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2000 Volume 11 Issue 5
2000, 11(5): 377-380
Abstract:
1-Ethyl-2-fluoropyridinium tetrafluoroborate(FEP)was shown to be a very efficient coupling reagent for the synthesis of the hindered peptide with fast reaction speed,low racemization and good yields.
1-Ethyl-2-fluoropyridinium tetrafluoroborate(FEP)was shown to be a very efficient coupling reagent for the synthesis of the hindered peptide with fast reaction speed,low racemization and good yields.
2000, 11(5): 381-382
Abstract:
Two new type of 1,3,2-oxazaborolidines were prepared from (1s,2s)-2-amino-1-(4-nitrophenyl)-propane-1,3-diol and were used as catalyst in the asymmetric reduction of acetophenone. The influence of the reaction temperature as well as the effect of the structure of catalyst on the enantioselectivity was investigated. The origin of the products' configuration was discussed.
Two new type of 1,3,2-oxazaborolidines were prepared from (1s,2s)-2-amino-1-(4-nitrophenyl)-propane-1,3-diol and were used as catalyst in the asymmetric reduction of acetophenone. The influence of the reaction temperature as well as the effect of the structure of catalyst on the enantioselectivity was investigated. The origin of the products' configuration was discussed.
2000, 11(5): 383-384
Abstract:
Two new chiral Ru(Ⅱ)-sulfonamide complex have been used to catalyze the enantioselective transfer hydrogenation of prochiral ketones and the secondary alcohols are obtained with good to excellent optical yields.
Two new chiral Ru(Ⅱ)-sulfonamide complex have been used to catalyze the enantioselective transfer hydrogenation of prochiral ketones and the secondary alcohols are obtained with good to excellent optical yields.
2000, 11(5): 385-386
Abstract:
Reductive debromination of anhydro-6-(R)-hydroxyethyl-6-bromopenicillin 7 by zinc in ammonium acetate gave 9 in 81% yield with high stereoselectivity of 6-(α):6-(β)=13:1.
Reductive debromination of anhydro-6-(R)-hydroxyethyl-6-bromopenicillin 7 by zinc in ammonium acetate gave 9 in 81% yield with high stereoselectivity of 6-(α):6-(β)=13:1.
2000, 11(5): 387-388
Abstract:
Nitrodisulfides were reduced by SmI2/HMPA in anhydrous THF at room temperature to produce active intermediates (samarium thiolates and amides), which were "living" double-anions and reacted smoothly with aldehydes or ketones to afford benzothiazolines in good yields under mild and neutral conditions.
Nitrodisulfides were reduced by SmI2/HMPA in anhydrous THF at room temperature to produce active intermediates (samarium thiolates and amides), which were "living" double-anions and reacted smoothly with aldehydes or ketones to afford benzothiazolines in good yields under mild and neutral conditions.
2000, 11(5): 389-390
Abstract:
3,4-Dihydro-(2H)-1,2,4-benzothiadizine-1,1-dioixdes were prepared in good yields via reductive cyclization of o-nitrobenzenesulfonamides with aldehydes promoted by SmI2 under mild and neutral condition.
3,4-Dihydro-(2H)-1,2,4-benzothiadizine-1,1-dioixdes were prepared in good yields via reductive cyclization of o-nitrobenzenesulfonamides with aldehydes promoted by SmI2 under mild and neutral condition.
2000, 11(5): 391-394
Abstract:
A series of novel N-[α-(isoflavone-7-O-) acetyl] amino acid methyl esters were prepared from the efficient and regioselective alkylation of isoflavones with chloroacetyl amino acid derivatives under mild condition.
A series of novel N-[α-(isoflavone-7-O-) acetyl] amino acid methyl esters were prepared from the efficient and regioselective alkylation of isoflavones with chloroacetyl amino acid derivatives under mild condition.
