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1996 Volume 7 Issue 12
1996, 7(12): 1067-1068
Abstract:
This paper reports the primary results of the study on the regioselectivity of the cyclization reaction of 5-amino-1,2,4-triazole and its analogues with asym-1,3-dicarbonyl compounds.The mechanistic explanation for the regioselectivity is presented.
This paper reports the primary results of the study on the regioselectivity of the cyclization reaction of 5-amino-1,2,4-triazole and its analogues with asym-1,3-dicarbonyl compounds.The mechanistic explanation for the regioselectivity is presented.
1996, 7(12): 1069-1072
Abstract:
The reactions of α-(alkoxysilyl)allyl anions 4 with electrophiles were studied.α-Alkylation with alkyl halides was favoured,whereas γ-selection was achieved in the reaction with aldehydes.
The reactions of α-(alkoxysilyl)allyl anions 4 with electrophiles were studied.α-Alkylation with alkyl halides was favoured,whereas γ-selection was achieved in the reaction with aldehydes.
1996, 7(12): 1073-1076
Abstract:
The reaction between 3-substituted-4-hydroxy-2H-1,2-benzothiazine 1,1-dioxides and phenyl isocyanate in the presence of different equivalents of strong base NaH has been studied.The structures of new derivatives were characterized by 1H NMR.IR.elementary analysis and FeCl3 test.
The reaction between 3-substituted-4-hydroxy-2H-1,2-benzothiazine 1,1-dioxides and phenyl isocyanate in the presence of different equivalents of strong base NaH has been studied.The structures of new derivatives were characterized by 1H NMR.IR.elementary analysis and FeCl3 test.
1996, 7(12): 1077-1078
Abstract:
Homologation of protected taxol side chain Homologation of protected taxol side chain 8 from 4 was accomplished stereospecifically through the key intermediate diazo ketone 5 which was actually isolated.The structures of 5 and 7 were identified by spectrometric methods,mainly 1H-NMR,IR,13C-NMR and DEPT techniques.
Homologation of protected taxol side chain Homologation of protected taxol side chain 8 from 4 was accomplished stereospecifically through the key intermediate diazo ketone 5 which was actually isolated.The structures of 5 and 7 were identified by spectrometric methods,mainly 1H-NMR,IR,13C-NMR and DEPT techniques.
1996, 7(12): 1081-1082
Abstract:
The convenient synthesis of (-)-5αH,7β,10α-eudesmane-3,11-diene 1 has been achieved in four steps starting from R-(-)-carvone.The key step is the reductive deoxygenation of α,β-unsaturated tosylhydrazone together with the migration of the double bond.
The convenient synthesis of (-)-5αH,7β,10α-eudesmane-3,11-diene 1 has been achieved in four steps starting from R-(-)-carvone.The key step is the reductive deoxygenation of α,β-unsaturated tosylhydrazone together with the migration of the double bond.
1996, 7(12): 1083-1084
Abstract:
Aryl telluroesters were prepared from the reaction of tellurium and Grignard reagents then acylation with acyl chlorides.Addition of telluroesters to arylpropiolates produced (2Z)-β-aryltelluro-α,β-unsaturated esters with high stereoselectivity.
Aryl telluroesters were prepared from the reaction of tellurium and Grignard reagents then acylation with acyl chlorides.Addition of telluroesters to arylpropiolates produced (2Z)-β-aryltelluro-α,β-unsaturated esters with high stereoselectivity.
1996, 7(12): 1085-1086
Abstract:
The terminal alkylselenylacetylenes (RSe-C≡C-H) 3a-h were prepared by the reaction of ethynylmagnesium bromide at -20℃ in THF with alkylselenyl bromides derived from dialkyl diselenides and bromide.
The terminal alkylselenylacetylenes (RSe-C≡C-H) 3a-h were prepared by the reaction of ethynylmagnesium bromide at -20℃ in THF with alkylselenyl bromides derived from dialkyl diselenides and bromide.
