The reaction mechanism of the intramolecular cycloaddition of N-3-butenyl nitrone has been investigated theoretically by using AM1 MO method and transition state theory.There are two parallel reactions leading to two ...The reaction mechanism of the intramolecular cycloaddition of N-3-butenyl nitrone has been investigated theoretically by using AM1 MO method and transition state theory.There are two parallel reactions leading to two different regioisomers.The ratio of the rate constants of these two reactions was calculated to be 124.1(at 383.75 K).The obtained results can be used to explain the high regiospecificity of the reaction product.展开更多
A stereoselective and regiospecific synthesis of procursors(2),(4),(6)and(7)of prostacyclin analogues from 2,3-epoxylbicyclo[3.2.0]hept-6-one(1)are described.
The regiospecific oxidation of alkyl group of both sterically hindered and unhindered aromatic amine to corresponding carbonyl compound was done in aq. medium by using DDQ. The optimized reaction protocol was found to...The regiospecific oxidation of alkyl group of both sterically hindered and unhindered aromatic amine to corresponding carbonyl compound was done in aq. medium by using DDQ. The optimized reaction protocol was found to be most simple, high yielding and novel method for oxidation of alkyl group of aromatic amine in to its carbonyl compound.展开更多
An easy and efficient method for the aminobromination of β,β-dicyanostyrene derivatives with NBS as the aminobrominating reagent in CH3CN catalyzed by NaOAc （10 mol%） is developed. This protocol provides con- veni...An easy and efficient method for the aminobromination of β,β-dicyanostyrene derivatives with NBS as the aminobrominating reagent in CH3CN catalyzed by NaOAc （10 mol%） is developed. This protocol provides con- venient process to convert β,β-dicyanostyrene derivatives into the vicinal haloamines with full regiospecificity and high stereoselectivety in the ice-water bath in air. The reaction is high efficient in yielding the corresponding ami- nobrominated products in excellent yields （up to 95%） under these conditions. The outcome indicated that the reac- tion has an electrophilic addition feature. 12 Eexamples of β,β-dicyanostyrene derivatives have been investigated.展开更多
An efficient method for the bromoamidation of β,β-dicyanostyrene derivatives with N-bromoacetamide （NBA） was developed.This protocol provides a convenient process to convert β,β-dicyanostyrene derivatives into t...An efficient method for the bromoamidation of β,β-dicyanostyrene derivatives with N-bromoacetamide （NBA） was developed.This protocol provides a convenient process to convert β,β-dicyanostyrene derivatives into the vicinal haloamines in excellent yields（up to 99％） at room temperature in the presence of anhydrous K3PO4 as a catalyst without the protection of the inert gaseous in CH2Cl2.A total of 11 examples were investigated and all the products showed the regionspecific feature.Based on the observation of different activities for the different substrates involving the electron-rich or electron-deficient β,β-dicyanostyrenes,a possible Michael addition mechanism was proposed.展开更多
The syntheses of a number of C-aryl-N-3-butenyl nitrones [aryl ring=4-CH_3O-phenyl (1a), phenyl(1b), 4-Cl-phenyl(1e), 4-Br-phenyl(1d), 4-NO2-phenyl(1e), 2-furyl (1f), 2-thienyl (1g), 2-pyrryl(1h)] and their thermochem...The syntheses of a number of C-aryl-N-3-butenyl nitrones [aryl ring=4-CH_3O-phenyl (1a), phenyl(1b), 4-Cl-phenyl(1e), 4-Br-phenyl(1d), 4-NO2-phenyl(1e), 2-furyl (1f), 2-thienyl (1g), 2-pyrryl(1h)] and their thermochemical reactions have been investigated. The thermocycloadditions of 1a-1h are regiospecific in forming a novel heterobicyclic ring system. Exo-aryl-1-aza-7-oxabicyclo- [2.2.1]heptane.展开更多
The eme reactions of α-ionones with singlet oxygen were examined to ascertain the effect of secondary Me interaction between the reactants on the reaction regiospecificity. Exclusive formation of 3-hydroxy-γ-ionones...The eme reactions of α-ionones with singlet oxygen were examined to ascertain the effect of secondary Me interaction between the reactants on the reaction regiospecificity. Exclusive formation of 3-hydroxy-γ-ionones found in the reactions reveals favorable interaction of singlet oxygen with the acyclic α-hydrogen atom,On the other hand,no formation of 3-hy- droxy-β-ionones implies that the steric requirement was not met for the bond formation between zwitterionic perepoxide with C_1-hydrogen in the process.The MMP21 and MNDO calculations indicate minus value of the secondary interaction energy for the aeyelie α-hydrogen abstrac- tion and a repulsion between the oxygen with C_1-hydrogen atom.Twisting tilting of the double bond may account for favorable attack of singlet oxygen on C_3.An explanation of the excellent regiospecificity was addressed and placed in proper mechanic prospective.展开更多
The reaction of chiral N-（tert-butanesulfinyl）ketimines and α,β-unsaturated trifluorotuethyl ketones catalyzed by DBU was achieved under mild conditions. 1,2-Addition products, precursors of chiral trifluoromethyl...The reaction of chiral N-（tert-butanesulfinyl）ketimines and α,β-unsaturated trifluorotuethyl ketones catalyzed by DBU was achieved under mild conditions. 1,2-Addition products, precursors of chiral trifluoromethylated 1,3-amino alcohols, were obtained diastereoselectively （dr value up to 95 ： 5） in moderate yields （up to 76%）. A possible catalytic cycle was proposed.展开更多
文摘The reaction mechanism of the intramolecular cycloaddition of N-3-butenyl nitrone has been investigated theoretically by using AM1 MO method and transition state theory.There are two parallel reactions leading to two different regioisomers.The ratio of the rate constants of these two reactions was calculated to be 124.1(at 383.75 K).The obtained results can be used to explain the high regiospecificity of the reaction product.
