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1999 Volume 10 Issue 7
1999, 10(7): 529-530
Abstract:
Terminal alkynes couple smoothly in the presence of PhI(OAc)2 or PhI(OH)OTs. catalytic CuI and base, alfordine conjugated diynes.
Terminal alkynes couple smoothly in the presence of PhI(OAc)2 or PhI(OH)OTs. catalytic CuI and base, alfordine conjugated diynes.
1999, 10(7): 531-532
Abstract:
Diels-Alder reaction of hedychenone 1 and malefic anhydride 2 gave several products 4~7, whose structures were identified by spectral methods. Effect of temperature on the reaction was disscussed.
Diels-Alder reaction of hedychenone 1 and malefic anhydride 2 gave several products 4~7, whose structures were identified by spectral methods. Effect of temperature on the reaction was disscussed.
1999, 10(7): 533-536
Abstract:
Using galvinoxyl as catalyst, the phase transfer catalyzed method of oxidation of primary amines to symmetrical azobenzenes with a saturated solution of potassium ferricyanide in 2 mol/L aqueous potassium hydroxide and dichloromethane is described. The reaction has intimate relation with Hammett substituent constants. This report offers an efficient and rapid method to prepare azobenzenes and a possible mechanism is also suggested.
Using galvinoxyl as catalyst, the phase transfer catalyzed method of oxidation of primary amines to symmetrical azobenzenes with a saturated solution of potassium ferricyanide in 2 mol/L aqueous potassium hydroxide and dichloromethane is described. The reaction has intimate relation with Hammett substituent constants. This report offers an efficient and rapid method to prepare azobenzenes and a possible mechanism is also suggested.
1999, 10(7): 537-538
Abstract:
In order to further confirm the biomimic properties of N-phosphoamino acids. A series of model compounds, analogue of phosphoryl amino acids, were synthesized and their biomimic mechanism was also investigated by NMR and MS methods. The results indicated that the reactivity of phosphoryl biological small molecules was depended on the configuration, function groups and positions.
In order to further confirm the biomimic properties of N-phosphoamino acids. A series of model compounds, analogue of phosphoryl amino acids, were synthesized and their biomimic mechanism was also investigated by NMR and MS methods. The results indicated that the reactivity of phosphoryl biological small molecules was depended on the configuration, function groups and positions.
1999, 10(7): 539-542
Abstract:
25,27-bis-(2-aminoethoxy)-p-tert-butylcalix[4]arene was linked to double calix[4]arene derivatives by the Schiff-base moiety in its lower rim. They behave strong ability to complex with Pb2+,Cu2+ and Co2+.
25,27-bis-(2-aminoethoxy)-p-tert-butylcalix[4]arene was linked to double calix[4]arene derivatives by the Schiff-base moiety in its lower rim. They behave strong ability to complex with Pb2+,Cu2+ and Co2+.
1999, 10(7): 543-546
Abstract:
Asymmetric synthesis of novel optically active nucleoside analogues 7 from natural tartaric acid is described. In the given nucleoside analogues an optically active polyhydroxy pyrrolidinonyl ring is in place of the tetrahydrofuran ring.
Asymmetric synthesis of novel optically active nucleoside analogues 7 from natural tartaric acid is described. In the given nucleoside analogues an optically active polyhydroxy pyrrolidinonyl ring is in place of the tetrahydrofuran ring.
1999, 10(7): 547-548
Abstract:
A total synthesis of (E,E)-3,7-dimethyl-2,6-decadiene-1,10-diol, using 1,3-transfor-mation of 2. 3-epoxy alcohol and Claisen rearrangement of allyl vinyl ether as key steps. is described.
A total synthesis of (E,E)-3,7-dimethyl-2,6-decadiene-1,10-diol, using 1,3-transfor-mation of 2. 3-epoxy alcohol and Claisen rearrangement of allyl vinyl ether as key steps. is described.
