Sulfoxides and sulfide compounds have broad-spectrum biological properties and have received considerable attention in the past few decades.Herein we reported two metal and oxidant-free,practical and efficient methods...Sulfoxides and sulfide compounds have broad-spectrum biological properties and have received considerable attention in the past few decades.Herein we reported two metal and oxidant-free,practical and efficient methods for the synthesis of highly synthetically useful and structurally diverse ortho-aminoaryl sulfoxides and 3,4,5-trisubstituted oxazolones from readily accessible N-arylhydroxylamines and N-thiophthalimides.This rapid transformation occurred smoothly to achieve chemo-and regioselective cascade rearrangements due to the differences of the protecting-groups of the nitrogen atom of N-arylhydroxyamines.DFT studies suggested that the competing S-O and S-C bond formations via SN2 nucleophilic substitution are crucial for the observed protecting-group-dependent chemoselectivity.Subsequent applications have shown that these two protocols might be powerful tools for the construction of sulfur-containing complex molecules under simple conditions.展开更多
Regioselevtive functionalization of perylene diimides(PDIs)at bay area often requires multistep synthesis and strenuous recrystallization.Direct bromination of perylene diimides only afford the 1,6 and 1,7-regioisomer...Regioselevtive functionalization of perylene diimides(PDIs)at bay area often requires multistep synthesis and strenuous recrystallization.Direct bromination of perylene diimides only afford the 1,6 and 1,7-regioisomers.More importantly,the 1,6-dibromo regioisomers could only be separated by preparative HPLC.Herein,we report a promising strategy for constructing Janus backbone of BN-doped perylene diimide derivatives.This Janus-type configuration results in the unique regioselective functionalization of BN-JPDIs,which yields exclusively the 1,6-regioisomers.Further investigation shows that the Janus-type configuration leads to a net dipole moment of 1.94 D and intramolecular charge transfer,which causes substantial changes on the optoelectronic properties.Moreover,the single crystal organic field-effect transistors based on BN-JPDIs exhibit electron mobilities up to 0.57 cm^(2)V^(-1)s^(-1),showcasing their potential as versatile building block towards high-performance n-type organic semiconductors.展开更多
The 3＇-OH, 4＇-OH and 2＂-OH of kanamycin A were modified in search of new aminoglycosides to overcome resistant enzymes, ANTs and APHs. The key intermediate was a dibenzylidene-protected derivative of kanamycin A. T...The 3＇-OH, 4＇-OH and 2＂-OH of kanamycin A were modified in search of new aminoglycosides to overcome resistant enzymes, ANTs and APHs. The key intermediate was a dibenzylidene-protected derivative of kanamycin A. The aimed sites were masked by benzyl, methyl and allyl groups. Multi-step reactions gave the desired aminoglycoside derivatives but showed less antibiotic activity than kanamycin A.展开更多
Regioselective addition reactions of silyl enolates to a, b-unsaturated aldehyde and its acetal catalyzed by MgI2 etherate give aldol adducts (1, 2-addition) preferentially over Michael adducts (1, 4-addition). This ...Regioselective addition reactions of silyl enolates to a, b-unsaturated aldehyde and its acetal catalyzed by MgI2 etherate give aldol adducts (1, 2-addition) preferentially over Michael adducts (1, 4-addition). This unique regioselectivity is distinctly different with other Lewis acidic promoters and may be attributed to the high oxyphilicity of IMg+.展开更多
Polymerizations of linear α-olefins(CnH2n, CH2=CH―R, R = Cn-2) catalyzed by early transition metals typically afford amorphous polymers with alkyl chains(Cn-2), while chain-straightening polymerizations of α-olefin...Polymerizations of linear α-olefins(CnH2n, CH2=CH―R, R = Cn-2) catalyzed by early transition metals typically afford amorphous polymers with alkyl chains(Cn-2), while chain-straightening polymerizations of α-olefins with nickel-based catalysts produce semicrystalline polyolefins. Polymerizations of various α-olefins were carried out using an α-diamine nickel catalyst with a significantly distorted chelating ring. The influences of temperature, monomer concentration, and chain length of α-olefins on polyolefin microstructure were examined in detail. The α-diamine nickel catalyst realized highly regioselective 2,1-insertion of α-olefins regardless of reaction temperature and monomer concentration. Increased chain length of α-olefins led to the formation of more linear polyolefin.Semicrystalline polyolefins with high melting temperatures(Tm) were made from α-olefins through highly regioselective 2,1-insertion and precise chain-straightening.展开更多
