Michael addition of nitroalkanes to α,β-unsaturated carbonyl compounds occurs in the presence of KF/AI_2O_3/PEG4000 without solvent.Yields are fair to good and work-ups are easy.
Corrosion inhibition of three α,β-unsaturated carbonyl compounds on N80 steel at high temperature and in concentrated acid medium was evaluated, and the inhibition mechanism was investigated. The results proved that...Corrosion inhibition of three α,β-unsaturated carbonyl compounds on N80 steel at high temperature and in concentrated acid medium was evaluated, and the inhibition mechanism was investigated. The results proved that both cinnamaldehyde and benzalacetone had an evident anticorrosion effect and could reduce the corrosion of steel effectively in acid medium, α,β-unsaturated carbonyl compounds with a benzene ring structure had good adsorption on steel surface. The experiments proved that polymerization of α,β-unsaturated carbonyl compounds on the steel surface at a high temperature and in concentrated acid medium resulted in a good corrosion inhibiting effect, which was attributed to the structures of α,β-unsaturated carbonyl compounds.展开更多
The selectivity of organosamarium(Ⅲ) hydride in reducing unsaturated carbonyl compounds has been studied. Dimeric organosamarium hydride[(C_9H_7)_2SmH]_2·4THF·NaCl prepared by the reaction of (C_9H_7)_2SmCl...The selectivity of organosamarium(Ⅲ) hydride in reducing unsaturated carbonyl compounds has been studied. Dimeric organosamarium hydride[(C_9H_7)_2SmH]_2·4THF·NaCl prepared by the reaction of (C_9H_7)_2SmCl·2THF with NaH in THF reacts with unsaturated carbonyl compounds to give the corresponding reduction products with a high selectivity. The carbonyl groups have been reduced while the carbon-carbon double bonds are not affected.展开更多
A simple and efficient Knoevenagel condensation between a b-unsaturated aldehydes and active methylene compounds is reported.Notably,this condensation can be catalyzed by PPL（lipase from porcine pancreas） with satis...A simple and efficient Knoevenagel condensation between a b-unsaturated aldehydes and active methylene compounds is reported.Notably,this condensation can be catalyzed by PPL（lipase from porcine pancreas） with satisfied yields（49%–92%）.Moreover,PPL induces moderate Z/E selectivity in the Knoevenagel condensation.展开更多
In the presence of CrC13 /Fe bimetal couple,per(poly)fluoroalkyl iodides add to vinyl cyclopropane compounds giving addition-ring-opening products in good yields.
Regio and stereoselective synthesis of substituted dihydrofurans were accomplished by eeric ammonium nitrate mediated oxidative cycloaddition of 1,3-dicarbonyls to β-aryl-α,β-unsaturated ketones in moderate yields.
N-Alkylhydroxylamines have been shown to undergo a stereospecific cis addition to 1-phenyl-2 -nitropropene compounds, whereas the corresponding O-alkylhydroxylamines give no diastereoselectivity. The concerted additio...N-Alkylhydroxylamines have been shown to undergo a stereospecific cis addition to 1-phenyl-2 -nitropropene compounds, whereas the corresponding O-alkylhydroxylamines give no diastereoselectivity. The concerted addition mechanism was provided to explain the difference.展开更多
Catalyzed by ytterbium（III） triflate hydrate [Yb（OTf）3.xH20], the Michael addition and cyclocondensation of α,β-unsaturated ketones with active methylene compounds to afford the 1,4-adducts and benzo[b]pyran der...Catalyzed by ytterbium（III） triflate hydrate [Yb（OTf）3.xH20], the Michael addition and cyclocondensation of α,β-unsaturated ketones with active methylene compounds to afford the 1,4-adducts and benzo[b]pyran derivatives, respectively were studied.展开更多
β,γ-Unsaturated a-diazocarbonyl compounds possess two reactive sites for electrophilic addition-one at the diazo carbon and the other at the vinylogous γ-position.Controlled by catalyst,divergent transformations ar...β,γ-Unsaturated a-diazocarbonyl compounds possess two reactive sites for electrophilic addition-one at the diazo carbon and the other at the vinylogous γ-position.Controlled by catalyst,divergent transformations are achieved starting from the same starting materials,either by Lewis acid-catalyzed addition or by dirhodium-catalyzed metal carbene reactions.In select cases two catalysts working in combination or in sequence provide a relay for cascade transformations.In this review,we summarize advances in catalyst-dependent divergent transformations of β,γ-unsaturated α-diazocarbonyl compounds and highlight the potential of this exciting research area and the many challenges that remain.展开更多