1999, 10(7): 549-552
Abstract:
Peptide analogs of salmon calcitonin (sCT) were synthesized by using Fmoc-based chemistry on MBHA resins. Salmon calcitonin was modified by 1)cysteines at positions 1 and 7 were replaced by valine and alanine respectively to result in open chain analogs,2) the glycine at position 30 was replaced by alanine, D-alanine and sarcosine respectively, and 3) some residues were deleted besides the above two modifications. A modified two-step deprotection/cleavage procedure, in which a solvent of TFA/TMSBr/thioanisole/EDT/m-cresol combines with HF cleavage, was adopted in SPPS.
Peptide analogs of salmon calcitonin (sCT) were synthesized by using Fmoc-based chemistry on MBHA resins. Salmon calcitonin was modified by 1)cysteines at positions 1 and 7 were replaced by valine and alanine respectively to result in open chain analogs,2) the glycine at position 30 was replaced by alanine, D-alanine and sarcosine respectively, and 3) some residues were deleted besides the above two modifications. A modified two-step deprotection/cleavage procedure, in which a solvent of TFA/TMSBr/thioanisole/EDT/m-cresol combines with HF cleavage, was adopted in SPPS.
1999, 10(7): 553-554
Abstract:
It is introduced that the carbonylations of cyclohexene with CO2 can take place under ambient conditions by catalysis of Co(acac)2 in the presence of ultraviolet irradiation.
It is introduced that the carbonylations of cyclohexene with CO2 can take place under ambient conditions by catalysis of Co(acac)2 in the presence of ultraviolet irradiation.
1999, 10(7): 555-558
Abstract:
Secondary structure of [Val1, Ala7]sCT, an analog of salmon caleitonin (sCT) not containing an N-terminal disultide bridge. was investigated by circular dichroism (CD) and Fourier-transform infrared spectroscopy (FTIR) methods. Both CD and FTIR results show that the main conformational structure of [Val1, Ala7]sCT in aqueous solution is random coil structure while in trifluorethanol (TFE) it displays a strong α-helical structure. The relationship between the biological activity and the conformational structure of [Val1, Ala7]sCT is also discussed.
Secondary structure of [Val1, Ala7]sCT, an analog of salmon caleitonin (sCT) not containing an N-terminal disultide bridge. was investigated by circular dichroism (CD) and Fourier-transform infrared spectroscopy (FTIR) methods. Both CD and FTIR results show that the main conformational structure of [Val1, Ala7]sCT in aqueous solution is random coil structure while in trifluorethanol (TFE) it displays a strong α-helical structure. The relationship between the biological activity and the conformational structure of [Val1, Ala7]sCT is also discussed.
1999, 10(7): 559-562
Abstract:
The racemic spiro[4.4]nonane-l,6-dione was efficiently resolved through an enantioselective inclusion complexation using chiral host BINOL by simple recrystallization with 31.9~38.4% yield and 100%ee.
The racemic spiro[4.4]nonane-l,6-dione was efficiently resolved through an enantioselective inclusion complexation using chiral host BINOL by simple recrystallization with 31.9~38.4% yield and 100%ee.
1999, 10(7): 563-566
Abstract:
Two novel sesquiterpene diglycusides named dictamnosides F 1 and G 2 were isolated from methanol extract of the root bark of Dictanuurs dcrsvcanptrs. Their structures were determined on the basis of spectroscopic and chemical analysis.
Two novel sesquiterpene diglycusides named dictamnosides F 1 and G 2 were isolated from methanol extract of the root bark of Dictanuurs dcrsvcanptrs. Their structures were determined on the basis of spectroscopic and chemical analysis.
1999, 10(7): 567-570
Abstract:
From the leaves of Rhododendron latouclreae (Ericaceae), two new natural phenolic compounds named (+)-rhodolatouchol 1 and isoepirhododendrin 4 were identified. Six other known compounds. (+)-rhododendrol, epirhododendrin, 4-[3'-O-(3-D-glucopyranosyl-4'-hydroxyphenyl]-2-butanone, 4-(4'-O-(3-D-glucopyranosylphenyl)-2-butanone, benzyl-O-[3-D-glucopyranoside and arbutin were also obtained.