Permanganate has attracted much attention in wide range of chemistry and particularly in degradation of environmental pollutants.However,few studies have discussed the feature of regioselective reactivity of permangan...Permanganate has attracted much attention in wide range of chemistry and particularly in degradation of environmental pollutants.However,few studies have discussed the feature of regioselective reactivity of permanganate with specific moiety of the target compound.Herein,we studied the reaction between permanganate and tetracycline that is an emerging micropollutant with different species containing several electron-rich groups.The second-order rate constants increased from 6.0 to 9.0 and could be quantitatively modeled by considering the speciation of both reactants,yielding kTC0=11.7(mol/L)^-1 sec^-1,kTC-=35.7(mol/L)^-1 sec^-1,kTC2-=43.1(mol/L)^-1 sec^-1 for individual reaction channels.Degradation products were then identified as the hydroxylated and demethylated compounds.The result suggested a rate-limiting step of simple hydroxylation at the phenolic and/or alkene moieties,while the demethylation should be caused by the unavoidably formed manganese oxide via single electron oxidation.This is supported by the DFT calculation,indicating the primary oxidation of phenolic group of TC0 with activation barrier of 44.5 kcal/mol and of alkene group of TC-and TC2-with activation barriers of 44.0 and 43.4 kcal/mol,respectively.This is in agreement with the experimental results,implying the alternation of regioselectivity associated with the deprotonation process.The result was further supported by performing the Fukui function and electrostatic potential analysis,reflecting the more probable site and better electron donating tendency beneficial to the permanganate oxidation.展开更多
A series of monosubstituted troxerutin esters have been synthesized by enzyme-catalyzed regioselective acylation of troxerutin in nonaqueous medium.Using divinyl dicarboxylates(CH_2=CH-OOC-(CH_2)_n-COO-CH=CH_2,n = 2,3...A series of monosubstituted troxerutin esters have been synthesized by enzyme-catalyzed regioselective acylation of troxerutin in nonaqueous medium.Using divinyl dicarboxylates(CH_2=CH-OOC-(CH_2)_n-COO-CH=CH_2,n = 2,3,4,7,8,11) featuring different chain length as acyl donors and alkaline protease from Bacillus subtilis as catalyst,troxerutin was regioselective acylated at B ethoxyl group.The results indicated that the regioselectivity of the enzyme-catalyzed acylation was not affected by the chain length o...展开更多
An efficient route for the palladium-catalyzed reductive aminocarbonylation of olefins with nitroarenes was developed using carbon monoxide(CO)as both reductant and carbonyl source,which enables facile access to amide...An efficient route for the palladium-catalyzed reductive aminocarbonylation of olefins with nitroarenes was developed using carbon monoxide(CO)as both reductant and carbonyl source,which enables facile access to amides with excellent regioselectivity and broad substrate scope.It is found that the counter anions of the Pd catalyst precursors significantly affect the reaction chemoselectivity and amide regioselectivity.Branched amides were mainly obtained with K2PdCl4 as the metal catalyst,and phosphine ligands had no influence on the regioselectivity but affected the catalytic reactivity.However,phosphine ligands had significant effects on aminocarbonylation regioselectivity when Pd(CH3CN)4(OTf)2 was used;monodentate phosphines tended to form branched amides,and bidentate phosphines mainly formed linear amides.Trapping experiments,primary kinetic studies,and control reactions with all possible N-species reduced from nitroarene indicated that the catalytic synthesis of branched and linear amides produced nitrene(further converted to enamide)and aniline,respectively,different from the previous ligand-controlled regioselective synthesis of amides via the aminocarbonylation of olefins with amines.Furthermore,the proposed synthesis route could be applied in the synthesis of gram-scale propanil under mild conditions.展开更多
Hydroalkoxycarbonylation of olefins has been considered to be one of the most attractive methods to synthesize esters. Controlling the regioselectivities of linear esters(L) and branched esters(B) is a challenging pro...Hydroalkoxycarbonylation of olefins has been considered to be one of the most attractive methods to synthesize esters. Controlling the regioselectivities of linear esters(L) and branched esters(B) is a challenging project for researchers working in this reaction. Although most of the attention has been paid to control the regioselectivity through ligand design in homogeneous catalytic systems, study in the area is still limited. Herein, Ru-clusters/CeO2 is employed as a heterogeneous catalyst for the hydromethoxycarbonylation of styrene without any additives. After optimization of the reaction conditions, the conversion of styrene is > 99% with 83% and 12% regioselectivity of linear and branched ester, respectively. By using different supports(CeO2(nanoparticle), CeO2-rod, and CeO2-cube), three catalysts including Ru-clusters/CeO2, Ru/CeO2-rod, and Ru/CeO2-cube are prepared and applied in the reaction. Structural characterizations demonstrate that the L/B ratio is related to the Ru size of supported Ru catalysts. Further Raman characterization and NH3-TPD demonstrate that the metal-support interaction and the concentration of oxygen vacancy of the catalyst have a great influence on the Ru size. The mechanism and kinetic analysis for this reaction are also investigated in this work.展开更多
