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1995 Volume 6 Issue 4
1995, 6(4): 267-270
Abstract:
Chemically,N-phosphoryl homo-serine was much more stable than the homologous compoundphosphorylated serine.The latter was very reactive to undergo N→O migration,formation of peptide and cyclophosphoroamidate but not the former when they were warmed in alcohol or chloroform at 40℃.For the N-phospho-homo-serine,only a small extent of ester exchange occurred on the phosphorus.A second type of penta-coordinate phosphorus intermediate was proposed.
Chemically,N-phosphoryl homo-serine was much more stable than the homologous compoundphosphorylated serine.The latter was very reactive to undergo N→O migration,formation of peptide and cyclophosphoroamidate but not the former when they were warmed in alcohol or chloroform at 40℃.For the N-phospho-homo-serine,only a small extent of ester exchange occurred on the phosphorus.A second type of penta-coordinate phosphorus intermediate was proposed.
1995, 6(4): 271-272
Abstract:
β-(2-Imidazolinyl)-ethyl methyl diethoxy silane was obtained from β-cyanoethyl methyl diethoxy silane with ethylenediamine by using sulphur as the catalyst.
β-(2-Imidazolinyl)-ethyl methyl diethoxy silane was obtained from β-cyanoethyl methyl diethoxy silane with ethylenediamine by using sulphur as the catalyst.
1995, 6(4): 273-274
Abstract:
A new analogue of AMD,[5',5'-bis (valine)]actinomycin D was synthesized
A new analogue of AMD,[5',5'-bis (valine)]actinomycin D was synthesized
1995, 6(4): 275-278
Abstract:
In the presence of BF3.OEt2,l-O-trimethylsilyl-2,3,4,6-tetra-O-benzyl-α-D-mannopyranose (1)reacted stereoselectively with a series of carboxylic acids to give the corresponding α-mannosyl carboxylates in good yields.The configuration of products was assigned mainly by 1H-NMR spectra (δH1 and3J1,2).
In the presence of BF3.OEt2,l-O-trimethylsilyl-2,3,4,6-tetra-O-benzyl-α-D-mannopyranose (1)reacted stereoselectively with a series of carboxylic acids to give the corresponding α-mannosyl carboxylates in good yields.The configuration of products was assigned mainly by 1H-NMR spectra (δH1 and3J1,2).
1995, 6(4): 279-280
Abstract:
Synthesis of CF3-substituted enediynes through palladium-catalyzed reaction of (Z)-1,2-dibromo-3,3,3-trifluoropropene with 1-alkynes in good to excellent yields is described.
Synthesis of CF3-substituted enediynes through palladium-catalyzed reaction of (Z)-1,2-dibromo-3,3,3-trifluoropropene with 1-alkynes in good to excellent yields is described.
1995, 6(4): 281-284
Abstract:
The reaction of the adducts of per (poly)fluoroalkyl iodides and vinyl acetate with hydrazine monohydrate to give the corresponding 3-per (poly)fluoroalkylpyrazoles in excellent yields is described.The reaction might go through a hydrazone intermediate.
The reaction of the adducts of per (poly)fluoroalkyl iodides and vinyl acetate with hydrazine monohydrate to give the corresponding 3-per (poly)fluoroalkylpyrazoles in excellent yields is described.The reaction might go through a hydrazone intermediate.
1995, 6(4): 285-288
Abstract:
We synthesized Deltorphin Ⅰ,Deltorphin Ⅱ,and their L-Alanine analogs at position 2.The synthesis was carried out with SPPS and Boc strategy.The data we got from FAB MS,AAA and sequence analysis were in agreement with the caculated values.We studied the 2D NMR for Deltorphin Ⅱ and[L-Ala2]Deltorphin Ⅱ in DMSO solution.The 1H-1H COSY and 2D NOESY spectra were resolved by computer treatment.The conformations of C-fragment tetrapeptides of Deltorphin Ⅱ and its L-Ala analog might form a 310 α-helix.The molecular models of these two peptides were established.
We synthesized Deltorphin Ⅰ,Deltorphin Ⅱ,and their L-Alanine analogs at position 2.The synthesis was carried out with SPPS and Boc strategy.The data we got from FAB MS,AAA and sequence analysis were in agreement with the caculated values.We studied the 2D NMR for Deltorphin Ⅱ and[L-Ala2]Deltorphin Ⅱ in DMSO solution.The 1H-1H COSY and 2D NOESY spectra were resolved by computer treatment.The conformations of C-fragment tetrapeptides of Deltorphin Ⅱ and its L-Ala analog might form a 310 α-helix.The molecular models of these two peptides were established.
