A direct Michael addition reaction between imidazo[1,2-a]pyridines andα,β-unsaturated ketones using acidic alumina as a C(sp3)—H acid catalyst has been developed.The abundant C(sp3)—H acid sites(Al^(3+))on the aci...A direct Michael addition reaction between imidazo[1,2-a]pyridines andα,β-unsaturated ketones using acidic alumina as a C(sp3)—H acid catalyst has been developed.The abundant C(sp3)—H acid sites(Al^(3+))on the acidic alumina surface effectively activate the carbonyl group ofα,β-unsaturated ketones,significantly enhancing the electrophilicity of theβ-carbon and thereby facilitating selective alkylation at the C3 position of imidazo[1,2-a]pyridines.This method demonstrates excellent functional group compatibility,mild reaction conditions,low reagent costs,and operational simplicity,providing a novel strategy for the efficient synthesis of alkylated imidazo[1,2-a]pyridine derivatives.展开更多
Nineβ‐cyclodextrin derivatives containing an amino group were synthesized via nucleophilic sub‐stitution from mono（6‐O‐p‐tolylsulfonyl）‐β‐cyclodextrin and used in asymmetric biomimetic Mi‐chael addition re...Nineβ‐cyclodextrin derivatives containing an amino group were synthesized via nucleophilic sub‐stitution from mono（6‐O‐p‐tolylsulfonyl）‐β‐cyclodextrin and used in asymmetric biomimetic Mi‐chael addition reactions in water at room temperature. The mechanism responsible for the moder‐ate activity and enantioselectivity of the β‐cyclodextrin derivatives was explored using nuclear magnetic resonance spectroscopy, namely 2D 1H rotating‐frame overhauser effect spectroscopy （ROESY）, ultraviolet absorption spectroscopy, and quantum chemical calculations, which provide a useful technique for investigating the formation of inclusion complexes. The effects of the pH of the reaction medium, theβ‐cyclodextrin derivative dosage, the structure of the modifying amino group, and various substrates on the yield and enantioselectivity were investigated. The results indicated that these factors had an important effect on the enantiomeric excess （ee） in the reaction system. Experiments using a competitor for inclusion complex formation showed that a hydrophobic cavity is necessary for enantioselective Michael addition. A comparison of the reactions using 4‐nitro‐β‐nitrostyrene and 2‐nitro‐β‐nitrostyrene showed that steric hindrance improved the enan‐tioselectivity. This was verified by the optimized geometries obtained from quantum chemical cal‐culations. An ee of 71%was obtained in the asymmetric Michael addition of cyclohexanone and 2‐nitro‐β‐nitrostyrene, using （S）‐2‐aminomethylpyrrolidine‐modified β‐CD as the catalyst, in an aqueous buffer solution, i.e., CH3COONa‐HCl （pH 7.5）.展开更多
Nitroalkanes react smoothly with CF_3CCl_2COCH=CHPh via Michael addition in the presence of inorganic bases such as KF/Al2O3 or K2CO3, giving fluorinecontaining γ-nitro ketones in good yields.
