Asymmetric 1,3-dipolar cycloaddihon of the chiral nitronic esters with acrylate giving the enantiomerically pure novel chiral bisheterocyclic compounds is describcd
Of organic compounds,nitronic esters are a group of unusual compounds.Accordingto their chemical formula（R<sub>1</sub>R<sub>2</sub>C=NO<sub>2</sub>R<sub>3</sub>）,they ...Of organic compounds,nitronic esters are a group of unusual compounds.Accordingto their chemical formula（R<sub>1</sub>R<sub>2</sub>C=NO<sub>2</sub>R<sub>3</sub>）,they might be formally obtained fromcondensation of aci-nitro compounds（intronic acids）and alcohols with an equivalentamount of water eliminated.In fact,neither could nitronic esters be produced by thismethod,nor could they be hydrolyzed into nitronic acids and alcohols.Since they展开更多
On the basis of investigation on structural characteristics and stability of more than one hundred nitronic acids and nitronic esters, an equilibrium theory of electronic effects in conjugated systems is put forward a...On the basis of investigation on structural characteristics and stability of more than one hundred nitronic acids and nitronic esters, an equilibrium theory of electronic effects in conjugated systems is put forward and the type of structures is classified. On that basis, an empirical rule for the correlation between structure and stability of nitronic acids and nitronic esters is proposed, which predicts that stable nitronic acids and nitronic esters should have the C type of structure that meets the matching principle of electronic effects.展开更多
The development of general and practical strategies toward the construction of medium-sized rings is still challenging in organic synthesis,especially for the multiple stereocenters control of substituted groups on th...The development of general and practical strategies toward the construction of medium-sized rings is still challenging in organic synthesis,especially for the multiple stereocenters control of substituted groups on the ring owing to the long distance between groups.Thus,stereoselective synthesis of multi-substituted ten-membered rings is attractive.Herein,a rapid assembly of various highly substituted ten-membered nitrogen heterocycles between two 1,3-dipoles through a tandem[3+3]cycloaddition/aza-Claisen rearrangement of N-vinyl-α,β-unsaturated nitrones and aza-oxyallyl or oxyallyl cations are disclosed.Products containing two or multiple stereocenters could be obtained in up to 96%yield with high regioselectivity and diastereoselectivity.Selective N-O bond cleavages of ten-membered nitrogen heterocycles lead to various novel 5,6,6-perifused benzofurans,bicyclo[4.4.0]or bicyclo[5.3.0]skeletons containing three or multiple continuous stereocenters in good yields and high diastereoselectivity.Biological tests show that the obtained ten-membered N-heterocycles and bicyclo[4.4.0]skeletons inhibited nitric oxide generation in LPS-stimulated RAW264.7 cells and might serve as good anti-inflammatory agents.展开更多
α-Aryl nitrone are one of the most useful kinds of nitrones and have been extensively explored in recent years.However,the sugar moieties have not been introduced into these molecules before.We presented here an effi...α-Aryl nitrone are one of the most useful kinds of nitrones and have been extensively explored in recent years.However,the sugar moieties have not been introduced into these molecules before.We presented here an efficient synthesis ofα-aryl nitrone Oglycosides via condensation of N-substituted hydroxylamine and aryl aldehydes glycosides in benzene.展开更多
1,4-Addition reaction of Grignard's reagent to 5-methoxy-2(5H)-furanone 1 was accomplished. which provided a new possible route for synthesizing beta -alkyl-Y-alkyloxy-Y-butyrolactone. A novel concise method of pr...1,4-Addition reaction of Grignard's reagent to 5-methoxy-2(5H)-furanone 1 was accomplished. which provided a new possible route for synthesizing beta -alkyl-Y-alkyloxy-Y-butyrolactone. A novel concise method of preparing fused heterocyclic compounds was offered by 1,3-dipolar cycloaddition reaction of silyl nitronates to 1.展开更多
OBJECTIVE Amyotrophic lateral sclerosis(ALS)is a fatal neurodegenerative dis⁃ease characterized by progressive loss of upper and lower motor neurons that results in skeletal muscle atrophy,weakness and paralysis.Oxida...OBJECTIVE Amyotrophic lateral sclerosis(ALS)is a fatal neurodegenerative dis⁃ease characterized by progressive loss of upper and lower motor neurons that results in skeletal muscle atrophy,weakness and paralysis.Oxida⁃tive stress plays a key role in the pathogenesis of ALS,including familial forms of the disease arising from mutation of the gene coding for superoxide dismutase 1(SOD1).Moreover,although the pathogenesis of ALS is unclear,the abnormal accumulation of TAR DNA-binding pro⁃tein of 43 ku(TDP-43)is a pathological feature that exists in almost all patients.Thus far,there is no drug that can cure ALS/FTLD.Tetramethyl⁃pyrazine nitrone(TBN)is a derivative of tetra⁃methylapyrazine,derived