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2002 Volume 13 Issue 12
2002, 13(12): 1141-1142
Abstract:
A unique sliver (I)-promoted oxidation reaction of polyphenyl-cyclopentadiene is described, in which an oxygen is inserted into the cyclopentadiene-ring, forming a six-membered pyrylium cation.
A unique sliver (I)-promoted oxidation reaction of polyphenyl-cyclopentadiene is described, in which an oxygen is inserted into the cyclopentadiene-ring, forming a six-membered pyrylium cation.
2002, 13(12): 1143-1146
Abstract:
Four stereoisomers of a copper-(Schiff-base) complex with double chiral centers were applied to catalyze the asymmetric cyclopropanation. Two of the stereoisomers were also efficient catalysts affording high enantiomeric excess of up to 91.8%. A mechanism that predicts the observed results accurately was proposed.
Four stereoisomers of a copper-(Schiff-base) complex with double chiral centers were applied to catalyze the asymmetric cyclopropanation. Two of the stereoisomers were also efficient catalysts affording high enantiomeric excess of up to 91.8%. A mechanism that predicts the observed results accurately was proposed.
2002, 13(12): 1147-1148
Abstract:
An asymmetric borane reduction of prochiral ketones catalyzed by simple amino alcohols and corresponding amino acids was examined to give alcohols with e.e. value up to 92%.
An asymmetric borane reduction of prochiral ketones catalyzed by simple amino alcohols and corresponding amino acids was examined to give alcohols with e.e. value up to 92%.
2002, 13(12): 1149-1151
Abstract:
Catalytic amination of aryl bromides with in situ generated dimethylamines from N,N-dimethylacetamide (DMA) has been successfully carried out using Ni(Phen)Cl2 as catalyst. Both electron-rich and electron-poor aromatic system reacted smoothly under the conditions to give N,N-dimethylarylamines in good yields.
Catalytic amination of aryl bromides with in situ generated dimethylamines from N,N-dimethylacetamide (DMA) has been successfully carried out using Ni(Phen)Cl2 as catalyst. Both electron-rich and electron-poor aromatic system reacted smoothly under the conditions to give N,N-dimethylarylamines in good yields.
2002, 13(12): 1152-1153
Abstract:
An easy and mild way to construct 13-hydroxy-9,15-cyclo GA skeletons was reported and it could be used as a general protocol in the synthesis of GAs with this structure.
An easy and mild way to construct 13-hydroxy-9,15-cyclo GA skeletons was reported and it could be used as a general protocol in the synthesis of GAs with this structure.
2002, 13(12): 1154-1157
Abstract:
Laminin nonapeptide CR9 was synthesized via two different methods. A notably enhanced yield (46.8%) was obtained from method B compared to that (12.4%) from standard protocol (method A).
Laminin nonapeptide CR9 was synthesized via two different methods. A notably enhanced yield (46.8%) was obtained from method B compared to that (12.4%) from standard protocol (method A).
2002, 13(12): 1158-1161
Abstract:
A polymer-bound photosensitizer was synthesized by the reaction of Merrifield resin with 9-anthracenemethanol in the presence of potassium hydride. The photoisomerization of trans-vitamin D3 to cis-vitamin D3 was carried out with this polymer-bound photosensitizer in ethanol and toluene solutions. The experiment results demonstrate that this solid photosensitizer is efficient for the photoismerization and easy for separation from the reaction mixtures.
A polymer-bound photosensitizer was synthesized by the reaction of Merrifield resin with 9-anthracenemethanol in the presence of potassium hydride. The photoisomerization of trans-vitamin D3 to cis-vitamin D3 was carried out with this polymer-bound photosensitizer in ethanol and toluene solutions. The experiment results demonstrate that this solid photosensitizer is efficient for the photoismerization and easy for separation from the reaction mixtures.
2002, 13(12): 1162-1163
Abstract:
The cyclohexene 1 was oxidized with polymer-supported 2.2'-bipyridine cobalt(II) complex in the presence of CO2. The conversion and selectivity was sensitive to the pressure of CO2.
The cyclohexene 1 was oxidized with polymer-supported 2.2'-bipyridine cobalt(II) complex in the presence of CO2. The conversion and selectivity was sensitive to the pressure of CO2.
