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1997 Volume 8 Issue 8
1997, 8(8): 653-654
Abstract:
The title compound 1 was synthesized from 1.2:5,6-dianhydro-3,4-isopropylidene-D-mannitol 2 through four steps in a total yield of 53%.The absolute configuration of this compound was confirmed by X-ray diffraction.
The title compound 1 was synthesized from 1.2:5,6-dianhydro-3,4-isopropylidene-D-mannitol 2 through four steps in a total yield of 53%.The absolute configuration of this compound was confirmed by X-ray diffraction.
1997, 8(8): 655-656
Abstract:
Lawesson's reagent undergoes [2+4] cycloaddition reaction with 2-methyl-1,3-butadiene,cyclopentadiene to yield heterocycles 4 and 5,respectively.
Lawesson's reagent undergoes [2+4] cycloaddition reaction with 2-methyl-1,3-butadiene,cyclopentadiene to yield heterocycles 4 and 5,respectively.
1997, 8(8): 657-660
Abstract:
The title scission was studied with the result that dimenzation of the scission products was observed,their structures were identified and modes of dimerization proposed.
The title scission was studied with the result that dimenzation of the scission products was observed,their structures were identified and modes of dimerization proposed.
1997, 8(8): 661-664
Abstract:
BrCF2CF2CH=CHCH2X(x=Cl,OAc,OH) reacted smoothly with alkynes in the presence of BrCo(dmgh)2Py/Zn,giving 4,4,5,5-tetrafluorocyclopentene derivatives in moderate yields.
BrCF2CF2CH=CHCH2X(x=Cl,OAc,OH) reacted smoothly with alkynes in the presence of BrCo(dmgh)2Py/Zn,giving 4,4,5,5-tetrafluorocyclopentene derivatives in moderate yields.
1997, 8(8): 665-668
Abstract:
Nitroalkanes react smoothly with CF3CCl2COCH=CHPh via Michael addition in the presence of inorganic bases such as KF/Al2O3 or K2CO3,giving fluorine-containing γ-nitro ketones in good yields.
Nitroalkanes react smoothly with CF3CCl2COCH=CHPh via Michael addition in the presence of inorganic bases such as KF/Al2O3 or K2CO3,giving fluorine-containing γ-nitro ketones in good yields.
1997, 8(8): 669-672
Abstract:
Trifluorovinyl compounds were obtained in good yields when BrCF2CFClR were subjected to sulfinatodehalogenation conditions(Na2S2O4/NaHCO3).
Trifluorovinyl compounds were obtained in good yields when BrCF2CFClR were subjected to sulfinatodehalogenation conditions(Na2S2O4/NaHCO3).
1997, 8(8): 673-676
Abstract:
When ethyl 3-fluoroalkyl-3-haloacrylate was treated with excess CH2N2,1-methyl-3-ethoxycarbonyl-4-fluoroalkylpyr-azoles(3) and 1-methyl-5-ethoxycarbonyl-4-fluoroalkylpyra-zoles(4) were obtained with a ratio of 90-95:10-5 in good yield.
When ethyl 3-fluoroalkyl-3-haloacrylate was treated with excess CH2N2,1-methyl-3-ethoxycarbonyl-4-fluoroalkylpyr-azoles(3) and 1-methyl-5-ethoxycarbonyl-4-fluoroalkylpyra-zoles(4) were obtained with a ratio of 90-95:10-5 in good yield.
1997, 8(8): 677-678
Abstract:
The reductive coupling reactions of aryl sulfonyl chloride induced by (TiCl4-Zn) reagent affords diaryl disulfide.However,reaction of aryl sulfonyl chloride with α,β-unsaturated ester under the same condition affords β-arylsulfo ester.
The reductive coupling reactions of aryl sulfonyl chloride induced by (TiCl4-Zn) reagent affords diaryl disulfide.However,reaction of aryl sulfonyl chloride with α,β-unsaturated ester under the same condition affords β-arylsulfo ester.