Reaction of activated aromatics containing phenobs, naphthol, methoxynaphthalenes,anisole etc. with 1-butyl-3-methylimidazolium tribromide （[Bmim]Br3） under solvent-free conditions, selectively gave the correspondin...Reaction of activated aromatics containing phenobs, naphthol, methoxynaphthalenes,anisole etc. with 1-butyl-3-methylimidazolium tribromide （[Bmim]Br3） under solvent-free conditions, selectively gave the corresponding monobromination products with excellent yields.展开更多
Synthetic studies on the construction of 7-O-methylquercetin from quercetin in 36% yield in four steps is reported, this strategy relies on one hand on the selective protection of the catechol group with dichlorodiphe...Synthetic studies on the construction of 7-O-methylquercetin from quercetin in 36% yield in four steps is reported, this strategy relies on one hand on the selective protection of the catechol group with dichlorodiphenylmethane using dephenyl ether as a solvent, on the other hand, on the selective protection of the 3-hydroxyl group with benzyl bromide, these two different protecting groups can be removed under the same hydrogenation.展开更多
The development of a new silane reagent derived from tetrachlorosilane (TCS) was applied in the present work. TCS-sodium nitrate (NaNO3) binary reagent and zinc chloride (ZnCl2) were reported here as a homogeneous nit...The development of a new silane reagent derived from tetrachlorosilane (TCS) was applied in the present work. TCS-sodium nitrate (NaNO3) binary reagent and zinc chloride (ZnCl2) were reported here as a homogeneous nitrating system. The later was used for the efficient mono nitration, in most cases, with high para-regioselectivity. The nitration proceeded smoothly under mild condition, fairly clean and in good yields. This readily available and inexpensive system is superior to other methods by avoidance of the use of corrosive nitrating reagents and therefore considered to be convenient in terms of risk reduction, economic advantages and environment protection. The present protocol was convenient and applicable to a variety of aromatic hydrocarbons and could be amenable to high throughput synthesis of combinatorial libraries for potential drug development, which needs to be studied as part of future investigations.展开更多
An efficient triethylamine-catalyzed synthesis of 4-amino-3,5-dicyano-6-arylphthalates is described.A one-pot,simple pseudo four-component reaction between arylaldehydes,dialkyl acetylenedicarboxylates, and twice as m...An efficient triethylamine-catalyzed synthesis of 4-amino-3,5-dicyano-6-arylphthalates is described.A one-pot,simple pseudo four-component reaction between arylaldehydes,dialkyl acetylenedicarboxylates, and twice as much malononitrile gave 4-amino-3,5-dicyano-6-arylphthalates in good to excellent yields.展开更多
The first three-component and regioselective synthesis of pyridazinones and phthalazinones from arenes,anhydrides and ArNHNH;in the presence of efficient recyclable heterogeneous catalyst,montmorillonite-KSF,in high y...The first three-component and regioselective synthesis of pyridazinones and phthalazinones from arenes,anhydrides and ArNHNH;in the presence of efficient recyclable heterogeneous catalyst,montmorillonite-KSF,in high yield and short reaction time is reported.展开更多
Transesterification reaction of lactose with divinyladipate in pyridine catalyzed by an alkaline protease from Bacillus subtilis at 50C for 3 days gave 6-O-vinyladipoyl-lactose (yield 35%). Poly(6-O-vinyladipoyl-lacto...Transesterification reaction of lactose with divinyladipate in pyridine catalyzed by an alkaline protease from Bacillus subtilis at 50C for 3 days gave 6-O-vinyladipoyl-lactose (yield 35%). Poly(6-O-vinyladipoyl-lactose) with Mn = 21,200, Mw = 32,900, Mw/Mn = 1.56 could be obtained by chemical polymerization. Poly(vinyl alcohol) containing lactose branch was biodegradable. After 6 days in aqueous buffer (PH 7), this alkaline protease could degrade the polymer to an Mn of ca. 2100, Mw/Mn = 2.56.展开更多
A facile, rapid and regioselective method for the 1-O-deacylation of peracylated glycopyranoses is described which occurs under mild conditions by absorption onto alumina using microwave irradiation.