2000, 11(5): 395-398
Abstract:
A new organic dye, trans-4-[4'-(N-hydroxyethyl-N-methylamino)styryl]-N-methylpyri-dinium p-toluene sulfonate (HMASPS) has been synthesized and its structure has been determined. Pumped with a 1064 nm, 50 ps laser pulses, 0.05 mol/L HMASPS/DMF solution showed the two-photon pumped (TPP) output/input efficiency of 8.4% which is higher than that of trans-4-[p-(N-hydroxyethyl-N-methylamino) styryl]-N-methylpyridinium iodide (ASPI)1 at the same pump level.
A new organic dye, trans-4-[4'-(N-hydroxyethyl-N-methylamino)styryl]-N-methylpyri-dinium p-toluene sulfonate (HMASPS) has been synthesized and its structure has been determined. Pumped with a 1064 nm, 50 ps laser pulses, 0.05 mol/L HMASPS/DMF solution showed the two-photon pumped (TPP) output/input efficiency of 8.4% which is higher than that of trans-4-[p-(N-hydroxyethyl-N-methylamino) styryl]-N-methylpyridinium iodide (ASPI)1 at the same pump level.
2000, 11(5): 399-400
Abstract:
A new synthetic route for α-agarofuran(1b) is described. Several agarofuran derivatives were synthesized in similar way. Derivative 1d was also synthesized in a novel way, in which the substitution at C-4 was performed quantitatively. An ideal condition for cyclization of diol 7 to agarofuran (1) was found.
A new synthetic route for α-agarofuran(1b) is described. Several agarofuran derivatives were synthesized in similar way. Derivative 1d was also synthesized in a novel way, in which the substitution at C-4 was performed quantitatively. An ideal condition for cyclization of diol 7 to agarofuran (1) was found.
2000, 11(5): 401-402
Abstract:
A variety of novel N-t-butyl-N'-aminocarbonyl-N-(substituted)benzoylhydrazines containing α-aminoalkylphosphonate groups were synthesized by the addition of N-t-butyl-N-(substituted)benzoylhydrazines to α-isocyanatoalkylphosphonates, which were synthesized by the reaction of α-aminoalkylphosphonates with triphosgene in good yields. The structures of products including by-products were confirmed by 1H NMR, 31P NMR, IR, mass spectroscopy, and elemental analysis.
A variety of novel N-t-butyl-N'-aminocarbonyl-N-(substituted)benzoylhydrazines containing α-aminoalkylphosphonate groups were synthesized by the addition of N-t-butyl-N-(substituted)benzoylhydrazines to α-isocyanatoalkylphosphonates, which were synthesized by the reaction of α-aminoalkylphosphonates with triphosgene in good yields. The structures of products including by-products were confirmed by 1H NMR, 31P NMR, IR, mass spectroscopy, and elemental analysis.
2000, 11(5): 402-404
Abstract:
The macrocyclic lactones building on calix[4]arenes 3a-b and double calix[4]arenes 4a-b were synthesized by the reaction of p-tert-butylcalix[4]arene (1a) or calix[4]arene (1b) with glycol bis(2-chloroacetate) (2). The conditions to improve the yields of double calix[4]arenes have been discussed.
The macrocyclic lactones building on calix[4]arenes 3a-b and double calix[4]arenes 4a-b were synthesized by the reaction of p-tert-butylcalix[4]arene (1a) or calix[4]arene (1b) with glycol bis(2-chloroacetate) (2). The conditions to improve the yields of double calix[4]arenes have been discussed.
2000, 11(5): 405-406
Abstract:
Stereocomplexes formed in atactic poly(methyl methacrylate) (a-PMMA) films cast form different solvents were studied by means of Fourier transform infrared spectroscopy (FTIR), and differential scanning calorimetry (DSC). The growth of stereocomplex was a function of annealing temperature and annealing time, respectively.
Stereocomplexes formed in atactic poly(methyl methacrylate) (a-PMMA) films cast form different solvents were studied by means of Fourier transform infrared spectroscopy (FTIR), and differential scanning calorimetry (DSC). The growth of stereocomplex was a function of annealing temperature and annealing time, respectively.