from the traditional Chinese medicine Ligusticum chuanxiong,which has been widely proven to have therapeutic effects on models of various neurodegenerative diseases.TBN is currently under clinical investi⁃gation for several indications including a phaseⅡtrial of ALS.Here,we explored the therapeutic effect of TBN in the SOD1G93A and TDP-43M337V ALS mouse model.METHODS In the SOD1G93A transgenic mouse model,TBN was administered to mice by intraperitoneal or intragastric injection after the onset of motor deficits.At the same time,we unilaterally and bilaterally injected the TDP-43M337V virus into the striatum of the WT mouse,and gave the TBN treatment after the mice developed a phenotype.After administering these two models for a period of time,we con⁃ducted behavioral tests,including rotarod test,balance beam test,climbing pole test,etc,to evaluate the efficacy of TBN on SOD1G93A and TDP-43M337V models.Furthermore,we explored the possible mechanism of action of TBN in the treatment of ALS through Western blotting and immunohistochemistry/immunofluorescence staining analysis.RESULTS In the SOD1G93A transgenic mouse model,TBN slowed the pro⁃gression of motor neuron disease as evidenced by improved motor performance,reduced spinal motor neuron loss and the associated glial response,and decreased skeletal muscle fiber denervation and fibrosis.TBN treatment activated mitochondrial antioxidant activity through the PGC-1α/Nrf2/HO-1 pathway and decreased the expression of human SOD1.What′s more,in the TDP-43M337V mice model,the results showed that in mice with unilateral injection of TDP-43M337V,TBN improved motor deficits and cognitive im⁃pairment in the early stages of disease progres⁃sion.In mice with bilateral injection of TDP-43M337V into the striatum,TBN not only improved motor function but also prolonged survival rate.Moreover,we show that its therapeutic effect may be through activation of the Akt/mTOR/GSK-3βand AMPK/PGC-1α/Nrf2 signaling pathways.In summary,TBN is a promising agent for the treat⁃ment of ALS/FTLD.CONCLUSION TBN has shown good efficacy in both SOD1 and TDP-43 ALS-related models,and it may act by activating the AMPK/PGC-1α/Nrf2 signaling pathway,which shows some light for the development of ALS therapeutic drugs.展开更多
In this article, winter clothes, bedding, pillows, mattresses are produced in the Republic of Uzbekistan and used in the export products of foreign countries in domestic market shopping centers;existing nonwoven fabri...In this article, winter clothes, bedding, pillows, mattresses are produced in the Republic of Uzbekistan and used in the export products of foreign countries in domestic market shopping centers;existing nonwoven fabric samples were used as toys, children’s clothing as a heat retainer, a space-filler was selected on the basis of marketing survey analysis. Chemical bonding, processing technology, methods, linear density, thickness, air permeability, hygroscopicity, heat storage and heat transfer properties of the samples were analyzed experimentally based on the preparation methods, the fiber content was compared with the standard technology. The advantages and disadvantages of the samples were studied and recommendations for use in sewing according to consumer requirements were given.展开更多
A new organocatalytic double annulation cascade involving scission/recombination of N-O bonds of nitrones is reported for the first time, and used to produce a range of hitherto unprecedented tricyclic bridged-fused b...A new organocatalytic double annulation cascade involving scission/recombination of N-O bonds of nitrones is reported for the first time, and used to produce a range of hitherto unprecedented tricyclic bridged-fused benzo[d]azepines bearing three stereogenic centers with moderate to good yields and complete diastereoselectivity. A quinine-catalyzed reaction of yne–allenone esters with nitrones worked well and provided a convergent and regioselective pathway to access these three-dimensional scaffolds from the planar conjugated system. Density functional theory(DFT) calculations have been applied to understand the key process for forming diradical intermediates.展开更多
The reaction mechanism of the intramolecular cycloaddition of N-3-butenyl nitrone has been investigated theoretically by using AM1 MO method and transition state theory.There are two parallel reactions leading to two ...The reaction mechanism of the intramolecular cycloaddition of N-3-butenyl nitrone has been investigated theoretically by using AM1 MO method and transition state theory.There are two parallel reactions leading to two different regioisomers.The ratio of the rate constants of these two reactions was calculated to be 124.1(at 383.75 K).The obtained results can be used to explain the high regiospecificity of the reaction product.展开更多
In the presence of metallic samariumcobalt (II) chloride hexahydrate, the nitrones can be reduced to the corresponding imines in moderate to high yields under mild and neutral conditions.