Acid-catalyzed dehydration of alcohols has been widely employed for the synthesis of alkenes. However, activated alcohols when employed as substrates in dehydration reactions are often pla-gued by the lack of alkene s...Acid-catalyzed dehydration of alcohols has been widely employed for the synthesis of alkenes. However, activated alcohols when employed as substrates in dehydration reactions are often pla-gued by the lack of alkene selectivity. In this work, the reaction system can be significantly improved through enhancing the performance of Lewis acid catalysts in the dehydration of activated alcohols by combining with a Lewis base. Observations of the reaction mechanism revealed that the Lewis base component might have changed the reaction rate order. Although both the principal and side reaction rates decreased, the effect was markedly more observed on the latter reaction. Therefore, the selectivity of the dehydration reaction was improved. On the basis of this observation, a new route to synthesize 2-cinnamyl-1,3-dicarbonyl compounds was developed by using 2-aryl-3,4- di-hydropyran as a starting substrate in the presence of a Lewis acid/Lewis base combined catalyst system.展开更多
The significant demand for high quality food has motivated us to adopt appropriate processing methods to improve the food nutritional quality and flavors.In this study,the effects of five drying methods,namely,pulsed ...The significant demand for high quality food has motivated us to adopt appropriate processing methods to improve the food nutritional quality and flavors.In this study,the effects of five drying methods,namely,pulsed vacuum drying(PVD),freeze drying(FD),infrared drying(IRD),hot-air drying(HAD)and sun drying(SD)on free amino acids(FAAs),α-dicarbonyl compounds(α-DCs)and volatile compounds(VOCs)in rape bee pollen(RBP)were determined.The results showed that FD significantly released the essential amino acids(EAAs)compared with fresh samples while SD caused the highest loss.Glucosone was the dominantα-DCs in RBP and the highest loss was observed after PVD.Aldehydes were the dominant volatiles of RBP and SD samples contained more new volatile substances(especially aldehydes)than the other four drying methods.Comprehensively,FD and PVD would be potential methods to effectively reduce the quality deterioration of RBP in the drying process.展开更多
Two new α,β-unsaturated butyrolactone derivatives, 4-(4″-hydroxybenzyl)-3-(3′-hydroxy-phenethyl)furan-2(5H)-one (1) and 3-(3′-hydroxyphenethyl)furan-2(5H)-one (2), together with one known phenolic compound (3), w...Two new α,β-unsaturated butyrolactone derivatives, 4-(4″-hydroxybenzyl)-3-(3′-hydroxy-phenethyl)furan-2(5H)-one (1) and 3-(3′-hydroxyphenethyl)furan-2(5H)-one (2), together with one known phenolic compound (3), were isolated from the tubers of Pleione bulbocodioides (Franch.) Rolfe. Their structures were elucidated by analysis of spectroscopic data.展开更多
Phosphine-catalyzed[5+1]annulation reaction of Morita-Baylis-Hillman(MBH)carbonates with 1,3-dicarbonyl compounds has been developed,producing biologically interesting spirocyclohexene derivatives in high yields with ...Phosphine-catalyzed[5+1]annulation reaction of Morita-Baylis-Hillman(MBH)carbonates with 1,3-dicarbonyl compounds has been developed,producing biologically interesting spirocyclohexene derivatives in high yields with moderate to excellent diastereoselectivities.The annulation was achieved through sequential 1,6-conjugate addition/nucleophilic substution reaction of phosphine ylides with dinucleophiles.展开更多
The asymmetric α-amination of 1,3-dicarbonyl compounds with dialkyl azodicarboxylates has been achieved by C2-symmetric BINOL-squaramide bearing multiple hydrogen bond donors to provide the desired products in excell...The asymmetric α-amination of 1,3-dicarbonyl compounds with dialkyl azodicarboxylates has been achieved by C2-symmetric BINOL-squaramide bearing multiple hydrogen bond donors to provide the desired products in excellent yields and enantioselectivities （up to 99% yield and 98% ee）.展开更多
