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151.
152.
Lev M. Yagupolskii Irina I. Maletina Liubov V. Sokolenko Yurii G. Vlasenko Maria V. Drozdova Vitaliy V. Polovinko 《Journal of fluorine chemistry》2010,131(2):238-247
The aza analogues of carboxylic acids chlorides containing the NSO2CF3 and NSO2CH3 groups instead of oxygen atom were used in the Arndt–Eistert reaction. It was found that N-trifluoromethylsulfonyl-(4-fluorophenyl)-carboximidoyl chloride 1 reacts with diazomethane vigorously even at ?70 °C with formation of 1-trifluoromethylsulfonylamino-2-(4-fluorophenyl)-2,3-dimorpholine-4-yl-propane 3, 2-trifluoromethylsulfonylamino-2-(4-fluorobenzyl)-7-oxa-4-azonia-spiro[3.5]nonane 4, 2-trifluoromethylsulfonylamino-2-(4-fluorobenzyl)-1,3-dimorpholine-4-yl-propane 5 and 1-trifluoromethylsulfonylamino-2-(4-fluorobenzyl)-2,3-dimorpholine-4-yl-propane 6. Reaction of N-methylsulfonylbenzcarboximidoyl chloride 8 with diazomethane proceeds at ?15 °C yielding 4-chloro-4-methylsulfonylaminomethyl-3-phenyl-4,5-dihydro-1H-pyrazoline 9. 相似文献
153.
Valentine P. Ananikov Prof. Konstantin A. Gayduk Nikolay V. Orlov Dr. Irina P. Beletskaya Prof. Victor N. Khrustalev Dr. Mikhail Yu. Antipin Prof. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2010,16(7):2063-2071
The present study reports the evidence for the multiple carbon–carbon bond insertion into the metal–heteroatom bond via a five‐coordinate metal complex. Detailed analysis of the model catalytic reaction of the carbon–sulfur (C? S) bond formation unveiled the mechanism of metal‐mediated alkyne insertion: a new pathway of C? S bond formation without preliminary ligand dissociation was revealed based on experimental and theoretical investigations. According to this pathway alkyne insertion into the metal–sulfur bond led to the formation of intermediate metal complex capable of direct C? S reductive elimination. In contrast, an intermediate metal complex formed through alkyne insertion through the traditional pathway involving preliminary ligand dissociation suffered from “improper” geometry configuration, which may block the whole catalytic cycle. A new catalytic system was developed to solve the problem of stereoselective S? S bond addition to internal alkynes and a cost‐efficient Ni‐catalyzed synthetic procedure is reported to furnish formation of target vinyl sulfides with high yields (up to 99 %) and excellent Z/E selectivity (>99:1). 相似文献
154.
Elena M. Kirilova Inta Kalnina Tija Zvagule Natalija Gabruseva Natalja Kurjane Irina I. Solomenikova 《Journal of fluorescence》2011,21(3):923-927
The use of hydrophobic fluorescent probe ABM (benzanthrone derivative) and albumin autofluorescence allowed show conformational
alterations in Chernobyl clean-up workers blood plasma. Results obtained in 1996–1997 suggest that acidic expansion of plasma
albumin takes place. Latest data (2006–2008) result in splitting of albumin alterations onto two stages - acidic expansion
and N-F transition. The N-F transition is accompanied by the blue shift of fluorescence spectra and dehydration of tryptophanyl
region of albumin molecule. In 2007 obtained.patterns of ABM spectra had never been previously seen in examined healthy individuals
or patients with tuberculosis, multiple sclerosis, rheumatoid arthritis, etc. Patterns of ABM fluorescence spectra are associated
with conformational changes of blood plasma albumin. The use of probe ABM and albumin auto-fluorescence allowed show conformational
alterations in albumin of Chernobyl clean-up workers blood plasma. It is necessary to note that all investigated parameters
significantly differ in observed groups of patients. These findings reinforce our understanding that the blood plasma albumin
is a significant biological target of radiation. It may be concluded that fluorescence characteristics are representative
of radiation induced albumin alterations and its carrier function. 相似文献
155.
156.
157.
Stanislav V. Maslennikov Roman A. Ignatyev Alexandr V. Piskounov Irina V. Spirina 《应用有机金属化学》2001,15(3):161-168
Synthesis of magnesium dicyclopentadienide from metal and cyclopentadiene in THF is effectively catalyzed by the derivatives of vanadium and titanium. The kinetics of the synthesis, as well as thermodynamic parameters of reagents adsorption on the magnesium surface, have been determined. The process catalyzed by titanium derivatives is accompanied by the quantitative hydrogenation of cyclopentadiene to cyclopentene whereas the catalysis by vanadium derivatives leads to hydrogen gas evolution. A number of reaction intermediates including Cp2TiCl, Cp2TiH2MgCl, Cp2Ti(cyclo‐C5H7) and Cp2V, were identified by the electron spin resonance method. The equilibrium constants, enthalpies and entropies of adsorption of metal halides on the magnesium surface were calculated. Copyright © 2001 John Wiley & Sons, Ltd. 相似文献
158.
159.
Irina Iovel Lena Golomba Sergey Belyakov Andrejs Kemme Edmunds Lukevics 《应用有机金属化学》2001,15(9):733-743
A series of novel Shiff bases (1a–h) was synthesized by condensation of pyridinecarboxaldehydes (1–4) with 3‐ and 4‐trifluoromethylanilines (5, 6) in the presence of molecular sieves (4 Å). It was found that AlCl3 and AlBr3 catalyzed the addition of Me3SiCN to the C?N bond of the imines obtained, whereas the other Lewis acids studied (YCl3, LaCl3, ZnI2) were not active. The reactivity of the imines in the title reaction, on the whole, correlated with their basicity. Besides the addition giving the expected α‐amino nitriles (2a,b,d–f,h), an unusual reaction leading to unsaturated nitriles (3a–h) was observed. The structures of saturated and unsaturated products 2d and 3c were determined by X‐ray diffraction. Copyright © 2001 John Wiley & Sons, Ltd. 相似文献
160.
We propose new robust classification algorithms for planar and spatial curves subjected to affine transformations. Our motivation
comes from the problems in computer image recognition. To each planar or spatial curve, we assign a planar signature curve.
Curves, equivalent under an affine transformation, have the same signature. The signatures are based on integral invariants,
which are significantly less sensitive to small perturbations of curves and noise than classically known differential invariants.
Affine invariants are derived in terms of Euclidean invariants. We present two types of signatures: the global and the local
signature. Both signatures are independent of curve parameterization. The global signature depends on a choice of the initial
point and, therefore, cannot be used for local comparison. The local signature, albeit being slightly more sensitive to noise,
is independent of the choice of the initial point and can be used to solve local equivalence problem. An experiment that illustrates
robustness of the proposed signatures is presented. 相似文献