1995, 6(4): 289-292
Abstract:
A derivative of 2-arylbenzofuranoid pattern fashioned after the naturally occurring isolates from Salviamiltiorrhiza was synthesized by Perkin condensation and oxidative ring closure.
A derivative of 2-arylbenzofuranoid pattern fashioned after the naturally occurring isolates from Salviamiltiorrhiza was synthesized by Perkin condensation and oxidative ring closure.
1995, 6(4): 293-296
Abstract:
Abstract Reaction of 6-deoxy-6-(N-imidazolyl)-β-cyclodextrin 2 with α,α'-dibromoxylene afforded cyclodextrin dimer 3 with two imidazolium residues as catalytic site and two cyclodextrin cavities as binding site.
Abstract Reaction of 6-deoxy-6-(N-imidazolyl)-β-cyclodextrin 2 with α,α'-dibromoxylene afforded cyclodextrin dimer 3 with two imidazolium residues as catalytic site and two cyclodextrin cavities as binding site.
1995, 6(4): 297-300
Abstract:
A new heterocyclic fulgide:E-(α)-(1,2-dimethyl-4-isopropyl-5-phenyl)-3-pyrryl ethylidene (isopropylidene) succinic anhydride (1) has been synthesized.The molecular conformation and atomic labelling structure of (1) was obtained by X-ray analyses.Compound (1) shows a twisted structure between different ring systems.The short distance between C1 atom and C22 atom (3.567 Å) offers a favourable structure for the photoinduced intramolecular cyclization of 1.
A new heterocyclic fulgide:E-(α)-(1,2-dimethyl-4-isopropyl-5-phenyl)-3-pyrryl ethylidene (isopropylidene) succinic anhydride (1) has been synthesized.The molecular conformation and atomic labelling structure of (1) was obtained by X-ray analyses.Compound (1) shows a twisted structure between different ring systems.The short distance between C1 atom and C22 atom (3.567 Å) offers a favourable structure for the photoinduced intramolecular cyclization of 1.
1995, 6(4): 301-304
Abstract:
In the presence of transition metal chloride and potassium iodide,di-Grignard reagents can be produced efficiently by the reactions of aryl dichlorides with active magnesium species,which are formed in situ from commercial magnesium powder activated by a small amount of anthracene.
In the presence of transition metal chloride and potassium iodide,di-Grignard reagents can be produced efficiently by the reactions of aryl dichlorides with active magnesium species,which are formed in situ from commercial magnesium powder activated by a small amount of anthracene.
1995, 6(4): 305-308
Abstract:
ABSTRACT:Two new polyoxygenated cyclohexenes,uvarigranol A and uvarigranol B,together with the known zeylenol were isolated from the roots of Uvaria grandiflora Roxb (Annonaceae).Their structures were established on the bases of 1HNMR,MS,IR,CD spectra and chemical correlation.
ABSTRACT:Two new polyoxygenated cyclohexenes,uvarigranol A and uvarigranol B,together with the known zeylenol were isolated from the roots of Uvaria grandiflora Roxb (Annonaceae).Their structures were established on the bases of 1HNMR,MS,IR,CD spectra and chemical correlation.
1995, 6(4): 309-310
Abstract:
Two new diterpene alkaloids named swinanine C and D were isolated from Delphinium swinanense var leptopogon (H.-M.) W.T.Wang.Their structures were elucidated by means of spectral methods,principally 1H-NMR,DEPT and 13C-NMR techniques.
Two new diterpene alkaloids named swinanine C and D were isolated from Delphinium swinanense var leptopogon (H.-M.) W.T.Wang.Their structures were elucidated by means of spectral methods,principally 1H-NMR,DEPT and 13C-NMR techniques.
1995, 6(4): 311-314
Abstract:
The stereospecific rule of the cycloaddition reaction of ketene and imine has been treated theoretically in this paper.By comparing the barrier heights,it can be seen that for trans imine the reaction will give cis product,and for cis imine the reaction will give trans product.
The stereospecific rule of the cycloaddition reaction of ketene and imine has been treated theoretically in this paper.By comparing the barrier heights,it can be seen that for trans imine the reaction will give cis product,and for cis imine the reaction will give trans product.
