共查询到20条相似文献,搜索用时 31 毫秒
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Ryabova S. Yu. Alekseeva L. M. Lisitza E. A. Shashkov A. S. Chernyshev V. V. Tichomirova G. B. Goyzman M. S. Granik V. G. 《Russian Chemical Bulletin》2001,50(8):1449-1456
The possibility of transformation of 3-cyano-1-p-nitrophenyl--carbolin-2-one into 2-amino-3-cyano-1-p-nitrophenyl-1H-pyrido[3,2-b]indole derivatives and 2-imino-3-cyano-1-p-nitrophenyl-5H-pyrido[3,2-b]indole derivatives (-carbolines) is demonstrated. Methylation of 1-p-nitrophenyl-2-piperidino-1H--carboline followed by treatment with acetone in an alkaline medium yields 4-acetonyl-5-methyl-1,4-dihydro-5H-pyrido[3,2-b]indole derivative. The rearrangement of 2-arylimino-3-cyano-1-p-nitrophenyl-5H-pyrido[3,2-b]indoles into 2-(aryl)nitrophenylamino-3-cyano-5H-pyrido[3,2-b]indoles was accomplished on heating above the melting point or on treatment with potassium tert-butoxide. The structures of the resulting compounds were proved by 1H and 13C NMR spectroscopy and X-ray diffraction analysis. 相似文献
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Yurii V. Svyaschenko 《Tetrahedron letters》2010,51(48):6316-6318
A novel approach to 1,2λ5-azaphosphinines has been elaborated. Aminophosphonium chlorides bearing a β-dialkylaminocrotonic nitrile residue react with N,N-dimethylformamide dimethylacetal to afford 1,2λ5-azaphosphinines. 相似文献
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Xing Hai Li Xin Ling Yang Xiao Mei Liang Zhen Peng Kai Yun Ling Fu Heng Chen Dao Quan Wang 《中国化学快报》2007,18(12):1476-1478
α-Chlorocycloalkanones(Ⅳ) were synthesized from cycloalkanones via potassiumα-oxocycloalkylsulfonates(Ⅱ).A two-step mechanism was proposed to explain the formation ofⅣfromⅡ. 相似文献
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《Tetrahedron: Asymmetry》2000,11(13):2741-2751
The four stereoisomers of Δ2-isoxazoline 2, a β-adrenergic receptor antagonist structurally related to Falintolol 1, were prepared by an enzyme-catalyzed kinetic resolution of the unsaturated secondary alcohol (±)-7 followed by its cycloaddition to pyruvonitrile oxide. Through this strategy, diastereomeric aminoalcohols (+)-2a/(−)-2b and (−)-2a/(+)-2b were obtained in 99 and 92% enantiomeric excess, respectively. The absolute configuration to the target compounds was assigned via chemical correlation to the enantiomers of epoxides 4a and 4b, whose stereochemistry had been previously established. 相似文献
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《Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy》1994,50(14):2271-2280
The dimer approach was proposed for the normal coordinate analysis of BEDT—TTF+ molecular vibrations. It was shown that, within the framework of the approximation used, the appearance of additional bands in the IR as well as in Raman spectra may be explained as due to the reduction of symmetry of the dimerized system in comparison with the monomeric one. The strength of intermolecular interaction in the dimer was estimated by adjusting the calculated frequencies to the observed positions of intense “vibronic” bands recorded in the IR spectra of BEDT—TTF-based monovalent charge transfer salts. It was found that for the reproduction of “vibronic shifts” observed for some vibrations it should be assumed that the intermolecular interaction takes effect not only on the totally symmetric ag modes, but also on the vibrations of other symmetry species. 相似文献
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A domino approach of Heck coupling was used to synthesize β-trifluoromethylstyrene derivatives from iodoarenes and 1-iodo-3,3,3-trifluoropropane in moderate to good yields. This method avoids the use of low-boiling, gaseous reagents such as 3,3,3-trifluoropropene, and additives and phosphines in the catalytic system. 相似文献
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Peter Puschnig Claudia Ambrosch-Draxl 《Monatshefte für Chemie / Chemical Monthly》2008,139(4):389-399
We show how ab initio calculations based on density functional theory contribute to the understanding of the electronic and optical properties of organic semiconducting materials, which form the active layers in many opto-electronic applications. As a textbook example, we present the electronic structure and the optical properties of the oligo-phenylenes as evolving from their benzene-constituents. Thereby we discuss the dependence on the molecular length and introduce the modifications in the opto-electronic properties due to intermolecular interactions which are inherently present in the bulk phase. 相似文献
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Peed J Davies IR Peacock LR Taylor JE Kociok-Köhn G Bull SD 《The Journal of organic chemistry》2012,77(1):543-555