1996, 7(12): 1087-1088
Abstract:
In this paper four new 1,2-benzothiazine 1,1-dioxide derivatives 4 were synthesized by the reaction of 4-ethylenedioxy-2H-1,2-benzothiazine 1,1-dioxide 2 with 2-chloroacetamides 3 under the action of base.The biological tests indicated that these four compounds have good herbicidal activity.
In this paper four new 1,2-benzothiazine 1,1-dioxide derivatives 4 were synthesized by the reaction of 4-ethylenedioxy-2H-1,2-benzothiazine 1,1-dioxide 2 with 2-chloroacetamides 3 under the action of base.The biological tests indicated that these four compounds have good herbicidal activity.
1996, 7(12): 1089-1090
Abstract:
3-(R)-3-(adenin-9'-yl)-4-(R)-hydroxy-5-(R)-hydroxymethyltetrahydrofuran was synthesized by the regeoselective substitution of 3,4-epoxy-(trans)-5-(R)-dimethoxymethyltetrahydrofuran which was obtained by 4 steps from L-xylose.
3-(R)-3-(adenin-9'-yl)-4-(R)-hydroxy-5-(R)-hydroxymethyltetrahydrofuran was synthesized by the regeoselective substitution of 3,4-epoxy-(trans)-5-(R)-dimethoxymethyltetrahydrofuran which was obtained by 4 steps from L-xylose.
1996, 7(12): 1089-1080
Abstract:
A new method for direct conversion of nitrites to primary alcohols using ZnCoCI2 reagent in AcOH/EtOH system is reported.
A new method for direct conversion of nitrites to primary alcohols using ZnCoCI2 reagent in AcOH/EtOH system is reported.
1996, 7(12): 1091-1092
Abstract:
The site-specific microbiological hydrolysis of a natural taxoid,1β-hydroxybaccatin I,with the culture of Aspergillus niger,is described.
The site-specific microbiological hydrolysis of a natural taxoid,1β-hydroxybaccatin I,with the culture of Aspergillus niger,is described.
1996, 7(12): 1093-1094
Abstract:
-Phytochemical re-investigation of the anti-leukemia plant Laggera pterodonta afford four new eudemsanes (1-4) and six new eudesmanoic glucosides (5-10).Their structures were elucidated by high field 1D and 2D NMR techniques and chemical methods.
-Phytochemical re-investigation of the anti-leukemia plant Laggera pterodonta afford four new eudemsanes (1-4) and six new eudesmanoic glucosides (5-10).Their structures were elucidated by high field 1D and 2D NMR techniques and chemical methods.
1996, 7(12): 1095-1096
Abstract:
From the aerial part of Hypericum Japonicum Thunb.ex Murray,two new pyrones,japonicumone-A and-B,were isolated and their structures were determined on basis of spectroscopic evidence.
From the aerial part of Hypericum Japonicum Thunb.ex Murray,two new pyrones,japonicumone-A and-B,were isolated and their structures were determined on basis of spectroscopic evidence.
1996, 7(12): 1097-1099
Abstract:
Subvellerolactone C(I),a new 3,8-oxa-13-hydroxy-lactar-6-en-5-oic acid γ-lactone was isolated from the fruit bodies of Lactarius Subvellereus (Russulaceae),and its structure was elucidated by means of spectroscopic methods(UV,IR,HRMS,1H-NMR,13C-NMR,13C-1HCORR.,1H-1HCOSY,HMBC,NOEDIFF.).
Subvellerolactone C(I),a new 3,8-oxa-13-hydroxy-lactar-6-en-5-oic acid γ-lactone was isolated from the fruit bodies of Lactarius Subvellereus (Russulaceae),and its structure was elucidated by means of spectroscopic methods(UV,IR,HRMS,1H-NMR,13C-NMR,13C-1HCORR.,1H-1HCOSY,HMBC,NOEDIFF.).