From the leaves of Rhododendron latouclreae (Ericaceae), two new natural phenolic compounds named (+)-rhodolatouchol 1 and isoepirhododendrin 4 were identified. Six other known compounds. (+)-rhododendrol, epirhododendrin, 4-[3'-O-(3-D-glucopyranosyl-4'-hydroxyphenyl]-2-butanone, 4-(4'-O-(3-D-glucopyranosylphenyl)-2-butanone, benzyl-O-[3-D-glucopyranoside and arbutin were also obtained.
1999, 10(7): 571-572
Abstract:
Chemical investigation of L.fischeri afforded two new eremophilenolides, which wereidentitied as 6β-methoxy-8β-hydroy-eremophil-7(11)-en-12.8a-olide 1; 6-oxo-8β-hydroxy-eremophil-7(11)-en-12.8α-olide 2.
Chemical investigation of L.fischeri afforded two new eremophilenolides, which wereidentitied as 6β-methoxy-8β-hydroy-eremophil-7(11)-en-12.8a-olide 1; 6-oxo-8β-hydroxy-eremophil-7(11)-en-12.8α-olide 2.
1999, 10(7): 573-574
Abstract:
A new isopimarane diterpene, isopimar-l5-en-3β, 8β, 20-triol, was isolated from ,Nepeta prattii. Its structure was elucidated by spectral methods (EIMS, 1D and 2D NMR).
A new isopimarane diterpene, isopimar-l5-en-3β, 8β, 20-triol, was isolated from ,Nepeta prattii. Its structure was elucidated by spectral methods (EIMS, 1D and 2D NMR).
1999, 10(7): 575-578
Abstract:
Two new oxindole alkaloids, 17-demethoxy-hydroisorhynchophylline 1 and 17-demethoxv-hydroisorhynchophylline N-oxide 2, have been isolated from the aerial parts of Erva-ramin yunnanensis, and their structures were elucidated on the basis of spectroscopic analysis.
Two new oxindole alkaloids, 17-demethoxy-hydroisorhynchophylline 1 and 17-demethoxv-hydroisorhynchophylline N-oxide 2, have been isolated from the aerial parts of Erva-ramin yunnanensis, and their structures were elucidated on the basis of spectroscopic analysis.
1999, 10(7): 579-582
Abstract:
Two new dimeric stilbenes, named gnetifolin L and gnetifolin O, were isolated from the alcoholic ewract of lianas of Gnetum montanhn.Their structures were elucidated mainly on the basis of spectroscopic data including 2D-NMR studies on peracetate derivatives.
Two new dimeric stilbenes, named gnetifolin L and gnetifolin O, were isolated from the alcoholic ewract of lianas of Gnetum montanhn.Their structures were elucidated mainly on the basis of spectroscopic data including 2D-NMR studies on peracetate derivatives.
1999, 10(7): 583-586
Abstract:
Rigid PSDVB microbeads have been modified with poly（vinyl alcohol) (PVA) adsorbed on their surface to produce an affinny medium. Then Cibacron Blue F3GA was covalentlv attached to the supports. The initial concentration of PVA has effect on the adsorption of PVA. The non-specific interaction of bovine serum albumin (BSA) on the microbeads decreases、、ith the PVA adsorbed. The pH stability test shows that the aftinitv medium is stable up to pH 11.0. And it has specific interaction with lysoryme, but not with pepsin.
Rigid PSDVB microbeads have been modified with poly（vinyl alcohol) (PVA) adsorbed on their surface to produce an affinny medium. Then Cibacron Blue F3GA was covalentlv attached to the supports. The initial concentration of PVA has effect on the adsorption of PVA. The non-specific interaction of bovine serum albumin (BSA) on the microbeads decreases、、ith the PVA adsorbed. The pH stability test shows that the aftinitv medium is stable up to pH 11.0. And it has specific interaction with lysoryme, but not with pepsin.