The behaviour of cyanothioacetamide 1 and the acetonitrile derivatives 6 and 10, respectively, towards the nitrones 2a-i induced by free solar thermal energy is reported. Structures and reaction mechanisms are also di...The behaviour of cyanothioacetamide 1 and the acetonitrile derivatives 6 and 10, respectively, towards the nitrones 2a-i induced by free solar thermal energy is reported. Structures and reaction mechanisms are also discussed.展开更多
A novel C-branched polyhydroxylated cyclic nitrone 25.which could be a valuable intermediate for the synthesis of C-branched pyrrolidine iminosugars,was synthesized starting from the commercially available i.-arabinos...A novel C-branched polyhydroxylated cyclic nitrone 25.which could be a valuable intermediate for the synthesis of C-branched pyrrolidine iminosugars,was synthesized starting from the commercially available i.-arabinose in 29.0%total yield.展开更多
The ground state interaction of C-(4-chlorophenyl)-N-phenylnitrone (N1) with three different α, β-unsaturated ketones (K1 - K3) in very dilute solution (10-6 mol dm-3) has been noticed through charge transfer band f...The ground state interaction of C-(4-chlorophenyl)-N-phenylnitrone (N1) with three different α, β-unsaturated ketones (K1 - K3) in very dilute solution (10-6 mol dm-3) has been noticed through charge transfer band formation in the visible region. The experimentally measured transition dipole, ground state resonance energy and formation constants of the complexes indicate interaction selectivity of the acyclic nitrone (N1) for the ketones. Molar absorptivity of the absorbing complexes were determined for all the three N1/K (1:1) interacting systems in toluene. Experimental findings were well rationalized with the help of electron density based global electrophilicity and nucleophilicity indices as well as with frontier molecular orbital calculations.展开更多
A series of C-7 modified analogues of casuarine have been synthesized from sugar-derived nitrone and assayed against various glycosidases. Introduction of C-7 aminomethyl or amide group led to sharp decrease of the in...A series of C-7 modified analogues of casuarine have been synthesized from sugar-derived nitrone and assayed against various glycosidases. Introduction of C-7 aminomethyl or amide group led to sharp decrease of the inhibitory activities.展开更多
The new synthetic method of isoxazole derivatives was succesfully achieved. The experimental results demonstrate that thermal decomposition reactions of nitrone could take place with yields of 41 similar to 81%, to gi...The new synthetic method of isoxazole derivatives was succesfully achieved. The experimental results demonstrate that thermal decomposition reactions of nitrone could take place with yields of 41 similar to 81%, to give a series of new isoxazole derivatives.展开更多
The demands for effective assembly of structurally complex molecular scaffolds from simple starting materials are continuously growing along with the development of organic chemistry.We have developed a tandem approac...The demands for effective assembly of structurally complex molecular scaffolds from simple starting materials are continuously growing along with the development of organic chemistry.We have developed a tandem approach that assembles simple 6-chloroethylphosphane,alkynyl imines(or alkynyl ketones),and nitrones into structurally complex isoxazolidine fused phospholene scaffolds through a sequential process involving phospha-Michael addition,intramolecular cyclization,and dearomatizing[3+2]cycloaddition reactions.The isoxazolidine-fused phospholene has three heteroatoms,including a junction phosphorus atom.After removing the coordinated tungsten group,these compounds can serve as potential P-stereogenic ligands and may have biological activities.Contrary to pyrroles and furans,the aromatic 2-phosphapyrroles and 2-phosphafurans are good 2r-electron candidates in the dearomative[3+2]cycloaddition reactions due to the poor overlap of the 2p-3p orbitals of the C=P moiety.展开更多
Comprehensive Summary.Herein,we have developed a facile method for the synthesis of various polysubstituted pyridine derivatives through selective 6π-electrocyclization of N-vinyl-α,β-unsaturated nitrones.It was fo...Comprehensive Summary.Herein,we have developed a facile method for the synthesis of various polysubstituted pyridine derivatives through selective 6π-electrocyclization of N-vinyl-α,β-unsaturated nitrones.It was found that gold catalysts promoted carbon-6π-electrocyclization of N-vinyl-α,β-unsaturated nitrones to afford 6-alkenyl pyridine N-oxides in 43%—75%yields,whereas copper catalysts facilitated oxygen-6π-electrocyclization to give 6-epoxy pyridines in 41%—83%yields.The present method features broad substrate scope,good functional group tolerance,high cyclization selectivity,and diversity of polysubstituted pyridine scaffolds.展开更多
文摘Asymmetric 1,3-dipolar cycloaddihon of the chiral nitronic esters with acrylate giving the enantiomerically pure novel chiral bisheterocyclic compounds is describcd
基金Project supported by the National Natural Science Foundation of China.
