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1997 Volume 8 Issue 2
1997, 8(2): 95-96
Abstract:
It is reported that 6-methyl-flavanone oxime would rearrange to isoxazoline in the presence of trifluroacetic acid and the rearrangement would not take place in anhydrous ethanol with catalytic amount of pyridine.However,6-nitro-benzopyran-4-one when treated with hydroxylamine hydrochloride,gave oxime and its isomeric isoxazoline through rearrangement under acid or alkali condition.
It is reported that 6-methyl-flavanone oxime would rearrange to isoxazoline in the presence of trifluroacetic acid and the rearrangement would not take place in anhydrous ethanol with catalytic amount of pyridine.However,6-nitro-benzopyran-4-one when treated with hydroxylamine hydrochloride,gave oxime and its isomeric isoxazoline through rearrangement under acid or alkali condition.
1997, 8(2): 97-98
Abstract:
The cyclizations of L-(+)-prolinol 1 derived from L-proline with (thio) phosphoro(-no) dichlorides 2 give 1,2,3-azaphosphaoxabicyclo[3.3.0]octanes 3 consisting of unequal amounts of diastereoisomers,eight pairs of which have been successfully separated by silica gel column chromatography or recrystallization.
The cyclizations of L-(+)-prolinol 1 derived from L-proline with (thio) phosphoro(-no) dichlorides 2 give 1,2,3-azaphosphaoxabicyclo[3.3.0]octanes 3 consisting of unequal amounts of diastereoisomers,eight pairs of which have been successfully separated by silica gel column chromatography or recrystallization.
1997, 8(2): 99-100
Abstract:
An oxetane ring can be constructed from 5α-acyloxy-△4(20)-taxoids with osmylation as the first step in the usual manner.The innovation reported here is the use of an intramolecularly available acyl group for the protection of 20-OH by an unexpected 5-to 20-migration under slightly basic conditions.
An oxetane ring can be constructed from 5α-acyloxy-△4(20)-taxoids with osmylation as the first step in the usual manner.The innovation reported here is the use of an intramolecularly available acyl group for the protection of 20-OH by an unexpected 5-to 20-migration under slightly basic conditions.
1997, 8(2): 101-102
Abstract:
Kadsurenin M (7s,8s-3,4,3'-trimethoxy-7'-oxo-nor-8',9'-7.O.4'-8,5'-neolignan) (1),a benzofuranoid neolignan isolated from the aerial part of Piper Kadsura (Choisy) Ohwi,was synthesized in 6 steps from vanillin via a key intermediate 3,4-dimethoxycinnamyl (2'-methoxy-4'-formyl) phenyl ether (7).The overall yield is 15%.
Kadsurenin M (7s,8s-3,4,3'-trimethoxy-7'-oxo-nor-8',9'-7.O.4'-8,5'-neolignan) (1),a benzofuranoid neolignan isolated from the aerial part of Piper Kadsura (Choisy) Ohwi,was synthesized in 6 steps from vanillin via a key intermediate 3,4-dimethoxycinnamyl (2'-methoxy-4'-formyl) phenyl ether (7).The overall yield is 15%.
1997, 8(2): 103-106
Abstract:
The total synthesis of (+)villosol was accomplished by using the readily available (-)2 as starting material.
The total synthesis of (+)villosol was accomplished by using the readily available (-)2 as starting material.
1997, 8(2): 107-110
Abstract:
A metal-free Robson-type macrocycle was synthesized for first time by proton-templation and from that the metal complexes were prepared.By X-ray study the structure of Ni(I)-complex was characterized.
A metal-free Robson-type macrocycle was synthesized for first time by proton-templation and from that the metal complexes were prepared.By X-ray study the structure of Ni(I)-complex was characterized.
1997, 8(2): 111-113
Abstract:
A four-chiral-center portion of A-23187 was synthesized from a chiral synthon which was obtained from lipase-catalyzed resolution.
A four-chiral-center portion of A-23187 was synthesized from a chiral synthon which was obtained from lipase-catalyzed resolution.