The selective brominations of 3, 4-dimethoxytoluene with N-bromosuccinimide were reported. The nuclear and side-chain brominated products were obtained under different reaction conditions. The mechanism was also discu...The selective brominations of 3, 4-dimethoxytoluene with N-bromosuccinimide were reported. The nuclear and side-chain brominated products were obtained under different reaction conditions. The mechanism was also discussed.展开更多
基金Financial supports from the National Natural Science Foundation of China(Nos.22271176,22371171)the Taishan Scholar Project of Shandong Province(No.tsqn202306015)Shandong University were gratefully appreciated.
文摘Sulfoxides and sulfide compounds have broad-spectrum biological properties and have received considerable attention in the past few decades.Herein we reported two metal and oxidant-free,practical and efficient methods for the synthesis of highly synthetically useful and structurally diverse ortho-aminoaryl sulfoxides and 3,4,5-trisubstituted oxazolones from readily accessible N-arylhydroxylamines and N-thiophthalimides.This rapid transformation occurred smoothly to achieve chemo-and regioselective cascade rearrangements due to the differences of the protecting-groups of the nitrogen atom of N-arylhydroxyamines.DFT studies suggested that the competing S-O and S-C bond formations via SN2 nucleophilic substitution are crucial for the observed protecting-group-dependent chemoselectivity.Subsequent applications have shown that these two protocols might be powerful tools for the construction of sulfur-containing complex molecules under simple conditions.
基金support from the National Natural Science Foundation of China(Nos.22071007,22020102001,22335002)the National Key R&D Program of China(No.2022YFB3602802)+3 种基金Beijing Natural Science Foundation(No.Z220025)the National Facility for Protein Science in Shanghai,Shanghai Advanced Research Institute,CAS,for providing technical support in X-ray diffraction data collectionthe High-Performance Computing Platform of Peking University for supporting the computational workthe support of BMS Junior Fellow program。
文摘Regioselevtive functionalization of perylene diimides(PDIs)at bay area often requires multistep synthesis and strenuous recrystallization.Direct bromination of perylene diimides only afford the 1,6 and 1,7-regioisomers.More importantly,the 1,6-dibromo regioisomers could only be separated by preparative HPLC.Herein,we report a promising strategy for constructing Janus backbone of BN-doped perylene diimide derivatives.This Janus-type configuration results in the unique regioselective functionalization of BN-JPDIs,which yields exclusively the 1,6-regioisomers.Further investigation shows that the Janus-type configuration leads to a net dipole moment of 1.94 D and intramolecular charge transfer,which causes substantial changes on the optoelectronic properties.Moreover,the single crystal organic field-effect transistors based on BN-JPDIs exhibit electron mobilities up to 0.57 cm^(2)V^(-1)s^(-1),showcasing their potential as versatile building block towards high-performance n-type organic semiconductors.
基金National Basic Research Program(973 Program,Grant No.2004CB518904).
文摘The 3＇-OH, 4＇-OH and 2＂-OH of kanamycin A were modified in search of new aminoglycosides to overcome resistant enzymes, ANTs and APHs. The key intermediate was a dibenzylidene-protected derivative of kanamycin A. The aimed sites were masked by benzyl, methyl and allyl groups. Multi-step reactions gave the desired aminoglycoside derivatives but showed less antibiotic activity than kanamycin A.
基金We are grateful for the financial supports from the National Outstanding Youth Fund No.29925204)the Foundation for University Key Teacher by the Ministry of Education of Chinaa Visiting Fund of the National Laboratory of Applied Organic Chemistry.
文摘Regioselective addition reactions of silyl enolates to a, b-unsaturated aldehyde and its acetal catalyzed by MgI2 etherate give aldol adducts (1, 2-addition) preferentially over Michael adducts (1, 4-addition). This unique regioselectivity is distinctly different with other Lewis acidic promoters and may be attributed to the high oxyphilicity of IMg+.