1997, 8(8): 679-680
Abstract:
Two new chiral oxazaborolidine derivated from L-cystine have been used to catalyze the enantioselective reduction of prochiral ketones and the secondary alcohols are obtained with good to excellent opitical yields.
Two new chiral oxazaborolidine derivated from L-cystine have been used to catalyze the enantioselective reduction of prochiral ketones and the secondary alcohols are obtained with good to excellent opitical yields.
1997, 8(8): 681-682
Abstract:
α-Bromoesters can react with diselenides by metallic tin in THF to give α-selenoesters in moderate to good yields.
α-Bromoesters can react with diselenides by metallic tin in THF to give α-selenoesters in moderate to good yields.
1997, 8(8): 683-684
Abstract:
Aromatic nitro compounds were reduced to the corresponding anilines by refluxing with potassium selenated borohydride (KBH2Se3) prepared from potassium borohydride and selenium in refluxed formamide.
Aromatic nitro compounds were reduced to the corresponding anilines by refluxing with potassium selenated borohydride (KBH2Se3) prepared from potassium borohydride and selenium in refluxed formamide.
1997, 8(8): 685-688
Abstract:
Sulfur containing calixcrown 1 and 2 are synthesized from bromoethoxycalix[4] arene 3,and their complexing properties are also studied.
Sulfur containing calixcrown 1 and 2 are synthesized from bromoethoxycalix[4] arene 3,and their complexing properties are also studied.
1997, 8(8): 689-690
Abstract:
The reaction of phenacyl benzoate derivatives with acetamide at about 140° in the presence of BF3 catalyst gave 2-aryl-4-phenyloxazoles.This method can be applied to the preparation of 2-alkyl-4-phenyloxazoles as well.
The reaction of phenacyl benzoate derivatives with acetamide at about 140° in the presence of BF3 catalyst gave 2-aryl-4-phenyloxazoles.This method can be applied to the preparation of 2-alkyl-4-phenyloxazoles as well.
1997, 8(8): 691-692
Abstract:
Two bridged purine dinucleosides,bis (2-N-acetyl-6-N-alkylylene-2,6-diaminopurine-2',3',5'-triacetyl-β-D-ribofuranoside),were synthesized from the reaction of the key medium 3,2-acetylamino-6-[1-(1,2,4-triazolyl)]-purine-2',3',5'-triacetyl-β-D-ribofuranoside with dialkylamine.
Two bridged purine dinucleosides,bis (2-N-acetyl-6-N-alkylylene-2,6-diaminopurine-2',3',5'-triacetyl-β-D-ribofuranoside),were synthesized from the reaction of the key medium 3,2-acetylamino-6-[1-(1,2,4-triazolyl)]-purine-2',3',5'-triacetyl-β-D-ribofuranoside with dialkylamine.
1997, 8(8): 693-694
Abstract:
The stereoselective synthesis of (+)-preussin has been achieved by utilizing the Sharpless asymmetric epoxidation of the divinylcarbinol (3) and the oxidative cyclization of 9 with PDC as the key steps.
The stereoselective synthesis of (+)-preussin has been achieved by utilizing the Sharpless asymmetric epoxidation of the divinylcarbinol (3) and the oxidative cyclization of 9 with PDC as the key steps.
1997, 8(8): 695-696
Abstract:
Saprorthoquinone (1),isolated from the roots of salvia prionitis Hance,was synthesized starting from p-methoxyphenylacetic acid.
Saprorthoquinone (1),isolated from the roots of salvia prionitis Hance,was synthesized starting from p-methoxyphenylacetic acid.
1997, 8(8): 697-700
Abstract:
The first total synthesis of (-)-baimuxifuranic acid (1) starting from (-)-carvone has been described.In our studies a surprising allylic oxidation was found in the oxidation of α,β-unsaturated aldehyde 5 with silver oxide.
