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1.
Acyl group migration from N to C in aziridine-2-carboxylates takes place in deprotonation reactions and, as a result, aziridine-2,2-dicarboxylates are formed. Mechanistic studies proved that the observed migration is an intramolecular reaction. 相似文献
2.
Coordination Chemistry of Cyclopropenylidene‐Stabilized Phosphenium Cations: Synthesis and Reactivity of Pd and Pt Complexes 下载免费PDF全文
Ágnes Kozma Tobias Deden Dr. Javier Carreras Christian Wille Dr. Jekaterina Petuškova Jörg Rust Dr. Manuel Alcarazo 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(8):2208-2214
A straightforward synthesis of cyclopropenylidene‐stabilized phosphenium cations 1 a – g through the reaction of [(iPr2N)2C3+Cl]BF4 with secondary phosphines is described. Their donor ability was evaluated by analysis of the CO stretching frequency in Rh complexes [RhCl(CO)L2](BF4)2 and electrochemical methods. The cyclopropenium ring induces a phosphite‐type behavior that can be tuned by the other two substituents attached to the phosphorus atom. Despite of the positive charge that they bear, phosphenium cations 1 a – g still act as two‐electron donor ligands, forming adducts with PdII and PtII precursors. Conversely, in the presence of Pd0 species, an oxidative insertion of the Pd atom into the Ccarbene–phosphorus bond takes place, providing dimeric structures in which each Pd atom is bonded to a cyclopropenyl carbene while two dialkyl/diaryl phosphide ligands serve as bridges between the two Pd centers. The catalytic performance of the resulting library of PtII complexes was tested; all of the cationic phosphines accelerated the prototype 6‐endo‐dig cyclization of 2‐ethynyl‐1,1′‐biphenyl to afford pentahelicene. The best ligand 1 g was used in the synthesis of two natural products, chrysotoxene and epimedoicarisoside A. 相似文献
3.
Kuleshova J Koukharenko E Li X Frety N Nandhakumar IS Tudor J Beeby SP White NM 《Langmuir : the ACS journal of surfaces and colloids》2010,26(22):16980-16985
High-quality films of bismuth antimony telluride were synthesized by electrodeposition from nitric acid electroplating baths. The influence of a surfactant, sodium ligninsulfonate, on the structure, morphology, stoichiometry, and homogeneity of the deposited films has been investigated. It was found that addition of this particular surfactant significantly improved the microstructural properties as well as homogeneity of the films with a significant improvement in the thermoelectric properties over those deposited in the absence of surfactant. A detailed microprobe analysis of the deposited films yielded a stoichiometric composition of Bi(0.35)Sb(1.33)Te(3) for the films electrodeposited in the absence of surfactant and a stoichiometry of Bi(0.32)Sb(1.33)Te(3) for films deposited in the presence of surfactant. 相似文献
4.
E. Yu. Osipova A. N. Rodionov Yu. A. Belousov M. M. Il’in A. L. Nikolaev A. V. Gopin S. E. Mazina A. A. Simenel 《Russian Journal of Organic Chemistry》2016,52(1):127-130
The condensation of 1-(ferrocenylalkyl)pyrazole-3-carbaldehydes with 4′-aminotetraphenylporphyrin, followed by reduction with NaBH(OAc)3 in 1,2-dichloroethane, provides a convenient method for the synthesis of 5-{4-[({1-[1-(ferrocen-1-yl)alkyl]-5-methyl-1H-pyrazol-3-yl}methyl)amino]phenyl}-10,15,20-triphenylporphyrins which exhibit pronounced cytotoxicity against Staphylococcus aureus under ultrasonic irradiation. 相似文献
5.
A high-performance liquid chromatographic method was developed for separation of the furochromone fraction and for determination of visnagin inAmmi visnagahairy root cultures. Lyophilized samples were extracted with chloroform:methanol (1:1, v/v) and purified on solid-phase extraction cartridges. HPLC analyses were performed on a Eurospher 100-C8Knauer column and the mobile phase was 29:28:526:417 (v/v/v/v) acetonitrile:tetrahydrofuran:30 mM citric acid (pH 3.0):methanol. Quercetin was used as internal standard. Peaks were identified by addition of authentic standards and/or by diode-array detection. 相似文献
6.