1995, 6(4): 315-316
Abstract:
The intramolecular aromatic-ring stacking interaction of mixed-ligand complexes Pd (A) (ATP)2- in the system Pd2+-A-ATP4- has been determined by 1HNMR,where A=1,10-phenanthroline (Phen),2,2'-bipyridyl (Bpy) and L-tryptophan (Trp-);ATP4-=adenosine 5'-triphosphate.The result indicates that it is the partial stacking between the indole ring of ATP4- and the heterocyclic ring of A that makes H(2),H(8) and H(1') in the ATP4- shift upfield significantly.Accordingly,the order of aromatic-ring interaction in the mixed-ligand complexes has been obtained as follows:Pd (Phen) (ATP)2- > Pd(Bpy) (ATP)2- > Pd(Trp) (ATP)3-.
The intramolecular aromatic-ring stacking interaction of mixed-ligand complexes Pd (A) (ATP)2- in the system Pd2+-A-ATP4- has been determined by 1HNMR,where A=1,10-phenanthroline (Phen),2,2'-bipyridyl (Bpy) and L-tryptophan (Trp-);ATP4-=adenosine 5'-triphosphate.The result indicates that it is the partial stacking between the indole ring of ATP4- and the heterocyclic ring of A that makes H(2),H(8) and H(1') in the ATP4- shift upfield significantly.Accordingly,the order of aromatic-ring interaction in the mixed-ligand complexes has been obtained as follows:Pd (Phen) (ATP)2- > Pd(Bpy) (ATP)2- > Pd(Trp) (ATP)3-.
1995, 6(4): 317-320
Abstract:
An empirical method is proposed to estimate atomic charge for electrical neutral molecules containing multi-centers or groups.The harmonic mean is adopted and extended to estimate the electron density distribution of this kind of molecules.The results show that the data calculated not only are consistant with the principle of electronegativity equalization,but also more reasonable.Why organic acids are stronger than organic alcohols in acidity has been discussed on the basis of calculated partial charges.
An empirical method is proposed to estimate atomic charge for electrical neutral molecules containing multi-centers or groups.The harmonic mean is adopted and extended to estimate the electron density distribution of this kind of molecules.The results show that the data calculated not only are consistant with the principle of electronegativity equalization,but also more reasonable.Why organic acids are stronger than organic alcohols in acidity has been discussed on the basis of calculated partial charges.
1995, 6(4): 321-324
Abstract:
A polarographic catalytic wave of glycyrrhizic acid (Ⅰ) in the presence of H2O2 is described.The electrochemical process is considered to be that I yielded a free radical intermediate through a one-electron reduction of its C=C double bond,and the active intermediate was oxidized to regenerate I.The catalytic wave should be new-type one due to reduction and regeneration of organic depolarizer.
A polarographic catalytic wave of glycyrrhizic acid (Ⅰ) in the presence of H2O2 is described.The electrochemical process is considered to be that I yielded a free radical intermediate through a one-electron reduction of its C=C double bond,and the active intermediate was oxidized to regenerate I.The catalytic wave should be new-type one due to reduction and regeneration of organic depolarizer.
1995, 6(4): 325-326
Abstract:
Abstract In this paper,the effect of partical size,in fluorination assisted ETV-ICP-AES.The results experimental show that when the partical size of slurry samples is less than 170μm,the signal intensities of analytes were identical to those obtained with aqueous solutions.Comparing with the data given by slurry nebulization ICP-AES in literature,the tolerable particle size in this method is large by about 17-fold.
Abstract In this paper,the effect of partical size,in fluorination assisted ETV-ICP-AES.The results experimental show that when the partical size of slurry samples is less than 170μm,the signal intensities of analytes were identical to those obtained with aqueous solutions.Comparing with the data given by slurry nebulization ICP-AES in literature,the tolerable particle size in this method is large by about 17-fold.
1995, 6(4): 327-328
Abstract:
A comb polymer (CP350) with oligo-oxyethlene side chains was prepared from methyl vinyl ether/maleic anhydride copolymer.Homogeneous amorphous polymer electrolyte were made from the comb polymer and LiCF3SO3 by solvent casting from acetone,and their conductivities were measured as a function of temperature and salt concentration.Maximum conductivity close to 5.08×10-5S/cm was achieved at room temperature at [Li]/[EO] ratio of about 0.12.