文摘A stereoselective and regiospecific synthesis of procursors(2),(4),(6)and(7)of prostacyclin analogues from 2,3-epoxylbicyclo[3.2.0]hept-6-one(1)are described.
文摘The regiospecific oxidation of alkyl group of both sterically hindered and unhindered aromatic amine to corresponding carbonyl compound was done in aq. medium by using DDQ. The optimized reaction protocol was found to be most simple, high yielding and novel method for oxidation of alkyl group of aromatic amine in to its carbonyl compound.
文摘An easy and efficient method for the aminobromination of β,β-dicyanostyrene derivatives with NBS as the aminobrominating reagent in CH3CN catalyzed by NaOAc （10 mol%） is developed. This protocol provides con- venient process to convert β,β-dicyanostyrene derivatives into the vicinal haloamines with full regiospecificity and high stereoselectivety in the ice-water bath in air. The reaction is high efficient in yielding the corresponding ami- nobrominated products in excellent yields （up to 95%） under these conditions. The outcome indicated that the reac- tion has an electrophilic addition feature. 12 Eexamples of β,β-dicyanostyrene derivatives have been investigated.
基金Supported by the Natural Science Foundation of Shaanxi Province,China（No.2009JM2001）,the Innovation Foundation of Pastgraduate Cultivation of Shaanxi Normal University,China（No.2008CXB009） and Fundamental Research Funds for the Central Universities of China（No.GK261001095）.
文摘An efficient method for the bromoamidation of β,β-dicyanostyrene derivatives with N-bromoacetamide （NBA） was developed.This protocol provides a convenient process to convert β,β-dicyanostyrene derivatives into the vicinal haloamines in excellent yields（up to 99％） at room temperature in the presence of anhydrous K3PO4 as a catalyst without the protection of the inert gaseous in CH2Cl2.A total of 11 examples were investigated and all the products showed the regionspecific feature.Based on the observation of different activities for the different substrates involving the electron-rich or electron-deficient β,β-dicyanostyrenes,a possible Michael addition mechanism was proposed.
文摘The syntheses of a number of C-aryl-N-3-butenyl nitrones [aryl ring=4-CH_3O-phenyl (1a), phenyl(1b), 4-Cl-phenyl(1e), 4-Br-phenyl(1d), 4-NO2-phenyl(1e), 2-furyl (1f), 2-thienyl (1g), 2-pyrryl(1h)] and their thermochemical reactions have been investigated. The thermocycloadditions of 1a-1h are regiospecific in forming a novel heterobicyclic ring system. Exo-aryl-1-aza-7-oxabicyclo- [2.2.1]heptane.
基金project supported by the National Natural Science Foundation of China.
文摘The eme reactions of α-ionones with singlet oxygen were examined to ascertain the effect of secondary Me interaction between the reactants on the reaction regiospecificity. Exclusive formation of 3-hydroxy-γ-ionones found in the reactions reveals favorable interaction of singlet oxygen with the acyclic α-hydrogen atom,On the other hand,no formation of 3-hy- droxy-β-ionones implies that the steric requirement was not met for the bond formation between zwitterionic perepoxide with C_1-hydrogen in the process.The MMP21 and MNDO calculations indicate minus value of the secondary interaction energy for the aeyelie α-hydrogen abstrac- tion and a repulsion between the oxygen with C_1-hydrogen atom.Twisting tilting of the double bond may account for favorable attack of singlet oxygen on C_3.An explanation of the excellent regiospecificity was addressed and placed in proper mechanic prospective.
基金Project supported by the National Natural Science Foundation of China （No. 20872166）.
文摘The reaction of chiral N-（tert-butanesulfinyl）ketimines and α,β-unsaturated trifluorotuethyl ketones catalyzed by DBU was achieved under mild conditions. 1,2-Addition products, precursors of chiral trifluoromethylated 1,3-amino alcohols, were obtained diastereoselectively （dr value up to 95 ： 5） in moderate yields （up to 76%）. A possible catalytic cycle was proposed.