The solvents and substituents of two similar fluorescent sensors for cyanide, 7-diethylamino- 3-formylcoumarin （sensor a） and 7-diethylamino-3-（2-nitrovinyl）coumarin （sensor b）, are proposed to account for their...The solvents and substituents of two similar fluorescent sensors for cyanide, 7-diethylamino- 3-formylcoumarin （sensor a） and 7-diethylamino-3-（2-nitrovinyl）coumarin （sensor b）, are proposed to account for their distinct sensing mechanisms and experimental phenomena. The time-dependent density functional theory has been applied to investigate the ground states and the first singlet excited electronic states of the sensor as well as their possible Michael reaction products with cyanide, with a view to monitoring their geometries and photophysieal properties. The theoretical study indicates that the protic water solvent could lead to final Michael addition product of sensor a in the ground state, while the aprotic acetonitrile solvent could lead to carbanion as the final product of sensor b. Furthermore, the Michael reaction product of sensor a has been proved to have a torsion structure in its first singlet excited state. Correspondingly, sensor b also has a torsion structure around the nitrovinyl moiety in its first singlet excited state, while not in its carbanion structure. This could explain the observed strong fluorescence for sensor a and the quenching fluorescence for the sensor b upon the addition of the cyanide anions in the relevant sensing mechanisms.展开更多
A facile and efficient 1, 4-conjungate addition（Michael addition） reaction of active methylene compounds to aft-unsaturated compounds, catalyzed by guanidinium lactate ionic liquid（IL9）, has been developed. A rang...A facile and efficient 1, 4-conjungate addition（Michael addition） reaction of active methylene compounds to aft-unsaturated compounds, catalyzed by guanidinium lactate ionic liquid（IL9）, has been developed. A range of chalcones and nitroalkenes together with active methylene compounds have been converted smoothly to the corresponding products in high yields.展开更多
Sulfur dioxide（SO_2） is a harmful environmental pollutant. Inhaled SO_2 can be rapidly hydrated into its derivatives, bisulfite（HSO_3^-） and sulfite（SO_3^（2-））. SO_2 derivatives are well known as preservatives...Sulfur dioxide（SO_2） is a harmful environmental pollutant. Inhaled SO_2 can be rapidly hydrated into its derivatives, bisulfite（HSO_3^-） and sulfite（SO_3^（2-））. SO_2 derivatives are well known as preservatives and antioxidants, which are used in food and beverages to prevent oxidation and bacterial growth. Although SO_2 can be endogenously generated in mammals and exhibits unique bioactivities in regulating cardiovascular function, excessive SO_2 and its derivatives have toxic effects on humans and animals for triggering adverse reactions and diseases. A large number of fluorescent probes for SO_2 and its derivatives have been designed and reported due to their high sensitivity and selectivity, high temporal and spatial resolution, non-invasive and non-destructive detection as well as real-time visualization in situ. In this review, we have summarized the recent progress of Michael addition-based fluorescent probes for SO_2 and its derivatives. These probes are categorized and concluded according to the different α,β-unsaturated compounds（i.e., Michael acceptors）. The design strategies, sensing performances, detection mechanisms and applications of these probes are discussed in detailed. Finally, a general overview about the design of probes for SO_2 and its derivatives is provided, which will facilitate the development of ideal probes for SO_2 and its derivatives.展开更多
A series of novel Michael addition products of fluorene to chalcone were obtained in the presence of sodium hydroxide under solvent-free condition. The advantages of this procedure were mild reaction conditions, simpl...A series of novel Michael addition products of fluorene to chalcone were obtained in the presence of sodium hydroxide under solvent-free condition. The advantages of this procedure were mild reaction conditions, simple protocol, and high yields. The structures of the products were characterized by IR, 1H NMR, MS and X-ray diffraction. The crystal of the new compound 3 h is Triclinic, space group P-1 with a = 0.97352（6） nm, b = 1.08918（7） nm, c = 2.58418（16） nm, α = 80.1400（10）°, β = 79.5490（10）°, γ = 64.2440（10）°, V = 2.4137（3） nm3, Z = 4, Dc=1.220 g/cm3,μ = 0.286 mm-1, F（000） = 920, R = 0.0656 and wR = 0.1554 for 5664 observed reflection with I 〉 2σ（I）.展开更多
Michael addition of active methylene compounds to α,β-unsaturated carboxylic esters and nitriles was effectively catalyzed by a basic ionic liquid, 1-butyl-3-methylimidazolium acetate（[Bmim]OAc）. The his-addition ...Michael addition of active methylene compounds to α,β-unsaturated carboxylic esters and nitriles was effectively catalyzed by a basic ionic liquid, 1-butyl-3-methylimidazolium acetate（[Bmim]OAc）. The his-addition products were selectively obtained in high yields under mild reaction conditions.展开更多
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.