2000, 11(5): 407-408
Abstract:
Nucleosides were phosphorylated with different N-(O, O-diisopropyl) phosphoryl amino acids to give nucleoside mono phosphates in aqueous solution. 2', 3', and 5'-isomers had been confirmed by comparison with authentic samples on the basis of HPLC analysis. The conversion percentage of nucleoside indicated that N-(O, O-diisopropyl) phosphoryl aspartic acid reacted with adenosine and guanosine at a much higher rate than other kinds of N-phosphoryl amino acids, while phosphorylation of cytidine and uridine was relatively easy by using N-(O, O-diisopropyl) phosphoryl threonine. The result could give some clue to the prebiotic code origin of nucleic acid and protein.
Nucleosides were phosphorylated with different N-(O, O-diisopropyl) phosphoryl amino acids to give nucleoside mono phosphates in aqueous solution. 2', 3', and 5'-isomers had been confirmed by comparison with authentic samples on the basis of HPLC analysis. The conversion percentage of nucleoside indicated that N-(O, O-diisopropyl) phosphoryl aspartic acid reacted with adenosine and guanosine at a much higher rate than other kinds of N-phosphoryl amino acids, while phosphorylation of cytidine and uridine was relatively easy by using N-(O, O-diisopropyl) phosphoryl threonine. The result could give some clue to the prebiotic code origin of nucleic acid and protein.
2000, 11(5): 409-410
Abstract:
A new azafluorenone (onychine) alkaloid, 6,7-dimethoxy-5-hydroxy onychine N-oxide, was isolated from the stem and branch of Alphonsea monogyma. Its structure was established on the basis of spectral and chemical analysis.
A new azafluorenone (onychine) alkaloid, 6,7-dimethoxy-5-hydroxy onychine N-oxide, was isolated from the stem and branch of Alphonsea monogyma. Its structure was established on the basis of spectral and chemical analysis.
2000, 11(5): 411-414
Abstract:
A new diterpenoid alkaloid, racemulodine (1), was isolated from the whole plants of Aconitum racemulosum Franch var. pengzhounense.
A new diterpenoid alkaloid, racemulodine (1), was isolated from the whole plants of Aconitum racemulosum Franch var. pengzhounense.
2000, 11(5): 415-416
Abstract:
Two new iridoid glucosides, named 7β-coumaroyloxyugandoside (1) and 7β-cinnamoyloxyugandoside (2) were isolated from the leaves of Clerodendrum serratum, and their structures were elucidated by spectral means.
Two new iridoid glucosides, named 7β-coumaroyloxyugandoside (1) and 7β-cinnamoyloxyugandoside (2) were isolated from the leaves of Clerodendrum serratum, and their structures were elucidated by spectral means.
2000, 11(5): 417-420
Abstract:
Demethoxylation and O-demethylation of the norditerpenoid alkaloids pseudaconine and isolatatizidine were described.
Demethoxylation and O-demethylation of the norditerpenoid alkaloids pseudaconine and isolatatizidine were described.
2000, 11(5): 421-424
Abstract:
Oxidation of 1 with KMnO4 in acetone-H2O (1:1) for 1h gave nevadenine 2 (38%). But, 3 was formed in 98% yield when prolonging time and raising temperature (40℃). Reaction of 1 and 10 with Conforth reagent afforded the ketones 11 (55%), 12 (30%), and 13 (13%), 14 (20%), respectively. While oxidation of 7 and 15 with a variety of the oxidizing agents gave 17 only in low 20% of yield besides the minor 16. In addition, 1 was converted to 2 by the fungi Curvularia lunata.