A method of preparing enantiopure hydroxy-γ-butyrolactones containing multiple contiguous stereocenters in high yield with good diastereoselectivity has been developed. Osmium tetroxide mediated dihydroxylation of a range of β-alkenyl-β-hydroxy-N-acyloxazolidin-2-ones results in formation of triols that undergo spontaneous intramolecular 5-exo-trig cyclization reactions to provide hydroxy-γ-butyrolactones. The stereochemistry of these hydroxy-γ-butyrolactones has been established using NOE spectroscopy, which revealed that 1-substituted, 1,1-disubstituted, (E)-1,2-disubstituted, (Z)-1,2-disubstituted, and 1,1,2-trisubstituted alkenes undergo dihydroxylation with anti-diastereoselectivity, while 1,2,2-trisubstituted systems afford syn-diastereoisomers. The synthetic utility of this methodology has been demonstrated for the asymmetric synthesis of the natural product 2-deoxy-D-ribonolactone. 相似文献
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Broekaert JA 《Analytical and bioanalytical chemistry》1996,355(7-8):847-852
The importance of gaining knowledge on the fundamental processes in glow discharges in the field of the signal generation, the sputtering phenomena taking place in the case of solids and the analyte breakdown in the excitation of gases is treated. For gaining more knowledge on the plasma processes diagnostics including temperature and electron number density as well as gas and analyte atom and ion densities are required. For the sputtering process, it is shown at the hand of measurements with gas-jet enhanced sputtering and magnetically enhanced sputtering that selective sputtering may occur and that the influence of the analyte loading of the glow discharge plasma needs further study. For the case of the introduction of gaseous samples, the analyte distribution as well as the break-down mechanisms and kinetics in the case of molecular species ask for further study as shown by experiments with gas-sampling glow discharges. 相似文献
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WU Xiong-Wu SHI JunDepartment of Chemical Engineering Nanjing Institute of Chemical Technology Nanjing Jiangsu ChinaWANG Wen-ChuanDepartment of Chemical Engineering Beijing Institute of Chemical Technology Beijing China 《中国化学》1994,12(2):105-112
A new approach to the computation of the chemical potential of fluids is presented. In this method the particle-insertion operation in the conventional test particle method is replaced by the growth of a specific particle. Application of the new technique to hard sphere and Lennard-Jones fluids shows that it is capable of providing reliable estimates of the chemical potential, even at high density where the conventional test particle methods are difficult to apply. 相似文献
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Hiroshi Kamitakahara Arata Yoshinaga Hajime Aono Fumiaki Nakatsubo Dieter Klemm Walther Burchard 《Cellulose (London, England)》2008,15(6):797-801
In the present paper we suggest a new concept to overcome some of the so far unsolved problems of the structure–property relationship
of methylcellulose, the most important nonionic cellulose ether industrially produced in large scale. Not only from the viewpoint
of scientific understanding, but also from that of the peculiar and application-determining behavior, the aggregation in aqueous
solution and phase separation on heating are the most important questions. As a part of the concept, we had prepared amphiphilic
block co-oligomers of tri-O-methylated and unmodified cello-oligosaccharides as structural models of typical sequences in methylcellulose chains. Now
static and dynamic light scattering measurements and transmission electron microscopy (TEM) were carried out using solutions
of the oligomers in water. Ellipsoidal particles with dimensions of about 50 nm for the semi-major axis and of circa 25 nm
for the semi-minor one could be detected. These findings agree with the radii of gyration and the hydrodynamic radii, determined
by static and dynamic light scattering. The data preliminary obtained demonstrate the strong aggregation tendency of block-like
methylated cello-oligosaccharides. 相似文献
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A six-step approach to the tetracyclic core of merrilactone A is described that uses an intramolecular Paterno-Büchi photoaddition to install the key oxetane ring. Irradiation of bicyclic enone 16, constructed through cyclopentenone alkylation followed by a domino oxy-/carbopalladation reaction, produces the tetracyclic oxetane 17 in excellent yield, having the core carbon skeleton of the target compound merrilactone A. [reaction: see text] 相似文献
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A new safe and technologically advantageous method to obtain an active substance of Agsular® pharmaceutical was developed. For the first time, potassium persulfate was used as a sulfating agent for polysaccharides. The structures, physicochemical properties, and anticoagulating and hypolipidemic activities of the Agsular® pharmaceutical ingredients obtained using different methods were studied in comparison. 相似文献
15.
