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1994 Volume 5 Issue 6
1994, 5(6): 455-456
Abstract:
Nine new nucleosides were prepared by the treatment of 3-[5-(3-pyridyl) tetrazol-2-yl-methylene]-4-aryl-1,2,4-triazole-5(4H)-thione (Ⅰ)with 1-O-trifluoroacetyl-2,3,5-O-tribenzoyl-β-D-ribofuranose (Ⅱ) in anhydrous CH2Cl2 in the presence of BF3·Et2O as catalyst.In this reaction,trifluoroacetoxy group used as leaving group is very effective.The structures and compositions were characterized by elemental analysis and spectroscopic methods.
Nine new nucleosides were prepared by the treatment of 3-[5-(3-pyridyl) tetrazol-2-yl-methylene]-4-aryl-1,2,4-triazole-5(4H)-thione (Ⅰ)with 1-O-trifluoroacetyl-2,3,5-O-tribenzoyl-β-D-ribofuranose (Ⅱ) in anhydrous CH2Cl2 in the presence of BF3·Et2O as catalyst.In this reaction,trifluoroacetoxy group used as leaving group is very effective.The structures and compositions were characterized by elemental analysis and spectroscopic methods.
1994, 5(6): 457-458
Abstract:
A convenient synthetic route to a series of hydroxyl cyclic di-and tri-aza compounds was described.Condensation of 1,3-dichloropropanol[2] with the appropriate disodium salts of N-tosylated di-and triamine in EtOH gave the corresponding 7-,8-and 10-membered di-and triamine cycles in reasonable yields.The tosyl groups were removed with 33% HBr-HOAc in ca. 90% yields.
A convenient synthetic route to a series of hydroxyl cyclic di-and tri-aza compounds was described.Condensation of 1,3-dichloropropanol[2] with the appropriate disodium salts of N-tosylated di-and triamine in EtOH gave the corresponding 7-,8-and 10-membered di-and triamine cycles in reasonable yields.The tosyl groups were removed with 33% HBr-HOAc in ca. 90% yields.
1994, 5(6): 459-460
Abstract:
A formal convergent synthesis of leukotriene B4 has been carried out using D-mannitol and L-ascorbic acid as the chiral pool and formyl-enyl-olefination as the key step.
A formal convergent synthesis of leukotriene B4 has been carried out using D-mannitol and L-ascorbic acid as the chiral pool and formyl-enyl-olefination as the key step.
1994, 5(6): 461-464
Abstract:
(S)-2-(6-methoxy-2-naphtyl)-propionic acid (S-Naproxen) 1 and (S)-2-(4-isobutylphenyl)-propionic acid (S-Ibuprofen) 2 have been synthesized enantioselectively. The steoreochemistry was established by a combination of Sharpless asymmetric dihydroxylation and catalytic hydrogenolysis of the chiral terminal epoxide.
(S)-2-(6-methoxy-2-naphtyl)-propionic acid (S-Naproxen) 1 and (S)-2-(4-isobutylphenyl)-propionic acid (S-Ibuprofen) 2 have been synthesized enantioselectively. The steoreochemistry was established by a combination of Sharpless asymmetric dihydroxylation and catalytic hydrogenolysis of the chiral terminal epoxide.
1994, 5(6): 465-466
Abstract:
α Linked O-and S-galactopyranosides,and galactopyranosyl carboxylates were synthesized as the sole products from 2.3,4,6-tetra-O-benzyl-1-O-trifluoroacetyl-α-D-galacto-pyranose (2).The behavior of the nucleophiles and the two kinds of catalysts (BF3·OEt2 and TMSOTf) were discussed.
α Linked O-and S-galactopyranosides,and galactopyranosyl carboxylates were synthesized as the sole products from 2.3,4,6-tetra-O-benzyl-1-O-trifluoroacetyl-α-D-galacto-pyranose (2).The behavior of the nucleophiles and the two kinds of catalysts (BF3·OEt2 and TMSOTf) were discussed.
1994, 5(6): 467-470
Abstract:
A new bifunctional phosphitylating agent 9-fluorenemethylphosphorodiimidazolide has been synthesized,and its high regioselectivity was demonstrated by the synthesis of a series of oligonucleotides.
A new bifunctional phosphitylating agent 9-fluorenemethylphosphorodiimidazolide has been synthesized,and its high regioselectivity was demonstrated by the synthesis of a series of oligonucleotides.