Oxidation of 1 with KMnO4 in acetone-H2O (1:1) for 1h gave nevadenine 2 (38%). But, 3 was formed in 98% yield when prolonging time and raising temperature (40℃). Reaction of 1 and 10 with Conforth reagent afforded the ketones 11 (55%), 12 (30%), and 13 (13%), 14 (20%), respectively. While oxidation of 7 and 15 with a variety of the oxidizing agents gave 17 only in low 20% of yield besides the minor 16. In addition, 1 was converted to 2 by the fungi Curvularia lunata.
2000, 11(5): 425-426
Abstract:
A continuous phosphine (PH3) generation was developed and applied to the sensitive detection of phosphorus by ICP-AES. Phosphate ion in aqueous solution was converted to phosphine by passing the sample solution through an incandescent copper silica-tube. Detection limit is 2 ng/mL. The relative standard deviation is 4.2% for 20 ng/mL. The method is rapid and simple with low contamination and high sensitivity.
A continuous phosphine (PH3) generation was developed and applied to the sensitive detection of phosphorus by ICP-AES. Phosphate ion in aqueous solution was converted to phosphine by passing the sample solution through an incandescent copper silica-tube. Detection limit is 2 ng/mL. The relative standard deviation is 4.2% for 20 ng/mL. The method is rapid and simple with low contamination and high sensitivity.
2000, 11(5): 427-430
Abstract:
The chemiluminescence (CL) reaction between lucigenin (Lu) and molybdenum (Ⅲ) produced by a Jones reductor was investigated using a flow injection system. On the basis of this, a novel method for the determination of trace amount of molybdenum has been established. The emission intensity was linear with molybdenum concentration in the range of 0.1-1000 ng/mL; the detection limit was 0.02 ng/mL molybdenum; the relative standard deviation was less than 2% for the determination of 0.1 ng/mL molybdenum (n=11). The method has been applied successfully to the analysis of trace molybdenum in water and steel samples.
The chemiluminescence (CL) reaction between lucigenin (Lu) and molybdenum (Ⅲ) produced by a Jones reductor was investigated using a flow injection system. On the basis of this, a novel method for the determination of trace amount of molybdenum has been established. The emission intensity was linear with molybdenum concentration in the range of 0.1-1000 ng/mL; the detection limit was 0.02 ng/mL molybdenum; the relative standard deviation was less than 2% for the determination of 0.1 ng/mL molybdenum (n=11). The method has been applied successfully to the analysis of trace molybdenum in water and steel samples.
2000, 11(5): 431-434
Abstract:
A new spectrofluorimetric method for determination of trace terbium based on its reaction with 2,6-bis-(1'-phenyl-3'-methyl-5'-oxopyrazole-4') pyridinediacyl (H2PMBPP) and N-cetylpyridium bromide (CPB), at an apparent pH=5.0 provided by a hexamethylenetetramine (5% w/w)-hydrochloric acid buffer, is proposed. The calibration graph is linear in the range from 1.43×10-5 to 0.1589 μg/ml.
A new spectrofluorimetric method for determination of trace terbium based on its reaction with 2,6-bis-(1'-phenyl-3'-methyl-5'-oxopyrazole-4') pyridinediacyl (H2PMBPP) and N-cetylpyridium bromide (CPB), at an apparent pH=5.0 provided by a hexamethylenetetramine (5% w/w)-hydrochloric acid buffer, is proposed. The calibration graph is linear in the range from 1.43×10-5 to 0.1589 μg/ml.
2000, 11(5): 435-438
Abstract:
A rapid and simple method is presented for determining β-N-oxalyl-α,β-diaminopropionic acid (β-ODAP) and its much less toxic α-isomer (α-ODAP) in Lathyrus sativus. Seed and foliage extracts of Lathyrus sativus were treated with 1-fluoro-2,4-dinitrobenzene (FDNB) and a reversed-phase high-performance liquid chromatographic method for the separation of the derivatives in the pmol range is reported.
A rapid and simple method is presented for determining β-N-oxalyl-α,β-diaminopropionic acid (β-ODAP) and its much less toxic α-isomer (α-ODAP) in Lathyrus sativus. Seed and foliage extracts of Lathyrus sativus were treated with 1-fluoro-2,4-dinitrobenzene (FDNB) and a reversed-phase high-performance liquid chromatographic method for the separation of the derivatives in the pmol range is reported.