基金financially supported by the National Natural Science Foundation of China (Nos. 21674130, 51873234)Natural Science Foundation of Guangdong Province (No. 2017A030310 349)+1 种基金Fundamental Research Funds for the Central Universities (No. 17lgjc02)PetroChina Innovation Foundation (No. 2017D-5007-0505)
文摘Polymerizations of linear α-olefins(CnH2n, CH2=CH―R, R = Cn-2) catalyzed by early transition metals typically afford amorphous polymers with alkyl chains(Cn-2), while chain-straightening polymerizations of α-olefins with nickel-based catalysts produce semicrystalline polyolefins. Polymerizations of various α-olefins were carried out using an α-diamine nickel catalyst with a significantly distorted chelating ring. The influences of temperature, monomer concentration, and chain length of α-olefins on polyolefin microstructure were examined in detail. The α-diamine nickel catalyst realized highly regioselective 2,1-insertion of α-olefins regardless of reaction temperature and monomer concentration. Increased chain length of α-olefins led to the formation of more linear polyolefin.Semicrystalline polyolefins with high melting temperatures(Tm) were made from α-olefins through highly regioselective 2,1-insertion and precise chain-straightening.
基金supported by the National Key R&D Program of China(No.2018YFC0406304)the Central Public-Interest Scientific Institution Basal Research Fund(No.1610232019005)the Agricultural Science and Technology Innovation Program(No.ASTIPTRIC06)
文摘Permanganate has attracted much attention in wide range of chemistry and particularly in degradation of environmental pollutants.However,few studies have discussed the feature of regioselective reactivity of permanganate with specific moiety of the target compound.Herein,we studied the reaction between permanganate and tetracycline that is an emerging micropollutant with different species containing several electron-rich groups.The second-order rate constants increased from 6.0 to 9.0 and could be quantitatively modeled by considering the speciation of both reactants,yielding kTC0=11.7(mol/L)^-1 sec^-1,kTC-=35.7(mol/L)^-1 sec^-1,kTC2-=43.1(mol/L)^-1 sec^-1 for individual reaction channels.Degradation products were then identified as the hydroxylated and demethylated compounds.The result suggested a rate-limiting step of simple hydroxylation at the phenolic and/or alkene moieties,while the demethylation should be caused by the unavoidably formed manganese oxide via single electron oxidation.This is supported by the DFT calculation,indicating the primary oxidation of phenolic group of TC0 with activation barrier of 44.5 kcal/mol and of alkene group of TC-and TC2-with activation barriers of 44.0 and 43.4 kcal/mol,respectively.This is in agreement with the experimental results,implying the alternation of regioselectivity associated with the deprotonation process.The result was further supported by performing the Fukui function and electrostatic potential analysis,reflecting the more probable site and better electron donating tendency beneficial to the permanganate oxidation.
基金the Science and Technology hall of Henan Province(No.072300420070No.82102330014)China,for financially supported to this work.
文摘A series of monosubstituted troxerutin esters have been synthesized by enzyme-catalyzed regioselective acylation of troxerutin in nonaqueous medium.Using divinyl dicarboxylates(CH_2=CH-OOC-(CH_2)_n-COO-CH=CH_2,n = 2,3,4,7,8,11) featuring different chain length as acyl donors and alkaline protease from Bacillus subtilis as catalyst,troxerutin was regioselective acylated at B ethoxyl group.The results indicated that the regioselectivity of the enzyme-catalyzed acylation was not affected by the chain length o...
文摘An efficient route for the palladium-catalyzed reductive aminocarbonylation of olefins with nitroarenes was developed using carbon monoxide(CO)as both reductant and carbonyl source,which enables facile access to amides with excellent regioselectivity and broad substrate scope.It is found that the counter anions of the Pd catalyst precursors significantly affect the reaction chemoselectivity and amide regioselectivity.Branched amides were mainly obtained with K2PdCl4 as the metal catalyst,and phosphine ligands had no influence on the regioselectivity but affected the catalytic reactivity.However,phosphine ligands had significant effects on aminocarbonylation regioselectivity when Pd(CH3CN)4(OTf)2 was used;monodentate phosphines tended to form branched amides,and bidentate phosphines mainly formed linear amides.Trapping experiments,primary kinetic studies,and control reactions with all possible N-species reduced from nitroarene indicated that the catalytic synthesis of branched and linear amides produced nitrene(further converted to enamide)and aniline,respectively,different from the previous ligand-controlled regioselective synthesis of amides via the aminocarbonylation of olefins with amines.Furthermore,the proposed synthesis route could be applied in the synthesis of gram-scale propanil under mild conditions.