The first total synthesis of (-)-baimuxifuranic acid (1) starting from (-)-carvone has been described.In our studies a surprising allylic oxidation was found in the oxidation of α,β-unsaturated aldehyde 5 with silver oxide.
1997, 8(8): 701-704
Abstract:
Total synthesis of bilobetin and isoginkgetin has been achieved by Pd(PPh3)4 catalytic coupling of 8-fiavone-boronic acids with iodoflavones.
Total synthesis of bilobetin and isoginkgetin has been achieved by Pd(PPh3)4 catalytic coupling of 8-fiavone-boronic acids with iodoflavones.
1997, 8(8): 705-706
Abstract:
Three new diterpenoids,gesneroidins D-F (1-3),were isolated from Isodon gesneroides.The structure was determined as 3β,7β,11β,15β-tetraacetoxy-ent-kaur-16-en-6-one;15β-hydroxy-1 α,3β,6α,7β,11β-pentaacetoxy-ent-kaur-16-ene;6α,11β-dibydroxy-3β,7β-diacetoxy-ent-kaur-16-en-15-one based on 1D and 2D NMR techniques (COSY,NOESY,HXTCOR,COLOC).
Three new diterpenoids,gesneroidins D-F (1-3),were isolated from Isodon gesneroides.The structure was determined as 3β,7β,11β,15β-tetraacetoxy-ent-kaur-16-en-6-one;15β-hydroxy-1 α,3β,6α,7β,11β-pentaacetoxy-ent-kaur-16-ene;6α,11β-dibydroxy-3β,7β-diacetoxy-ent-kaur-16-en-15-one based on 1D and 2D NMR techniques (COSY,NOESY,HXTCOR,COLOC).
1997, 8(8): 707-710
Abstract:
Rhodamine B-ethylenediamine-β-cyclodextrins (RhB-β-CDen) and rhodamine B-β-cyclodextrins (RhB-β-CD) form inclusion complexes with many guest molecules,which can be used as nucleic acid probe.In this paper we determined the most stable conformations of RhB-β-CDen and RhB-β-CD by molecular mechanics and dynamics simulation.The interaction between RhB-β-CDen and two guest molecules,1-borneol and cyclohexanol,have been investigated both theoretically and experimentally.The results show that the interaction between borneol and RhB-β-CDen is stronger than that between cyclohexanol and RhB-β-CDen.
Rhodamine B-ethylenediamine-β-cyclodextrins (RhB-β-CDen) and rhodamine B-β-cyclodextrins (RhB-β-CD) form inclusion complexes with many guest molecules,which can be used as nucleic acid probe.In this paper we determined the most stable conformations of RhB-β-CDen and RhB-β-CD by molecular mechanics and dynamics simulation.The interaction between RhB-β-CDen and two guest molecules,1-borneol and cyclohexanol,have been investigated both theoretically and experimentally.The results show that the interaction between borneol and RhB-β-CDen is stronger than that between cyclohexanol and RhB-β-CDen.
1997, 8(8): 711-714
Abstract:
In this paper,the direct photooxidation mechanism of near-infrared absorbing benzothiazolone cyanine dye has been studied by VIS absorption spectroscopy and Electron Spin Resonance (ESR).The technique of spin trapping has been successfully applied to the detection of the photoinduced formation of singlet oxygen (1O2) and superoxide (O2-).It was reveled that the singlet oxygen and superoxide anion all contributed to the photofading of cyanine dye.
In this paper,the direct photooxidation mechanism of near-infrared absorbing benzothiazolone cyanine dye has been studied by VIS absorption spectroscopy and Electron Spin Resonance (ESR).The technique of spin trapping has been successfully applied to the detection of the photoinduced formation of singlet oxygen (1O2) and superoxide (O2-).It was reveled that the singlet oxygen and superoxide anion all contributed to the photofading of cyanine dye.