2002, 13(12): 1164-1167
Abstract:
(Z)-α-Selanyl alkenyl Grignard reagents 2 were prepared conveniently by treatment of α-bromovinylselenides 1 with magnesium filings in THF. Intermediates 2 were reacted with alkyl iodides in the presence of CuI or Pd(PPh3)4 to afford (Z)-1,2-disubstituted vinylselenides 3,which were cross-coupled with Grignard reagents in the presence of (PPh3)2NiCl2 to give trisubstituted alkenes 4 stereoselectively in good yields.
(Z)-α-Selanyl alkenyl Grignard reagents 2 were prepared conveniently by treatment of α-bromovinylselenides 1 with magnesium filings in THF. Intermediates 2 were reacted with alkyl iodides in the presence of CuI or Pd(PPh3)4 to afford (Z)-1,2-disubstituted vinylselenides 3,which were cross-coupled with Grignard reagents in the presence of (PPh3)2NiCl2 to give trisubstituted alkenes 4 stereoselectively in good yields.
2002, 13(12): 1168-1169
Abstract:
The title complex, Cl3SnCH2CH(CH3)CO2CH3·L (1), was synthesized by the reaction of methyl 2-methyl-3-trichlorostannylpropionate with benzylmethylsulfoxide (L) in solid state at room temperature and readily underwent transesterification into the corresponding analogues Cl3SnCH2CH(CH3)CO2R·L when reacted with an alcohol ROH. The structural features of these compounds were described, and the possible mechanism of transesterification was suggested.
The title complex, Cl3SnCH2CH(CH3)CO2CH3·L (1), was synthesized by the reaction of methyl 2-methyl-3-trichlorostannylpropionate with benzylmethylsulfoxide (L) in solid state at room temperature and readily underwent transesterification into the corresponding analogues Cl3SnCH2CH(CH3)CO2R·L when reacted with an alcohol ROH. The structural features of these compounds were described, and the possible mechanism of transesterification was suggested.
2002, 13(12): 1170-1173
Abstract:
In this paper, four functional substituted derivatives of cyclopalladated ferrocenylketimines 1~4, which were as mimetics of metal-dependent esterases for catalyzing the hydrolysis of thiophosphoric acid esters pesticides, were synthesized and characterized. All the four cyclopalladated complexes can efficiently catalyze the degradation of thiophosphoric acid pesticides, such as methyl parathion. The Pd catalyst with coordinated oxime is more active and exhibits an increased selectivity towards sulfur containing pesticides.
In this paper, four functional substituted derivatives of cyclopalladated ferrocenylketimines 1~4, which were as mimetics of metal-dependent esterases for catalyzing the hydrolysis of thiophosphoric acid esters pesticides, were synthesized and characterized. All the four cyclopalladated complexes can efficiently catalyze the degradation of thiophosphoric acid pesticides, such as methyl parathion. The Pd catalyst with coordinated oxime is more active and exhibits an increased selectivity towards sulfur containing pesticides.
2002, 13(12): 1174-1177
Abstract:
The initiation reactions in the anionic non-equilibrium polymerization of octamethylcyclotetrasiloxane (D4) initiated by silazyllithiums were investigated. It was found that the structure of the substituents on the Si atom had great influences on the initiation activity of silazyllithiums.
The initiation reactions in the anionic non-equilibrium polymerization of octamethylcyclotetrasiloxane (D4) initiated by silazyllithiums were investigated. It was found that the structure of the substituents on the Si atom had great influences on the initiation activity of silazyllithiums.
2002, 13(12): 1178-1180
Abstract:
Kansuinine A is a macrocyclic jatrophane diterpene that was isolated from Euphorbia kansui. Further investigation of the structure was revealed that the benzoyl group located at C-8 and the position of C-3 was the present of an acetyl group by means of HMQC, HMBC spectra.
Kansuinine A is a macrocyclic jatrophane diterpene that was isolated from Euphorbia kansui. Further investigation of the structure was revealed that the benzoyl group located at C-8 and the position of C-3 was the present of an acetyl group by means of HMQC, HMBC spectra.
2002, 13(12): 1181-1184
Abstract:
Two new triterpene esters, 2-O-caffeoylalphitolic acid (1) and methyl 2-O-caffeoylalphitolate (2), together with two known triterpenes were isolated from the shrub Daphniphyllum oldhami. The structures of new compounds were elucidated on the basis of detailed spectroscopic analysis and compared with related compound.
