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2000 Volume 11 Issue 11
2000, 11(11): 941-942
Abstract:
Magnesium methoxide can be used for TCP-containing substrates to remove acetyl group successfully while leaving the TCP-group virtually intact.
Magnesium methoxide can be used for TCP-containing substrates to remove acetyl group successfully while leaving the TCP-group virtually intact.
2000, 11(11): 943-944
Abstract:
The crude product was purified by column chromatography, eluting with 25:1 CHCl3/MeOH to afford the title compound in 75% yield. Rf:0.32(CHCl3/MeOH 20:1).
The crude product was purified by column chromatography, eluting with 25:1 CHCl3/MeOH to afford the title compound in 75% yield. Rf:0.32(CHCl3/MeOH 20:1).
2000, 11(11): 945-948
Abstract:
The photoinitiated reaction of β-bromonaphthalene with excess pinacolone enolate does not yield expected normal SRN 1 product 1-β-naphthyl-3,3-dimethyl-2-butanone, 3, but a more complex molecule 2,2-dimethyl-5-(1',1'-dimethylethyl)-6-β-naphthyl-5-hexene-3-one, 4, deriving from it. The reaction is inhibited by m-dinitrobenzene and do not occur in the absence of light. Structure analysis of the product, along with other evidence, indicates a mechanism for this reaction, where addition of a further pinacolone molecule to carbonyl group of 3 and subsequent elimination of a water molecule would afford product 4, once the SRN1 substitution product 3 has formed.
The photoinitiated reaction of β-bromonaphthalene with excess pinacolone enolate does not yield expected normal SRN 1 product 1-β-naphthyl-3,3-dimethyl-2-butanone, 3, but a more complex molecule 2,2-dimethyl-5-(1',1'-dimethylethyl)-6-β-naphthyl-5-hexene-3-one, 4, deriving from it. The reaction is inhibited by m-dinitrobenzene and do not occur in the absence of light. Structure analysis of the product, along with other evidence, indicates a mechanism for this reaction, where addition of a further pinacolone molecule to carbonyl group of 3 and subsequent elimination of a water molecule would afford product 4, once the SRN1 substitution product 3 has formed.
2000, 11(11): 949-950
Abstract:
An abnormal intramolecular nucleophilic reaction of αβ-carbon of α,β-unsaturated ester was discovered and the reaction makes it very easy to form imidazo[1,5-a]pyridine derivatives. The mechanism of the reaction was discussed.
An abnormal intramolecular nucleophilic reaction of αβ-carbon of α,β-unsaturated ester was discovered and the reaction makes it very easy to form imidazo[1,5-a]pyridine derivatives. The mechanism of the reaction was discussed.
2000, 11(11): 951-954
Abstract:
Electrospray mass spectrometry investigation shows that denatured oxidized insulin B chain can be selectively cleaved by simple Cu(Ⅱ) ion and the site of cleavage is at Gly8-Ser9 bond which is second amide bond left from His 10 in the sequence of oxidized insulin B chain.
Electrospray mass spectrometry investigation shows that denatured oxidized insulin B chain can be selectively cleaved by simple Cu(Ⅱ) ion and the site of cleavage is at Gly8-Ser9 bond which is second amide bond left from His 10 in the sequence of oxidized insulin B chain.
2000, 11(11): 955-956
Abstract:
Synthesis of β-carbolines on solid phase using TCCA as the key reagent is developed.
Synthesis of β-carbolines on solid phase using TCCA as the key reagent is developed.
2000, 11(11): 957-960
Abstract:
(3R,5R)-3-((tert-Butyldimethylsily)oxy)-5-((Z)-2-bromovinyl)-tetrahydro-furan-2-one, an intermediate for the synthesis of Fostriecin was achieved by intramolecular asymmetric induction in propene addition of (-)-8-phenylmenthyl glyoxylate followed by inversion of C3-hydroxyl group and Sharpless asymmetric dihydroxylation with simultaneous cyclization to give lactone 5. Then protection of C3-hydroxyl group and oxidation of the C6-primary hydroxyl group which reacted with Wittig reagent to yield the target compound4.
