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
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.
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
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
Asymmetric 1,3-dipolar cycloaddihon of the chiral nitronic esters with acrylate giving the enantiomerically pure novel chiral bisheterocyclic compounds is describcd
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
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
We described a Yb(OTf)_(3) combined with Pybox ligand catalyzed asymmetric[3+3]cycloaddition of N-vinyl cinnamaldehyde nitrones with activated cyclopropanes to prepare various functionalized 1,2-oxazines in 24%—95% y...We described a Yb(OTf)_(3) combined with Pybox ligand catalyzed asymmetric[3+3]cycloaddition of N-vinyl cinnamaldehyde nitrones with activated cyclopropanes to prepare various functionalized 1,2-oxazines in 24%—95% yields and 22%—96%ee.Experimental results revealed that the reaction underwent a domino[3+3]cycloaddition,dealkenylation,and aza-1,4-addition in three steps.The chiral 1,2-oxazine could be obtained in gram scales and easily converted into various 1,2-oxazine scaffolds.The present method features broad substrate scope,good functional group compatibility,three-component domino reaction,and asymmetric[3+3]cycloaddition of N-vinyl nitrones with activated cyclopropanes.展开更多
A [3＋3] formal cycloaddition reaction between in situ formed azaoxyallyl cations and nitrones from isatins has been developed, furnishing a spectrum of spiro[1,2,4-oxadiazinan-5-one]oxindoles in good to excellent yie...A [3＋3] formal cycloaddition reaction between in situ formed azaoxyallyl cations and nitrones from isatins has been developed, furnishing a spectrum of spiro[1,2,4-oxadiazinan-5-one]oxindoles in good to excellent yields with excellent diastereoselectivity. This method provides direct and efficient access to potentially bioactive spirooxin- doles incorporating a six-membered heterocyclic scaffold.展开更多
Benzohydroxamic acid reacts with dimethyl acetylenedicarboxylate in the presence of 10 mol% NaOAc to gen- erate （E）-N-（1,4-dimethoxy-l,4-dioxobutan-2-ylidene）-l-phenylcarboxamide oxide in good-to-excellent yield i...Benzohydroxamic acid reacts with dimethyl acetylenedicarboxylate in the presence of 10 mol% NaOAc to gen- erate （E）-N-（1,4-dimethoxy-l,4-dioxobutan-2-ylidene）-l-phenylcarboxamide oxide in good-to-excellent yield in water at room temperature for 2 h, which supplies a simple, efficient and environmentally friendly method to syn- thesize a wide range of nitrones. The benefits of this strategy not only conform to the requirment of green chemisty, but also possess atom economy.展开更多
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
Dipolar cycloaddition reactions of ethyl 2-hydropolyfluoroalk-2-enoates (1) with some nitrones were de-scribed. The reaction of 3,4-dihydroisoquinoline N-oxide (2) with 1 took place readily in methylene chloride at ro...Dipolar cycloaddition reactions of ethyl 2-hydropolyfluoroalk-2-enoates (1) with some nitrones were de-scribed. The reaction of 3,4-dihydroisoquinoline N-oxide (2) with 1 took place readily in methylene chloride at room temperature to give the corresponding 5-fluoroalkylisoxazolidines regioselectively as a mixture of two di-astereoisomers (trans and cis) in high yields, while longer reaction time and higher temperature were needed in the case of non-cyclic nitrones. Under similar conditions the reaction of quinoline N-oxide (14) with 1 did not give the expected adducts and a ring-opening product was obtained.展开更多
The dipolar cycloaddition reaction of allenyl perfluoroalkyl sulfones （1） to nitrones （2） was described. Unlike nonfluorine-containing allenyl sulfones, 1 reacted readily with 2 in ether at room temperatttre and u...The dipolar cycloaddition reaction of allenyl perfluoroalkyl sulfones （1） to nitrones （2） was described. Unlike nonfluorine-containing allenyl sulfones, 1 reacted readily with 2 in ether at room temperatttre and unusual zwitterionic cycloadducts （3） were obtained in good yields due to the strong electron-withdrawing effect of perfluoroalkyl groups. The structure of 3 was characterized by spectral analyses and X-ray crystallography.展开更多
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.
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.
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.
基金Financial support from the NSFC(22071035)Natural Science Foundation of Guangxi(2023GXNSFDA026025)+3 种基金Guangxi Science and Technology Plan Project(AD23026046)Graduate Innovation Training Program of Guangxi(YCSW2024160)Natural Science Foundation of Sichuan(2023NSFSC1087)Guangxi Bagui Young Scholar is greatly appreciated.
文摘We described a Yb(OTf)_(3) combined with Pybox ligand catalyzed asymmetric[3+3]cycloaddition of N-vinyl cinnamaldehyde nitrones with activated cyclopropanes to prepare various functionalized 1,2-oxazines in 24%—95% yields and 22%—96%ee.Experimental results revealed that the reaction underwent a domino[3+3]cycloaddition,dealkenylation,and aza-1,4-addition in three steps.The chiral 1,2-oxazine could be obtained in gram scales and easily converted into various 1,2-oxazine scaffolds.The present method features broad substrate scope,good functional group compatibility,three-component domino reaction,and asymmetric[3+3]cycloaddition of N-vinyl nitrones with activated cyclopropanes.
文摘A [3＋3] formal cycloaddition reaction between in situ formed azaoxyallyl cations and nitrones from isatins has been developed, furnishing a spectrum of spiro[1,2,4-oxadiazinan-5-one]oxindoles in good to excellent yields with excellent diastereoselectivity. This method provides direct and efficient access to potentially bioactive spirooxin- doles incorporating a six-membered heterocyclic scaffold.
文摘Benzohydroxamic acid reacts with dimethyl acetylenedicarboxylate in the presence of 10 mol% NaOAc to gen- erate （E）-N-（1,4-dimethoxy-l,4-dioxobutan-2-ylidene）-l-phenylcarboxamide oxide in good-to-excellent yield in water at room temperature for 2 h, which supplies a simple, efficient and environmentally friendly method to syn- thesize a wide range of nitrones. The benefits of this strategy not only conform to the requirment of green chemisty, but also possess atom economy.
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. 20172065).
文摘Dipolar cycloaddition reactions of ethyl 2-hydropolyfluoroalk-2-enoates (1) with some nitrones were de-scribed. The reaction of 3,4-dihydroisoquinoline N-oxide (2) with 1 took place readily in methylene chloride at room temperature to give the corresponding 5-fluoroalkylisoxazolidines regioselectively as a mixture of two di-astereoisomers (trans and cis) in high yields, while longer reaction time and higher temperature were needed in the case of non-cyclic nitrones. Under similar conditions the reaction of quinoline N-oxide (14) with 1 did not give the expected adducts and a ring-opening product was obtained.
文摘The dipolar cycloaddition reaction of allenyl perfluoroalkyl sulfones （1） to nitrones （2） was described. Unlike nonfluorine-containing allenyl sulfones, 1 reacted readily with 2 in ether at room temperatttre and unusual zwitterionic cycloadducts （3） were obtained in good yields due to the strong electron-withdrawing effect of perfluoroalkyl groups. The structure of 3 was characterized by spectral analyses and X-ray crystallography.
