The effect of cosolvent on the palladium catalyst which catalyze alkoxycarbonylation of allyl bromide in supercritical CO2 has been investigated. It was found that a small amount of cosolvent such as ethanol, CH2Cl2 a...The effect of cosolvent on the palladium catalyst which catalyze alkoxycarbonylation of allyl bromide in supercritical CO2 has been investigated. It was found that a small amount of cosolvent such as ethanol, CH2Cl2 and cyclohexane can affect both reaction yields and selectivities largely. Ethanol was the most favorable cosolvent for increasing the total yield of unsaturated esters and the selectivity of 3-butenoic acid ester. Using cosolvent ethanol and cocatalyst FeCl2 Simultaneously can lead to better reaction results.展开更多
Heterogenization of the homogeneous catalysis has been studied for almost 50 years.Single-atom catalysis has the advantages of both homo-and heterogeneous catalysis.It has been proposed,and subsequently experimentally...Heterogenization of the homogeneous catalysis has been studied for almost 50 years.Single-atom catalysis has the advantages of both homo-and heterogeneous catalysis.It has been proposed,and subsequently experimentally verified that single-atom catalysis is able to bridge homo-and heterogeneous catalysis,thus providing a new avenue to realize the heterogenization of homogeneous catalysis.Alkoxycarbonylation of aryl halides is an effective method for the direct synthesis of carboxylic acid derivatives,and is commonly catalyzed by Pd-based homogeneous complexes with N/P-containing ligands and organic/inorganic base.Herein,we firstly reported that Pd1/CeO2 single-atom catalyst showed good performance in the alkoxycarbonylation of aryl iodides reaction.Under base-free and ligand-free conditions,Pd1/CeO2 single-atom catalyst can transfer different aryl iodides to corresponding products.The catalyst can be easily recovered and reused four times without significant loss of reactivity.展开更多
Quinoxaline-3-carboxylates and analogues are prevalent key structural motifs in bioactive natural products and synthetic drugs.However, the practical protocol for preparation of these motifs from simple raw materials ...Quinoxaline-3-carboxylates and analogues are prevalent key structural motifs in bioactive natural products and synthetic drugs.However, the practical protocol for preparation of these motifs from simple raw materials under mild conditions remains rare. In this article, we report a facile protocol for the efficient preparation of various quinoxaline-3-carbonyl compounds(30 examples,63%–92%) through oxidation coupling of quinoxalin-2(1H)-ones with readily available carbazates(or acyl hydrazines) in the presence of K_2S_2O_8 as an oxidant in metal-and base-free conditions. When tert-butyl carbazate was used as the coupling reagent,the decarboxylation product 3-(tert-butyl)-1-methylquinoxalin-2(1H)-one was obtained. The application of this process into a gram-scale synthesis can be easily accomplished. Mechanistic investigations reveal that the functionalization of quinoxalin-2(1H)-ones via a free-radical pathway.展开更多
A novel alkoxycarbonyl thiourea resin(ATR)was synthesized by monomer polymerization of oxydiethane-2,1-diyl dicarbonisothiocyanatidate and polyethylene polyamine,and characterized by FT-IR.The adsorption properties of...A novel alkoxycarbonyl thiourea resin(ATR)was synthesized by monomer polymerization of oxydiethane-2,1-diyl dicarbonisothiocyanatidate and polyethylene polyamine,and characterized by FT-IR.The adsorption properties of ATR were investigated by batch test.The adsorption capacities for Au(Ⅲ),Ag(Ⅰ),Cu(Ⅱ),Zn(Ⅱ),Fe(Ⅲ),Ca(Ⅱ)and Mg(Ⅱ)are 4.65,4.40,0.40,0.90,0.86,0.0080 and 0.016 mmol/g,respectively,when the adsorption condition is as follows:contact time 24 h,temperature 30℃,initial concentration of Au(Ⅲ)5.08 mmol/L and that of other metals 0.10 mol/L,and concentration of acid 1.0 mol/L.The adsorption capacity for Au(Ⅲ)increases with the increase of contact time,temperature and initial concentration of Au(Ⅲ).The capacity after five adsorption-desorption cycles remains 90%that of the first time,and the separation factors of ATR for binary metal ion solutions are larger than 995,indicating that ATR is of good regeneration property and selectivity.XPS results show that the functional atoms of ATR supply electrons for Au and coordinate with Au during the adsorption.展开更多
Functionalized free radical addition/cyclization reactions represent an efficient way for introducing new functionality or coupling fragments to molecules.Ynones are good regional selectivity radical acceptors in orga...Functionalized free radical addition/cyclization reactions represent an efficient way for introducing new functionality or coupling fragments to molecules.Ynones are good regional selectivity radical acceptors in organic synthesis,and many of bio-relevant cyclic compounds could be easily obtained by direct radical cyclization reaction.Here,we report a photocatalytic cascade radical addition of biaryl ynones,for the divergent synthesis of privileged carbon cycles.Additionally,further transformation of the multi-functional group product into a variety of other derivatives demonstrates the synthetic value of this developed method.展开更多
A new type of intramolecular electrophilic rearrangements involving the shift of alkoxycarbonyl or acetyl groups from a carbon atom to an N-anionic center is presented.