1997, 8(2): 114-116
Abstract:
Ointment-like poly(ortho esters) were synthesized from the reaction of 3,9-bis (methylene)-2,4,8,10-tetraoxaspiro[5.5] undecane with PEG-400,N,N-bis(2-hydroxyethyl)-n-hexadecylamine and N,N-bis(2-hydroxyethyl) palmitamide respectively.The influence of the catalyst on the intrinsic viscosity of polymers was also studied.
Ointment-like poly(ortho esters) were synthesized from the reaction of 3,9-bis (methylene)-2,4,8,10-tetraoxaspiro[5.5] undecane with PEG-400,N,N-bis(2-hydroxyethyl)-n-hexadecylamine and N,N-bis(2-hydroxyethyl) palmitamide respectively.The influence of the catalyst on the intrinsic viscosity of polymers was also studied.
1997, 8(2): 117-120
Abstract:
A new reagent.trimethylammonium chlorochromate adsorbed on alumina.suitable for the oxidation of hydroxy compounds to the corresponding carbonyl compounds is described
A new reagent.trimethylammonium chlorochromate adsorbed on alumina.suitable for the oxidation of hydroxy compounds to the corresponding carbonyl compounds is described
1997, 8(2): 121-124
Abstract:
TPPR and XPS characterizations were combined to study the reaction mechanism of CO2-reforming of methane to syngas over Co/γ-Al2O3 catalysts.CH4 shows a tendency to form surface carbons by deep dissociation at high temperatures.CO2 dissociation reaction also occurs at >673K.It is believed that carbide carbons are active species to generate CO by reacting with O atoms dissociated from CO2.In the reaction,Co(0) particles are responsible for dissociating CH4 to form active C.abstracting an O atom from CO2 molecule,and transferring O atom to C to form CO.
TPPR and XPS characterizations were combined to study the reaction mechanism of CO2-reforming of methane to syngas over Co/γ-Al2O3 catalysts.CH4 shows a tendency to form surface carbons by deep dissociation at high temperatures.CO2 dissociation reaction also occurs at >673K.It is believed that carbide carbons are active species to generate CO by reacting with O atoms dissociated from CO2.In the reaction,Co(0) particles are responsible for dissociating CH4 to form active C.abstracting an O atom from CO2 molecule,and transferring O atom to C to form CO.
1997, 8(2): 125-128
Abstract:
Five new monoterpenoid glycosides named ligurobustosides E(1),F(2),I(3),J (4) and K (5) were isolated from the leaves of Ligustrum robustum.Their structures were established by spectroscopic and chemical methods.
Five new monoterpenoid glycosides named ligurobustosides E(1),F(2),I(3),J (4) and K (5) were isolated from the leaves of Ligustrum robustum.Their structures were established by spectroscopic and chemical methods.
1997, 8(2): 129-132
Abstract:
From the aerial parts of Clerodendrum indicum,five new compounds,cleroindicins B-F (1-5) were isolated and their structures identified by spectral method.
From the aerial parts of Clerodendrum indicum,five new compounds,cleroindicins B-F (1-5) were isolated and their structures identified by spectral method.
1997, 8(2): 133-134
Abstract:
Nine compounds were isolated from the acetone soluble fraction of ethanolic extract of the roots of Belamcanda chinensis (L.)DC.The structure of new compound I,named shegansu A,has been established as irigenin-5-0-(6"-O-vanillin acid)-β-D-glucoside(I) by the use of spectroscopic evidence (UV,IR,FAB-MS,1HNMR,13CNMR,1H-13CNMR and NOE difference spectrum) and chemical methods.The well known compounds were identified as isorhapotigenin (Ⅲ),resveratrol(Ⅳ),p-hydroxy benzoic acid (Ⅴ),iridin (Ⅵ),tectoridin (Ⅶ),tectorigenin (Ⅷ) and daucosterol (Ⅸ).Ⅲ-Ⅸ were isolated from the plant for the first time.
