenyl) azetidin 2 one mono^crystal] were obtained, the structures of which were determined by X ray dif fraction analysis. The effects of Schiff base of benzaldehyde with chlorine subs titu tion at different position in benzene ring on stereoselectivity of Staudinger cy cloaddition reaction products were discussed and the results are showed as below : 2 chlorophenyl Schiff base favored to yield 3 S ,4 R configuration prod uct, but 4 chlorophenyl Schiff base favored to yield 3 R ,4 S configuration produc t. The re action orientation of 2,4 dichlorophenyl Schiff base was determined by corporat e effect of 2 and 4 chlorine, and that of the 4 chlorine was more obvious. In co ntrast to 4 chlorophenyl, although the main product was 3 R ,4 S configur ation, 3 chlorophenyl owned lower selectivity.展开更多
The cycloaddition reactions of methane and ethylene mediated by Ir^(+) have been designed and studied by the techniques of mass spectrometry in conjunction with theoretical calculations.Studies have shown that Ir^(+) ...The cycloaddition reactions of methane and ethylene mediated by Ir^(+) have been designed and studied by the techniques of mass spectrometry in conjunction with theoretical calculations.Studies have shown that Ir^(+) can mediate the cycloaddition reaction of CH4and two C_(2)H_(4) to generate a half-sandwich structure IrHCp^(+)(Cp=η^(5)-C_(5)H_(5))including pentamethylcyclopentadienyl ligand by continuous dehydrogenation reaction with the forming of three C-C bonds and seven C-H bonds.The orbital analysis indicates the mechanism of the cyclization reaction to generation of pentamethylcyclopentadienyl ligand with odd number carbon atom depends on the overlap ofπorbitals in-C_(2)H_(2) and carbene,which is more difficult than the forming of cyclobutadiene ligand and benzene.This study may help to understand the reaction mechanism in the cycloaddition reactions of organic compounds,which will be useful to guide the rational design of new catalysts with tailored selectivity and increased efficiency.展开更多
In the present study, we synthesized well-defined tadpole-shaped polystyrene(PS) via the combination of atom transfer radical polymerization(ATRP) and UV-induced strain promoted azide-alkyne cycloaddtion(SPAAC) reacti...In the present study, we synthesized well-defined tadpole-shaped polystyrene(PS) via the combination of atom transfer radical polymerization(ATRP) and UV-induced strain promoted azide-alkyne cycloaddtion(SPAAC) reaction. A di-bromo ATRP initiator(Br-ini-Br) containing cyclopropenone-masked dibenzocyclooctyne group was used to prepare the linear PS with a cyclopropenone-masked dibenzocyclooctyne in the middle of the chain and bromo groups at both ends(Br-PS-Br). Then we used the single electron transfer-nitroxide radical coupling(SET-NRC) reaction to transfer the bromo end groups to azide groups(N_3-PS-N_3). After UV irradiation, the dibenzocyclooctyne group was quantitatively released, and intramolecularly reacted with alternative azide end group to produce the tadpole-shaped PS based on SPAAC reaction.展开更多
X2Ge=Sn:(X=H,Me,F,Cl,Br,Ph,Ar…)are new species of chemistry.The cycloaddition reaction of X2Ge=Sn:is a new study field of stannylene chemistry.To explore the rules of cycloaddition reaction between X2Ge=Sn:and the sy...X2Ge=Sn:(X=H,Me,F,Cl,Br,Ph,Ar…)are new species of chemistry.The cycloaddition reaction of X2Ge=Sn:is a new study field of stannylene chemistry.To explore the rules of cycloaddition reaction between X2Ge=Sn:and the symmetric p-bonded compounds,the cycloaddition reactions of Me2Ge=Sn:and ethylene were selected as model reactions in this paper,and the mechanism was investigated for the first time here using the MP2 theory together with the 6-311++G**basis set for C,H and Ge atoms and the LanL2dzbasis set for Sn atoms.From the potential energy profile,it could be predicted that the reaction has one dominant reaction channel.The reaction rule present is that the 5p unoccupied orbital of Sn in Me2Ge=Sn:and theπorbital of ethylene form a p→p donor–acceptor bond,resulting in an intermediate which,due to its instability,makes itself isomerize