Tiit Kaljuvee Jekaterina Jefimova Valli Loide Mai Uibu Marve Einard 《Journal of Thermal Analysis and Calorimetry》2018,132(1):47-57
The power and heat production in Estonia is based over 90% on the combustion of a local solid fossil fuel—Estonian oil shale (OS), and at that 7–8 million tons of OS ash are formed annually. One promising possibility for large-scale utilization of cheap alkali ashes is the liming of acidic soils. In Estonia, there is 350,000 ha of agricultural land that needs permanent liming. To eliminate possible environmental contamination at liming of soils the oil shale ashes should be granulated. Thermal analysis was used for determination of the relationships between physico-mechanical and physico-chemical characteristics of granulated products and the post-granulation treatment conditions. For determination of leachability of ash components, the granulated products as well as the origin ashes were tested using laboratory lysimetries. Depending on OS ash and different post-granulation treatment used, it was possible to obtain granulated product with compressive strength between 5 and 15 N per granule. The leaching of Ca2+ decreased up to 26 and 34%, SO4 2? 70 and 53%, Mg2+ and K+ up to 7–12% for granulated CA and ESPA, respectively, comparing with original ashes. The results of soil analysis indicate that the use of OS ashes improved the pH level of soil significantly. pH increased equally with initial and granulated ash: from 4.7 up to 6.4 and 5.8, respectively, using for that CA and ESPA. Prolonged effect of soil neutralizing ability by granulated product (if compare with fine ashes) was proven by decrease in the content of leached ions in filtrate solutions as well as not mobile ions in soil. 相似文献
7.
V. B. Rybakov S. G. Zhukov E. V. Babaev O. S. Mazina L. A. Aslanov 《Crystallography Reports》2000,45(2):261-263
The crystal structure of 1-methyl-2-oxo-2,3-dihydroimidazo[1,2-a]pyridinium bromide C8H9BrN2O is determined by X-ray diffraction. The structure is solved by the direct method and refined by the least-squares procedure to R = 0.0599. The geometry of the pyridinium fragment observed in the molecule corresponds to the limited number of centers at which the positive charge can be delocalized. Apparently, this delocalization predominantly occurs in the NCN fragment of the imidazole ring and only slightly affects the pyridine moiety of the molecule. 相似文献
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9.
Junpeng Zhao Jekaterina Jeromenok Jens Weber Helmut Schlaad 《Macromolecular bioscience》2012,12(9):1272-1278
Bioconjugate amphiphiles comprising triterpene and poly(ethylene oxide) (PEO) were studied according to their thermoresponsive aggregation behavior (LCST) in water. Cholesteryl?PEO (CE) and betulinyl?PEO (BE) comprising <70 wt% PEO precipitated from water upon heating. CE, but not BE, solutions contained nanoscopic aggregates at room temperature causing different thermoprecipitation behaviors. Solutions containing 5 wt% solutions of BE with short PEO chains demonstrated dual thermoresponsive behavior, precipitating at high temperature and forming hydrogel at low temperature. A BE multiblock copolymer was found to form large aggregates, presumably vesicles, in water. Results suggest that the solution properties of triterpene–PEO amphiphiles can be controlled by the chemical composition and structure.
10.
Jekaterina Rjabova Vitālijs Rjabovs Antonio J. Moreno Vargas Elena Moreno Clavijo Māris Turks 《Central European Journal of Chemistry》2012,10(2):386-394
Recently, monosaccharide-triazole conjugates have proved to possess a large variety of useful biological activities. This
paper describes synthesis of a new series of 3-deoxy-3-C-triazolylmethyl-allose derivatives. These new compounds are obtained from acetonide-protected 3-deoxy-3-azidomethyl allose
and commercial alkynes via Cu(I) catalyzed 1,3-dipolar cycloaddition. The obtained molecular scaffolds differ from those described
earlier by the presence of a methylene linker (-CH2-) between the C(3) of allose and the triazole moiety. It was demonstrated that acetonide-protected monosaccharide, 3-deoxy-3-C-(4-phenyl-1H-1,2,3-triazol-1-yl)methyl-1,2:5,6-di-O-isopropylidene-α-d-allofuranose, inhibited α-L-fucosidase for 26% at 0.1 mM concentration, but a deprotected analog, 3-deoxy-3-C-(4-(4-tert-butylphenyl)-1H-1,2,3-triazol-1-yl)methyl-β-d-allofuranose, showed 15% inhibition of β-glucosidase at 1 mM concentration.
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