Nine compounds were isolated from the acetone soluble fraction of ethanolic extract of the roots of Belamcanda chinensis (L.)DC.The structure of new compound I,named shegansu A,has been established as irigenin-5-0-(6"-O-vanillin acid)-β-D-glucoside(I) by the use of spectroscopic evidence (UV,IR,FAB-MS,1HNMR,13CNMR,1H-13CNMR and NOE difference spectrum) and chemical methods.The well known compounds were identified as isorhapotigenin (Ⅲ),resveratrol(Ⅳ),p-hydroxy benzoic acid (Ⅴ),iridin (Ⅵ),tectoridin (Ⅶ),tectorigenin (Ⅷ) and daucosterol (Ⅸ).Ⅲ-Ⅸ were isolated from the plant for the first time.
1997, 8(2): 135-136
Abstract:
Lactariolide (Ⅰ),a new 14-membered-ring lactone was isolated from the fruit bodies of Lactarius subvellereus (Russulaceae),and its structure was elucidated as (R)-13-hydroxy-trans-9,11-octadecadienoic acid lactone by means of physical and spectral data.
Lactariolide (Ⅰ),a new 14-membered-ring lactone was isolated from the fruit bodies of Lactarius subvellereus (Russulaceae),and its structure was elucidated as (R)-13-hydroxy-trans-9,11-octadecadienoic acid lactone by means of physical and spectral data.
1997, 8(2): 137-140
Abstract:
A new norditerpenoid alkaloid,hemsleyasine 1,has been isolated from the roots of Aconitum hemsleyanum var.circinatum W.T.Wang and its structure was established by spectral methods (1H-and 13C-NMR,1H COSY,COLOC and nOes).
A new norditerpenoid alkaloid,hemsleyasine 1,has been isolated from the roots of Aconitum hemsleyanum var.circinatum W.T.Wang and its structure was established by spectral methods (1H-and 13C-NMR,1H COSY,COLOC and nOes).
1997, 8(2): 141-144
Abstract:
A method for the analysis of the relationship between the helical structure and optical activity was proposed by the study of the conformations and X-ray diffraction structures of some cyclic esters prepared by esterification of L-(-)-2,3-O-methylidene threitol and L-(+)-2,3-O-isopropylidene threitol with alkanedioyl dichlorides and o-,m-,and p-phthaloyl dichlorides.
A method for the analysis of the relationship between the helical structure and optical activity was proposed by the study of the conformations and X-ray diffraction structures of some cyclic esters prepared by esterification of L-(-)-2,3-O-methylidene threitol and L-(+)-2,3-O-isopropylidene threitol with alkanedioyl dichlorides and o-,m-,and p-phthaloyl dichlorides.
1997, 8(2): 145-148
Abstract:
The association constant (Ka) values were calculated by the function-strengthening neural networks (FNN) for the inclusion complexation of α-CD with mono-and 1,4-disubstituted benzenes.The lnKa predicted by FNN from Rm,π and σ constants of substituents are in great agreement with the experimental data.
The association constant (Ka) values were calculated by the function-strengthening neural networks (FNN) for the inclusion complexation of α-CD with mono-and 1,4-disubstituted benzenes.The lnKa predicted by FNN from Rm,π and σ constants of substituents are in great agreement with the experimental data.
1997, 8(2): 149-152
Abstract:
The reaction of monocyclic oxyphosphorane compounds 1a,1b,1c with ethylene glycol in pyridine was studied by 31P NMR.The results show that compound 1a with an unsaturated five-membered ring reacts faster than compound 1b with a saturated ring attached by two trans p-nitro phenyl groups,which in turn reacts greatly faster than the cis-compound 1c.To interpret the mechanism,a hexacoordinate intermediate whose five-membered ring occupied the e-,e- position was proposed.
The reaction of monocyclic oxyphosphorane compounds 1a,1b,1c with ethylene glycol in pyridine was studied by 31P NMR.The results show that compound 1a with an unsaturated five-membered ring reacts faster than compound 1b with a saturated ring attached by two trans p-nitro phenyl groups,which in turn reacts greatly faster than the cis-compound 1c.To interpret the mechanism,a hexacoordinate intermediate whose five-membered ring occupied the e-,e- position was proposed.
1997, 8(2): 153-156
Abstract:
The constant Centrifugal potential approximation is Corrected so as to apply to the reactions of rotational excited reactants for D+H2(ji,νi=0)→DH(jf,νf=0)+H.Our results show that the contributions from ji≠0 and Ωi terms are not negligible.