(3R,5R)-3-((tert-Butyldimethylsily)oxy)-5-((Z)-2-bromovinyl)-tetrahydro-furan-2-one, an intermediate for the synthesis of Fostriecin was achieved by intramolecular asymmetric induction in propene addition of (-)-8-phenylmenthyl glyoxylate followed by inversion of C3-hydroxyl group and Sharpless asymmetric dihydroxylation with simultaneous cyclization to give lactone 5. Then protection of C3-hydroxyl group and oxidation of the C6-primary hydroxyl group which reacted with Wittig reagent to yield the target compound4.
2000, 11(11): 961-962
Abstract:
A series of novel isoxazole-contained analogues of Losartan were designed and synthesized with 1,3-DC reaction. The regioselectivity of the reaction was discussed and the compounds are potential antihypertensive.
A series of novel isoxazole-contained analogues of Losartan were designed and synthesized with 1,3-DC reaction. The regioselectivity of the reaction was discussed and the compounds are potential antihypertensive.
2000, 11(11): 963-966
Abstract:
A novel method was used to obtain demethoxy-amino-substituted hypocrellin derivatives. Peri-hydroxylated perylenequinone structure of hypocrellin was reserved when hypocrellin reacted with an amine in pyridine. The products were new compounds with significant cytotoxicity against tumor cells. Their structures have been established on the basis of their mass and 1H NMR spectra.
A novel method was used to obtain demethoxy-amino-substituted hypocrellin derivatives. Peri-hydroxylated perylenequinone structure of hypocrellin was reserved when hypocrellin reacted with an amine in pyridine. The products were new compounds with significant cytotoxicity against tumor cells. Their structures have been established on the basis of their mass and 1H NMR spectra.
2000, 11(11): 967-970
Abstract:
6-alkyl-5-fluorouracil derivatives (5a~5f) were synthesized by facile alkylation of lithiation of 5-fluorouracil derivatives with mthyl iodide (MeI) or alkyl trifluoromethanesulfonate (ROTf) in yield of 42~58%. We found that the methylated product was ethyl-substituted derivatives, not methyl-substituted derivatives.
6-alkyl-5-fluorouracil derivatives (5a~5f) were synthesized by facile alkylation of lithiation of 5-fluorouracil derivatives with mthyl iodide (MeI) or alkyl trifluoromethanesulfonate (ROTf) in yield of 42~58%. We found that the methylated product was ethyl-substituted derivatives, not methyl-substituted derivatives.
2000, 11(11): 971-974
Abstract:
A short convenient synthesis of a novel lignan, 2-(3',4',5'-trimethyoxyphenyl)-1,3-dimethyl-6,7,8-trimethoxy-naphthalene has been accomplished by the condensation of key intermediates, 3,4,5-trimethoxybenzyl methyl ketone with TiCl4.
A short convenient synthesis of a novel lignan, 2-(3',4',5'-trimethyoxyphenyl)-1,3-dimethyl-6,7,8-trimethoxy-naphthalene has been accomplished by the condensation of key intermediates, 3,4,5-trimethoxybenzyl methyl ketone with TiCl4.
2000, 11(11): 975-978
Abstract:
Asymmetric cyclomercuration of chiral ferrocenylimines (+)-(R)-2 and (-)-(S)-2 with mercuric acetate and subsequent treatment by lithium chloride gave a mixture of diastereomeric cyclomercurated ferrocenylimines. The four enantiomeric pure compounds with both planar and central chirality were isolated from the two mixtures by the thin layer chromatography.
Asymmetric cyclomercuration of chiral ferrocenylimines (+)-(R)-2 and (-)-(S)-2 with mercuric acetate and subsequent treatment by lithium chloride gave a mixture of diastereomeric cyclomercurated ferrocenylimines. The four enantiomeric pure compounds with both planar and central chirality were isolated from the two mixtures by the thin layer chromatography.
2000, 11(11): 979-980
Abstract:
Two cis-cyclopentene bridged titanocenes have been synthesized. Two homogeneous Ziegler catalysts prepared by activation of synthesized compounds with methylalumoxane are active for ethylene polymerization reactions.
Two cis-cyclopentene bridged titanocenes have been synthesized. Two homogeneous Ziegler catalysts prepared by activation of synthesized compounds with methylalumoxane are active for ethylene polymerization reactions.