A comb polymer (CP350) with oligo-oxyethlene side chains was prepared from methyl vinyl ether/maleic anhydride copolymer.Homogeneous amorphous polymer electrolyte were made from the comb polymer and LiCF3SO3 by solvent casting from acetone,and their conductivities were measured as a function of temperature and salt concentration.Maximum conductivity close to 5.08×10-5S/cm was achieved at room temperature at [Li]/[EO] ratio of about 0.12.
1995, 6(4): 329-332
Abstract:
New comblike polymers (CP) have been synthesized by reacting monomethyl ether of polyethylene glycol (PEGME) with poly (methyl vinyl ether-alt-maleic anhydride) (MA) and endcapping the residual carboxylic acid with methanol.Butanone was selected as a solvent for the esterification reaction in order to obtain a completely soluble product.They were characterized by IR,13C NMR and elemental analysis.
New comblike polymers (CP) have been synthesized by reacting monomethyl ether of polyethylene glycol (PEGME) with poly (methyl vinyl ether-alt-maleic anhydride) (MA) and endcapping the residual carboxylic acid with methanol.Butanone was selected as a solvent for the esterification reaction in order to obtain a completely soluble product.They were characterized by IR,13C NMR and elemental analysis.
1995, 6(4): 333-334
Abstract:
ABSTRACT A novel crosslinking polyphosphate was synthesized.The polymer was characterized by FT-IR,1HNMR,31PNMR and elemental analysis.In vitro release of Levonorgestrel by single-matrix and sandwich pellet with polyphosphate as drug carrier were carried out in pH 7.4 phosphate buffer solution at 37℃.Sustained release rate from the sandwich pellet was more controlled than that from single-matrix pellet.
ABSTRACT A novel crosslinking polyphosphate was synthesized.The polymer was characterized by FT-IR,1HNMR,31PNMR and elemental analysis.In vitro release of Levonorgestrel by single-matrix and sandwich pellet with polyphosphate as drug carrier were carried out in pH 7.4 phosphate buffer solution at 37℃.Sustained release rate from the sandwich pellet was more controlled than that from single-matrix pellet.
1995, 6(4): 335-336
Abstract:
Abstract Eight water-insoluble polyphosphate esters were prepared.The degradation of the polyphosphate esters was enhanced either by the additional acetal bonds in polymer backbone or by the action of enzyme.
Abstract Eight water-insoluble polyphosphate esters were prepared.The degradation of the polyphosphate esters was enhanced either by the additional acetal bonds in polymer backbone or by the action of enzyme.
1995, 6(4): 337-338
Abstract:
Allantoin was synthesized with the yield as high as 68.5% using H3PW12O40·xH2O as catalyst.Optimum conditions for the synthesis were determined.It was found that the heteropoiy compound has higher catalytic activity than conventional inorganic acid catalysts (such as hydrochloric acid,etc.)
Allantoin was synthesized with the yield as high as 68.5% using H3PW12O40·xH2O as catalyst.Optimum conditions for the synthesis were determined.It was found that the heteropoiy compound has higher catalytic activity than conventional inorganic acid catalysts (such as hydrochloric acid,etc.)
1995, 6(4): 339-342
Abstract:
A series of thermotropic liquid crystalline copolyesters were synthesized by thermal polycondensation of p-hydroxybenzoic acid,terephthalic acid,bis (4-hydroxyphenyl)methanone and diols.The resulting copolyesters were characterized by WAXD,DSC and PLM.All the copolyesters formed a nematic phase.
A series of thermotropic liquid crystalline copolyesters were synthesized by thermal polycondensation of p-hydroxybenzoic acid,terephthalic acid,bis (4-hydroxyphenyl)methanone and diols.The resulting copolyesters were characterized by WAXD,DSC and PLM.All the copolyesters formed a nematic phase.
1995, 6(4): 343-344
Abstract:
The sequence of homogeneous catalytic reactivity of triphenylphosphine complexes of Ru,Rh,Pd,Fe,Co,Ni in the maleic anhydride hydrogenation is:RuCl2 (PPh3)3) > RhCl (PPh3)3 > NiCl2 (PPh3)2 > CoCl2 (PPh3)2 > FeCl2 (PPh3)2 > PdCl2 (PPh3)2.This is consistent with the metal atoms' ionization potentials.