Selective hydrogenation of the carbonyl bond inα,β-unsaturated carbonyl compounds is rather challenging owing to the more feasible hydrogenation of ethylenic bond from both thermodynamic and kinetic aspects.Here,we ...Selective hydrogenation of the carbonyl bond inα,β-unsaturated carbonyl compounds is rather challenging owing to the more feasible hydrogenation of ethylenic bond from both thermodynamic and kinetic aspects.Here,we demonstrate a facile emulsionbased molecule-nanoparticle self-assembly strategy for the atomic engineering of Ir species on three-dimensional CeO_(2)spheres(Ir1@CeO_(2)).When applied to the hydrogenation ofα,β-unsaturated aldehydes,Ir1@CeO_(2)catalyst remarkably exhibited~100%selectivity towards unsaturated alcohols,whereas the formation of Ir nanoparticles on CeO_(2)drastically decreased the selectivity for unsaturated alcohols.Spectroscopic studies revealed that strong metal-support interactions triggered the charge transfer from Ir to CeO_(2),leading to the partial reduction of Ce^(4+)to Ce^(3+)along with the formation new Ir^(δ+)-O_(2)--Ce^(3+)(OV)interfaces.The electrophilic atomic Ir species at the Ir^(δ+)-O_(2)--Ce^(3+)(OV)interfaces would therefore preferentially adsorb and facilitate hydrogenation of polar C=O bond to achieve exceptional selectivity.展开更多
Advanced glycation end products(AGEs),a group of complex compounds generated by nonenzymatic interactions between amino acids,proteins and reducing sugars or lipids,accumulate in vivo and activate various signaling pa...Advanced glycation end products(AGEs),a group of complex compounds generated by nonenzymatic interactions between amino acids,proteins and reducing sugars or lipids,accumulate in vivo and activate various signaling pathways closely related to the occurrence of various chronic metabolic diseases.This study aims to explore the structure-activity relationship between phenolic acids with different structure and affecting the AGEs generation,and to provide data support for AGEs control.Phenolic acids(4-hydroxybenzoic,protocatechuic,gallic,p-coumaric,caffeic,ferulic and sinapic acids)were employed to indicate the AGEs formation condition in Maillard reaction performed in the glucose-lysine model system.Three 1,2-dicarbonyl compounds were reacted with phenolic acids and then tested by liquid chromatography-mass spectrometry.The results showed that N^(ε)-carboxy-methyl-lysine(CML),N^(ε)-carboxy-ethyl-lysine(CEL),and pyrraline formation inhibited by phenolic acids varied from(8.7±2.5)%to(33.2±2.5)%,(10.5±0.8)%to(57.1±3.2)%and(1.3±0.3)%to(23.3±0.8)%,respectively.The p-coumaric acid has no inhibitory effect on CML and CEL formation.Gallic acid shows the best inhibitory effect on CML formation due to its strong antioxidant activity.Sinapic acid showed the best glyoxal(GO)trapping rate and thus had the stronger inhibitory effect on CML formation.Ferulic acid can react with mono-,di-,and tri-methylglyoxal(MGO)to form adduct products,showing the best MGO scavenging rate and a good inhibitory effect on CEL formation.The main role of phenolic acid is an antioxidant agent to inhibit pyrraline formation.The glucose itself or ammonia-induced degradation and Amadori rearrangement products oxidation were lowered by protocatechuic,gallic and caffeic acids due to their antioxidant activities to form AGEs,while AGEs inhibited by ferulic and sinapic acids were mainly dependent on their trapping ability on 1,2-dicarbonyl compounds.展开更多
We report a new, effective and simple method for preparing a,fl-unsaturated carbonyl compounds by reacting ketones and aromatic alcohols at 56 ℃ in the presence of CrO3 （CrO3 acts as an oxidant and also a catalyst）...We report a new, effective and simple method for preparing a,fl-unsaturated carbonyl compounds by reacting ketones and aromatic alcohols at 56 ℃ in the presence of CrO3 （CrO3 acts as an oxidant and also a catalyst） for around 10 h. The condensation reactions occurred effectively among a wide combination of ketones and alcohols. The procedure is simple and the yields can be high up to 98%. And a probable mechanism is proposed.展开更多
Per-and poly-fluoroalkylated α,β-unsaturated alkenals were synthesized by the reaction of silyl enol ether of alkanals with per-and poly-fluoroalkyl iodide initiated by Na_2S_2_O4 conveniently in high yield.Their co...Per-and poly-fluoroalkylated α,β-unsaturated alkenals were synthesized by the reaction of silyl enol ether of alkanals with per-and poly-fluoroalkyl iodide initiated by Na_2S_2_O4 conveniently in high yield.Their corresponding alkenol and 2,4-dinitrophenylhydrazone were also synthesized.展开更多
文摘Michael addition of nitroalkanes to α,β-unsaturated carbonyl compounds occurs in the presence of KF/AI_2O_3/PEG4000 without solvent.Yields are fair to good and work-ups are easy.