2000, 11(11): 981-984
Abstract:
The binding conformations of bidentate ligand DABCO(1,4-diazobicyclo[2,2,2]octane) to a series of p/p type zinc porphyrin dimers covalently linked with flexible alkoxy chain-O(CH2)n O- (n=2~10) are described by 1H NMR and UV-vis spectroscopy. DABCO can bind inside the cavities of porphyrin dimers and form a ternary sandwich complex as the alkoxy chain length is long enough. The thermodynamic parameters which control the binding behavior are investigated.
The binding conformations of bidentate ligand DABCO(1,4-diazobicyclo[2,2,2]octane) to a series of p/p type zinc porphyrin dimers covalently linked with flexible alkoxy chain-O(CH2)n O- (n=2~10) are described by 1H NMR and UV-vis spectroscopy. DABCO can bind inside the cavities of porphyrin dimers and form a ternary sandwich complex as the alkoxy chain length is long enough. The thermodynamic parameters which control the binding behavior are investigated.
2000, 11(11): 985-988
Abstract:
Molecular orbital PM3 calculation was performed on the complexation of cyclobis(para-quat-p-phenylene) with a number of 1,4-disubstituted benzenes and biphenyl derivatives. A fair correlation was found between the PM3 calculated binding energies and the experimental ones, which enabled the PM3 calculation to predict the experimental binding energies for a number of important complexes. A good structure-activity relationship was also found between the PM3 calculated binding energies and the substituent molar refraction Rm and Hammett ó constants, indicating that the van der Waals force and the electronic interactions constituted the major driving forces for the complexation of cyclobis(paraquat-p-phenylene).
Molecular orbital PM3 calculation was performed on the complexation of cyclobis(para-quat-p-phenylene) with a number of 1,4-disubstituted benzenes and biphenyl derivatives. A fair correlation was found between the PM3 calculated binding energies and the experimental ones, which enabled the PM3 calculation to predict the experimental binding energies for a number of important complexes. A good structure-activity relationship was also found between the PM3 calculated binding energies and the substituent molar refraction Rm and Hammett ó constants, indicating that the van der Waals force and the electronic interactions constituted the major driving forces for the complexation of cyclobis(paraquat-p-phenylene).
2000, 11(11): 989-992
Abstract:
A new equation of state based on hard-sphere perturbed theory was developed. This equation combined the CS repulsive term and Guo-Du attractive term. Parameters of 38 substances were estimated, the pressure-volume-temperature properties were calculated and compared with two other equations. The results show that this equation is more accurate.
A new equation of state based on hard-sphere perturbed theory was developed. This equation combined the CS repulsive term and Guo-Du attractive term. Parameters of 38 substances were estimated, the pressure-volume-temperature properties were calculated and compared with two other equations. The results show that this equation is more accurate.
2000, 11(11): 993-994
Abstract:
A new compound, 2, 4-dihydroxy-5-methoxybenzophenone was isolated from the root and heartwood of Dalbergia odorifera T. Chen.
A new compound, 2, 4-dihydroxy-5-methoxybenzophenone was isolated from the root and heartwood of Dalbergia odorifera T. Chen.
2000, 11(11): 995-996
Abstract:
Two new ent-kaurane diterpenoids, adenanthins B (1) and C (2), were isolated from the EtOAc extract of Isodon adenantha. Their structures were elucidated by spectroscopic evidences.
Two new ent-kaurane diterpenoids, adenanthins B (1) and C (2), were isolated from the EtOAc extract of Isodon adenantha. Their structures were elucidated by spectroscopic evidences.
2000, 11(11): 997-1000
Abstract:
A novel depsides 1, together with three known ones 2~4 and two phenylpropanoids 5~6 were isolated from the ethanol extract of the spikes of Prunella vulgaris. On the basis of spectral and chemical evidence, their structures were deternined as butyl rosmarinate 1, ethyl rosmarinate 2, methyl rosmarinate 3, rosmarinic acid 4, 3,4,α-trihydroxy-methyl phenylpropionate 5 and p-coumaric acid 6, respectively.
A novel depsides 1, together with three known ones 2~4 and two phenylpropanoids 5~6 were isolated from the ethanol extract of the spikes of Prunella vulgaris. On the basis of spectral and chemical evidence, their structures were deternined as butyl rosmarinate 1, ethyl rosmarinate 2, methyl rosmarinate 3, rosmarinic acid 4, 3,4,α-trihydroxy-methyl phenylpropionate 5 and p-coumaric acid 6, respectively.