into a four-membered Ge-heterocyclic ring stannylene.Because the 5p unoccupied orbital of Sn atom in the four-membered Ge-heterocyclic ring stannylene and theπorbital of ethylene form a p→p donor-acceptor bond,the four-membered Ge-heterocyclic ring stannylene further combines with ethylene to get another intermediate.Because the Sn atom in this intermediate exhibits sp3 hybridization after transition state,the intermediate isomerizes to a Ge-heterocyclic spiro-Sn-heterocyclic ring compound.The research result indicates the laws of cycloaddition reaction between X2Ge=Sn:and the symmetricπ-bonded compounds.This study opens up a new research field for stannylene chemistry.展开更多
The mechanism of the cycloaddition reaction between singlet silylene silylene （H2Si = Si：） and acetone has been investigated with the CCSD （T）//MP2/6-31 G＊ method, According to the potential energy profile, it c...The mechanism of the cycloaddition reaction between singlet silylene silylene （H2Si = Si：） and acetone has been investigated with the CCSD （T）//MP2/6-31 G＊ method, According to the potential energy profile, it can be predicted that the reaction has two competitive dominant reaction channels. The present rule of this reaction is that the [2 ＋ 2] cycloaddition reaction of the two ^-bonds in silylene silylene （H2Si=Si：） and acetone leads to the formation of a four-membered ring silylene （E3）. Because of the unsaturated property of Si： atom in E3, it further reacts with ace- tone to form a silicic bis-heterocyclic compound （P7）. Simultaneously, the ring strain of the four-membered ring silylene （E3） makes it isomerize to a twisted four-membered ring product （P4）.展开更多
The syntheses of a number of C-aryl-N-3-butenyl nitrones [aryl ring=4-CH_3O-phenyl (1a), phenyl(1b), 4-Cl-phenyl(1e), 4-Br-phenyl(1d), 4-NO2-phenyl(1e), 2-furyl (1f), 2-thienyl (1g), 2-pyrryl(1h)] and their thermochem...The syntheses of a number of C-aryl-N-3-butenyl nitrones [aryl ring=4-CH_3O-phenyl (1a), phenyl(1b), 4-Cl-phenyl(1e), 4-Br-phenyl(1d), 4-NO2-phenyl(1e), 2-furyl (1f), 2-thienyl (1g), 2-pyrryl(1h)] and their thermochemical reactions have been investigated. The thermocycloadditions of 1a-1h are regiospecific in forming a novel heterobicyclic ring system. Exo-aryl-1-aza-7-oxabicyclo- [2.2.1]heptane.展开更多
文摘5-(1-Menthyloxy)-2(5-H)-furanone is used as s chiral dipolarophile for thermal asymmetric 1,3-dipolar cycloaddition reaction with C-phenyl-N-phenyl nitrone to give the diastereomerically pure cycloaddition product.
文摘An unexpected tricyclic compound 2,3,3a,4,5,9b-hexahydrophenylfuro[3.2-c] quinoline 4 and its aromatized product 6 were obtained when the cycloaddtion of imine 1 and substituted norbornene 2 was carried out in THF with a catalytic amount of boron trifluoride. The structures of the products were determined by spectral data and the mechanism of reaction was substantiated by the imitation reaction.
文摘The 1.3-dipolar cycloaddition reaction of 2-trifluoromethyl- oxazolone and the activated carbon-carbon multiple bond was studied and gave a convenient way to synthesize 2-trifluoromethylpyrrole derivatives.
文摘Lewis acid catalyzed cycloaddition reactions of N-arylideneaniline Ⅰ with 2,3-dihydrofuran Ⅱ gave a pair of epimers d1-2, 3, 3a, 4, 5, 9b-hexahydro-4-arylfuro [3,2-c]quinolines Ⅲ and Ⅲ) and a few of their corresponding aromatized compounds Ⅳ.
文摘The cycloaddition reactions between ketene or substituted ketenes and cyelopentadiene have been studied theoretically by means of the semiempirical AMI method.Three different substituted ketenes have been selected and ten transition states,corresponding to different approach geometries have been located and characterized,The regioselectivity and stereoselectivity of the reactions are correctly predicted by the calculations and the reaction mechanisms are analyzed in terms of electronic and steric effects of the substitutents on the reacting ketene and cyc-lopentadiene.
基金The authors are grateful for the financial support by the National Key R&D Program of China under grant(No.2020YFA0710404)the innovative talents of North China Electric Power University(NCEPU).