1999, 10(7): 587-590
Abstract:
In this work, electron transfer across Au supported octadecanethiolphosphatidyl-choline (Au/ODT-PC) bilayers, which were modified with 7.7,8,8-tetracyanoquinodimethane (TCNQ). were investigated using electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). Results of EIS experiments show that the TCNQ molecules act as electron conductors in the bilayer. Cyclic voltammetry indicates that the TCNQ moditied Au/thiol-lipid bilavers display strong asymmetrical conductivity in Fe(CN)63/4 solution.
In this work, electron transfer across Au supported octadecanethiolphosphatidyl-choline (Au/ODT-PC) bilayers, which were modified with 7.7,8,8-tetracyanoquinodimethane (TCNQ). were investigated using electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). Results of EIS experiments show that the TCNQ molecules act as electron conductors in the bilayer. Cyclic voltammetry indicates that the TCNQ moditied Au/thiol-lipid bilavers display strong asymmetrical conductivity in Fe(CN)63/4 solution.
1999, 10(7): 591-592
Abstract:
The effects of physical aging on the tensile property of notched samples and the endothermic peak at glass transition region of polyphenylquinoxaline films were studied.
The effects of physical aging on the tensile property of notched samples and the endothermic peak at glass transition region of polyphenylquinoxaline films were studied.
1999, 10(7): 593-596
Abstract:
A series of butylene terephthalate-ε-caprolactone copolyesters (BCL) with different hard segment content were successfully synthesized and characterized by 1H-NMR. DSC. PLM and U-iscometer. the sequence structure and crystallization characteristics of BCI, copolyesters were carefully investigated.
A series of butylene terephthalate-ε-caprolactone copolyesters (BCL) with different hard segment content were successfully synthesized and characterized by 1H-NMR. DSC. PLM and U-iscometer. the sequence structure and crystallization characteristics of BCI, copolyesters were carefully investigated.
1999, 10(7): 597-600
Abstract:
Polymerization of styrene and 1,3-butadiene were performed by calix[4]arene- neodymium complexes using di-n-butylmagnesium and tri-iso-butylaluminum as cocatalyst respectively. The effect of the substituent groups in calix[4]arene on the catalytic activity was first investigated.
Polymerization of styrene and 1,3-butadiene were performed by calix[4]arene- neodymium complexes using di-n-butylmagnesium and tri-iso-butylaluminum as cocatalyst respectively. The effect of the substituent groups in calix[4]arene on the catalytic activity was first investigated.
1999, 10(7): 601-602
Abstract:
The polymerization of acrylic acid (AA) with dissolved carbon dioxide and tetrahydrofuran (THF) in the monomer is studied. Viscosity measurement, differential scanning calorimetn (DSC). and scanning electron microscopy (SEM) indicate that the concentration of tetrahvdrofuran has pronounced effect on the molecular weight (Mη). glass transition temperature (Tg), and the morphology ofthe product.
The polymerization of acrylic acid (AA) with dissolved carbon dioxide and tetrahydrofuran (THF) in the monomer is studied. Viscosity measurement, differential scanning calorimetn (DSC). and scanning electron microscopy (SEM) indicate that the concentration of tetrahvdrofuran has pronounced effect on the molecular weight (Mη). glass transition temperature (Tg), and the morphology ofthe product.
1999, 10(7): 603-606
Abstract:
A new type of binuclear europium y-dihetone chelates EumY1-m (TTA); phen (0≤m≤1) and the influence of the proportion of Y3+ on fluorescence intensity of the Lu-complexes were studied. It was found the proportion of Y3+ could atlect the fluorescence properties and the film formation seriously. only m≥0.5Y3+ could increase the luminescent intensity and improve the film formation. As a result, three new binuclear europiump-dihetone chelates con5fisted of EumY1-m (TTA)3 phen (m=0.9. 0.7 and 0.5) were designed and synthesized. Their structures were elucidated by IR. UV. DSC and Eaementary Analysis. Their PL properties were studied. The results showed that the three binuclear europiump-diketone chelates had better PI. properties and film formation than Eu(TTA)3phen. They could emit sharply red light, and fluorescent wavelength of them was all at 613nm (half bandwidth: lOnm). They can be used as red organic electroluminescent materials (OELMs) in organic electroluminescent devices (GELDS).