The constant Centrifugal potential approximation is Corrected so as to apply to the reactions of rotational excited reactants for D+H2(ji,νi=0)→DH(jf,νf=0)+H.Our results show that the contributions from ji≠0 and Ωi terms are not negligible.
1997, 8(2): 157-160
Abstract:
DTPA or DOTA ligand was introduced into the pendent amino groups of polylysine (DP 268) by mono-mixed anhydride of DTPA or DOTA,and then translated with Gd-EDTA.The resultant polymer chelates were further reacted with 6-O-bromoacetyl-D-galactose to give liver-specific contrast agents for magnetic resonance imaging.These new polymer conjugates were characterized by FT-IR,ICP-AES,UV-Vis spectrophotometry and elemental analysis.Their in vitro spin-lattice relaxivity and body distribution in mice were investigated.
DTPA or DOTA ligand was introduced into the pendent amino groups of polylysine (DP 268) by mono-mixed anhydride of DTPA or DOTA,and then translated with Gd-EDTA.The resultant polymer chelates were further reacted with 6-O-bromoacetyl-D-galactose to give liver-specific contrast agents for magnetic resonance imaging.These new polymer conjugates were characterized by FT-IR,ICP-AES,UV-Vis spectrophotometry and elemental analysis.Their in vitro spin-lattice relaxivity and body distribution in mice were investigated.
1997, 8(2): 161-164
Abstract:
Silica gel thin-layer plates covered with L-arginine and copper acetate were used for the separation of amino acid enantiomers.The chromatographic selectivity and the effects of plate different preparation methods,sample molecular structure and solvent compositions on resolution performance were also discussed.
Silica gel thin-layer plates covered with L-arginine and copper acetate were used for the separation of amino acid enantiomers.The chromatographic selectivity and the effects of plate different preparation methods,sample molecular structure and solvent compositions on resolution performance were also discussed.
1997, 8(2): 165-166
Abstract:
Two new stationary phases:(Ⅰ)[bikis(2,6-di-O-pentyl-3-O-hex-6-enyl)-pentakis(2.6-di-O-pentyl-3-O-methyl)-β-CD-polysiloxane] and (Ⅱ)[heptkis(2,6-di-O-methyl-3-O-hex-6-enyl)-β-CD-polysiloxane] were synthesized and successfully used for GC separation of chiral isomers.They possess high column efficiency and exhibit fine chiral separation ability.
Two new stationary phases:(Ⅰ)[bikis(2,6-di-O-pentyl-3-O-hex-6-enyl)-pentakis(2.6-di-O-pentyl-3-O-methyl)-β-CD-polysiloxane] and (Ⅱ)[heptkis(2,6-di-O-methyl-3-O-hex-6-enyl)-β-CD-polysiloxane] were synthesized and successfully used for GC separation of chiral isomers.They possess high column efficiency and exhibit fine chiral separation ability.
1997, 8(2): 167-170
Abstract:
In a procedure for electrolytic dissolving pure copper and common brasses,the approximate electrochemical mole mass(k) of the sample was determined in accordance with the brand of the sample,a suitable electrolyte was selected to make the current efficiency equal to 100%,and then the dissolved mass of samples was calculated according to Faraday's law (m=kIt).Three representative samples were sampled by the electrolytic dissolution method and the calculated dissolved amounts were equal to the values by weighing the anode.The experimental results of zinc and copper in the anode liquor are in agreement with certified values.
In a procedure for electrolytic dissolving pure copper and common brasses,the approximate electrochemical mole mass(k) of the sample was determined in accordance with the brand of the sample,a suitable electrolyte was selected to make the current efficiency equal to 100%,and then the dissolved mass of samples was calculated according to Faraday's law (m=kIt).Three representative samples were sampled by the electrolytic dissolution method and the calculated dissolved amounts were equal to the values by weighing the anode.The experimental results of zinc and copper in the anode liquor are in agreement with certified values.