文摘Of organic compounds,nitronic esters are a group of unusual compounds.Accordingto their chemical formula（R<sub>1</sub>R<sub>2</sub>C=NO<sub>2</sub>R<sub>3</sub>）,they might be formally obtained fromcondensation of aci-nitro compounds（intronic acids）and alcohols with an equivalentamount of water eliminated.In fact,neither could nitronic esters be produced by thismethod,nor could they be hydrolyzed into nitronic acids and alcohols.Since they
文摘On the basis of investigation on structural characteristics and stability of more than one hundred nitronic acids and nitronic esters, an equilibrium theory of electronic effects in conjugated systems is put forward and the type of structures is classified. On that basis, an empirical rule for the correlation between structure and stability of nitronic acids and nitronic esters is proposed, which predicts that stable nitronic acids and nitronic esters should have the C type of structure that meets the matching principle of electronic effects.
基金the National Natural Science Foundation of China(No.22071035)the Natural Science Foundation of Guangxi(Nos.2023GXNSFDA026025,2022GXNSFBA035494)+2 种基金Guangxi Minzu University Scientific Research Funds for Talent Introduction(2022KJQD14)the Student Innovation Training Program(No.202310602014)are greatly appreciated.
文摘The development of general and practical strategies toward the construction of medium-sized rings is still challenging in organic synthesis,especially for the multiple stereocenters control of substituted groups on the ring owing to the long distance between groups.Thus,stereoselective synthesis of multi-substituted ten-membered rings is attractive.Herein,a rapid assembly of various highly substituted ten-membered nitrogen heterocycles between two 1,3-dipoles through a tandem[3+3]cycloaddition/aza-Claisen rearrangement of N-vinyl-α,β-unsaturated nitrones and aza-oxyallyl or oxyallyl cations are disclosed.Products containing two or multiple stereocenters could be obtained in up to 96%yield with high regioselectivity and diastereoselectivity.Selective N-O bond cleavages of ten-membered nitrogen heterocycles lead to various novel 5,6,6-perifused benzofurans,bicyclo[4.4.0]or bicyclo[5.3.0]skeletons containing three or multiple continuous stereocenters in good yields and high diastereoselectivity.Biological tests show that the obtained ten-membered N-heterocycles and bicyclo[4.4.0]skeletons inhibited nitric oxide generation in LPS-stimulated RAW264.7 cells and might serve as good anti-inflammatory agents.
基金support from National Natural Science Foundation of China(No.20962017) the Natural Science Foundation of Gansu Province,China(No.2007GS03630)
文摘α-Aryl nitrone are one of the most useful kinds of nitrones and have been extensively explored in recent years.However,the sugar moieties have not been introduced into these molecules before.We presented here an efficient synthesis ofα-aryl nitrone Oglycosides via condensation of N-substituted hydroxylamine and aryl aldehydes glycosides in benzene.
基金This work was supported by the NNSFC (No.29672004).
文摘1,4-Addition reaction of Grignard's reagent to 5-methoxy-2(5H)-furanone 1 was accomplished. which provided a new possible route for synthesizing beta -alkyl-Y-alkyloxy-Y-butyrolactone. A novel concise method of preparing fused heterocyclic compounds was offered by 1,3-dipolar cycloaddition reaction of silyl nitronates to 1.