An efficient Michael addition of indoles to unsaturated enones, such as chalcones and β-nitrostyrenes, was achieved in the presence of a catalytic amount of nitrosonium tetrafluoroborate in ethyl ether. 2007 Long M...An efficient Michael addition of indoles to unsaturated enones, such as chalcones and β-nitrostyrenes, was achieved in the presence of a catalytic amount of nitrosonium tetrafluoroborate in ethyl ether. 2007 Long Min Wu. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved.展开更多
An efficient method was developed for the conjugate addition of water to various a,β-unsaturated ketones by using bismuth(Ⅲ)chlo ride as a catalyst.The reactions proceeded smoothly in the presence of a catalytic amo...An efficient method was developed for the conjugate addition of water to various a,β-unsaturated ketones by using bismuth(Ⅲ)chlo ride as a catalyst.The reactions proceeded smoothly in the presence of a catalytic amount of BiCl3(20 mol%)in aqueous media to furnish a variety of synthetically usefulβ-hydroxyl ketones in moderate to good yields.Apart from water molecule,various alcohols could also be employed as nucleophiles to react withα,β-unsaturated ketones,leading toβ-alkoxyl ketones in modest to high yields.In addition,the mild reaction conditions also entailed the conjugate addition reactions to proceed with the tolerance to a range of functional groups.展开更多
A dabco-based basic ionic liquid,1-butyl-4-aza-1-azaniabicyclo[2.2.2]octane hydroxide,has been developed as a catalyst for a convenient and rapid method for the Michael addition of active methylene compounds to a b-un...A dabco-based basic ionic liquid,1-butyl-4-aza-1-azaniabicyclo[2.2.2]octane hydroxide,has been developed as a catalyst for a convenient and rapid method for the Michael addition of active methylene compounds to a b-unsaturated carboxylic esters and nitriles.The method is very simple,and the yields are very high.The catalyst can be recycled several times without much loss of activity.展开更多
Cinchona alkaloid is one of the most effective organocatalysts that facilitate a wide range of transformations. To elucidate the mechanistic details and especially the origins of the observed high enantio- and diaster...Cinchona alkaloid is one of the most effective organocatalysts that facilitate a wide range of transformations. To elucidate the mechanistic details and especially the origins of the observed high enantio- and diastereoselectivities, computational chemists have contributed dramatic efforts in this important area. This review covers the recent computational studies on the cinchona alkaloid-catalyzed asymmetric Michael additions, including both C-C and C-S bond formations, to present a general viewpoint of these fruitful advances. Based on the types of bond formation and the cinchona alkaloid catalysts, key information regarding the activation model and the origins of enantioselectivities is discussed.展开更多
A catalyst-free, facile and efficient Michael addition reaction of active methylene compounds as well as nitromethane with chalcones catalyzed by guanidinium lactate ionic liquid was done. A series of chalcones, nitro...A catalyst-free, facile and efficient Michael addition reaction of active methylene compounds as well as nitromethane with chalcones catalyzed by guanidinium lactate ionic liquid was done. A series of chalcones, nitromethane, and active methylene compounds were converted smoothly to the corresponding products in high yields. The simple procedure, very mild conditions, high yields, and reuse of the IL without any loss of catalytic activity make this protocol considerably attractive for academic researches and practical applications.展开更多
Multiple hydrogen bonds containing nucleophilic phosphines derived from dipeptide dual-reagents catalyzed asymmetric Michael addition reactions between indene esters and activated olefins in high yields and good to ex...Multiple hydrogen bonds containing nucleophilic phosphines derived from dipeptide dual-reagents catalyzed asymmetric Michael addition reactions between indene esters and activated olefins in high yields and good to excellent enantioselectivities under mild reaction conditions.The success of current highly selective reactions should provide inspiration for expansion to other reactions and would open up new paradigms for the synthesis of indanone derivatives bearing chiral quaternary carbon centers.展开更多