1997, 8(8): 715-718
Abstract:
It was found that cyanocobinamide (CN-Cbi) can be reduced at about-0.50V.The reduction process has an EC mechanism,i.e.the electrochemical reduction of CN-Cbi is accompanied by a decyanation of CN-Cbi.The electrochemical characteristics of CN-Cbi and vitamin B12 were compared.
It was found that cyanocobinamide (CN-Cbi) can be reduced at about-0.50V.The reduction process has an EC mechanism,i.e.the electrochemical reduction of CN-Cbi is accompanied by a decyanation of CN-Cbi.The electrochemical characteristics of CN-Cbi and vitamin B12 were compared.
1997, 8(8): 719-720
Abstract:
A new polymer,poly (N,N-dimethylacrylamide),labeled with acenaphthylene has been synthesized.The rotational relaxation time of this polymer has been studied using steady state fluorescence depolarization measurement in combination with fluorescence quenching measurement.
A new polymer,poly (N,N-dimethylacrylamide),labeled with acenaphthylene has been synthesized.The rotational relaxation time of this polymer has been studied using steady state fluorescence depolarization measurement in combination with fluorescence quenching measurement.
1997, 8(8): 721-724
Abstract:
The photoelectrochemical behaviour of the multilayer semiconductive electrode (GaAs/AlxGa1-xAs)with the structure of N+NP and N+NPP was studied in Na2SO4 solution.Compared with single kind semiconductor electrode,the commposite one has broader photoresponse spectral region and larger open-circuit photovoltage,consequently gives higher solar energy conversion efficiency.
The photoelectrochemical behaviour of the multilayer semiconductive electrode (GaAs/AlxGa1-xAs)with the structure of N+NP and N+NPP was studied in Na2SO4 solution.Compared with single kind semiconductor electrode,the commposite one has broader photoresponse spectral region and larger open-circuit photovoltage,consequently gives higher solar energy conversion efficiency.
1997, 8(8): 725-728
Abstract:
The catalyst boron trifluoride etherate was used to catalyze the reaction of epoxy resin with polyethylene glycol (PEG),and the effect of the concentration of the catalyst on the reaction is studied.It is shown that there exist two competitive reactions:I,self polymerization of epoxy resin via chain growth and Ⅱ,copolymerization of epoxy resin with PEG via step growth.At high concentration of the catalyst,reaction I dominates and reaction Ⅱ is negligible.On the contrary,at low concentration of the catalyst,reaction Ⅱ dominates and block copolymers are formed.In the intermediate case,the two reactions are comparable with the result that a gel structure is obtained.
The catalyst boron trifluoride etherate was used to catalyze the reaction of epoxy resin with polyethylene glycol (PEG),and the effect of the concentration of the catalyst on the reaction is studied.It is shown that there exist two competitive reactions:I,self polymerization of epoxy resin via chain growth and Ⅱ,copolymerization of epoxy resin with PEG via step growth.At high concentration of the catalyst,reaction I dominates and reaction Ⅱ is negligible.On the contrary,at low concentration of the catalyst,reaction Ⅱ dominates and block copolymers are formed.In the intermediate case,the two reactions are comparable with the result that a gel structure is obtained.
1997, 8(8): 729-732
Abstract:
Based on the capture force field potential model and the adiabatic invariant proposed by Bates,adopting improved average dipole orientation (IADO) theory,the force constants between transition metal ions and benzene (bz) and also a series of inner-sphere reoganization energy (REin) were calculated.The reasons for the differences between theoretical predictions and experimental results were discussed.
Based on the capture force field potential model and the adiabatic invariant proposed by Bates,adopting improved average dipole orientation (IADO) theory,the force constants between transition metal ions and benzene (bz) and also a series of inner-sphere reoganization energy (REin) were calculated.The reasons for the differences between theoretical predictions and experimental results were discussed.