文摘OBJECTIVE Amyotrophic lateral sclerosis(ALS)is a fatal neurodegenerative dis⁃ease characterized by progressive loss of upper and lower motor neurons that results in skeletal muscle atrophy,weakness and paralysis.Oxida⁃tive stress plays a key role in the pathogenesis of ALS,including familial forms of the disease arising from mutation of the gene coding for superoxide dismutase 1(SOD1).Moreover,although the pathogenesis of ALS is unclear,the abnormal accumulation of TAR DNA-binding pro⁃tein of 43 ku(TDP-43)is a pathological feature that exists in almost all patients.Thus far,there is no drug that can cure ALS/FTLD.Tetramethyl⁃pyrazine nitrone(TBN)is a derivative of tetra⁃methylapyrazine,derived from the traditional Chinese medicine Ligusticum chuanxiong,which has been widely proven to have therapeutic effects on models of various neurodegenerative diseases.TBN is currently under clinical investi⁃gation for several indications including a phaseⅡtrial of ALS.Here,we explored the therapeutic effect of TBN in the SOD1G93A and TDP-43M337V ALS mouse model.METHODS In the SOD1G93A transgenic mouse model,TBN was administered to mice by intraperitoneal or intragastric injection after the onset of motor deficits.At the same time,we unilaterally and bilaterally injected the TDP-43M337V virus into the striatum of the WT mouse,and gave the TBN treatment after the mice developed a phenotype.After administering these two models for a period of time,we con⁃ducted behavioral tests,including rotarod test,balance beam test,climbing pole test,etc,to evaluate the efficacy of TBN on SOD1G93A and TDP-43M337V models.Furthermore,we explored the possible mechanism of action of TBN in the treatment of ALS through Western blotting and immunohistochemistry/immunofluorescence staining analysis.RESULTS In the SOD1G93A transgenic mouse model,TBN slowed the pro⁃gression of motor neuron disease as evidenced by improved motor performance,reduced spinal motor neuron loss and the associated glial response,and decreased skeletal muscle fiber denervation and fibrosis.TBN treatment activated mitochondrial antioxidant activity through the PGC-1α/Nrf2/HO-1 pathway and decreased the expression of human SOD1.What′s more,in the TDP-43M337V mice model,the results showed that in mice with unilateral injection of TDP-43M337V,TBN improved motor deficits and cognitive im⁃pairment in the early stages of disease progres⁃sion.In mice with bilateral injection of TDP-43M337V into the striatum,TBN not only improved motor function but also prolonged survival rate.Moreover,we show that its therapeutic effect may be through activation of the Akt/mTOR/GSK-3βand AMPK/PGC-1α/Nrf2 signaling pathways.In summary,TBN is a promising agent for the treat⁃ment of ALS/FTLD.CONCLUSION TBN has shown good efficacy in both SOD1 and TDP-43 ALS-related models,and it may act by activating the AMPK/PGC-1α/Nrf2 signaling pathway,which shows some light for the development of ALS therapeutic drugs.
文摘In this article, winter clothes, bedding, pillows, mattresses are produced in the Republic of Uzbekistan and used in the export products of foreign countries in domestic market shopping centers;existing nonwoven fabric samples were used as toys, children’s clothing as a heat retainer, a space-filler was selected on the basis of marketing survey analysis. Chemical bonding, processing technology, methods, linear density, thickness, air permeability, hygroscopicity, heat storage and heat transfer properties of the samples were analyzed experimentally based on the preparation methods, the fiber content was compared with the standard technology. The advantages and disadvantages of the samples were studied and recommendations for use in sewing according to consumer requirements were given.
基金financial support from the National Natural Science Foundation of China (Nos. 21871112 and 21971090)。
文摘A new organocatalytic double annulation cascade involving scission/recombination of N-O bonds of nitrones is reported for the first time, and used to produce a range of hitherto unprecedented tricyclic bridged-fused benzo[d]azepines bearing three stereogenic centers with moderate to good yields and complete diastereoselectivity. A quinine-catalyzed reaction of yne–allenone esters with nitrones worked well and provided a convergent and regioselective pathway to access these three-dimensional scaffolds from the planar conjugated system. Density functional theory(DFT) calculations have been applied to understand the key process for forming diradical intermediates.
文摘The reaction mechanism of the intramolecular cycloaddition of N-3-butenyl nitrone has been investigated theoretically by using AM1 MO method and transition state theory.There are two parallel reactions leading to two different regioisomers.The ratio of the rate constants of these two reactions was calculated to be 124.1(at 383.75 K).The obtained results can be used to explain the high regiospecificity of the reaction product.