文摘Carbon dioxide (CO_(2)) is a principal greenhouse gas with a substantial impact on global climate change. The photocatalytic reduction of CO_(2) represents an economically viable and environmentally benign approach. This technique involves the catalysis of the reaction between CO_(2) and epoxides under photocatalytic conditions to yield cyclic carbonates. Notably, this process has garnered significant attention due to its high atomic efficiency and alignment with green chemistry principles. Increasingly, photocatalysts are employed to facilitate the synthesis of cyclic carbonates, demonstrating outstanding performance even under natural light. This review evaluates the current state of research on the photocatalytic cycloaddition of CO_(2) with epoxides, analyzes the reaction mechanism and key influencing factors, and provides a comparative summary of the photocatalysts developed in this domain. Additionally, this paper underscores the significance of the reaction devices. The paper explores reaction devices with potential applications for photocatalytic CO_(2) and epoxides and envisions future integrations of CO_(2) photocatalytic cycloaddition reactions with advanced reaction devices for practical applications in this area.
基金financial support provided by the National Natural Science Foundation of China(NSFC,grant nos.92156025 and 22271212)the National Key Research and Development Program of China(grant nos.2019YFA0905100 and 2021YFF0701700)X.T.thanks the China Postdoctoral Science Foundation(grant no.2022M712350).
文摘Given the widespread applications of fluorinated substances in pharmaceuticals,biology,and materials,the development of fluorine-containing building blocks remains an important topic in organic chemistry.In the repertoire of fluorinated diazo compounds,research on tri-and difluorodiazoethane is well-established,but the lack of synthetic methods has left studies related to monofluorodiazoethane as an unexplored territory.In our current work,the taming of the smallest monofluorodiazoethane reagent was realized using two phenylsulfonyl mask groups.This newly synthesized diazo reagent displayed intriguing reactivity patterns:the reaction with aryldiazonium salts gave monofluoromethyl tetrazoles,whereas its reactivity with alkynes and alkenes furnished monofluoromethyl isoxazoles and dihydro-isoxazoles.Furthermore,the removal of the masking groups provided access to a wide range of monofluoromethyl-functionalized heterocycles.
基金supported by the National Science Basic Research Program of Shaanxi(Nos.2024JC-YBQN-0103,2024JC-YBMS-127,2022JQ-102)the National Natural Science Foundation of China(No.52073228)the Xi’an Shiyou University Postgraduate Innovation and Practical Ability Training Project(No.YCS23213089).
文摘Among the many strategies for CO_(2)resource utilization,the synthetic technology of cyclic carbonates with 100%atom economy through CO_(2)and epoxide is one of the most industrially viable routes,but its efficiency has been severely hampered by the lack of highly active catalytic sites.Moreover,due to the intrinsic thermodynamic stability and kinetic inertia of CO_(2)and the higher energy barrier of the ring-opening reaction of epoxides,the heterogeneous catalytic conversion of CO_(2)highly depends on harsh operating conditions,high temperatures and pressures,and the incorporation of cocatalysts.The devel-opment of efficient heterogeneous catalysts for CO_(2)conversion under cocatalyst-free and mild conditions has always been a challenge.Herein,we have proposed a synergetic strategy of facet and vacancy engi-neering for the construction of highly efficient heterogeneous catalyst BiO1-x Br1-y-(010)for CO_(2)cycload-dition,where introducing the OVs-BrVs pairs into typical(010)facets BiOBr with simultaneous surface Lewis acid sites Bi^(3+)and nucleophilic sites Br^(−).By combining theoretical calculations and a series of systematic experiments,such as CO_(2)temperature-programmed desorption,electron paramagnetic res-onance and fluorescence probe analysis experiments,the introduced OVs-BrVs pair can not only form Bi^(3+)-Bi^(3-x)+dual active sites on the surface,which activate PO and CO_(2)respectively to reduce the energy barrier of CO_(2)insertion,but also activate Br^(−)near BrVs to enhance their nucleophilic attacking ability and reduce the energy barrier of epoxides ring-opening.As a result,the BiO1-x Br1-y-(010)with abundant surface OVs-BrVs pairs showed a high cyclic carbonates conversion of 99%with 100%selectivity un-der cocatalyst-free and mild conditions,far surpassing most heterogeneous catalytic systems.This work provides a completely new strategy to construct high-performance heterogeneous CO_(2)cycloaddition cata-lysts through a simple facet and vacancy engineering strategy to overcome the harsh operating conditions limitation and the use of cocatalysts.
基金Project supported by the Natural Science Foundation of Shandong Province of China （No. Y2002B07）.