Michael addition of the chiral alpha,beta -unsaturated ester 2 with furyl lithium proceeded in syn manner with excellent diastereoselectivity. The diastereoselectivity was not affected by the configuration of the doub...Michael addition of the chiral alpha,beta -unsaturated ester 2 with furyl lithium proceeded in syn manner with excellent diastereoselectivity. The diastereoselectivity was not affected by the configuration of the double bond in 2.展开更多
The synthesis of three isomers based on Michael addition mechanism for the detection of sulfurcontaining species in aqueous solution is described. These compounds are constructed by conjugating an enone to a coumarin ...The synthesis of three isomers based on Michael addition mechanism for the detection of sulfurcontaining species in aqueous solution is described. These compounds are constructed by conjugating an enone to a coumarin fluorophore. A substituted-phenyl（o, m, or p-） was appended at the carbonyl carbon to adjust the reactivity. The experimental results showed that（E）-7-（diethylamino）-3-（3-（3-hydroxyphenyl）-3-oxoprop-1-en-1-yl）-2H-chromen-2-one（m-QPS） and（E）-7-（diethylamino）-3-（3-（4-hydroxyphenyl）-3-oxoprop-1-en-1-yl）-2H-chromen-2-one（p-QPS） barely react with sulfur-containing nucleophiles, while（E）-7-（diethylamino）-3-（3-（2-hydroxyphenyl）-3-oxoprop-1-en-1-yl）-2H-chromen-2-one（o-QPS） exhibited a fast response toward sulfite, sulfide and thiols in DMSO/phosphate buffer（2：1）. The above results are probably due to the intramolecular H-bonding activated Michael addition.More interestingly, cysteine triggered unusual photophysical responses of o-QPS： the original absorption（488 nm） and emission peaks（573 nm） underwent significant blue shifts initially and then recovered,which might be caused by the Michael addition and elimination reaction, respectively.展开更多
C-H bond can undergo vicarious Michael addition reaction （VMA） with doubleactivated double bond in the absence of strong base and catalyst under mild conditions. Intramolecular H-bonding, electron-withdrawing induct...C-H bond can undergo vicarious Michael addition reaction （VMA） with doubleactivated double bond in the absence of strong base and catalyst under mild conditions. Intramolecular H-bonding, electron-withdrawing inductive effect, and steric hindrance at aposition of nucleophile facilitates C-H addition over N-H addition. By using VMA, high branching multiplicity, novel branching pattern, controllable density and distribution of functional groups can be envisioned for novel dendrimer synthesis.展开更多
A novel upper-rim functionalized calix[4]squaramide organocatalyst bearing bis-squaramide and cyclohexanediamine scaffolds was designed and prepared to catalyse a serial of asymmetric Michael addition of 1,3-dicarbo n...A novel upper-rim functionalized calix[4]squaramide organocatalyst bearing bis-squaramide and cyclohexanediamine scaffolds was designed and prepared to catalyse a serial of asymmetric Michael addition of 1,3-dicarbo nyl compounds to a,β-unsaturated carbonyl compounds in high yields(up to 99%)and good to excellent enantiomeric excesses(up to 99%ee).The comparative experiments indicated that the cooperative effect between calixarenes cavitives and chiral catalytic centers on this calix[4]squaramide catalyst could promote these reactions.Moreover,this strategy also provides valuable and easy access to chiral chromene,naphthoquinone and acetylacetone derivatives,which are important skeletons in biological and pharmaceutical compounds.展开更多
文摘A direct Michael addition reaction between imidazo[1,2-a]pyridines andα,β-unsaturated ketones using acidic alumina as a C(sp3)—H acid catalyst has been developed.The abundant C(sp3)—H acid sites(Al^(3+))on the acidic alumina surface effectively activate the carbonyl group ofα,β-unsaturated ketones,significantly enhancing the electrophilicity of theβ-carbon and thereby facilitating selective alkylation at the C3 position of imidazo[1,2-a]pyridines.This method demonstrates excellent functional group compatibility,mild reaction conditions,low reagent costs,and operational simplicity,providing a novel strategy for the efficient synthesis of alkylated imidazo[1,2-a]pyridine derivatives.