Elena Salmina Maria A. Grishina Vladimir A. Potemkin 《Journal of computer-aided molecular design》2013,27(9):793-805
Fast and reliable prediction of bond orders in organic systems based upon experimentally measured quantities can be performed using electron density features at bond critical points (J Am Chem Soc 105:5061–5068, 1983; J Phys Org Chem 16:133–141, 2003; Acta Cryst B 61:418–428, 2005; Acta Cryst B 63:142–150, 2007). These features are outcomes of low-temperature high-resolution X-ray diffraction experiments. However, a time-consuming procedure of gaining these quantities makes the prediction limited. In the present work we have employed an empirical approach AlteQ (J Comput Aided Mol Des 22:489–505, 2008) for evaluation of electron density properties. This approach uses a simple exponential function derived from comparison of electron density, gained from high-resolution X-ray crystallography, and distance to atomic nucleus what allows calculating density distribution in time-saving manner and gives results which are very close to experimental ones. As input data AlteQ accepts atomic coordinates of isolated molecules or molecular ensembles (for instance, protein–protein complexes or complexes of small molecules with proteins, etc.). Using AlteQ characteristics we have developed regression models predicting Cioslowski–Mixon bond order (CMBO) indexes (J Am Chem Soc 113(42):4142–4145, 1991). The models are characterized by high correlation coefficients lying in the range from 0.844 to 0.988 dependently on the type of covalent bond, thereby providing a bonding quantification that is in reasonable agreement with that obtained by orbital theory. Comparative analysis of CMBOs approximated using topological properties of AlteQ and experimental electron densities has shown that the models can be used for fast determination of bond orders directly from X-ray crystallography data and confirmed that AlteQ characteristics can replace experimental ones with satisfactory extent of accuracy. 相似文献
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Irene Moraleja Estefanía Moreno-Gordaliza Diego Esteban-Fernández M. Luz Mena Michael W. Linscheid M. Milagros Gómez-Gómez 《Analytical and bioanalytical chemistry》2015,407(9):2393-2403
A shotgun approach including peptide-based OFFGEL-isoelectric focusing (IEF) fractionation has been developed with the aim of improving the identification of platinum-binding proteins in biological samples. The method is based on a filter-aided sample preparation (FASP) tryptic digestion under denaturing and reducing conditions of cisplatin–, oxaliplatin–, and carboplatin–protein complexes, followed by OFFGEL-IEF separation of the peptides. Any risk of platinum loss is minimized throughout the procedure due to the removal of the reagents used after each stage of the FASP method and the absence of thiol-based reagents in the focusing buffer employed in the IEF separation. The platinum–peptide complexes stability after the FASP digestion and the IEF separation was confirmed by size exclusion chromatography-inductively coupled plasma-mass spectrometry (SEC-ICP-MS). The suitability of peptide-based OFFGEL-IEF fractionation for reducing the sample complexity for further nano-liquid chromatography-electrospray ionization-tandem mass spectrometry (nLC-ESI-MS/MS) analysis has been demonstrated, allowing the detection of platinum-containing peptides, with significantly lower abundance and ionization efficiency than unmodified peptides. nLC-MS/MS analysis of selected OFFGEL-IEF fractions from tryptic digests with different complexity degrees: standard human serum albumin (HSA), a mixture of five proteins (albumin, transferrin, carbonic anhydrase, myoglobin, and cytochrome-c) and human blood serum allowed the identification of several platinum–peptides from cisplatin–HSA. Cisplatin-binding sites in HSA were elucidated from the MS/MS spectra and assessed considering the protein three-dimensional structure. Most of the potential superficial binding sites available on HSA were identified for all the samples, including a biologically relevant cisplatin-cross-link of two protein domains, demonstrating the capabilities of the methodology. 相似文献
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Both enantiomers of fluoxetine were synthesized in five steps from ethyl benzoylacetate(1)using microbial-chemical approach with overall yields of 59% and 62% respectively.(S)-Enan-tiomer can be obtained in >99% e.e.by resting cell of baker's yeast and the R form was produced in 81 %e.e.by immobilized Geotrichum sp.G 38. 相似文献
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Mikhail M. Shmakov Sergey A. Prikhod’ko Vadim V. Bardin Nicolay Yu. Adonin 《Mendeleev Communications》2018,28(4):369-371
A new approach for preparation of aromatic and fluoroaromatic difluoroboranes via the interaction between corresponding aryltrifluoroborates and ionic liquids containing tetrachloroaluminate-anion and aluminum chloride has been developed. Catalytic properties of obtained aryldifluoroboranes have been investigated in model reactions of phenols alkylation. The dependence of catalytic properties on both the nature of solvent used and the type of substituents in the aromatic ring of difluoroborane has been established. 相似文献
20.
Damian Mikulski Daniel Gasperowicz Jerzy Konarski 《Journal of mathematical chemistry》2015,53(9):1986-1996
By applying the algebraic approach and the displacement operator to the ground state, the unknown Gilmore–Perelomov coherent states for the rotating anharmonic Kratzer–Fues oscillator are constructed. In order to obtain the displacement operator the ladder operators have been applied. The deduced SU(1, 1) dynamical symmetry group associated with these operators enables us to construct this important class of the coherent states. Several important properties of these states are discussed. It is shown that the coherent states introduced are not orthogonal and form complete basis set in the Hilbert space. We have found that any vector of Hilbert space of the oscillator studied can be expressed in the coherent states basis set. It has been established that the coherent states satisfy the completeness relation. Also, we have proved that these coherent states do not possess temporal stability. The approach presented can be used to construct the coherent states for other anharmonic oscillators. The coherent states proposed can find applications in laser-matter interactions, in particular with regards to laser chemical processing, laser techniques, in micro-machinning and the patterning, coating and modification of chemical material surfaces. 相似文献