SYNTHESIS OF ANALOGUES OF HUPERZINE A 2. The Preparation of Some Analogues with Huperzine A Skeleton
1994, 5(6): 471-474
Abstract:
Huperzine A (1),a new Lycopodium alkaloid isolated from Chinese traditional medicine Huperzia Serrata,is a potent acetylcholinesterase inhibitor and a promising drug candidate of treating Alzheimer's disease as well.Several analogues of huperzine A,compound 8,10,14,15 and 17 were prepared and their inhibitory activities of acetylcholinesterase were evaluated.
Huperzine A (1),a new Lycopodium alkaloid isolated from Chinese traditional medicine Huperzia Serrata,is a potent acetylcholinesterase inhibitor and a promising drug candidate of treating Alzheimer's disease as well.Several analogues of huperzine A,compound 8,10,14,15 and 17 were prepared and their inhibitory activities of acetylcholinesterase were evaluated.
1994, 5(6): 475-476
Abstract:
An eight-step synthesis of the key intermediate 5 for the total syntheses of Taxamairin A,B from catechol and 1,3-cyclohexandione was described.
An eight-step synthesis of the key intermediate 5 for the total syntheses of Taxamairin A,B from catechol and 1,3-cyclohexandione was described.
1994, 5(6): 477-480
Abstract:
Model reaction of 1-O-(3,5-dinitrobenzoyl)-2,3,4,6-tetra-O-benzyl-α-D-mannopyranose 1 with a series of carboxylic acids,phenols,alcohols and saccharides respectively demonstrated that stereocontrolled mannosyl transfer with the retention of configuration at the anomeric center was best carried out in dichloromethane (-20℃→r.t.) with TMSOTf as the Lewis acid catalyst,DBMP as a deprotic agent and powdered 3A molecular sieves as a desiccating agent.Under these conditions,α-D-mannopyranosides and related oligosaccharides were obtained in good yields.
Model reaction of 1-O-(3,5-dinitrobenzoyl)-2,3,4,6-tetra-O-benzyl-α-D-mannopyranose 1 with a series of carboxylic acids,phenols,alcohols and saccharides respectively demonstrated that stereocontrolled mannosyl transfer with the retention of configuration at the anomeric center was best carried out in dichloromethane (-20℃→r.t.) with TMSOTf as the Lewis acid catalyst,DBMP as a deprotic agent and powdered 3A molecular sieves as a desiccating agent.Under these conditions,α-D-mannopyranosides and related oligosaccharides were obtained in good yields.
1994, 5(6): 481-484
Abstract:
The total synthesis of curvularin-type macrolides 12-oxocurvularin (1)and citreofuran (2)has been described.And the stereostructures of the two macrolides are unambiguously confirmed by this synthesis.
The total synthesis of curvularin-type macrolides 12-oxocurvularin (1)and citreofuran (2)has been described.And the stereostructures of the two macrolides are unambiguously confirmed by this synthesis.
1994, 5(6): 485-486
Abstract:
Ethyl 2,2-dihydropolyfluoroalkanoates reacted with C-nucleophiles in the presence of base under mild conditions to give the corresponding dehydrofluorination-addition products in good yields.
Ethyl 2,2-dihydropolyfluoroalkanoates reacted with C-nucleophiles in the presence of base under mild conditions to give the corresponding dehydrofluorination-addition products in good yields.
1994, 5(6): 487-488
Abstract:
α-Acyl phosphoranes can readily react with areneselenium cations,which can be obtained from diaryl diselenides by oxidative reaction,to give α-arylseleno-α-acyl phosphoranes in good yields.The α-arylseleno-α-acyl phosphoranes can undergo intramolecular Wittig reaction to afford a convenient synthesis of arylselenoacetylenes.
α-Acyl phosphoranes can readily react with areneselenium cations,which can be obtained from diaryl diselenides by oxidative reaction,to give α-arylseleno-α-acyl phosphoranes in good yields.The α-arylseleno-α-acyl phosphoranes can undergo intramolecular Wittig reaction to afford a convenient synthesis of arylselenoacetylenes.
1994, 5(6): 489-492
Abstract:
6-O-Demethyl-(19S)-dihydroetorphine (1),a new synthetic compound having analgesic activity,has been isolated from crude dihydroetorphine as a minor by-product and its structure was determined by means of spectroscopic methods including 2D NMR techniques.
6-O-Demethyl-(19S)-dihydroetorphine (1),a new synthetic compound having analgesic activity,has been isolated from crude dihydroetorphine as a minor by-product and its structure was determined by means of spectroscopic methods including 2D NMR techniques.
