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11.
Garcia Ruano JL Alemparte C Martin Castro AM Adams H Rodriguez Ramos JH 《The Journal of organic chemistry》2000,65(23):7938-7943
The behavior of (Z)-3-p-tolylsulfinylacrylonitrile (1) as a chiral dienophile has been evaluated from its reactions with furan and acyclic dienes. Electrostatic interactions of the cyano group with the sulfinyl one restrict the conformational mobility around the C-S bond, thus controlling the pi-facial selectivity, which is almost complete in all cases, the approach of the diene from the less-hindered face of the dienophile (that bearing the lone electron pair) in the predominant rotamer being the favored one. The regioselectivity is also completely controlled by the cyano group. Additionally, the reactivity of compound 1 as well as its endo-selectivity are both higher than those observed for the corresponding (Z)-3-sulfinylacrylates, thus proving the potential of sulfinylnitriles as chiral dienophiles. 相似文献
12.
Matthias Tacke Lorcan T. Allen William M. Gallagher Oscar Mendoza Franz-Josef K. Rehmann 《Journal of organometallic chemistry》2004,689(13):2242-2249
Starting from 6-(p−N,N-dimethylanilinyl)fulvene (1a) or 6-(pentamethylphenyl)fulvene (1b) [1,2-di(cyclopentadienyl)-1,2-di(p−N,N-dimethylaminophenyl)ethanediyl] titanium dichloride (2a) and [1,2-di(cyclopentadienyl)-1,2-bis(pentamethylphenyl)ethanediyl] titanium dichloride (2b) and their corresponding dithiocyanato complexes (3a, 3b) were synthesized. Titanocene 2b did not show a cytotoxic effect, but when 2a was tested against pig kidney carcinoma cells (LLC-PK) or human ovarian carcinoma cells (A2780/cp70) inhibitory concentrations (IC50) of 2.7 × 10−4 and 1.9 × 10−4 M, respectively, were observed. 相似文献
13.
Eduardo Corts Corts Rafael Sosa Mendoza Maximiliano Santibez Gutirrez Olivia Garca‐Mellado De Corts 《Journal of heterocyclic chemistry》2004,41(2):273-276
The preparation and spectral properties often novel methyl 5‐[(o‐, m‐, and p‐substituted)‐phenylthio]‐2‐benzimidazolecarbamates with possible pharmacological activity as antihelmintics is described; by condensation and cyclization between 5‐methylthioures sulfate chloroformic acid methyl ester and 3,4‐diaminophenyl‐substituted‐phenylthio ether dissolved in ethanol. The structures of all final products were corroborated by ir; 1H‐nmr, 13C‐nmr and ms. 相似文献
14.
Mendoza SM Whelan CM Jalkanen JP Zerbetto F Gatti FG Kay ER Leigh DA Lubomska M Rudolf P 《The Journal of chemical physics》2005,123(24):244708
Thin films of fumaramide [2]rotaxane, a mechanically interlocked molecule composed of a macrocycle and a thread in a "bead and thread" configuration, were prepared by vapor deposition on both Ag(111) and Au(111) substrates. X-ray photoelectron spectroscopy (XPS) and high-resolution electron-energy-loss spectroscopy were used to characterize monolayer and bulklike multilayer films. XPS determination of the relative amounts of carbon, nitrogen, and oxygen indicates that the molecule adsorbs intact. On both metal surfaces, molecules in the first adsorbed layer show an additional component in the C 1s XPS line attributed to chemisorption via amide groups. Molecular-dynamics simulation indicates that the molecule orients two of its eight phenyl rings, one from the macrocycle and one from the thread, in a parallel bonding geometry with respect to the metal surfaces, leaving three amide groups very close to the substrate. In the case of fumaramide [2]rotaxane adsorption on Au(111), the presence of certain out-of-plane phenyl ring and Au-O vibrational modes points to such bonding and a preferential molecular orientation. The theoretical and experimental results imply that the three-dimensional intermolecular configuration permits chemisorption at low coverage to be driven by interactions between the three amide functions of fumaramide [2]rotaxane and the Ag(111) or Au(111) surface. 相似文献
15.
16.
Jose Castro‐Perez Nathan Hatcher Nana Kofi Karikari Sheng‐Ping Wang Vivienne Mendoza Henry Shion Alan Millar John Shockcor Mark Towers David McLaren Vinit Shah Stephen Previs Karen Akinsanya Michele Cleary Thomas P. Roddy Douglas G. Johns 《Rapid communications in mass spectrometry : RCM》2014,28(22):2471-2479
17.
P. S. Bedregal P. A. Mendoza M. S. Ubillús I. M. Cohen E. H. Montoya 《Journal of Radioanalytical and Nuclear Chemistry》2014,300(2):673-678
The advantages of instrumental neutron activation analysis applied to archaeological ceramics have been enhanced through the analysis of entire objects, using both the k 0 method and the relative method, respectively, to determine the concentrations of chemical elements in aliquots of replicate objects used as comparators and in the sample object. Twenty-two chemical elements of archaeological importance were measured in mud figurines from Caral civilization (5000 year BC), irradiated inside a well-characterized radial channel facility of the nuclear research reactor at IPEN, Peru. The results showed less than 10 % of bias for most of the elements. 相似文献
18.
Dr. Kilian Colas A. Catarina V. D. dos Santos Dr. Stefanie V. Kohlhepp Dr. Abraham Mendoza 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(9):e202104053
The synthesis of ketones through addition of organometallic reagents to aliphatic carboxylic acids is a straightforward strategy that is limited to organolithium reagents. More desirable Grignard reagents can be activated and controlled with a bulky aniline-derived turbo-Hauser base. This operationally simple procedure allows the straightforward preparation of a variety of aliphatic and perfluoroalkyl ketones alike from functionalized alkyl, aryl and heteroaryl Grignard reagents. 相似文献
19.
Jérôme Deprince Manuel Bautista Stephan Fritzsche Javier García Timothy Kallman Claudio Mendoza Patrick Palmeri Pascal Quinet 《X射线光谱测定》2020,49(1):29-32
In the present work, we report an investigation of plasma environment effects on the atomic parameters associated with the K-vacancy states in highly charged iron ions within the astrophysical context of accretion disks around black holes. More particularly, the sensitivity of K-line X-ray fluorescence parameters (wavelengths, radiative transition probabilities, and Auger rates) in Fe XVII–Fe XXV ions has been estimated for plasma conditions characterized by an electron temperature ranging from 105 to 107 K and an electron density ranging from 1018 to 1022 cm−3. In order to do this, relativistic multiconfiguration Dirac-Fock atomic structure calculations have been carried out by considering a time averaged Debye-Hückel potential for both the electron–nucleus and electron–electron interactions. 相似文献
20.
P. G. Mendoza Jr. D. D. Jackson T. M. Niemczyk 《Journal of Radioanalytical and Nuclear Chemistry》1991,150(2):435-444
We investigated the plutonium assay method that uses the plutonyl trinitrate tetrapropyl-ammonium ion-pair solvent extraction with spectrophotometry of the extract as a candidate method capable of providing robustness and precision. To identify and assess the effect of factors on the precision, we looked at sampling techniques, silver oxide oxidation conditions extraction time, extract stability, and temperature dependence of the extract analytical peak height and position. We obtained a precision of 0.12%. 相似文献