2000, 11(5): 439-442
Abstract:
A new conductivity detector for capillary electrophoresis consisting of an electrochemical cell and a conductive meter was developed. In the cell, the microelectrode and capillary were inserted through the cell wall and fixed by screws and sealing ring, the ends of microelectrode and capillary were located by a guide with two cross holes. LOD for K+ was 1.5×10-5 mol/L.
A new conductivity detector for capillary electrophoresis consisting of an electrochemical cell and a conductive meter was developed. In the cell, the microelectrode and capillary were inserted through the cell wall and fixed by screws and sealing ring, the ends of microelectrode and capillary were located by a guide with two cross holes. LOD for K+ was 1.5×10-5 mol/L.
2000, 11(5): 443-446
Abstract:
A novel electroanalytical method, oscillographic chronopotentiometry with high and low frequency current, is presented in this paper. With this method, the sensitivity of almost all kinds of oscillographic chronopotentiometry can be enhanced about one order.
A novel electroanalytical method, oscillographic chronopotentiometry with high and low frequency current, is presented in this paper. With this method, the sensitivity of almost all kinds of oscillographic chronopotentiometry can be enhanced about one order.
2000, 11(5): 447-450
Abstract:
Density functional theory BLYP (using Becke's and Lee-Yang-Parr's correlation functionals), ab initio Hartree-Fock (HF) and hybrid DFT/HF B3LYP calculations were carried out to study the structure and vibrational spectra of pyruvic acid. The scaled B3LYP/6-31G* frequencies correspond well with available experimental assignment of the functional vibrational modes and the mean absolut devation is only 12.3cm-1.
Density functional theory BLYP (using Becke's and Lee-Yang-Parr's correlation functionals), ab initio Hartree-Fock (HF) and hybrid DFT/HF B3LYP calculations were carried out to study the structure and vibrational spectra of pyruvic acid. The scaled B3LYP/6-31G* frequencies correspond well with available experimental assignment of the functional vibrational modes and the mean absolut devation is only 12.3cm-1.
2000, 11(5): 451-452
Abstract:
The oil-in-water microemulsion containing N-butyl maleimide(NBMI, M1) and styrene(St, M2) was prepared. The complexation properties of NBMI and St in microemulsion were investigated by means of 1H-NMR. With the participation of charge-transfer complex(CTC), four reactivity ratios and the relative reactivity of free monomers and CTC were obtained. The result was compared with that measured by Mayo-Lewis method.
The oil-in-water microemulsion containing N-butyl maleimide(NBMI, M1) and styrene(St, M2) was prepared. The complexation properties of NBMI and St in microemulsion were investigated by means of 1H-NMR. With the participation of charge-transfer complex(CTC), four reactivity ratios and the relative reactivity of free monomers and CTC were obtained. The result was compared with that measured by Mayo-Lewis method.
2000, 11(5): 453-454
Abstract:
In the investigation of effect of KSCN on the partitioning of lysozyme in PEG2000/ammonium sulfate aqueous two-phase system, it was found that the KSCN could alter the pH difference between the two phases, and thus affect the partition of lysozyme. The relationship between partition coefficients of lysozyme and pH differences between two phases was discussed.
In the investigation of effect of KSCN on the partitioning of lysozyme in PEG2000/ammonium sulfate aqueous two-phase system, it was found that the KSCN could alter the pH difference between the two phases, and thus affect the partition of lysozyme. The relationship between partition coefficients of lysozyme and pH differences between two phases was discussed.
2000, 11(5): 455-458
Abstract:
The spinel LiMn2O4-δ Fδ cathode materials were synthesized by solid-state reaction, with calculated amounts of LiOH·H2O, MnO2(EMD), LiF. The results of electrochemical test demonstrated that these new materials exhibited excellent electrochemical properties. Its initial capacity reached~115 mAh·g-1 and reversible efficiency is about 100%. After 60 cycles, its capacity was still around 110 mAh·g-1, with nearly 100% reversible efficiency.