1994, 5(6): 493-496
Abstract:
Diisoferulic acid 3a which has the same configuration as salvianolic acid E was synthesized using isovanillin as starting material.Its Z isomer 3b was obtained during hydrolysis in a basic solution.
Diisoferulic acid 3a which has the same configuration as salvianolic acid E was synthesized using isovanillin as starting material.Its Z isomer 3b was obtained during hydrolysis in a basic solution.
1994, 5(6): 497-500
Abstract:
A new taxanoid,7,2'-didesacetoxy austrospicatine,and five known taxanoids were isolated from the barks of Taxus wallichiana Zucc.Their structures were established by 1-and 2-D NMR and X-ray diffraction methods.
A new taxanoid,7,2'-didesacetoxy austrospicatine,and five known taxanoids were isolated from the barks of Taxus wallichiana Zucc.Their structures were established by 1-and 2-D NMR and X-ray diffraction methods.
1994, 5(6): 501-504
Abstract:
Microfiltration cellulose membrane was chemically modified by epoxy method.Bovine serum albumin was successfully immobilized on the membrane after amination and diazotization.Efficient separation of α-interferon was carried out on the membrane with reactive dye as affinity ligand.
Microfiltration cellulose membrane was chemically modified by epoxy method.Bovine serum albumin was successfully immobilized on the membrane after amination and diazotization.Efficient separation of α-interferon was carried out on the membrane with reactive dye as affinity ligand.
1994, 5(6): 505-506
Abstract:
Intramolecular hydrogen bond of β-cyclodextrin was restudied by means of NMR techniques.
Intramolecular hydrogen bond of β-cyclodextrin was restudied by means of NMR techniques.
1994, 5(6): 507-510
Abstract:
By use of ab initio and analytic energy gradient method, twelve optimized electronic states of AlCB, AlBC, BAlC in six geometric configurations are determined at all electron UHF(RHF)/6-31G* level, their singles and doubles CI (CISD) energies are also obtained. The stabilities for the states of AlCB have been investigated based on the vibrational analysis,binding energy and fragmentation energy.The ground state is 3∑+ of AlCB (C∞, rAlC=1.7497, rBC=1.3511 Å ω=206.7,799.5,1802.9 cm-1, T■=0), the second state is 1A' of AlCB (Cs,rAlC=1.9162,rBC=1.3154 Å,∠ AlCB=179.8307°, ω=238.5,575.1,1767.5cm-1, T■=2432.84 cm-1).The fragmentations of various states (fragmentation products are AlB,AlC, BC diatomic clusters and Al, B, C free atoms) of AlBC, AlCB, BAlC are discussed in detail.
By use of ab initio and analytic energy gradient method, twelve optimized electronic states of AlCB, AlBC, BAlC in six geometric configurations are determined at all electron UHF(RHF)/6-31G* level, their singles and doubles CI (CISD) energies are also obtained. The stabilities for the states of AlCB have been investigated based on the vibrational analysis,binding energy and fragmentation energy.The ground state is 3∑+ of AlCB (C∞, rAlC=1.7497, rBC=1.3511 Å ω=206.7,799.5,1802.9 cm-1, T■=0), the second state is 1A' of AlCB (Cs,rAlC=1.9162,rBC=1.3154 Å,∠ AlCB=179.8307°, ω=238.5,575.1,1767.5cm-1, T■=2432.84 cm-1).The fragmentations of various states (fragmentation products are AlB,AlC, BC diatomic clusters and Al, B, C free atoms) of AlBC, AlCB, BAlC are discussed in detail.
1994, 5(6): 511-514
Abstract:
EHMO calculations and orbital analysis of fragments were performed for the synthetic reactions of oxygenates in Fischer-Tropsch synthesis using a butterfly model for four different metals (Ni,Ru,Rh,Pd) supported on SiO2 as catalysts.Four processes:CO dissociation;coupling of CO and H to produce CHO;insertion of CO to M-CH3;insertion of CH2 to M-CH3 have been calculated.We compared the degree of CO bond activation and the barriers of the foregoing processes for these four catalysts,it can be shown that Ni/SiO2 is a methanation catalyst;Ru/SiO2 and Rh/SiO2 can produce C2-oxygenated compound (acetaldehyde),especially Rh/SiO2 is a good catalyst for producing it,and Pd/SiO2 is a methanol synthesis catalyst.