基金supported by the National Natural Science Foundation of China (21425627,21376279)~~
文摘Nineβ‐cyclodextrin derivatives containing an amino group were synthesized via nucleophilic sub‐stitution from mono（6‐O‐p‐tolylsulfonyl）‐β‐cyclodextrin and used in asymmetric biomimetic Mi‐chael addition reactions in water at room temperature. The mechanism responsible for the moder‐ate activity and enantioselectivity of the β‐cyclodextrin derivatives was explored using nuclear magnetic resonance spectroscopy, namely 2D 1H rotating‐frame overhauser effect spectroscopy （ROESY）, ultraviolet absorption spectroscopy, and quantum chemical calculations, which provide a useful technique for investigating the formation of inclusion complexes. The effects of the pH of the reaction medium, theβ‐cyclodextrin derivative dosage, the structure of the modifying amino group, and various substrates on the yield and enantioselectivity were investigated. The results indicated that these factors had an important effect on the enantiomeric excess （ee） in the reaction system. Experiments using a competitor for inclusion complex formation showed that a hydrophobic cavity is necessary for enantioselective Michael addition. A comparison of the reactions using 4‐nitro‐β‐nitrostyrene and 2‐nitro‐β‐nitrostyrene showed that steric hindrance improved the enan‐tioselectivity. This was verified by the optimized geometries obtained from quantum chemical cal‐culations. An ee of 71%was obtained in the asymmetric Michael addition of cyclohexanone and 2‐nitro‐β‐nitrostyrene, using （S）‐2‐aminomethylpyrrolidine‐modified β‐CD as the catalyst, in an aqueous buffer solution, i.e., CH3COONa‐HCl （pH 7.5）.
文摘Nitroalkanes react smoothly with CF_3CCl_2COCH=CHPh via Michael addition in the presence of inorganic bases such as KF/Al2O3 or K2CO3, giving fluorinecontaining γ-nitro ketones in good yields.
基金This work was supported by the National Key Basic Research Special Foundation （No.2007CB815202 and No.2009CB220010） and the National Natural Science Foundation of China （No.20833008）.
文摘The solvents and substituents of two similar fluorescent sensors for cyanide, 7-diethylamino- 3-formylcoumarin （sensor a） and 7-diethylamino-3-（2-nitrovinyl）coumarin （sensor b）, are proposed to account for their distinct sensing mechanisms and experimental phenomena. The time-dependent density functional theory has been applied to investigate the ground states and the first singlet excited electronic states of the sensor as well as their possible Michael reaction products with cyanide, with a view to monitoring their geometries and photophysieal properties. The theoretical study indicates that the protic water solvent could lead to final Michael addition product of sensor a in the ground state, while the aprotic acetonitrile solvent could lead to carbanion as the final product of sensor b. Furthermore, the Michael reaction product of sensor a has been proved to have a torsion structure in its first singlet excited state. Correspondingly, sensor b also has a torsion structure around the nitrovinyl moiety in its first singlet excited state, while not in its carbanion structure. This could explain the observed strong fluorescence for sensor a and the quenching fluorescence for the sensor b upon the addition of the cyanide anions in the relevant sensing mechanisms.
基金Supported by the Jilin University Innovation Fund(No.419070200033).
文摘A facile and efficient 1, 4-conjungate addition（Michael addition） reaction of active methylene compounds to aft-unsaturated compounds, catalyzed by guanidinium lactate ionic liquid（IL9）, has been developed. A range of chalcones and nitroalkenes together with active methylene compounds have been converted smoothly to the corresponding products in high yields.
基金financially supported by the National Key Research and Development Program of China (No. 2017YFD0501406)the National Natural Science Foundation of China (Nos. 31400301, 31560712)
文摘Sulfur dioxide（SO_2） is a harmful environmental pollutant. Inhaled SO_2 can be rapidly hydrated into its derivatives, bisulfite（HSO_3^-） and sulfite（SO_3^（2-））. SO_2 derivatives are well known as preservatives and antioxidants, which are used in food and beverages to prevent oxidation and bacterial growth. Although SO_2 can be endogenously generated in mammals and exhibits unique bioactivities in regulating cardiovascular function, excessive SO_2 and its derivatives have toxic effects on humans and animals for triggering adverse reactions and diseases. A large number of fluorescent probes for SO_2 and its derivatives have been designed and reported due to their high sensitivity and selectivity, high temporal and spatial resolution, non-invasive and non-destructive detection as well as real-time visualization in situ. In this review, we have summarized the recent progress of Michael addition-based fluorescent probes for SO_2 and its derivatives. These probes are categorized and concluded according to the different α,β-unsaturated compounds（i.e., Michael acceptors）. The design strategies, sensing performances, detection mechanisms and applications of these probes are discussed in detailed. Finally, a general overview about the design of probes for SO_2 and its derivatives is provided, which will facilitate the development of ideal probes for SO_2 and its derivatives.