The spinel LiMn2O4-δ Fδ cathode materials were synthesized by solid-state reaction, with calculated amounts of LiOH·H2O, MnO2(EMD), LiF. The results of electrochemical test demonstrated that these new materials exhibited excellent electrochemical properties. Its initial capacity reached~115 mAh·g-1 and reversible efficiency is about 100%. After 60 cycles, its capacity was still around 110 mAh·g-1, with nearly 100% reversible efficiency.
2000, 11(5): 459-462
Abstract:
Crystal and molecular structure of (2,6-dipropylphenylamide) dimethyl (tetra-methyl cyclopentadienyl) silane titanium dichloride (Ⅰ) was fully characterized by X-ray diffraction. The crystal is obtained from a mixture of ether/hexane as orthorhombic, with a=12.658 (3)Å, b=16.62 (3)Å, c=11.760 (2)Å, V=2474.2 (9) Å 3, Z=4, space group Pnma, R=0.0399. Componud Ⅰ compose of the π-bounded ring with its dimethylsilyl-dipropyl phenyl amido group and the two terminal chloride atoms coordinated to central metal to form a so-called constrained geometry catalyst (CGC) structure. The result of molecular mechanics (MM) calculations on compound I shows that bond lengths and bond angles from the MM calculation are comparable to the data obtained from the X-ray diffraction study. The relation of the structure of CGCs and their catalytic activity by MM calculations is also discussed.
Crystal and molecular structure of (2,6-dipropylphenylamide) dimethyl (tetra-methyl cyclopentadienyl) silane titanium dichloride (Ⅰ) was fully characterized by X-ray diffraction. The crystal is obtained from a mixture of ether/hexane as orthorhombic, with a=12.658 (3)Å, b=16.62 (3)Å, c=11.760 (2)Å, V=2474.2 (9) Å 3, Z=4, space group Pnma, R=0.0399. Componud Ⅰ compose of the π-bounded ring with its dimethylsilyl-dipropyl phenyl amido group and the two terminal chloride atoms coordinated to central metal to form a so-called constrained geometry catalyst (CGC) structure. The result of molecular mechanics (MM) calculations on compound I shows that bond lengths and bond angles from the MM calculation are comparable to the data obtained from the X-ray diffraction study. The relation of the structure of CGCs and their catalytic activity by MM calculations is also discussed.
2000, 11(5): 463-466
Abstract:
A novel Pd(Ⅱ)-dibenzo-18-crown-6 (DB18C6) complex[K(DB18C6)]2[Pd(SCN)4] has been isolated and characterized by X-ray diffraction analysis. In the solid state, it displays a quasi-one-dimensional infinite chain of two[K(DB18C6)]+ complex cations and a[Pd(SCN)4]2- anion bridged by K+-π interactions between adjacent[K(DB18C6)]+ units.
A novel Pd(Ⅱ)-dibenzo-18-crown-6 (DB18C6) complex[K(DB18C6)]2[Pd(SCN)4] has been isolated and characterized by X-ray diffraction analysis. In the solid state, it displays a quasi-one-dimensional infinite chain of two[K(DB18C6)]+ complex cations and a[Pd(SCN)4]2- anion bridged by K+-π interactions between adjacent[K(DB18C6)]+ units.
2000, 11(5): 467-470
Abstract:
The hexagonal liquid crystal mediated synthesis of nanostructured PbS was studied. Thioacetamide and lead acetate were used as the sulfide and lead source, respectively. It was found that the nanohole structure of PdS was formed in this system.
The hexagonal liquid crystal mediated synthesis of nanostructured PbS was studied. Thioacetamide and lead acetate were used as the sulfide and lead source, respectively. It was found that the nanohole structure of PdS was formed in this system.