文摘Corrosion inhibition of three α,β-unsaturated carbonyl compounds on N80 steel at high temperature and in concentrated acid medium was evaluated, and the inhibition mechanism was investigated. The results proved that both cinnamaldehyde and benzalacetone had an evident anticorrosion effect and could reduce the corrosion of steel effectively in acid medium, α,β-unsaturated carbonyl compounds with a benzene ring structure had good adsorption on steel surface. The experiments proved that polymerization of α,β-unsaturated carbonyl compounds on the steel surface at a high temperature and in concentrated acid medium resulted in a good corrosion inhibiting effect, which was attributed to the structures of α,β-unsaturated carbonyl compounds.
文摘The selectivity of organosamarium(Ⅲ) hydride in reducing unsaturated carbonyl compounds has been studied. Dimeric organosamarium hydride[(C_9H_7)_2SmH]_2·4THF·NaCl prepared by the reaction of (C_9H_7)_2SmCl·2THF with NaH in THF reacts with unsaturated carbonyl compounds to give the corresponding reduction products with a high selectivity. The carbonyl groups have been reduced while the carbon-carbon double bonds are not affected.
基金the financial support from the National Natural Science Foundation of China (Nos. 21172093, 31070708, and 21072075)the Natural Science Foundation of Jilin Province of China (Nos. 201115039 and 20140101141JC)the Scientific Research Fund of Jilin University (No. 450060326007)
文摘A simple and efficient Knoevenagel condensation between a b-unsaturated aldehydes and active methylene compounds is reported.Notably,this condensation can be catalyzed by PPL（lipase from porcine pancreas） with satisfied yields（49%–92%）.Moreover,PPL induces moderate Z/E selectivity in the Knoevenagel condensation.
文摘In the presence of CrC13 /Fe bimetal couple,per(poly)fluoroalkyl iodides add to vinyl cyclopropane compounds giving addition-ring-opening products in good yields.
文摘Regio and stereoselective synthesis of substituted dihydrofurans were accomplished by eeric ammonium nitrate mediated oxidative cycloaddition of 1,3-dicarbonyls to β-aryl-α,β-unsaturated ketones in moderate yields.
文摘N-Alkylhydroxylamines have been shown to undergo a stereospecific cis addition to 1-phenyl-2 -nitropropene compounds, whereas the corresponding O-alkylhydroxylamines give no diastereoselectivity. The concerted addition mechanism was provided to explain the difference.
基金the National Natural Science Foundation of China (No.20676123) for financial support.
文摘Catalyzed by ytterbium（III） triflate hydrate [Yb（OTf）3.xH20], the Michael addition and cyclocondensation of α,β-unsaturated ketones with active methylene compounds to afford the 1,4-adducts and benzo[b]pyran derivatives, respectively were studied.
基金the National Institutes of Health(No.GM 46503)the National Science Foundation(No.CHE-1212446)the starting funding from Soochow University and Key Laboratory of Organic Synthesis of Jiangsu Province
文摘β,γ-Unsaturated a-diazocarbonyl compounds possess two reactive sites for electrophilic addition-one at the diazo carbon and the other at the vinylogous γ-position.Controlled by catalyst,divergent transformations are achieved starting from the same starting materials,either by Lewis acid-catalyzed addition or by dirhodium-catalyzed metal carbene reactions.In select cases two catalysts working in combination or in sequence provide a relay for cascade transformations.In this review,we summarize advances in catalyst-dependent divergent transformations of β,γ-unsaturated α-diazocarbonyl compounds and highlight the potential of this exciting research area and the many challenges that remain.