文摘Hydroalkoxycarbonylation of olefins has been considered to be one of the most attractive methods to synthesize esters. Controlling the regioselectivities of linear esters(L) and branched esters(B) is a challenging project for researchers working in this reaction. Although most of the attention has been paid to control the regioselectivity through ligand design in homogeneous catalytic systems, study in the area is still limited. Herein, Ru-clusters/CeO2 is employed as a heterogeneous catalyst for the hydromethoxycarbonylation of styrene without any additives. After optimization of the reaction conditions, the conversion of styrene is > 99% with 83% and 12% regioselectivity of linear and branched ester, respectively. By using different supports(CeO2(nanoparticle), CeO2-rod, and CeO2-cube), three catalysts including Ru-clusters/CeO2, Ru/CeO2-rod, and Ru/CeO2-cube are prepared and applied in the reaction. Structural characterizations demonstrate that the L/B ratio is related to the Ru size of supported Ru catalysts. Further Raman characterization and NH3-TPD demonstrate that the metal-support interaction and the concentration of oxygen vacancy of the catalyst have a great influence on the Ru size. The mechanism and kinetic analysis for this reaction are also investigated in this work.
文摘Reaction of activated aromatics containing phenobs, naphthol, methoxynaphthalenes,anisole etc. with 1-butyl-3-methylimidazolium tribromide （[Bmim]Br3） under solvent-free conditions, selectively gave the corresponding monobromination products with excellent yields.
基金supported by the Natural Science Foundation of the Jiangsu Higher Education Institutions of China (No.08KJD350001)program for New Century Excellent Talents by the Ministry of Education(No.NCET-09-0163)+1 种基金program for Outstanding Scientific and Technological Innovation Team of Jiangsu Higher Education(2009)Innovative Training Programs for Students in Jiangsu Higher Education Institutions(2009)
文摘Synthetic studies on the construction of 7-O-methylquercetin from quercetin in 36% yield in four steps is reported, this strategy relies on one hand on the selective protection of the catechol group with dichlorodiphenylmethane using dephenyl ether as a solvent, on the other hand, on the selective protection of the 3-hydroxyl group with benzyl bromide, these two different protecting groups can be removed under the same hydrogenation.
文摘The development of a new silane reagent derived from tetrachlorosilane (TCS) was applied in the present work. TCS-sodium nitrate (NaNO3) binary reagent and zinc chloride (ZnCl2) were reported here as a homogeneous nitrating system. The later was used for the efficient mono nitration, in most cases, with high para-regioselectivity. The nitration proceeded smoothly under mild condition, fairly clean and in good yields. This readily available and inexpensive system is superior to other methods by avoidance of the use of corrosive nitrating reagents and therefore considered to be convenient in terms of risk reduction, economic advantages and environment protection. The present protocol was convenient and applicable to a variety of aromatic hydrocarbons and could be amenable to high throughput synthesis of combinatorial libraries for potential drug development, which needs to be studied as part of future investigations.
基金the financial support from the Research Council of Payame Noor University(PNU),Abhar-lran, and my colleague Ismail Hasani Asl
文摘An efficient triethylamine-catalyzed synthesis of 4-amino-3,5-dicyano-6-arylphthalates is described.A one-pot,simple pseudo four-component reaction between arylaldehydes,dialkyl acetylenedicarboxylates, and twice as much malononitrile gave 4-amino-3,5-dicyano-6-arylphthalates in good to excellent yields.
文摘The first three-component and regioselective synthesis of pyridazinones and phthalazinones from arenes,anhydrides and ArNHNH;in the presence of efficient recyclable heterogeneous catalyst,montmorillonite-KSF,in high yield and short reaction time is reported.
文摘Transesterification reaction of lactose with divinyladipate in pyridine catalyzed by an alkaline protease from Bacillus subtilis at 50C for 3 days gave 6-O-vinyladipoyl-lactose (yield 35%). Poly(6-O-vinyladipoyl-lactose) with Mn = 21,200, Mw = 32,900, Mw/Mn = 1.56 could be obtained by chemical polymerization. Poly(vinyl alcohol) containing lactose branch was biodegradable. After 6 days in aqueous buffer (PH 7), this alkaline protease could degrade the polymer to an Mn of ca. 2100, Mw/Mn = 2.56.
基金This work was financially supported by the National Natural Science Foundation of China(No.20272051).
文摘A facile, rapid and regioselective method for the 1-O-deacylation of peracylated glycopyranoses is described which occurs under mild conditions by absorption onto alumina using microwave irradiation.
文摘The selective brominations of 3, 4-dimethoxytoluene with N-bromosuccinimide were reported. The nuclear and side-chain brominated products were obtained under different reaction conditions. The mechanism was also discussed.