1997, 8(8): 733-736
Abstract:
NH3-CH3OH system was studied by ab initio calculations at the Hartree-Fock level using the 6-31G* basis set.Equilibrium geometries of both of its ionic (type Ⅰ and Ⅱ) and neutral clusters are obtained.Different dissociation channels are evaluated for Ⅰ and Ⅱ,respectively.The results suggest that when NH3-CH3OH is vertically ionized,CH3O+NH4+ are the dominant products via a proton transfer reaction,and accompanying the dissociation of (NH3-CH3OH)ver+ to NH3++CH3OH,intracluster charge transfer process takes place in the system.
NH3-CH3OH system was studied by ab initio calculations at the Hartree-Fock level using the 6-31G* basis set.Equilibrium geometries of both of its ionic (type Ⅰ and Ⅱ) and neutral clusters are obtained.Different dissociation channels are evaluated for Ⅰ and Ⅱ,respectively.The results suggest that when NH3-CH3OH is vertically ionized,CH3O+NH4+ are the dominant products via a proton transfer reaction,and accompanying the dissociation of (NH3-CH3OH)ver+ to NH3++CH3OH,intracluster charge transfer process takes place in the system.
1997, 8(8): 737-740
Abstract:
Four isomers of the three-dimensionally connected bare boron cationic cluster B17+ were investigated by using ab initio molecular orbital theory at the HF/6-31G level.The results show that the D5h symmetric isomer of B17+ is a possible isomer candidate of its stable geometries with closed structure.
Four isomers of the three-dimensionally connected bare boron cationic cluster B17+ were investigated by using ab initio molecular orbital theory at the HF/6-31G level.The results show that the D5h symmetric isomer of B17+ is a possible isomer candidate of its stable geometries with closed structure.
1997, 8(8): 741-744
Abstract:
The crystal structure of the title complex salt has been determined by single-crystal X-ray structure analysis.The crystal data are as follows;Monoclinic,P21/c,a=15.6480 (10)Å,b=16.7870 (10)Å,c=10.347 (2)Å,β=90.790 (10),V=2717.7 (6)Å3,Z=3,and R=0.0333 for 4789 unique reflections.The complex anion has a pseudo-octahedral structure distorted more than the CrⅢ and CoⅢ analogs,in which cach iminodiacetato ligand (ida2-) is coordinated in a facial fashion with the two N atoms in a cis configuration,resulting in an unsym-fac structure.
The crystal structure of the title complex salt has been determined by single-crystal X-ray structure analysis.The crystal data are as follows;Monoclinic,P21/c,a=15.6480 (10)Å,b=16.7870 (10)Å,c=10.347 (2)Å,β=90.790 (10),V=2717.7 (6)Å3,Z=3,and R=0.0333 for 4789 unique reflections.The complex anion has a pseudo-octahedral structure distorted more than the CrⅢ and CoⅢ analogs,in which cach iminodiacetato ligand (ida2-) is coordinated in a facial fashion with the two N atoms in a cis configuration,resulting in an unsym-fac structure.
1997, 8(8): 745-746
Abstract:
Affinity membrane was used for the endotoxin adsorption.The matrix macropore membrane was prepared from filterpaper by chemically crosslinking,and polymyxin B was immobilized as affinity ligand.The prepared membrane cartridge can be used for the removal of endotoxin from aqueous solutions.With a cartridge of 40 sheets affinity membrane containing,the endotoxin level of the processed solution can be reduced to a minimum of 4 pg/mL.
Affinity membrane was used for the endotoxin adsorption.The matrix macropore membrane was prepared from filterpaper by chemically crosslinking,and polymyxin B was immobilized as affinity ligand.The prepared membrane cartridge can be used for the removal of endotoxin from aqueous solutions.With a cartridge of 40 sheets affinity membrane containing,the endotoxin level of the processed solution can be reduced to a minimum of 4 pg/mL.