2000, 11(11): 1001-1002
Abstract:
Two new phenolic glycosides, 3, 4-dihydroxy-allylbenzene-3-O-α-L-rhamnopyranosyl (1→6)β-D-glucopyranoside (1) and 3, 4-dihydroxy-allylbenzene-3-O-α-L-rhamnopyranosyl (1→2) β-D-glucopyranoside (2), were isolated from the barks of Magnolia rostrata. Their structures were elucidated by spectroscopic and chemical methods, specially 2D NMR techniques.
Two new phenolic glycosides, 3, 4-dihydroxy-allylbenzene-3-O-α-L-rhamnopyranosyl (1→6)β-D-glucopyranoside (1) and 3, 4-dihydroxy-allylbenzene-3-O-α-L-rhamnopyranosyl (1→2) β-D-glucopyranoside (2), were isolated from the barks of Magnolia rostrata. Their structures were elucidated by spectroscopic and chemical methods, specially 2D NMR techniques.
2000, 11(11): 1003-1004
Abstract:
A norditerpenoid alkaloid, 6-epiforsticine, has been isolated from the roots of the plants Aconitum hemsleyanum var. pengzhouense and A. kuzsnezoffii and its structure has been established as 1 on the basis of 2D-NMR and X-ray diffraction analysis. The structure of forsticine has accordingly been revised from 1 to 2.
A norditerpenoid alkaloid, 6-epiforsticine, has been isolated from the roots of the plants Aconitum hemsleyanum var. pengzhouense and A. kuzsnezoffii and its structure has been established as 1 on the basis of 2D-NMR and X-ray diffraction analysis. The structure of forsticine has accordingly been revised from 1 to 2.
2000, 11(11): 1005-1006
Abstract:
Two new diterpenoids, nagadine 1 and 14-benzoylsachaconitine 2 were isolated from the roots of Aconitum nagarum. Their structures were elucidated as 1 and 2 on the basis of spectral analysis.
Two new diterpenoids, nagadine 1 and 14-benzoylsachaconitine 2 were isolated from the roots of Aconitum nagarum. Their structures were elucidated as 1 and 2 on the basis of spectral analysis.
2000, 11(11): 1007-1008
Abstract:
A new sesquiterpene lactone glucoside, notoserolide C (1), was isolated from the whole plant of Notoseris psilolepis Shih. By means of spectral analysis including MS, NMR (1HNMR, 13C NMR,1H-1H COSY, HMQC, HMBC) and X-ray diffraction, the structure of notoserolide C was established as cichorioside B angelate.
A new sesquiterpene lactone glucoside, notoserolide C (1), was isolated from the whole plant of Notoseris psilolepis Shih. By means of spectral analysis including MS, NMR (1HNMR, 13C NMR,1H-1H COSY, HMQC, HMBC) and X-ray diffraction, the structure of notoserolide C was established as cichorioside B angelate.
2000, 11(11): 1009-1012
Abstract:
Two new sesquiterpenoid trialcohol isomers named 1β, 4α 11α-trihydroxyeudesmane (1) and Yunnanensehedychetriol (2), were isolated from the fresh rhizomes of Hedychium Yunnanense gagnep.Their structures were elucidated by spectroscopic methods.
Two new sesquiterpenoid trialcohol isomers named 1β, 4α 11α-trihydroxyeudesmane (1) and Yunnanensehedychetriol (2), were isolated from the fresh rhizomes of Hedychium Yunnanense gagnep.Their structures were elucidated by spectroscopic methods.
2000, 11(11): 1013-1014
Abstract:
A new triterpenoid glycoside 1, 1β, 2α, 3α, 19α-tetrahydroxyurs-12-en-28-oic acid β-D glucopyranosyl ester was isolated from Dichotomanthes tristaniaecarpa. The structure was elucidated on the basis of spectral means.
A new triterpenoid glycoside 1, 1β, 2α, 3α, 19α-tetrahydroxyurs-12-en-28-oic acid β-D glucopyranosyl ester was isolated from Dichotomanthes tristaniaecarpa. The structure was elucidated on the basis of spectral means.