文摘In the presence of metallic samariumcobalt (II) chloride hexahydrate, the nitrones can be reduced to the corresponding imines in moderate to high yields under mild and neutral conditions.
文摘The behaviour of cyanothioacetamide 1 and the acetonitrile derivatives 6 and 10, respectively, towards the nitrones 2a-i induced by free solar thermal energy is reported. Structures and reaction mechanisms are also discussed.
基金Financial support from National Basic Research Program of China(No.2012CB822101)the National Natural Science Foundation of China(No.21272240)+1 种基金National Science and Technology Major Projects for "Major New Drugs Innovation and Development"(No.2013ZX09508104)National Engineering Research Center for Carbohydrate Synthesis of Jiangxi Normal University
文摘A novel C-branched polyhydroxylated cyclic nitrone 25.which could be a valuable intermediate for the synthesis of C-branched pyrrolidine iminosugars,was synthesized starting from the commercially available i.-arabinose in 29.0%total yield.
文摘The ground state interaction of C-(4-chlorophenyl)-N-phenylnitrone (N1) with three different α, β-unsaturated ketones (K1 - K3) in very dilute solution (10-6 mol dm-3) has been noticed through charge transfer band formation in the visible region. The experimentally measured transition dipole, ground state resonance energy and formation constants of the complexes indicate interaction selectivity of the acyclic nitrone (N1) for the ketones. Molar absorptivity of the absorbing complexes were determined for all the three N1/K (1:1) interacting systems in toluene. Experimental findings were well rationalized with the help of electron density based global electrophilicity and nucleophilicity indices as well as with frontier molecular orbital calculations.
基金Financial support from the National Natural Science Foundation of China(Nos.21642012 and 21272240)National Science and Technology Major Projects for“Major New Drugs Innovation and Development”(No.2013ZX09508104)+1 种基金National Engineering Research Center for Carbohydrate Synthesis of Jiangxi Normal Universitysupported in part by a Grant-in-Aid for Scientific Research(C)(No.26460143)(AK)from the Japanese Society for the Promotion of Science(JSPS)
文摘A series of C-7 modified analogues of casuarine have been synthesized from sugar-derived nitrone and assayed against various glycosidases. Introduction of C-7 aminomethyl or amide group led to sharp decrease of the inhibitory activities.
文摘The new synthetic method of isoxazole derivatives was succesfully achieved. The experimental results demonstrate that thermal decomposition reactions of nitrone could take place with yields of 41 similar to 81%, to give a series of new isoxazole derivatives.
基金support from the National Natural Science Foundation of China(22171245).
文摘The demands for effective assembly of structurally complex molecular scaffolds from simple starting materials are continuously growing along with the development of organic chemistry.We have developed a tandem approach that assembles simple 6-chloroethylphosphane,alkynyl imines(or alkynyl ketones),and nitrones into structurally complex isoxazolidine fused phospholene scaffolds through a sequential process involving phospha-Michael addition,intramolecular cyclization,and dearomatizing[3+2]cycloaddition reactions.The isoxazolidine-fused phospholene has three heteroatoms,including a junction phosphorus atom.After removing the coordinated tungsten group,these compounds can serve as potential P-stereogenic ligands and may have biological activities.Contrary to pyrroles and furans,the aromatic 2-phosphapyrroles and 2-phosphafurans are good 2r-electron candidates in the dearomative[3+2]cycloaddition reactions due to the poor overlap of the 2p-3p orbitals of the C=P moiety.
基金Financial support from the NSFC(22071035)Natural Science Foundation of Guangxi(2023GXNSFDA026025)+1 种基金Guangxi Science and Technology Plan Project(AD23026046)Guangxi Bagui Youth Scholar is greatly appreciated.
文摘Comprehensive Summary.Herein,we have developed a facile method for the synthesis of various polysubstituted pyridine derivatives through selective 6π-electrocyclization of N-vinyl-α,β-unsaturated nitrones.It was found that gold catalysts promoted carbon-6π-electrocyclization of N-vinyl-α,β-unsaturated nitrones to afford 6-alkenyl pyridine N-oxides in 43%—75%yields,whereas copper catalysts facilitated oxygen-6π-electrocyclization to give 6-epoxy pyridines in 41%—83%yields.The present method features broad substrate scope,good functional group tolerance,high cyclization selectivity,and diversity of polysubstituted pyridine scaffolds.