1997, 8(2): 171-174
Abstract:
The structure of poly-o-phenylenediamine in the redox process has been studied using in-situ resonance Raman spectroscopy,in-situ UV-Vis subtractive reflectance spectroscopy and cyclic voltammetry.The results show that the structure of PoPD is dominated by a ladder polymer with phenazine rings,and at least three structures of PoPD are formed in the redox process.The three kinds of PoPD have different resonance enhancement effect,and the electronic structure of PoPD molecule is influenced obviously by protonation.The results also show that the most stable state of PoPD is its semi-oxidized state.
The structure of poly-o-phenylenediamine in the redox process has been studied using in-situ resonance Raman spectroscopy,in-situ UV-Vis subtractive reflectance spectroscopy and cyclic voltammetry.The results show that the structure of PoPD is dominated by a ladder polymer with phenazine rings,and at least three structures of PoPD are formed in the redox process.The three kinds of PoPD have different resonance enhancement effect,and the electronic structure of PoPD molecule is influenced obviously by protonation.The results also show that the most stable state of PoPD is its semi-oxidized state.
1997, 8(2): 175-176
Abstract:
The properties of the films formed in the electrolyte of PC/DME LiClO4 on two kinds of carbon materials were examined by cathodic polarization measurements.The result suggested that the films on both carbon electrodes have different morphology which resulted in the different cell performance of the two carbon anodes.
The properties of the films formed in the electrolyte of PC/DME LiClO4 on two kinds of carbon materials were examined by cathodic polarization measurements.The result suggested that the films on both carbon electrodes have different morphology which resulted in the different cell performance of the two carbon anodes.
1997, 8(2): 177-180
Abstract:
Endohedral dilutetium fullerenes,Lu2@C2n (2n=76~112),have been extracted from the soot prepared by arc-burning method for the first time and different from other lanthanide encapsulated fullerenes,there is no signal corresponding to Lu@C82 even in mass spectrum of the high-temperature,high-pressure extract.
Endohedral dilutetium fullerenes,Lu2@C2n (2n=76~112),have been extracted from the soot prepared by arc-burning method for the first time and different from other lanthanide encapsulated fullerenes,there is no signal corresponding to Lu@C82 even in mass spectrum of the high-temperature,high-pressure extract.
1997, 8(2): 181-182
Abstract:
The stability constants for rare earth complexes with 3,5,3'-triiodothyronine were determined at 37℃ and an ionic strength of 0.15 mole/L NaCl.The lanthanide induced shifts were measured for 1H nuclei of 3,5,3'-triiodothyronine.The coordination of rare earth with 3,5,3'-triiodothyronine was discussed.
The stability constants for rare earth complexes with 3,5,3'-triiodothyronine were determined at 37℃ and an ionic strength of 0.15 mole/L NaCl.The lanthanide induced shifts were measured for 1H nuclei of 3,5,3'-triiodothyronine.The coordination of rare earth with 3,5,3'-triiodothyronine was discussed.
1997, 8(2): 183-184
Abstract:
Fe3O4/PS magnetic particles with core/shell structure has been prepared in the presence of Fe3O4 magnetic fluid in ethanol/water mixture.Magnetic particles with diameter size range from 5.54 to 187.32 μm were obtained by different reaction conditions.Some parameters such as ethanol,PEG and monomer which affect particle size diameter and size distribution are discussed briefly in this paper.
Fe3O4/PS magnetic particles with core/shell structure has been prepared in the presence of Fe3O4 magnetic fluid in ethanol/water mixture.Magnetic particles with diameter size range from 5.54 to 187.32 μm were obtained by different reaction conditions.Some parameters such as ethanol,PEG and monomer which affect particle size diameter and size distribution are discussed briefly in this paper.
1997, 8(2): 185-188
Abstract:
GaN powder of nanometer scale was prepared by metal organic chemical vapor deposition using diethylgallium azide as precursor.The resulting powder was characterized by XRD and TEM.It has been found that the particle size of the powder obtabed is affected by the deposition temperature,and the fine crystals formed m temperature range 500~650℃ were hexagonal.
GaN powder of nanometer scale was prepared by metal organic chemical vapor deposition using diethylgallium azide as precursor.The resulting powder was characterized by XRD and TEM.It has been found that the particle size of the powder obtabed is affected by the deposition temperature,and the fine crystals formed m temperature range 500~650℃ were hexagonal.