文摘The mechanism of a cycloaddition reaction between singlet dichloromethylene germylene and ethylene has been investigated with B3LYP/6-31G＊ method, including geometry optimization and vibrational analysis for the involved stationary points on the potential energy surface. Energies for the involved conformations were calculated by CCSD（T）//B3LYP/6-31G＊ method. On the basis of the surface energy profile obtained with CCSD（T）// B3LYP/6-31G＊ method for the cycloaddition reaction between singlet dichloromethylene germylene and ethylene, it can be predicted that the dominant reaction pathway is that an intermediate INT1 is firstly formed between the two reactants through a barrier-free exothermic reaction of 61.7 kJ/mol, and the intermediate INT1 then isomerizes to an active four-membered ring product P2.1 via a transition state TS2, an intermediate INT2 and a transition state TS2.1, in which energy barriers are 57.7 and 42.2 kJ/mol, respectively.
文摘Mechanism of the cycloadditional formaldehyde has been investigated reaction between singlet with MP2/6-31G^＊ method, dichloro-germylidene and including geometry optimization, vibrational analysis and energies for the involved stationary points on the potential energy surface. From the potential energy profile, we predict that the cyeloaddition reaction between singlet dichloro-germylidene and formaldehyde has two competitive dominant reaction pathways, going with the formation of two side products （INT3 and INT4）, simultaneously. Both of the two competitive reactions consist of two steps, two reactants firstly form a three-membered ring intermediate INT1 and a twisted four-membered ring intermediate INT2, respectively, both of which are barrier-free exothermic reactions of 41.5 and 72.3 kJ/mol; then INT1 isomerizes to a four-membered ring product P1 via transition state TS1, and INT2 isomerizes to a chlorine-traasfer product P2 via transition state TS2, with the barriers of 2.9 and 0.3 kJ/mol, respectively. Simultaneously, P1 and INT2 further react with formaldehyde to form INT3 and INT4, respectively, which are also barrier-free exothermic reaction of 74.9 and 88.1 kJ/mol.
文摘The base mediated cycloaddition reactions of 4-dimethylamino-l-phenacylpyridinium bromides with two mo- lecular 3-phenaeylideneoxindoles in methylene dichloride afforded functionalized dispirocyclopentyl-3,3＇-bisoxin- doles in good yields and with high diastereoselectivity. The similar cycloaddition reactions of 1-（N,N-dialkylcarba- moylmethyl） and 1-cyanomethyl 4-dimethylamino-pyridinium bromide in refluxing ethanol in the presence of triethylamine a/so resulted in dispirocyclopentyl-3,3＇-bisoxindoles with high diastereoselectivity. The stereochemis- try of dispirocyclopentyl-3,3＇-bisoxindoles was elucidated on the basis of ^1H NMR data and single crystal struc- tures.
基金ProjectsupportedbytheNationalNaturalScienceofChina (No .2 0 1710 0 8)
文摘Syntheses of 4 novel chiral azetidin 2 one derivatives, which were characterized by 1H NMR, IR, specific rotation and elemental analysis, through Staudinger cycloaddition reaction of Schiff base of benzaldehyde with chlorine substitution at different position in benzene ring, were described. For the first time, this type of 3 S ,4 R configuration azetidin 2 one mono^crystals with many chiral centers [(3 S ,4 R ) 3 hydroxy N [( S ) (1 phenyl)ethyl ] 4 (2′ chlorophenyl) azetidin 2 one mono^crystal] were obtained, the structures of which were determined by X ray dif fraction analysis. The effects of Schiff base of benzaldehyde with chlorine subs titu tion at different position in benzene ring on stereoselectivity of Staudinger cy cloaddition reaction products were discussed and the results are showed as below : 2 chlorophenyl Schiff base favored to yield 3 S ,4 R configuration prod uct, but 4 chlorophenyl Schiff base favored to yield 3 R ,4 S configuration produc t. The re action orientation of 2,4 dichlorophenyl Schiff base was determined by corporat e effect of 2 and 4 chlorine, and that of the 4 chlorine was more obvious. In co ntrast to 4 chlorophenyl, although the main product was 3 R ,4 S configur ation, 3 chlorophenyl owned lower selectivity.
基金supported by Beijing Natural Science Foundation(No.2214064)the National Natural Science Foundation of China(Nos.21603037,21688102,92161115,21973016,91545122)the Fundamental Research Funds for the Central Universities(Nos.JB2015RCY03,JB2019MS052)supported by the fund of North China Electric Power University。
文摘The cycloaddition reactions of methane and ethylene mediated by Ir^(+) have been designed and studied by the techniques of mass spectrometry in conjunction with theoretical calculations.Studies have shown that Ir^(+) can mediate the cycloaddition reaction of CH4and two C_(2)H_(4) to generate a half-sandwich structure IrHCp^(+)(Cp=η^(5)-C_(5)H_(5))including pentamethylcyclopentadienyl ligand by continuous dehydrogenation reaction with the forming of three C-C bonds and seven C-H bonds.The orbital analysis indicates the mechanism of the cyclization reaction to generation of pentamethylcyclopentadienyl ligand with odd number carbon atom depends on the overlap ofπorbitals in-C_(2)H_(2) and carbene,which is more difficult than the forming of cyclobutadiene ligand and benzene.This study may help to understand the reaction mechanism in the cycloaddition reactions of organic compounds,which will be useful to guide the rational design of new catalysts with tailored selectivity and increased efficiency.