A synergistic Pd/Zn dual chiral catalyst system has been developed for the stereodivergent transformation of Morita–Baylis–Hillman(MBH)carbonates and unprotectedα-hydroxyketones to afford the corresponding allylati...A synergistic Pd/Zn dual chiral catalyst system has been developed for the stereodivergent transformation of Morita–Baylis–Hillman(MBH)carbonates and unprotectedα-hydroxyketones to afford the corresponding allylation products(>50 examples).These products bearing vicinal stereocenters were obtained in high yields with excellent regio-/diastereo-/enantioselectivities.On cyclization in an acidic medium,the allylation products could transform to the corresponding acyl-functionalizedβ,γ-disubstitutedα-methylene-γ-butyrolactones(AMGBLs).All four stereoisomers of AMGBL were readily accessed using the same starting materials with full control of the stereochemistry of the contiguous stereogenic centers,simply by switching the chiral ligand combination for the Pd/Zn system.A nucleophilic site-divergent reactivity was observed for the allylation of primary and secondaryα-hydroxyketones,suggesting that distinct enolate intermediates might have prevailed in these reactions.展开更多
A new approach for radical cross coupling of organic halides and oxalates toward esters has been developed via photoredox nickel dual catalysis.This method has been demonstrated for transformation of a wide range of a...A new approach for radical cross coupling of organic halides and oxalates toward esters has been developed via photoredox nickel dual catalysis.This method has been demonstrated for transformation of a wide range of aryl,heteroaryl,alkenyl,and alkyl bromides to various esters under mild conditions.Notably,fluoro-,chloro-,or iodo-substituents on the aryl bromides remain after the coupling reaction,which has been applied for the easy synthesis of drug molecules from simple aryl dihalides.Mechanistic studies indicate that an(alkoxycarbonyl)Ni(I)species might be generated via oxidation of Ni(0)species with an alkoxycarbonyl radical intermediate.Selective alkoxycarbonyl radical coupling over decarboxylative alkyl radical coupling is achieved here.展开更多
文摘The effect of cosolvent on the palladium catalyst which catalyze alkoxycarbonylation of allyl bromide in supercritical CO2 has been investigated. It was found that a small amount of cosolvent such as ethanol, CH2Cl2 and cyclohexane can affect both reaction yields and selectivities largely. Ethanol was the most favorable cosolvent for increasing the total yield of unsaturated esters and the selectivity of 3-butenoic acid ester. Using cosolvent ethanol and cocatalyst FeCl2 Simultaneously can lead to better reaction results.
基金financially supported by the National Natural Science Foundation of China (21776270)the Strategic Priority Research Program of the Chinese Academy of Sciences(XDB17020100)+3 种基金China Postdoctoral Science Foundation(2017M621170)DICP Outstanding Postdoctoral Foundation(2017YB02)Liaoning Revitalization Talents Programdedicated funds for methanol conversion from DICP
文摘Heterogenization of the homogeneous catalysis has been studied for almost 50 years.Single-atom catalysis has the advantages of both homo-and heterogeneous catalysis.It has been proposed,and subsequently experimentally verified that single-atom catalysis is able to bridge homo-and heterogeneous catalysis,thus providing a new avenue to realize the heterogenization of homogeneous catalysis.Alkoxycarbonylation of aryl halides is an effective method for the direct synthesis of carboxylic acid derivatives,and is commonly catalyzed by Pd-based homogeneous complexes with N/P-containing ligands and organic/inorganic base.Herein,we firstly reported that Pd1/CeO2 single-atom catalyst showed good performance in the alkoxycarbonylation of aryl iodides reaction.Under base-free and ligand-free conditions,Pd1/CeO2 single-atom catalyst can transfer different aryl iodides to corresponding products.The catalyst can be easily recovered and reused four times without significant loss of reactivity.
基金supported by the Hunan Provincial Natural Science Foundation of China (2019JJ20008)the Construct Program of Applied Characteristic Discipline in Hunan University of Science and Engineering
文摘Quinoxaline-3-carboxylates and analogues are prevalent key structural motifs in bioactive natural products and synthetic drugs.However, the practical protocol for preparation of these motifs from simple raw materials under mild conditions remains rare. In this article, we report a facile protocol for the efficient preparation of various quinoxaline-3-carbonyl compounds(30 examples,63%–92%) through oxidation coupling of quinoxalin-2(1H)-ones with readily available carbazates(or acyl hydrazines) in the presence of K_2S_2O_8 as an oxidant in metal-and base-free conditions. When tert-butyl carbazate was used as the coupling reagent,the decarboxylation product 3-(tert-butyl)-1-methylquinoxalin-2(1H)-one was obtained. The application of this process into a gram-scale synthesis can be easily accomplished. Mechanistic investigations reveal that the functionalization of quinoxalin-2(1H)-ones via a free-radical pathway.