EHMO calculations and orbital analysis of fragments were performed for the synthetic reactions of oxygenates in Fischer-Tropsch synthesis using a butterfly model for four different metals (Ni,Ru,Rh,Pd) supported on SiO2 as catalysts.Four processes:CO dissociation;coupling of CO and H to produce CHO;insertion of CO to M-CH3;insertion of CH2 to M-CH3 have been calculated.We compared the degree of CO bond activation and the barriers of the foregoing processes for these four catalysts,it can be shown that Ni/SiO2 is a methanation catalyst;Ru/SiO2 and Rh/SiO2 can produce C2-oxygenated compound (acetaldehyde),especially Rh/SiO2 is a good catalyst for producing it,and Pd/SiO2 is a methanol synthesis catalyst.
1994, 5(6): 515-518
Abstract:
The relationship between melting point and acid denaturing acidity of DNA was studied by ultraviolet spectrometer.According to our investigation there exists a good linear relationship between melting point and acid denaturing acidity of DNA.The acid denaturing acidity.which could be obtained easily.may be used in the field of biochemistry as an alternative to melting point.
The relationship between melting point and acid denaturing acidity of DNA was studied by ultraviolet spectrometer.According to our investigation there exists a good linear relationship between melting point and acid denaturing acidity of DNA.The acid denaturing acidity.which could be obtained easily.may be used in the field of biochemistry as an alternative to melting point.
1994, 5(6): 519-522
Abstract:
According to graph theory method,a new method is proposed for the prediction of vaporization heat at normal boiling point of paraffins with molecular structure,and it is compared with other methods.We predict the vaporization heat at normal boiling point for 57 different paraffins,and that is compared with experimental data,its overall absolute average deviation is 0.61%.The result is superior to other methods.
According to graph theory method,a new method is proposed for the prediction of vaporization heat at normal boiling point of paraffins with molecular structure,and it is compared with other methods.We predict the vaporization heat at normal boiling point for 57 different paraffins,and that is compared with experimental data,its overall absolute average deviation is 0.61%.The result is superior to other methods.
1994, 5(6): 523-526
Abstract:
The polymerization of acrylamide and acrylonitrile using ceric ion as initiator can be promoted greatly by the tartaric acid.The kinetics of acrylamide polymerization initiated by ceric ion/tartaric acid has been studied.The presence of the species of tartaric acid in polyacrylonitrile produced by using ceric ion/tartaric acid as initiator has been confimed by FT-IR analysis.
The polymerization of acrylamide and acrylonitrile using ceric ion as initiator can be promoted greatly by the tartaric acid.The kinetics of acrylamide polymerization initiated by ceric ion/tartaric acid has been studied.The presence of the species of tartaric acid in polyacrylonitrile produced by using ceric ion/tartaric acid as initiator has been confimed by FT-IR analysis.
1994, 5(6): 527-528
Abstract:
In this paper,the acidity function,Ho,of Keggin structure heteropolyacids H0XW12O40 (X=P,Si,Ge,B,Co) has been examined in acetonitrile solution by the UV-Hammett method.The dependence of catalytic activity on the acid strength in four different type of reactions was studied.
In this paper,the acidity function,Ho,of Keggin structure heteropolyacids H0XW12O40 (X=P,Si,Ge,B,Co) has been examined in acetonitrile solution by the UV-Hammett method.The dependence of catalytic activity on the acid strength in four different type of reactions was studied.
1994, 5(6): 529-530
Abstract:
WAXD and SAXS for PA1010+BMI system have been measured.The results obtained with the help of Ruland and 1D EDCF,showed that Wc,x,the long period L and the thickness of the crystal lamellae do decreased with BMI content at PA10101+BMI system.Comparing both experimental and calculated density ρc values indicated that the values were of better conformity.Adding BMI into PA1010 caused an increase in distortion.The results from SAXS analysis have also led to the conclusion that a crystal-amorphous interphase could exist in lamellae of semicrystalline polymers and a three-phase model instead of traditional two-phase model should be used.
WAXD and SAXS for PA1010+BMI system have been measured.The results obtained with the help of Ruland and 1D EDCF,showed that Wc,x,the long period L and the thickness of the crystal lamellae do decreased with BMI content at PA10101+BMI system.Comparing both experimental and calculated density ρc values indicated that the values were of better conformity.Adding BMI into PA1010 caused an increase in distortion.The results from SAXS analysis have also led to the conclusion that a crystal-amorphous interphase could exist in lamellae of semicrystalline polymers and a three-phase model instead of traditional two-phase model should be used.