Two new triterpene esters, 2-O-caffeoylalphitolic acid (1) and methyl 2-O-caffeoylalphitolate (2), together with two known triterpenes were isolated from the shrub Daphniphyllum oldhami. The structures of new compounds were elucidated on the basis of detailed spectroscopic analysis and compared with related compound.
2002, 13(12): 1185-1188
Abstract:
Two new furostanol oligoglycosides named as aspacochioside A (1) and B (2) were isolated from the roots of Asparagus cochinchinensis (Lour.) Merr.. Their structures were elucidated to be 3-O-[{α-L-rhamnopyranosyl-(1→4)}{β-D-glucopyranosyl}]-26-O-[β-D-glucopyranosyl]-(25S)-5β-furostane-3β,22α,26-triol 1 and 3-O-[{α-L-rhamnopyranosyl-(1→4)}{β-D-glucopyranosyl}]-26-O-[β-D-glucopyranosyl]-22α-methoxy-(25S)-5β-furostane-3β,26-diol 2 on the basis of spectroscopic techniques and chemical methods.
Two new furostanol oligoglycosides named as aspacochioside A (1) and B (2) were isolated from the roots of Asparagus cochinchinensis (Lour.) Merr.. Their structures were elucidated to be 3-O-[{α-L-rhamnopyranosyl-(1→4)}{β-D-glucopyranosyl}]-26-O-[β-D-glucopyranosyl]-(25S)-5β-furostane-3β,22α,26-triol 1 and 3-O-[{α-L-rhamnopyranosyl-(1→4)}{β-D-glucopyranosyl}]-26-O-[β-D-glucopyranosyl]-22α-methoxy-(25S)-5β-furostane-3β,26-diol 2 on the basis of spectroscopic techniques and chemical methods.
2002, 13(12): 1189-1192
Abstract:
A new minor pregnane glycoside was isolated from the fermented leaves of Agave americana. Its structure was elucidated as (20S)-5α-pregnane-3β, 20-diol 20-O-β-D-glucopyranoside (1) by spectral methods.
A new minor pregnane glycoside was isolated from the fermented leaves of Agave americana. Its structure was elucidated as (20S)-5α-pregnane-3β, 20-diol 20-O-β-D-glucopyranoside (1) by spectral methods.
2002, 13(12): 1193-1194
Abstract:
Amylose tris (phenylcarbamate) chiral stationary phase (ATPC-CSP) was prepared and used for optical resolution of clusters 1 and 2. n-Hexane/2-propanol (99/1;v/v) were found to be the most suitable mobile phase on ATPC-CSP
Amylose tris (phenylcarbamate) chiral stationary phase (ATPC-CSP) was prepared and used for optical resolution of clusters 1 and 2. n-Hexane/2-propanol (99/1;v/v) were found to be the most suitable mobile phase on ATPC-CSP
2002, 13(12): 1195-1198
Abstract:
A new method for the determination of utratrace silver(I) by near field thermal lens spectrometry has been developed. This method is based on the silver(I) catalyzed discoloring reaction of bromocresol green oxidized by sodium persulphate in the presence of α, α'-bipy as activator and Triton X-100 as sensitizer. The linear range of this method is 0~1.6 ng·mL-1 of silver. The detection limit is 2×10-2 ng·mL-1. The method has been applied to the determination of silver in lead power and photographic paper with satisfactory results.
A new method for the determination of utratrace silver(I) by near field thermal lens spectrometry has been developed. This method is based on the silver(I) catalyzed discoloring reaction of bromocresol green oxidized by sodium persulphate in the presence of α, α'-bipy as activator and Triton X-100 as sensitizer. The linear range of this method is 0~1.6 ng·mL-1 of silver. The detection limit is 2×10-2 ng·mL-1. The method has been applied to the determination of silver in lead power and photographic paper with satisfactory results.
2002, 13(12): 1199-1202
Abstract:
In this paper, a new HPLC method was established to determine the carbonyl compounds in air. As the absorbent, 2, 4-dinitrophenylhydrazine (2, 4-DNPH) reacted with carbonyls specifically, which form the corresponding 2,4-dinitrophenylhydrazones, then analyzed by HPLC. The chromatographic conditions, the recovery rate, stability of samples, reagent blank,sampling efficiency were all studied systematically. The results showed that this established method had high sensitivity and good selectivity compared with other analytical methods, and it can determine ten carbonyl compounds in air in 26 min simultaneously.