A new type of binuclear europium y-dihetone chelates EumY1-m (TTA); phen (0≤m≤1) and the influence of the proportion of Y3+ on fluorescence intensity of the Lu-complexes were studied. It was found the proportion of Y3+ could atlect the fluorescence properties and the film formation seriously. only m≥0.5Y3+ could increase the luminescent intensity and improve the film formation. As a result, three new binuclear europiump-dihetone chelates con5fisted of EumY1-m (TTA)3 phen (m=0.9. 0.7 and 0.5) were designed and synthesized. Their structures were elucidated by IR. UV. DSC and Eaementary Analysis. Their PL properties were studied. The results showed that the three binuclear europiump-diketone chelates had better PI. properties and film formation than Eu(TTA)3phen. They could emit sharply red light, and fluorescent wavelength of them was all at 613nm (half bandwidth: lOnm). They can be used as red organic electroluminescent materials (OELMs) in organic electroluminescent devices (GELDS).
1999, 10(7): 607-610
Abstract:
PVP-supported bimetallic catalyst. PVP-PdCl2-CdCl2, exhibits extremely high catalytic activity for the hydrogen transfer dechlorination of aryl chlorides in neutral environment. The yields of dechlorination products are high under mild reaction conditions and the operation is simple.
PVP-supported bimetallic catalyst. PVP-PdCl2-CdCl2, exhibits extremely high catalytic activity for the hydrogen transfer dechlorination of aryl chlorides in neutral environment. The yields of dechlorination products are high under mild reaction conditions and the operation is simple.
1999, 10(7): 611-614
Abstract:
The atom transfer radical polymerization (ATRP) of methyl methacrylate using α.α-dichlorotoluene or α.α,α-trichlorotoluene as the initiator and CuCl/2,2'-bipyridine complex as the catalyst was investigated. α,α-Dichlorotoluene gave good control of molecular weight with high initiation etliciency and low polydispersity. While α,α,α-trichlorotoluene gave very slow polymerization rate. which could be improved by the addition of Cu (0) to the system.
The atom transfer radical polymerization (ATRP) of methyl methacrylate using α.α-dichlorotoluene or α.α,α-trichlorotoluene as the initiator and CuCl/2,2'-bipyridine complex as the catalyst was investigated. α,α-Dichlorotoluene gave good control of molecular weight with high initiation etliciency and low polydispersity. While α,α,α-trichlorotoluene gave very slow polymerization rate. which could be improved by the addition of Cu (0) to the system.
1999, 10(7): 615-618
Abstract:
Three heuristic algorithms: simulated annealing, genetic algorithm. and Tabu search were compared to molecular docking procedure using 3 protein-ligand systems. Statistical analysis of the insults indicated that the Tabu search showed the best performance in terms of locating solutions close to the crystallographic ligand conformation. From the comparisons, a hybrid search algorithm was proposed. which gave superior results compared with any one of the algorithms alone.
Three heuristic algorithms: simulated annealing, genetic algorithm. and Tabu search were compared to molecular docking procedure using 3 protein-ligand systems. Statistical analysis of the insults indicated that the Tabu search showed the best performance in terms of locating solutions close to the crystallographic ligand conformation. From the comparisons, a hybrid search algorithm was proposed. which gave superior results compared with any one of the algorithms alone.
1999, 10(7): 619-622
Abstract:
Harmonic vibrational frequencies of hydrazoic acid and methy azidc calsulated using HF.MP2 methods and five pipular density functional(DFT)methods and compared with experimental results.Of these seven methods.BLYP reproduces the observed frequencies most satisfactorily.while the results in HF and MP2 are worse.These imdicate the BLYP calculation is a very promising approach for understanding the obser spectral features.
Harmonic vibrational frequencies of hydrazoic acid and methy azidc calsulated using HF.MP2 methods and five pipular density functional(DFT)methods and compared with experimental results.Of these seven methods.BLYP reproduces the observed frequencies most satisfactorily.while the results in HF and MP2 are worse.These imdicate the BLYP calculation is a very promising approach for understanding the obser spectral features.