基金Projects(20476105,50604016)supported by the National Natural Science Foundation of China
文摘A novel alkoxycarbonyl thiourea resin(ATR)was synthesized by monomer polymerization of oxydiethane-2,1-diyl dicarbonisothiocyanatidate and polyethylene polyamine,and characterized by FT-IR.The adsorption properties of ATR were investigated by batch test.The adsorption capacities for Au(Ⅲ),Ag(Ⅰ),Cu(Ⅱ),Zn(Ⅱ),Fe(Ⅲ),Ca(Ⅱ)and Mg(Ⅱ)are 4.65,4.40,0.40,0.90,0.86,0.0080 and 0.016 mmol/g,respectively,when the adsorption condition is as follows:contact time 24 h,temperature 30℃,initial concentration of Au(Ⅲ)5.08 mmol/L and that of other metals 0.10 mol/L,and concentration of acid 1.0 mol/L.The adsorption capacity for Au(Ⅲ)increases with the increase of contact time,temperature and initial concentration of Au(Ⅲ).The capacity after five adsorption-desorption cycles remains 90%that of the first time,and the separation factors of ATR for binary metal ion solutions are larger than 995,indicating that ATR is of good regeneration property and selectivity.XPS results show that the functional atoms of ATR supply electrons for Au and coordinate with Au during the adsorption.
基金the Natural Science Foundation of Zhejiang Province(LY22B020001)the Zhejiang Public Welfare Public Research Program(LGC22B010001)the National Natural Science Foundation of China(32201238)is greatly acknowledged.
文摘Functionalized free radical addition/cyclization reactions represent an efficient way for introducing new functionality or coupling fragments to molecules.Ynones are good regional selectivity radical acceptors in organic synthesis,and many of bio-relevant cyclic compounds could be easily obtained by direct radical cyclization reaction.Here,we report a photocatalytic cascade radical addition of biaryl ynones,for the divergent synthesis of privileged carbon cycles.Additionally,further transformation of the multi-functional group product into a variety of other derivatives demonstrates the synthetic value of this developed method.
文摘A new type of intramolecular electrophilic rearrangements involving the shift of alkoxycarbonyl or acetyl groups from a carbon atom to an N-anionic center is presented.
基金the National Key R&D Program of China(grant nos.2023YFA1506700,2022YFA1503702,and 2021YFF0701602)National Natural Science Foundation of China(NSFC,grant nos.22231011 and 22271303)Shanghai Scientific and Technological Innovation Project,China(grant no.22JC1401000).
文摘A synergistic Pd/Zn dual chiral catalyst system has been developed for the stereodivergent transformation of Morita–Baylis–Hillman(MBH)carbonates and unprotectedα-hydroxyketones to afford the corresponding allylation products(>50 examples).These products bearing vicinal stereocenters were obtained in high yields with excellent regio-/diastereo-/enantioselectivities.On cyclization in an acidic medium,the allylation products could transform to the corresponding acyl-functionalizedβ,γ-disubstitutedα-methylene-γ-butyrolactones(AMGBLs).All four stereoisomers of AMGBL were readily accessed using the same starting materials with full control of the stereochemistry of the contiguous stereogenic centers,simply by switching the chiral ligand combination for the Pd/Zn system.A nucleophilic site-divergent reactivity was observed for the allylation of primary and secondaryα-hydroxyketones,suggesting that distinct enolate intermediates might have prevailed in these reactions.
基金the financial support from the NSFC of China(21772208 and 21633013)Natural Science Foundation of Jiangsu Province(BK20201183)the Key Research Program of Frontier Sciences of Chinese Academy of Sciences(QYZDJSSW-SLH051).
文摘A new approach for radical cross coupling of organic halides and oxalates toward esters has been developed via photoredox nickel dual catalysis.This method has been demonstrated for transformation of a wide range of aryl,heteroaryl,alkenyl,and alkyl bromides to various esters under mild conditions.Notably,fluoro-,chloro-,or iodo-substituents on the aryl bromides remain after the coupling reaction,which has been applied for the easy synthesis of drug molecules from simple aryl dihalides.Mechanistic studies indicate that an(alkoxycarbonyl)Ni(I)species might be generated via oxidation of Ni(0)species with an alkoxycarbonyl radical intermediate.Selective alkoxycarbonyl radical coupling over decarboxylative alkyl radical coupling is achieved here.