In this paper, a new HPLC method was established to determine the carbonyl compounds in air. As the absorbent, 2, 4-dinitrophenylhydrazine (2, 4-DNPH) reacted with carbonyls specifically, which form the corresponding 2,4-dinitrophenylhydrazones, then analyzed by HPLC. The chromatographic conditions, the recovery rate, stability of samples, reagent blank,sampling efficiency were all studied systematically. The results showed that this established method had high sensitivity and good selectivity compared with other analytical methods, and it can determine ten carbonyl compounds in air in 26 min simultaneously.
2002, 13(12): 1203-1204
Abstract:
Micellar electrokinetic capillary chromatography (MECC) separation of four acidic drugs similar in structure was studied. Both anionic surfactant sodium dodecyl sulfate (SDS) and nonionic surfactant Tween 20 were used to form single micelles and mixed micelles as pseudostationary phases. The effects of the composition of micellar solution on retention behaviors were studied. The results indicate that there is markedly different selectivity among SDS, Tween 20 and the mixed micelles systems.
Micellar electrokinetic capillary chromatography (MECC) separation of four acidic drugs similar in structure was studied. Both anionic surfactant sodium dodecyl sulfate (SDS) and nonionic surfactant Tween 20 were used to form single micelles and mixed micelles as pseudostationary phases. The effects of the composition of micellar solution on retention behaviors were studied. The results indicate that there is markedly different selectivity among SDS, Tween 20 and the mixed micelles systems.
2002, 13(12): 1205-1208
Abstract:
The TDDFT method is first applied in a series of tetra-nuclear transition metal clusters studies for nonlinear optical properties. The results indicate that the charge transfer inside the metal core[MCu3X4] (M=W, Mo; X=S, O, Cl, Se, Br) makes contribution to the optical nonlinearity. It is possible to enhance the hyperpolarizability by substituting the ligands of the clusters.
The TDDFT method is first applied in a series of tetra-nuclear transition metal clusters studies for nonlinear optical properties. The results indicate that the charge transfer inside the metal core[MCu3X4] (M=W, Mo; X=S, O, Cl, Se, Br) makes contribution to the optical nonlinearity. It is possible to enhance the hyperpolarizability by substituting the ligands of the clusters.
2002, 13(12): 1209-1212
Abstract:
The new complexes[Ru(NO)(PPh3)]2(η2-Cm) (m=60 1 or 70 2) have been prepared by heating a solution of C60(or C70) with[Ru(NO)2(PPh3)2] in toluene. They have been characterized by elemental analysis, IR, UV/VIS, XPS, 13C and 31P NMR spectroscopy. The photovaltaic effect for the new compounds has been studied.
The new complexes[Ru(NO)(PPh3)]2(η2-Cm) (m=60 1 or 70 2) have been prepared by heating a solution of C60(or C70) with[Ru(NO)2(PPh3)2] in toluene. They have been characterized by elemental analysis, IR, UV/VIS, XPS, 13C and 31P NMR spectroscopy. The photovaltaic effect for the new compounds has been studied.
2002, 13(12): 1213-1216
Abstract:
A novel method of preparing pyruvate from DL-lactate catalyzed by enzymes from a bacterial strain of Pseudomonas sp. SM-6 was proposed. Catalytic processes of cell-free extract enzymes and immobilized enzymes were evaluated. The kinetic data were studied, too.
A novel method of preparing pyruvate from DL-lactate catalyzed by enzymes from a bacterial strain of Pseudomonas sp. SM-6 was proposed. Catalytic processes of cell-free extract enzymes and immobilized enzymes were evaluated. The kinetic data were studied, too.
2002, 13(12): 1217-1220
Abstract:
A new catalyst for methanol synthesis, ZnO-promoted rhodium supported on carbon nanotubes, was developed. It was found that the Rh-ZnO/CNTs catalyst had high activity of 411.4 mg CH3OH/g/cat/h and selectivity of 96.7% for methanol at 1 MPa and 523 K. The activity of this catalyst is much higher than that of NC 207 catalyst at the same reaction conditions.It was suggested that the multi-walled structure CNTs favored both the couple transfer of the proton and electron over the surface of the catalyst and the uptake of hydrogen which was favorable to methanol synthesis.
