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1.
A new and general synthesis of 2,5-dioxopiperazine condensed with the thiazolidine ring is described. The synthesis involves the use of N-ethoxy carbonyl-2-ethoxy-1-2-dihydroquinoleine (EEDQ) as activating agent to form the 2,5-diketopiperazine (EEDQ) as activating agent to form the 2,5-diketopiperazine ring. By this method 9-carbobutoxy-7,7-dimethyl-2,5-dioxo-8-this-1,4-diazabicyclo[4.3.0] nonane (6) and 9-carboxy-8,8 dimethyl-2,5-dioxo-7-thia-1,4-diazabicy clo [4.3.0] nonane (8) were obtained, with near quantitative yield, from 4-carboxy-2-carbobutoxy-5,5 dimethylthiazolidine (4). The former was transformed into acid 7 by hydrolysis with barium bydroxyde and the latter was esterified with diazornethane thus producing a methylester 9. The use of the ethy lester of N-(2-cabobutoxy-4-carboxy-5,5-dimethyl-thiazolidine)glycine (10) for synthesis of 6 was also successful. The spectromethric data were interpreted and confirm the proposed structure of the new compounds. 相似文献
2.
The resolved structure of the lowest-energy oxo to osmium charge-transfer absorption band of trans-[OsO2(malonate)2]2- is analyzed on the basis of the exact molecular Ci symmetry determined from the structure of a crystal used for spectroscopy. The multiple progressions observed in the polarized spectra are rationalized in terms of the deviations from idealized D4h point group symmetry and compared to the spectra observed for complexes with D2h symmetry such as trans-[OsO2(oxalate)2]2- that show only a single dominant progression for this transition. 相似文献
3.
Frédérique Malbec René Milcent Patrick Vicart Anne Marie Bure 《Journal of heterocyclic chemistry》1984,21(6):1769-1774
Thirty new 2-substituted-4-amino-5-alkyl or aryl-2,4-dihydro-1,2,4-triazol-3-ones and ten 2-substituted-5-alkyl or aryl-4-(5-nitro-2-furfurylidene)amino-2,4-dihydro-1,2,4-triazol-3-ones were synthesized and characterised by their sharp melting points, elemental analysis, ir and 1H nmr spectra. These new derivatives of 5-nitro-2-furaldehyde were screened for their antibacterial activities. Most of the compounds showed good activity against one test organism, Staphylococcus aureus. For a few compounds, C.M.I. ranged from 4 to 8 μg/ml (higher results than nitrofurantoin). 相似文献
4.
A new general synthesis of 4,5-disubstituted 2,4-dihydro-1,2,4-triazole-3-thiones is proposed. These heterocycles are obtained by the action of primary amines, arylhydrazines or aroylhydrazines on the thiosemicarbazones of eaters. These last compounds are prepared by action of chlorhydrates of iminoethers on thiosemicarbazide in dimethylformamide. These thiosemicarbazones react also with strong acids, acid anhydrides and chlorides; by thermolysis and they give 2-amino-1,3,4-thiadiazole derivatives. Also, two derivatives of 1,2,4-triazolo[3,4-b]-1,3,4-thiadiazole have been prepared. 相似文献
5.
We apply a recent result of Borichev–Golinskii–Kupin on the Blaschke-type conditions for zeros of analytic functions on the complex plane with a cut along the positive semi-axis to the problem of the eigenvalues distribution of the Fredholm-type analytic operator-valued functions. 相似文献
6.
Philippe Pinel Bertrand Thirion Sébastien Meriaux Antoinette Jobert Julien Serres Denis Le Bihan Jean-Baptiste Poline Stanislas Dehaene 《BMC neuroscience》2007,8(1):91
Background
Although cognitive processes such as reading and calculation are associated with reproducible cerebral networks, inter-individual variability is considerable. Understanding the origins of this variability will require the elaboration of large multimodal databases compiling behavioral, anatomical, genetic and functional neuroimaging data over hundreds of subjects. With this goal in mind, we designed a simple and fast acquisition procedure based on a 5-minute functional magnetic resonance imaging (fMRI) sequence that can be run as easily and as systematically as an anatomical scan, and is therefore used in every subject undergoing fMRI in our laboratory. This protocol captures the cerebral bases of auditory and visual perception, motor actions, reading, language comprehension and mental calculation at an individual level. 相似文献7.
Microwave heating methods have been combined with the use of solid-supported catalysts to produce small solution-phase libraries of medicinally-relevant compounds. Palladium supported on charcoal (Pd/C) has been used to produce libraries of pyrazole compounds for screening in COX II studies via Suzuki cross coupling reactions, while the same catalyst has been used also to produce styryl-based nAChR compounds using analogous chemistry. Although the reaction substrates are very different (aryl vs. vinyl), this catalyst system provided consistently good and reliable results. The use of a polystyrene-supported Ru catalyst for ring-closing metathesis (RCM) reactions was also evaluated to prepare benzolactam structures for evaluation as factor Xa inhibitors. 相似文献
8.
Treatment of various substituted semicarbazones of aromatic aldehydes with sulfur monochloride yields the corresponding substituted 2,4-dihydro-1,2,4-triazol-3-ones. With thiosemicarbazones, the products are derivatives either of the 2-amino-1,3,4 thiadiazole or of the 2,4-dihydro-1,2,4-triazole-3-thione depending on the experimental conditions. 相似文献
9.
Stanislas Vertu Jens Flügge Jean-Jacques Delaunay Olivier Haeberlé 《Central European Journal of Physics》2011,9(4):969-974
Tomographic Diffractive Microscopy is a technique, which permits to image transparent living specimens in three dimensions
without staining. It is commonly implemented in two configurations, by either rotating the sample illumination keeping the
specimen fixed, or by rotating the sample using a fixed illumination. Under the first-order Born approximation, the volume
of the frequency domain that can be mapped with the rotating illumination method has the shape of a “doughnut”, which exhibits
a so-called “missing cone” of non-captured frequencies, responsible for the strong resolution anisotropy characteristic of
transmission microscopes. When rotating the sample, the resolution is almost isotropic, but the set of captured frequencies
still exhibits a missing part, the shape of which resembles that of an apple core. Furthermore, its maximal extension is reduced
compared to tomography with rotating illumination. We propose various configurations for tomographic diffractive microscopy,
which combine both approaches, and aim at obtaining a high and isotropic resolution. We illustrate with simulations the expected imaging performances of these configurations. 相似文献
10.
In this work, we study the following nonlinear homogeneous Neumann boundary value problemβ (u) -diva (x, 7u) f in fΩ, a (x, u). η= 0 on Ω, where Ω is a smooth bounded open domain in RN, N ≥ 3 with smooth boundary Ωand ηthe outer unit normal vector on Ω . We prove the existence and uniqueness of an entropy solution for L1-data f. The functional setting involves Lebesgue and Sobolev spaces with variable exponent. 相似文献