The sequence of homogeneous catalytic reactivity of triphenylphosphine complexes of Ru,Rh,Pd,Fe,Co,Ni in the maleic anhydride hydrogenation is:RuCl2 (PPh3)3) > RhCl (PPh3)3 > NiCl2 (PPh3)2 > CoCl2 (PPh3)2 > FeCl2 (PPh3)2 > PdCl2 (PPh3)2.This is consistent with the metal atoms' ionization potentials.
1995, 6(4): 345-346
Abstract:
Au/NiO was prepared by coprecipitation and subjected to various heat and oxygen pretreatment prior to being used to promote carbon monoxide oxidation.The most active catalyst was obtained by heating in oxygen at 300℃ before use and can convert CO into CO2 completely at 30℃.The relative activities of these catalysts depended on the degree of heating and oxygen exposure before use.
Au/NiO was prepared by coprecipitation and subjected to various heat and oxygen pretreatment prior to being used to promote carbon monoxide oxidation.The most active catalyst was obtained by heating in oxygen at 300℃ before use and can convert CO into CO2 completely at 30℃.The relative activities of these catalysts depended on the degree of heating and oxygen exposure before use.
1995, 6(4): 347-348
Abstract:
The addition of BaF2 into LaOF catalyst significantly improves the catalytic properties of LaOF for the ODE reaction.
The addition of BaF2 into LaOF catalyst significantly improves the catalytic properties of LaOF for the ODE reaction.
1995, 6(4): 349-352
Abstract:
ABSTRACT Mg-Al layered double hydroxides pillared with various polyoxometalate anions were synthesized by direct ion-exchange reactions of Mg/Al-LDH with POMs at acidic pH conditions.
ABSTRACT Mg-Al layered double hydroxides pillared with various polyoxometalate anions were synthesized by direct ion-exchange reactions of Mg/Al-LDH with POMs at acidic pH conditions.
1995, 6(4): 353-356
Abstract:
ABSTRACT The binding of RuL2 pdphen2+ to calf thymus DNA was investigated using absorption fluorescence and CD spectroscopies,where pdphen is the planar ligand pyrido [3,2-f] [1,7] phenanthroline,L=2,2'-bipyridine,phenanthroline,2,9-dimethyl-phenanthroline and 5-nitro-phenanthroline.All coordination compounds show absorption hypochromicity associated with binding to calf thymus DNA.Ru (bipy)2pdphen2+ and Ru (phen)2pdphen2+ also show fluorescence intensities and excited state lifetime increase becanse of the interaction of coordination compounds with calf thymus DNA.CD spectra of dialyzates indicate enantioselectivity associated with binding to DNA.
ABSTRACT The binding of RuL2 pdphen2+ to calf thymus DNA was investigated using absorption fluorescence and CD spectroscopies,where pdphen is the planar ligand pyrido [3,2-f] [1,7] phenanthroline,L=2,2'-bipyridine,phenanthroline,2,9-dimethyl-phenanthroline and 5-nitro-phenanthroline.All coordination compounds show absorption hypochromicity associated with binding to calf thymus DNA.Ru (bipy)2pdphen2+ and Ru (phen)2pdphen2+ also show fluorescence intensities and excited state lifetime increase becanse of the interaction of coordination compounds with calf thymus DNA.CD spectra of dialyzates indicate enantioselectivity associated with binding to DNA.
1995, 6(4): 357-360
Abstract:
In the present work,16 states for BLi2,BLi2+ and BLi2- are found first.Their geometrical structures are determined by energy gradient method using a double-zeta plus polarization (DZP) basis set,and a diffuse(s,p) basis set having exponents of 0.0315 is added to the B atom.The correlation energy obtained for each state is considered with the configuration interaction (CISD) technique.The normal vibrational frequencies are performed using numerical method.The states 3Ⅱ■,1△■,1B2 and 1B2 for BLi2+ are transition states.The state 1△■ for BLi2- is unstable.Other states are stable.
In the present work,16 states for BLi2,BLi2+ and BLi2- are found first.Their geometrical structures are determined by energy gradient method using a double-zeta plus polarization (DZP) basis set,and a diffuse(s,p) basis set having exponents of 0.0315 is added to the B atom.The correlation energy obtained for each state is considered with the configuration interaction (CISD) technique.The normal vibrational frequencies are performed using numerical method.The states 3Ⅱ■,1△■,1B2 and 1B2 for BLi2+ are transition states.The state 1△■ for BLi2- is unstable.Other states are stable.