A new catalyst for methanol synthesis, ZnO-promoted rhodium supported on carbon nanotubes, was developed. It was found that the Rh-ZnO/CNTs catalyst had high activity of 411.4 mg CH3OH/g/cat/h and selectivity of 96.7% for methanol at 1 MPa and 523 K. The activity of this catalyst is much higher than that of NC 207 catalyst at the same reaction conditions.It was suggested that the multi-walled structure CNTs favored both the couple transfer of the proton and electron over the surface of the catalyst and the uptake of hydrogen which was favorable to methanol synthesis.
2002, 13(12): 1221-1224
Abstract:
An ultrafine Ru-B amorphous alloy catalyst was prepared by chemical reduction with KBH4 in aqueous solution, which exhibited perfect selectivity to sorbitol (~100%) and very high activity during the liquid phase glucose hydrogenation, much higher than the corresponding crystallized Ru-B, the pure Ru powder, and Raney Ni catalysts. The correlation of the catalytic activity to both the structural and surface electronic characteristics was discussed briefly.
An ultrafine Ru-B amorphous alloy catalyst was prepared by chemical reduction with KBH4 in aqueous solution, which exhibited perfect selectivity to sorbitol (~100%) and very high activity during the liquid phase glucose hydrogenation, much higher than the corresponding crystallized Ru-B, the pure Ru powder, and Raney Ni catalysts. The correlation of the catalytic activity to both the structural and surface electronic characteristics was discussed briefly.
2002, 13(12): 1225-1226
Abstract:
A new kind of polyorganozircosilazane as Si/Zr/C/N-based ceramic precursor was synthesized from the condensation reaction of hexamethylcyclotrisilazane lithium salts (D3NLi) and zirconium tetrachloride (ZrCl4). In the presence of N, N, N', N'-tetramethyl ethylene diamine (TMEDA), polyorganozircosilazane was obtained in high yield.
A new kind of polyorganozircosilazane as Si/Zr/C/N-based ceramic precursor was synthesized from the condensation reaction of hexamethylcyclotrisilazane lithium salts (D3NLi) and zirconium tetrachloride (ZrCl4). In the presence of N, N, N', N'-tetramethyl ethylene diamine (TMEDA), polyorganozircosilazane was obtained in high yield.
2002, 13(12): 1227-1230
Abstract:
The abstraction reaction of H atom with (CH3)3GeH has been studied using ab initio molecular orbital theory. The kinetics calculation has been deduced using the canonical variational transition state theory (CVT) with the small-curvature tunneling correction method (SCT) over the temperature range of 200-3000 K. The CVT/SCT rate constants exhibit typical non-Arrhenius behavior, and a three-parameter rate-temperature formula has been fitted as follows:k=6.66×10- 18T2.33 exp(-60.3/T) (in units of cm3 molecule-1 s-1).
The abstraction reaction of H atom with (CH3)3GeH has been studied using ab initio molecular orbital theory. The kinetics calculation has been deduced using the canonical variational transition state theory (CVT) with the small-curvature tunneling correction method (SCT) over the temperature range of 200-3000 K. The CVT/SCT rate constants exhibit typical non-Arrhenius behavior, and a three-parameter rate-temperature formula has been fitted as follows:k=6.66×10- 18T2.33 exp(-60.3/T) (in units of cm3 molecule-1 s-1).
2002, 13(12): 1231-1234
Abstract:
Photoinduced electron transfer processes between fullerenes (C60/C70) and N, N, N', N'-tetra-(p-methylphenyl)-4, 4'-diamino-1, 1'-diphenyl ether (TPDAE) have been studied by nanosecond laser flash photolysis. Quantum yields and rate constants of electron transfer from TPDAE to excited triplet state of fullerenes (C60/C70) in benzonitrile have been evaluated by observing the transient absorption bands in the near-IR region where the excited triplet state,radical anion of fullerenes (C60/C70) and radical cations of TPDAE appear.
Photoinduced electron transfer processes between fullerenes (C60/C70) and N, N, N', N'-tetra-(p-methylphenyl)-4, 4'-diamino-1, 1'-diphenyl ether (TPDAE) have been studied by nanosecond laser flash photolysis. Quantum yields and rate constants of electron transfer from TPDAE to excited triplet state of fullerenes (C60/C70) in benzonitrile have been evaluated by observing the transient absorption bands in the near-IR region where the excited triplet state,radical anion of fullerenes (C60/C70) and radical cations of TPDAE appear.
