共查询到20条相似文献,搜索用时 15 毫秒
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Heterocycle-fusedtroponoidsareakindofcompoundswithphysiologicalactivitysuchasanticancer'.germicide',antiphlogistic',antihypertension'andantidiabetics.Troponoidcompoundscanbesynthesizedinmanyways,amongwhichonewastooxidizethesidechainoftropoloneforcycl... 相似文献
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Molecular dynamics (MD) simulations of the glass-former 2Ca(NO(3))(2·3KNO(3), CKN, were performed as a function of temperature at pressures 0.1 MPa, 0.5 GPa, 1.0 GPa, and 2.0 GPa. Diffusion coefficient, relaxation time of the intermediate scattering function, and anion reorientational time were obtained as a function of temperature and densitiy ρ. These dynamical properties of CKN scale as ρ(γ)∕T with a common value γ = 1.8 ± 0.1. The scaling parameter γ is consistent with the exponent of the repulsive part of an effective intermolecular potential for the repulsion between the atoms at shortest distance in the equilibrium structure of liquid CKN, Ca(2+), and oxygen atoms of NO(3)(-). Correlation between potential energy and virial is obeyed for the short-range terms of the potential function, but not for the whole potential including coulombic interactions. Decoupling of diffusion coefficient and reorientational relaxation time from relaxation time take place at a given ρ(γ)∕T value, i.e., breakdown of Stokes-Einstein and Debye-Stokes-Einstein equations result from combined thermal and volume effects. The MD results agree with correlations proposed between long-time relaxation and short-time dynamics, lnτ ∝ 1∕, where the mean square displacement concerns a time window of 10.0 ps. It has been found that scales as ρ(γ)∕T above and below the glass transition temperature, so that thermodynamic scaling of liquid dynamics can be thought as a consequence of theories relating short- and long-time dynamics, and the more fundamental scaling concerns short-time dynamical properties. 相似文献
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Indole-3-methylamine (1) has been well demonstrated to be a very useful intermediate as a pharmaceutical building block and starting material for syntheses of phytoalexins.[1] The instability of indole-3-methylamine (1) has undoubtedly restricted its application in synthetic chemistry. Hofmann rearrangement that directly converts carboxamides to alky carbamates in the presence of alcohol required unexceptionally a strong base,[2] which devaluated the possible usefulness of Hofmann rearrangement in preparation of base sensitive amines, especially for the preparation of unstable indole-3-methylamine (1). Herein we would like to report a convenient method for the preparation of alkyl carbamates of 1-protected indole-3-methylamines (4) via the diacetoxyiodobenzene (DIB) promoted Hofmann rearrangement under neutral condition. 相似文献
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JinShengCHENG JinHengLI HuanFengJIANG XiaoYueOUYANG 《中国化学快报》2003,14(9):966-968
The chemoselectivities of PdCl2 and CuCl2-catalyzed oligomerization of 3, 3-dimethyl-butyne: 1, 3, 5-tri-tert-butylbenzene, 2, 2, 7, 7-tetramethyl-3, 6-dichloro-3, 5-octadiene and 2, 2, 7,7- tetramethyl-3, 5-octadiyne were obtained, respectively, by regulating the polarity of the solvent. 相似文献
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A. G. Mustafin R. R. Gataullin I. B. Abdrakhmanov L. V. Spirikhin G. A. Tolstikov 《Russian Chemical Bulletin》1998,47(10):2007-2008
A modified synthesis of 3′-azido-3′-deoxythymidine starting fromD-xylose is proposed.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 2062–2063, October, 1998. 相似文献
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BiflavonesareamorecomPlicatedclass0fflavonoids.MostofthemareusefulcomPonentsoftraditionalmedicinetocurediseases.Sincechamaejasminel,anewtoeofbiflavonoidpossessingaC-3/C-3"linkage,wasisolatedfromSteUerachamaejasmaeL.byHuangetal',especiallyafterthebiologicalactivityofani-cancerwasdiscovered',thestUdyof3,3"-biflavonoidshasattfactCdmuchattention.3-5ButtherehasbeennoprogressmentionedonthesynthesisofthiskindofcomPoundsinrecentdecades.AsaresultofoursystematicresearchonthesynthesisofchamaejasInin… 相似文献
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《Tetrahedron》1987,43(5):1003-1012
A number of penicillins functlonalized at the 3β-methyl position have been syntheslsed. The progenitor of these compounds Is the 3β-hydroxymethyl penicillin 1. 相似文献
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G. V. Giniyatullina O. B. Flekhter I. P. Baikova Z. A. Starikova G. A. Tolstikov 《Chemistry of Natural Compounds》2008,44(5):603-605
A practical method for preparing methyl 3β-amino-3-dexoybetulinate that is based on column chromatographic separation of 3α- and 3β-t-butoxycarbonates and subsequent removal of the protecting group using formic acid is proposed. The structure of methyl 3β-N-(t-butoxycarbonyl)-3-deoxybetulinate was established by an x-ray structure analysis.
Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 488–490, September-October, 2008. 相似文献
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Carbanions of 3-substituted-3-chloropropyl phenyl sulfones add to carbonyl groups of aldehydes to produce aldol type adducts that undergo 1,5-intramolecular substitution giving 2,3,5-trisubstituted tetrahydrofurans. The effect of substituents in the 3-position of these sulfones on the relative rates of 1,3-intramolecular substitution of the corresponding γ-chlorocarbanions and their intramolecular addition are disclosed. 相似文献
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Hong Ye Lincoln Noecker Walter J. Boyko Robert M. Giuliano Glenn P. A. Yap Arnold L. Rheingold 《Journal of carbohydrate chemistry》2013,32(3):373-383
Abstract The branched-chain nitro sugar methyl 2,3,6-trideoxy-3-C-methyl-3-nitro-α-D-ribo-hexopyranoside 4 was investigated as a precursor to D-rubranitrose, a nitro sugar found in the antibiotic rubradirin. X-ray cyrstallographic analysis of 4 shows that the pyranose ring adopts the 4 C 1 conformation with the methoxy group at C-1 and the nitro group at C-3 in a 1,3-diaxial relationship. There is an intermolecular hydrogen bond involving a nitro group oxygen of one monosaccharide residue and the C-4 hydroxyl group of the adjacent residue in the crystal lattice. This interaction results in a helical crystal packing. A series of nucleophilic displacement reactions was carried out on the triflate derivative of 4 in an attempt to introduce an axial carbon-oxygen bond at C-4 required for rubranitrose. Displacements with acetate and propionate gave as products the monosaccharide esters with the desired D-xylo configuration. 相似文献
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Qi CHEN Xing Hai SHEN* Hong Cheng GAO* College of Chemistry Molecular Engineering Peking University Beijing 《中国化学快报》2004,(2)
The hydrophobic cavities of cyclodextrins and the inclusion with various organic molecules in the aqueous solution make them useful in chemical and biological activities1, one of which is the modified cyclodextrins acting as indicators of molecular recognition. Cyclodextrins, which are spectroscopically inert, can be converted into spectroscopically active compounds by modifing one or two of the hydroxy groups with appropriate chromophores, and used as molecular sensor due to the capability of… 相似文献
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A clean, high‐yielding synthetic route to methyl 5‐(bromomethyl)‐1‐tritylindazole 3‐carboxylate 1 was needed. A principal intermediate was 5‐methyl‐3‐carboxyindazole 2. An analysis of a by‐product found after executing Schad's 3‐carboxyindazole synthesis led to undertaking this reaction with an inverse addition in the principal step. This simple modification gave 2 in excellent and reproducible yields. 相似文献
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Guo Jun ZHENG Jian Jun WANG Tian Rui REN Liu YANG Wan Ru SUN* State Key Laboratory of Microbial Resources Institute of Microbiology CAS Beijing Laboratory of Chemistry Computer Institute of Chemical Metallurgy CAS Beijing 《中国化学快报》2001,(4)
Large amount of facts indicated that enantiomers were different from each other in biological activity, physiological activity and toxicity in clinical applications1. It resulted in the increase of interest on preparation of chiral drugs. Optical active 3-phenylglycidic ester, especially (2R,3S)-methyl 3-phenylglycidate is an important starting material for production of many chiral drugs, such as taxol, (2R,3S)-diltiazem etc2,3.For the above purpose, a series of lipases were screened. Final… 相似文献
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The thermal behaviors of clusters [Ag3WS3Br](PPh3)3 and [Cu3WS3Br](PPh3)3 (PPh3=triphenyl phosphine) in a nitrogen atmosphere were studied under the non-isothermal conditions by simultaneous TG-DTG-DSC and EDS techniques. The results showed that the evolution of PPh3 generally proceeded before the release of the other moiety in one or two step-mode. The mechanisms, the kinetic and the thermodynamic parameters for decomposition of PPh3 of both clusters were determined and calculated by jointly using several methods, which showed that its evolution was controlled by Avrami-Erofeev equation. The results also showed that there was no new stable phase composed of W-Ag(Cu)-S-Br after release of organic moiety PPh3 and that CVD method was not applicable to their further processing. 相似文献
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SHEN Xing-gui SUN Li-wen JIAO Ming LI Zhao-fa ZHAO Zhi-zhuang LI Qing-shan FU Xue-qi ** HUANG Zhong-xiu . Edmond H. Fischer Signal Transduction Laboratory College of Life Sciences Jilin University Changchun P. R. China . Qianwei Campus Clinical Hospital of Jilin University Changchun P. R. China 《高等学校化学研究》2006,22(2):221-224
Introduction Proteintyrosinephosphatases(PTPs)playakey roleinsignaltransductionpathways,whichregulatethe growth,differentiationandmalignanttransformationof cells[1].PhosphataseofRegeneratingLiver3(PRL3)belongstoarecentlydiscoveredfamilyofproteinphos phata… 相似文献