2000, 11(11): 1015-1018
Abstract:
A short chain poly (acrylamide-dimethylacrylamide) was synthesized in water phase using isopropanol as a chain transfer agent. This copolymer can form a stable dynamic coating on the inner surface of the capillary, thereby suppressing the electroosmotic flow and DNA-capillary wall interaction. The high efficient separation of DNA fragments and SSCP analysis were obtained in bare capillaries using this copolymer as a sieving medium.
A short chain poly (acrylamide-dimethylacrylamide) was synthesized in water phase using isopropanol as a chain transfer agent. This copolymer can form a stable dynamic coating on the inner surface of the capillary, thereby suppressing the electroosmotic flow and DNA-capillary wall interaction. The high efficient separation of DNA fragments and SSCP analysis were obtained in bare capillaries using this copolymer as a sieving medium.
2000, 11(11): 1019-1022
Abstract:
A one-meter long column packed with silica gel is used to separate light hydrocarbons. The silica gel has been modified with several kinds of gas chromatography stationary phases. Among these, PEG 2000 shows fairly good effect when using 80-100 meshes silica gel for the separation of mixture of methane, ethane, ethylene, acetylene, propane, propylene and n-, i-butane. The different behavior of silica gel between batch to batch is also found. When silica gel is coated with a small amount of Al2O3prepared with sol-gel method, better resolution has been observed on a 2-meter column compared with the non-modified silica gel.
A one-meter long column packed with silica gel is used to separate light hydrocarbons. The silica gel has been modified with several kinds of gas chromatography stationary phases. Among these, PEG 2000 shows fairly good effect when using 80-100 meshes silica gel for the separation of mixture of methane, ethane, ethylene, acetylene, propane, propylene and n-, i-butane. The different behavior of silica gel between batch to batch is also found. When silica gel is coated with a small amount of Al2O3prepared with sol-gel method, better resolution has been observed on a 2-meter column compared with the non-modified silica gel.
2000, 11(11): 1023-1026
Abstract:
Since highly crystalline poly (L-lactide) (PLLA) degrades rather slowly in a biological environment and the crystalline domains remaining after partial degradation of the implant material give rise to an inflammatory response of the surrounding tissue, L- and D,L-lactide copolymer[P(L-DL)LA] having a low crystallinity is preferred in surgical applications. The thermal transitions and the mechanical properties of P(L-DL)LA rods were discussed in this paper. It was found that the self-reinforced P(L-DL)LA[SR-P(L-DL)LA] was strong enough in terms of mechanical properties compared with the self-reinforced PLLA[SR-PLLA].
Since highly crystalline poly (L-lactide) (PLLA) degrades rather slowly in a biological environment and the crystalline domains remaining after partial degradation of the implant material give rise to an inflammatory response of the surrounding tissue, L- and D,L-lactide copolymer[P(L-DL)LA] having a low crystallinity is preferred in surgical applications. The thermal transitions and the mechanical properties of P(L-DL)LA rods were discussed in this paper. It was found that the self-reinforced P(L-DL)LA[SR-P(L-DL)LA] was strong enough in terms of mechanical properties compared with the self-reinforced PLLA[SR-PLLA].
2000, 11(11): 1027-1030
Abstract:
A monolayer which is formed by a binuclear palladium complex of low rim methioninedisubstituted calix[4]arene exhibits extraordinary cohesiveness. Cohesiveness measurement and Brewster Angle Microscopy observation show that the monolayer is uniform and robust. This film is probably formed by self-assembly of precursor complex through strong chloride ion bridge between palladium centers.
A monolayer which is formed by a binuclear palladium complex of low rim methioninedisubstituted calix[4]arene exhibits extraordinary cohesiveness. Cohesiveness measurement and Brewster Angle Microscopy observation show that the monolayer is uniform and robust. This film is probably formed by self-assembly of precursor complex through strong chloride ion bridge between palladium centers.
2000, 11(11): 1031-1034
Abstract:
Carbon nanotubes were synthesized on a large scale by the catalytic decomposition of hydrocarbons over pre-reduced LaCoO3 using a fluidized-bed reactor. Reaction parameters such as reduction temperature, reduction time and reaction temperature were discussed.
Carbon nanotubes were synthesized on a large scale by the catalytic decomposition of hydrocarbons over pre-reduced LaCoO3 using a fluidized-bed reactor. Reaction parameters such as reduction temperature, reduction time and reaction temperature were discussed.