基金supported by the Ministry of Science and Technology of China(2014CB932200)the National Natural Science Foundation of China(51273100)the Natural Science Foundation of Shandong Province(ZR2014BQ022)
文摘In the present study, we synthesized well-defined tadpole-shaped polystyrene(PS) via the combination of atom transfer radical polymerization(ATRP) and UV-induced strain promoted azide-alkyne cycloaddtion(SPAAC) reaction. A di-bromo ATRP initiator(Br-ini-Br) containing cyclopropenone-masked dibenzocyclooctyne group was used to prepare the linear PS with a cyclopropenone-masked dibenzocyclooctyne in the middle of the chain and bromo groups at both ends(Br-PS-Br). Then we used the single electron transfer-nitroxide radical coupling(SET-NRC) reaction to transfer the bromo end groups to azide groups(N_3-PS-N_3). After UV irradiation, the dibenzocyclooctyne group was quantitatively released, and intramolecularly reacted with alternative azide end group to produce the tadpole-shaped PS based on SPAAC reaction.
基金Supported by the National Natural Science Foundation of China(No.31370090)Project of Key R&D of Shandong Province(No.2015GSF121006)。
文摘X2Ge=Sn:(X=H,Me,F,Cl,Br,Ph,Ar…)are new species of chemistry.The cycloaddition reaction of X2Ge=Sn:is a new study field of stannylene chemistry.To explore the rules of cycloaddition reaction between X2Ge=Sn:and the symmetric p-bonded compounds,the cycloaddition reactions of Me2Ge=Sn:and ethylene were selected as model reactions in this paper,and the mechanism was investigated for the first time here using the MP2 theory together with the 6-311++G**basis set for C,H and Ge atoms and the LanL2dzbasis set for Sn atoms.From the potential energy profile,it could be predicted that the reaction has one dominant reaction channel.The reaction rule present is that the 5p unoccupied orbital of Sn in Me2Ge=Sn:and theπorbital of ethylene form a p→p donor–acceptor bond,resulting in an intermediate which,due to its instability,makes itself isomerize into a four-membered Ge-heterocyclic ring stannylene.Because the 5p unoccupied orbital of Sn atom in the four-membered Ge-heterocyclic ring stannylene and theπorbital of ethylene form a p→p donor-acceptor bond,the four-membered Ge-heterocyclic ring stannylene further combines with ethylene to get another intermediate.Because the Sn atom in this intermediate exhibits sp3 hybridization after transition state,the intermediate isomerizes to a Ge-heterocyclic spiro-Sn-heterocyclic ring compound.The research result indicates the laws of cycloaddition reaction between X2Ge=Sn:and the symmetricπ-bonded compounds.This study opens up a new research field for stannylene chemistry.
文摘The mechanism of the cycloaddition reaction between singlet silylene silylene （H2Si = Si：） and acetone has been investigated with the CCSD （T）//MP2/6-31 G＊ method, According to the potential energy profile, it can be predicted that the reaction has two competitive dominant reaction channels. The present rule of this reaction is that the [2 ＋ 2] cycloaddition reaction of the two ^-bonds in silylene silylene （H2Si=Si：） and acetone leads to the formation of a four-membered ring silylene （E3）. Because of the unsaturated property of Si： atom in E3, it further reacts with ace- tone to form a silicic bis-heterocyclic compound （P7）. Simultaneously, the ring strain of the four-membered ring silylene （E3） makes it isomerize to a twisted four-membered ring product （P4）.
文摘The syntheses of a number of C-aryl-N-3-butenyl nitrones [aryl ring=4-CH_3O-phenyl (1a), phenyl(1b), 4-Cl-phenyl(1e), 4-Br-phenyl(1d), 4-NO2-phenyl(1e), 2-furyl (1f), 2-thienyl (1g), 2-pyrryl(1h)] and their thermochemical reactions have been investigated. The thermocycloadditions of 1a-1h are regiospecific in forming a novel heterobicyclic ring system. Exo-aryl-1-aza-7-oxabicyclo- [2.2.1]heptane.