1994, 5(6): 531-532
Abstract:
Hydroformylation of methyl methacrylate with a conversion of 95.6% and selectivity of 92.8% for the normal product,methyl β-formylisobutyrate has been achieved when the reaction was catalyzed by a silica-supported poly-γ-aminopropylsiloxane-rhodium-cobalt bimetallic complex (abbreviated as SiO2-NH2-Rh-Co).The catalyst was stable during the reaction and could be used repeatedly.
Hydroformylation of methyl methacrylate with a conversion of 95.6% and selectivity of 92.8% for the normal product,methyl β-formylisobutyrate has been achieved when the reaction was catalyzed by a silica-supported poly-γ-aminopropylsiloxane-rhodium-cobalt bimetallic complex (abbreviated as SiO2-NH2-Rh-Co).The catalyst was stable during the reaction and could be used repeatedly.
1994, 5(6): 533-536
Abstract:
Heats of immersion into a series of organic bases at 25℃ are reported for polymer protected catalyst PVC-AlCl3.There is a good correlation between the heats of immersion of PVC-AlCl3 and tbennochemical measurements of BF3 or SbCl5.The results have shown that the reaction of PVC-AlCl3 with various bases is essentially Lewis acid-base interaction and the surface acidity of PVC-AlCl3 is mainly attributed to Lewis acidity.
Heats of immersion into a series of organic bases at 25℃ are reported for polymer protected catalyst PVC-AlCl3.There is a good correlation between the heats of immersion of PVC-AlCl3 and tbennochemical measurements of BF3 or SbCl5.The results have shown that the reaction of PVC-AlCl3 with various bases is essentially Lewis acid-base interaction and the surface acidity of PVC-AlCl3 is mainly attributed to Lewis acidity.
1994, 5(6): 537-540
Abstract:
Two new dioxo tetraamine liganda L1 and L2 have been synthesized and characterized by 1H NMR,IR,MS and elemental analysis.Their protonation constants and complex formation constants with Cu2+ have been determined by potentiometric titration.
Two new dioxo tetraamine liganda L1 and L2 have been synthesized and characterized by 1H NMR,IR,MS and elemental analysis.Their protonation constants and complex formation constants with Cu2+ have been determined by potentiometric titration.
1994, 5(6): 541-542
Abstract:
A new kind of amphiphilic porphyrin containing only one carboxyl on the β point of porphyrin ring was synthesized.The surface potential and SHG (Second Harmonic Generation) efficiency of monolayer were measured and the relationship between the surface potential,SHG and the structure of molecule was discussed.
A new kind of amphiphilic porphyrin containing only one carboxyl on the β point of porphyrin ring was synthesized.The surface potential and SHG (Second Harmonic Generation) efficiency of monolayer were measured and the relationship between the surface potential,SHG and the structure of molecule was discussed.
1994, 5(6): 543-546
Abstract:
Complexes of salicylaldehyde-2,4-dinitrophenylhydrazine (HL) of the type ML2,[M=CoⅡ,NiⅡ,CuⅡ,ZnⅡ and MnⅡ] have been prepared and characterized by elemental analysis,molar conductance,magnetic susceptibility,TG-DTA,electronic,IR and XPS methods.The chelating models are discussed.
Complexes of salicylaldehyde-2,4-dinitrophenylhydrazine (HL) of the type ML2,[M=CoⅡ,NiⅡ,CuⅡ,ZnⅡ and MnⅡ] have been prepared and characterized by elemental analysis,molar conductance,magnetic susceptibility,TG-DTA,electronic,IR and XPS methods.The chelating models are discussed.
1994, 5(6): 547-548
Abstract:
A trisubstituted Dawson anion with tetravalent heteroelement titanium has been synthesized from the lacunary precursor Na12[α-P2W15O56].24H2O and characterized by IR.UV.and 183W NMR spectnm.183W NMR of the title anion consists of three lines (intensity ratio 1:2:2) as expected for the trisubstituted α-Dawson anion.
A trisubstituted Dawson anion with tetravalent heteroelement titanium has been synthesized from the lacunary precursor Na12[α-P2W15O56].24H2O and characterized by IR.UV.and 183W NMR spectnm.183W NMR of the title anion consists of three lines (intensity ratio 1:2:2) as expected for the trisubstituted α-Dawson anion.