1996, 7(12): 1100-1102
Abstract:
Two new sesquiterpenes were isolated from the rhizomes of Ligularia Intermedia.Their structures were determined as eremophil-7(8)-en-12,8(4β,6α)-diolide(1) and eremophil-7(8)-en-12,8(4β,6β)-diolide(2) by spectroscopic methods
Two new sesquiterpenes were isolated from the rhizomes of Ligularia Intermedia.Their structures were determined as eremophil-7(8)-en-12,8(4β,6α)-diolide(1) and eremophil-7(8)-en-12,8(4β,6β)-diolide(2) by spectroscopic methods
1996, 7(12): 1103-1104
Abstract:
The addition of methanol to the buffer enhanced 2,6-di-O-carboxymethyl-β-CD's enantioselectivity to nafronyl oxalate,of which four enantiomers were separated in CZE successfully.
The addition of methanol to the buffer enhanced 2,6-di-O-carboxymethyl-β-CD's enantioselectivity to nafronyl oxalate,of which four enantiomers were separated in CZE successfully.
1996, 7(12): 1105-1108
Abstract:
The present understanding of electrophoretic mobility cannot satisfactorily be used to explain the separation capability of capillary zone electrophoresis for isomeric anions.A molecular shape effect concept was proposed to describe the separation mechanism for isomeric anoins with o-,m-,p-hydroxybenzoates and two food colorants,amaranth and ponceau 4R as examples.
The present understanding of electrophoretic mobility cannot satisfactorily be used to explain the separation capability of capillary zone electrophoresis for isomeric anions.A molecular shape effect concept was proposed to describe the separation mechanism for isomeric anoins with o-,m-,p-hydroxybenzoates and two food colorants,amaranth and ponceau 4R as examples.
1996, 7(12): 1109-1112
Abstract:
Polyethylene glycol acrylate was covalently bound onto the capillary surface and crosslinked by azobisisobutyronitrile(AIBN).The coating is stable over pH 2-9,has a good coating reproducibility and can be used for the separation of proteins and polypeptides.
Polyethylene glycol acrylate was covalently bound onto the capillary surface and crosslinked by azobisisobutyronitrile(AIBN).The coating is stable over pH 2-9,has a good coating reproducibility and can be used for the separation of proteins and polypeptides.
1996, 7(12): 1113-1116
Abstract:
A sensitive high-performance chromatographic method for the detection of N-nitrosoamines with pre-column fluorescence derivatization has been developed.Eight representative N-nitrosoamines,which were separated on a reversed-phase C18column with methanol-water-triethylamine as eluent,were used as model compounds to optimize the derivatization and the chromatographic conditions.The relative standard deviations(n=7) at an analytical concentration of 4×10-6 mol/L are less than 5%.The detection limits (signal-to-noise ratio=3) for the N-nitrosoamines compounds are in the range of 0.02~0.14 nmol per injection volume(10 μl).
A sensitive high-performance chromatographic method for the detection of N-nitrosoamines with pre-column fluorescence derivatization has been developed.Eight representative N-nitrosoamines,which were separated on a reversed-phase C18column with methanol-water-triethylamine as eluent,were used as model compounds to optimize the derivatization and the chromatographic conditions.The relative standard deviations(n=7) at an analytical concentration of 4×10-6 mol/L are less than 5%.The detection limits (signal-to-noise ratio=3) for the N-nitrosoamines compounds are in the range of 0.02~0.14 nmol per injection volume(10 μl).
1996, 7(12): 1117-1120
Abstract:
The absorption spectra of agueous L-tyrosine at various total ionic strengths were measured by UV-240 spectrophotometer at 298.2±0.2K and the standard third dissociation constant of L-tyrosine was determined from the spectra by linear extrapolation and polynomial approximation.
The absorption spectra of agueous L-tyrosine at various total ionic strengths were measured by UV-240 spectrophotometer at 298.2±0.2K and the standard third dissociation constant of L-tyrosine was determined from the spectra by linear extrapolation and polynomial approximation.