基金supported by the National Natural Science Foundation of China (21173089 and 21373093)the Fundamental Research Funds for the Central Universities of China (2014ZZGH019)the Cooperative Innovation Center of Hubei Province
文摘Acid-catalyzed dehydration of alcohols has been widely employed for the synthesis of alkenes. However, activated alcohols when employed as substrates in dehydration reactions are often pla-gued by the lack of alkene selectivity. In this work, the reaction system can be significantly improved through enhancing the performance of Lewis acid catalysts in the dehydration of activated alcohols by combining with a Lewis base. Observations of the reaction mechanism revealed that the Lewis base component might have changed the reaction rate order. Although both the principal and side reaction rates decreased, the effect was markedly more observed on the latter reaction. Therefore, the selectivity of the dehydration reaction was improved. On the basis of this observation, a new route to synthesize 2-cinnamyl-1,3-dicarbonyl compounds was developed by using 2-aryl-3,4- di-hydropyran as a starting substrate in the presence of a Lewis acid/Lewis base combined catalyst system.
基金supported by National Natural Science Foundation of China(Nos.31871861 and 31501548)The Apicultural Industry Technology System(NCYTI-43-KXJ17)The Science and Technology Innovation Project of Chinese Academy of Agricultural Sciences(CAAS-ASTIP-2015-IAR)。
文摘The significant demand for high quality food has motivated us to adopt appropriate processing methods to improve the food nutritional quality and flavors.In this study,the effects of five drying methods,namely,pulsed vacuum drying(PVD),freeze drying(FD),infrared drying(IRD),hot-air drying(HAD)and sun drying(SD)on free amino acids(FAAs),α-dicarbonyl compounds(α-DCs)and volatile compounds(VOCs)in rape bee pollen(RBP)were determined.The results showed that FD significantly released the essential amino acids(EAAs)compared with fresh samples while SD caused the highest loss.Glucosone was the dominantα-DCs in RBP and the highest loss was observed after PVD.Aldehydes were the dominant volatiles of RBP and SD samples contained more new volatile substances(especially aldehydes)than the other four drying methods.Comprehensively,FD and PVD would be potential methods to effectively reduce the quality deterioration of RBP in the drying process.
文摘Two new α,β-unsaturated butyrolactone derivatives, 4-(4″-hydroxybenzyl)-3-(3′-hydroxy-phenethyl)furan-2(5H)-one (1) and 3-(3′-hydroxyphenethyl)furan-2(5H)-one (2), together with one known phenolic compound (3), were isolated from the tubers of Pleione bulbocodioides (Franch.) Rolfe. Their structures were elucidated by analysis of spectroscopic data.
文摘Phosphine-catalyzed[5+1]annulation reaction of Morita-Baylis-Hillman(MBH)carbonates with 1,3-dicarbonyl compounds has been developed,producing biologically interesting spirocyclohexene derivatives in high yields with moderate to excellent diastereoselectivities.The annulation was achieved through sequential 1,6-conjugate addition/nucleophilic substution reaction of phosphine ylides with dinucleophiles.
基金the Fundamental Research Funds for the Central Universities (No.2042014kf0248) for support of this research
文摘The asymmetric α-amination of 1,3-dicarbonyl compounds with dialkyl azodicarboxylates has been achieved by C2-symmetric BINOL-squaramide bearing multiple hydrogen bond donors to provide the desired products in excellent yields and enantioselectivities （up to 99% yield and 98% ee）.