文摘A series of novel Michael addition products of fluorene to chalcone were obtained in the presence of sodium hydroxide under solvent-free condition. The advantages of this procedure were mild reaction conditions, simple protocol, and high yields. The structures of the products were characterized by IR, 1H NMR, MS and X-ray diffraction. The crystal of the new compound 3 h is Triclinic, space group P-1 with a = 0.97352（6） nm, b = 1.08918（7） nm, c = 2.58418（16） nm, α = 80.1400（10）°, β = 79.5490（10）°, γ = 64.2440（10）°, V = 2.4137（3） nm3, Z = 4, Dc=1.220 g/cm3,μ = 0.286 mm-1, F（000） = 920, R = 0.0656 and wR = 0.1554 for 5664 observed reflection with I 〉 2σ（I）.
基金Supported by the National Natural Science Foundation of China(Nos.20533010 and 20873041)Shanghai Leading Academic Discipline Project,China(No.B409)
文摘Michael addition of active methylene compounds to α,β-unsaturated carboxylic esters and nitriles was effectively catalyzed by a basic ionic liquid, 1-butyl-3-methylimidazolium acetate（[Bmim]OAc）. The his-addition products were selectively obtained in high yields under mild reaction conditions.
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.
基金Project No. 20572040 was supported by National Natural Science Foundation of China.
文摘An efficient Michael addition of indoles to unsaturated enones, such as chalcones and β-nitrostyrenes, was achieved in the presence of a catalytic amount of nitrosonium tetrafluoroborate in ethyl ether. 2007 Long Min Wu. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved.
基金financial support from Nanjing Tech University(Start-up Grant No.39837118)Yancheng Teachers University,and Nanjing Forestry University。
文摘An efficient method was developed for the conjugate addition of water to various a,β-unsaturated ketones by using bismuth(Ⅲ)chlo ride as a catalyst.The reactions proceeded smoothly in the presence of a catalytic amount of BiCl3(20 mol%)in aqueous media to furnish a variety of synthetically usefulβ-hydroxyl ketones in moderate to good yields.Apart from water molecule,various alcohols could also be employed as nucleophiles to react withα,β-unsaturated ketones,leading toβ-alkoxyl ketones in modest to high yields.In addition,the mild reaction conditions also entailed the conjugate addition reactions to proceed with the tolerance to a range of functional groups.
文摘A dabco-based basic ionic liquid,1-butyl-4-aza-1-azaniabicyclo[2.2.2]octane hydroxide,has been developed as a catalyst for a convenient and rapid method for the Michael addition of active methylene compounds to a b-unsaturated carboxylic esters and nitriles.The method is very simple,and the yields are very high.The catalyst can be recycled several times without much loss of activity.
基金Financial support from the National Natural Science Foundation of China (NSFC, No. 21702182)the Chinese "Thousand Youth Talents Plan+1 种基金Fundamental Research Funds for the Central Universities"Zhejiang University
文摘Cinchona alkaloid is one of the most effective organocatalysts that facilitate a wide range of transformations. To elucidate the mechanistic details and especially the origins of the observed high enantio- and diastereoselectivities, computational chemists have contributed dramatic efforts in this important area. This review covers the recent computational studies on the cinchona alkaloid-catalyzed asymmetric Michael additions, including both C-C and C-S bond formations, to present a general viewpoint of these fruitful advances. Based on the types of bond formation and the cinchona alkaloid catalysts, key information regarding the activation model and the origins of enantioselectivities is discussed.