1996, 7(12): 1121-1124
Abstract:
The spectroscopic properties and photostability of three near-infrared absorbing indolenine cyanine dyes have been studied.It was found that photofading of cyanine dyes was mainly caused by photooxidation,and their photostability increased significantly when the cyclic unity was introduced into the polymethine chain.
The spectroscopic properties and photostability of three near-infrared absorbing indolenine cyanine dyes have been studied.It was found that photofading of cyanine dyes was mainly caused by photooxidation,and their photostability increased significantly when the cyclic unity was introduced into the polymethine chain.
1996, 7(12): 1125-1126
Abstract:
Using the Ar(3P0.2)+PCl3 reaction as a source of PCl(b1Σ+),We have measured the quenching rate constants of PCl(b) for 23 reagents.The E-V model is used to calculate the rate constants.The comparison between the experimental and calculated results is given.
Using the Ar(3P0.2)+PCl3 reaction as a source of PCl(b1Σ+),We have measured the quenching rate constants of PCl(b) for 23 reagents.The E-V model is used to calculate the rate constants.The comparison between the experimental and calculated results is given.
1996, 7(12): 1127-1130
Abstract:
Two new ruthenium polypyridine complexes,L2RuL'2+, where L=2,2'-bipyridine (bpy) and 2,9-dimethyl-1,10-phenanthroline (dmp);L' is Schiff base prepared from condensation of 4,5-diazafluoren-9-one (AFO) and aniline,have been prepared and characterized by elemental analyses,electronic absorption,IR spectra.The binding of the complexes to calf thymus DNA has been investigated by absorption,emission spectra and circular dichroism spectroscopy.Experimental results show these two complexes bind to DNA by electrostatic mode and non-intercalative binding mode.
Two new ruthenium polypyridine complexes,L2RuL'2+, where L=2,2'-bipyridine (bpy) and 2,9-dimethyl-1,10-phenanthroline (dmp);L' is Schiff base prepared from condensation of 4,5-diazafluoren-9-one (AFO) and aniline,have been prepared and characterized by elemental analyses,electronic absorption,IR spectra.The binding of the complexes to calf thymus DNA has been investigated by absorption,emission spectra and circular dichroism spectroscopy.Experimental results show these two complexes bind to DNA by electrostatic mode and non-intercalative binding mode.
1996, 7(12): 1131-1134
Abstract:
1996, 7(12): 1135-1138
Abstract:
On the surface of O,O'-bis(2-aminoethyl) dithiophosphate modified copper C60forms self-assembled monolayer films (SAMs) through the chemical bond.The film was characterized by contact angle,X-ray photoelectron spectroscopy,electrochemistry,TOF Mass Spectropy
On the surface of O,O'-bis(2-aminoethyl) dithiophosphate modified copper C60forms self-assembled monolayer films (SAMs) through the chemical bond.The film was characterized by contact angle,X-ray photoelectron spectroscopy,electrochemistry,TOF Mass Spectropy
1996, 7(12): 1139-1142
Abstract:
the synthesis of twelve new tenninal amino substituted titanocene dichlorides is reported.
the synthesis of twelve new tenninal amino substituted titanocene dichlorides is reported.
1996, 7(12): 1143-1144
Abstract:
Cp'2UCI2(Cp'=MeOCH2CH2C5H4) complex 1 has been synthesized by the reaction of UCI4 with Cp'Na in tetrahydrofuran.A single-crystal X-ray study shows that the uranium compound is a mononuclear complex with uranium in a pseudo-hexahedral co-ordination geometry if the cyclopentadienyl ring is regarded as occupying a single polyhedral vertex.
Cp'2UCI2(Cp'=MeOCH2CH2C5H4) complex 1 has been synthesized by the reaction of UCI4 with Cp'Na in tetrahydrofuran.A single-crystal X-ray study shows that the uranium compound is a mononuclear complex with uranium in a pseudo-hexahedral co-ordination geometry if the cyclopentadienyl ring is regarded as occupying a single polyhedral vertex.