基金the National Natural Science Foundation of China(No.21901007)the Natural Science Foundation of Anhui Province(No.2008085QB83)+1 种基金the Science and Technology Development Fund(FDCT)of Macao SAR(No.0032/2021/ITP)the University of Macao(No.MYRG2020-00026-FST)。
文摘Selective hydrogenation of the carbonyl bond inα,β-unsaturated carbonyl compounds is rather challenging owing to the more feasible hydrogenation of ethylenic bond from both thermodynamic and kinetic aspects.Here,we demonstrate a facile emulsionbased molecule-nanoparticle self-assembly strategy for the atomic engineering of Ir species on three-dimensional CeO_(2)spheres(Ir1@CeO_(2)).When applied to the hydrogenation ofα,β-unsaturated aldehydes,Ir1@CeO_(2)catalyst remarkably exhibited~100%selectivity towards unsaturated alcohols,whereas the formation of Ir nanoparticles on CeO_(2)drastically decreased the selectivity for unsaturated alcohols.Spectroscopic studies revealed that strong metal-support interactions triggered the charge transfer from Ir to CeO_(2),leading to the partial reduction of Ce^(4+)to Ce^(3+)along with the formation new Ir^(δ+)-O_(2)--Ce^(3+)(OV)interfaces.The electrophilic atomic Ir species at the Ir^(δ+)-O_(2)--Ce^(3+)(OV)interfaces would therefore preferentially adsorb and facilitate hydrogenation of polar C=O bond to achieve exceptional selectivity.
基金supported by the National Natural Science Foundation of China(32472468 and 32001817)the Fundamental Research Program of Shanxi Province(202303021221123)+1 种基金the Youth Project of the Shanxi Fundamental Research Program(202203021222032)the Start-up Funds forScientific Research atNorth University of China(304-1101285714).
文摘Advanced glycation end products(AGEs),a group of complex compounds generated by nonenzymatic interactions between amino acids,proteins and reducing sugars or lipids,accumulate in vivo and activate various signaling pathways closely related to the occurrence of various chronic metabolic diseases.This study aims to explore the structure-activity relationship between phenolic acids with different structure and affecting the AGEs generation,and to provide data support for AGEs control.Phenolic acids(4-hydroxybenzoic,protocatechuic,gallic,p-coumaric,caffeic,ferulic and sinapic acids)were employed to indicate the AGEs formation condition in Maillard reaction performed in the glucose-lysine model system.Three 1,2-dicarbonyl compounds were reacted with phenolic acids and then tested by liquid chromatography-mass spectrometry.The results showed that N^(ε)-carboxy-methyl-lysine(CML),N^(ε)-carboxy-ethyl-lysine(CEL),and pyrraline formation inhibited by phenolic acids varied from(8.7±2.5)%to(33.2±2.5)%,(10.5±0.8)%to(57.1±3.2)%and(1.3±0.3)%to(23.3±0.8)%,respectively.The p-coumaric acid has no inhibitory effect on CML and CEL formation.Gallic acid shows the best inhibitory effect on CML formation due to its strong antioxidant activity.Sinapic acid showed the best glyoxal(GO)trapping rate and thus had the stronger inhibitory effect on CML formation.Ferulic acid can react with mono-,di-,and tri-methylglyoxal(MGO)to form adduct products,showing the best MGO scavenging rate and a good inhibitory effect on CEL formation.The main role of phenolic acid is an antioxidant agent to inhibit pyrraline formation.The glucose itself or ammonia-induced degradation and Amadori rearrangement products oxidation were lowered by protocatechuic,gallic and caffeic acids due to their antioxidant activities to form AGEs,while AGEs inhibited by ferulic and sinapic acids were mainly dependent on their trapping ability on 1,2-dicarbonyl compounds.
基金Project supported by the National Natural Science Foundation of China （NSFC） （Nos. 50825303 and 30890140） and the Ministry of Science and Technology of China （No. 2009CB-930400）.
文摘We report a new, effective and simple method for preparing a,fl-unsaturated carbonyl compounds by reacting ketones and aromatic alcohols at 56 ℃ in the presence of CrO3 （CrO3 acts as an oxidant and also a catalyst） for around 10 h. The condensation reactions occurred effectively among a wide combination of ketones and alcohols. The procedure is simple and the yields can be high up to 98%. And a probable mechanism is proposed.
文摘Per-and poly-fluoroalkylated α,β-unsaturated alkenals were synthesized by the reaction of silyl enol ether of alkanals with per-and poly-fluoroalkyl iodide initiated by Na_2S_2_O4 conveniently in high yield.Their corresponding alkenol and 2,4-dinitrophenylhydrazone were also synthesized.