文摘A catalyst-free, facile and efficient Michael addition reaction of active methylene compounds as well as nitromethane with chalcones catalyzed by guanidinium lactate ionic liquid was done. A series of chalcones, nitromethane, and active methylene compounds were converted smoothly to the corresponding products in high yields. The simple procedure, very mild conditions, high yields, and reuse of the IL without any loss of catalytic activity make this protocol considerably attractive for academic researches and practical applications.
基金Financial support from Chinese Academy of Sciences (No.XDB 20020100)the National Natural Science Foundation of China (Nos.21572247,21871282) is gratefully acknowledged。
文摘Multiple hydrogen bonds containing nucleophilic phosphines derived from dipeptide dual-reagents catalyzed asymmetric Michael addition reactions between indene esters and activated olefins in high yields and good to excellent enantioselectivities under mild reaction conditions.The success of current highly selective reactions should provide inspiration for expansion to other reactions and would open up new paradigms for the synthesis of indanone derivatives bearing chiral quaternary carbon centers.
基金This work was partially supported by the National Natural Science Foundation of China.
文摘Michael addition of the chiral alpha,beta -unsaturated ester 2 with furyl lithium proceeded in syn manner with excellent diastereoselectivity. The diastereoselectivity was not affected by the configuration of the double bond in 2.
基金supported by National 973 Program (No. 2011CB910403)Shanghai Municipal Natural Science Foundation (No. 15ZR1409000)the open fund of Shanghai Key Laboratory of Chemical Biology (No. SKLCB-2013-03)
文摘The synthesis of three isomers based on Michael addition mechanism for the detection of sulfurcontaining species in aqueous solution is described. These compounds are constructed by conjugating an enone to a coumarin fluorophore. A substituted-phenyl（o, m, or p-） was appended at the carbonyl carbon to adjust the reactivity. The experimental results showed that（E）-7-（diethylamino）-3-（3-（3-hydroxyphenyl）-3-oxoprop-1-en-1-yl）-2H-chromen-2-one（m-QPS） and（E）-7-（diethylamino）-3-（3-（4-hydroxyphenyl）-3-oxoprop-1-en-1-yl）-2H-chromen-2-one（p-QPS） barely react with sulfur-containing nucleophiles, while（E）-7-（diethylamino）-3-（3-（2-hydroxyphenyl）-3-oxoprop-1-en-1-yl）-2H-chromen-2-one（o-QPS） exhibited a fast response toward sulfite, sulfide and thiols in DMSO/phosphate buffer（2：1）. The above results are probably due to the intramolecular H-bonding activated Michael addition.More interestingly, cysteine triggered unusual photophysical responses of o-QPS： the original absorption（488 nm） and emission peaks（573 nm） underwent significant blue shifts initially and then recovered,which might be caused by the Michael addition and elimination reaction, respectively.
文摘C-H bond can undergo vicarious Michael addition reaction （VMA） with doubleactivated double bond in the absence of strong base and catalyst under mild conditions. Intramolecular H-bonding, electron-withdrawing inductive effect, and steric hindrance at aposition of nucleophile facilitates C-H addition over N-H addition. By using VMA, high branching multiplicity, novel branching pattern, controllable density and distribution of functional groups can be envisioned for novel dendrimer synthesis.
基金the financial support from the National Natural Science Foundation of China(Nos.21572026 and 21702019)Advanced Catalysis and Green Manufacturing Collabo-rative Innovation Center,Changzhou University,and the Priority Academic Program Development of Jiangsu Higher Education Institutions.
文摘A novel upper-rim functionalized calix[4]squaramide organocatalyst bearing bis-squaramide and cyclohexanediamine scaffolds was designed and prepared to catalyse a serial of asymmetric Michael addition of 1,3-dicarbo nyl compounds to a,β-unsaturated carbonyl compounds in high yields(up to 99%)and good to excellent enantiomeric excesses(up to 99%ee).The comparative experiments indicated that the cooperative effect between calixarenes cavitives and chiral catalytic centers on this calix[4]squaramide catalyst could promote these reactions.Moreover,this strategy also provides valuable and easy access to chiral chromene,naphthoquinone and acetylacetone derivatives,which are important skeletons in biological and pharmaceutical compounds.
