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221.
The thermolysis of t-butyl perpent-4-enoate in ketones leads to the formation of 5-(α-alkanonyl) and 5-(α-cyclanonyl)-4-pentanolides with fairly good yields. 相似文献
222.
Using deeply virtual Compton scattering as a tool to study the structure of hadrons in an exclusive process, one expresses the amplitudes in terms of invariant quantities: the Compton form factors. In this paper the sensitivity of the hadronic part of the cross section to the Compton form factors is determined. 相似文献
223.
Les Sels de Bismuth (III) Comme Catalyseurs Dans la Reaction D'ouverture Des Epoxydes Par Les Amines
Adyl Oussaid Bernard Garrigues Boualem Oussaid Fatima Benyaquad 《Phosphorus, sulfur, and silicon and the related elements》2013,188(10):2315-2320
BiCl 3 and Bi (OTf) 3 catalyze the opening of epoxides ( 1-7 ) by amines ( 8-12 ). High regioselectivities are observed. BiCl 3 et Bi (OTf) 3 catalysent la réaction d'ouverture des époxydes ( 1-7 ) par les amines ( 8-12 ). La réaction est fortement régiosélective. 相似文献
224.
Heloisa Beraldo Ricardo F. F. da Costa Rejane Lima Geraldo M. de Lima Ivana S. Lula Bernard Mahieu 《Phosphorus, sulfur, and silicon and the related elements》2013,188(10):2455-2463
The reaction of tin(IV) tetrachloride with 3-formylpyridine semicarbazone and different 3-formylpyridine thiosemicarbazones produces [Sn(HL)CL 3 ][SnCl 5 ] where HL stands for the neutral ligand. The tin(IV) complexes were characterized using a variety of spectroscopic techniques. Coordination through the pyridine nitrogen occurs in all cases. Solvation studies in DMSO indicated that dissociation of the ligands and their complete replacement by solvent molecules occurs. 相似文献
225.
Adyl Bernard Bernard Garrigues 《Phosphorus, sulfur, and silicon and the related elements》2013,188(4):825-832
In presence of bismuth(III) triflate, a carbonylated electrophile (ethyl mesoxalate or glyoxylate) and usual diene led selectively (60-100) the hetero carbonyl-Diels-Alder reaction with the ene reaction product. Bi(OTf) 3 exhibits strong catalytic activity and reacts under mild conditions. En présence de triflate de bismuth(III) le mésoxalate et le glyoxylate d'éthyle réagissent avec des diènes usuels pour donner un mélange de carbonyl-Diels-Alder et du produit de la ène réaction. Bi(OTf) 3 présente une forte activité catalytique et réagit dans des conditions douces. 相似文献
226.
Polymerization of α-aminoisobutyric acid NCA by alkaline salts of various basicity as well as amines has been investigated. The study was focused on the effect on the initial polymerization rate of additives such as N-acetylglycine NCA and some other less electrophilic additives (l-acetyl-2-pyrrolidone, 3-acetyl-2-oxazolidone, 1-acetyl-3-methylhydantoin) which are all models of the growing chain end produced by the NCA anion pathway. The acetyl endgroup was detected by 250 MHz 1H-NMR in all the polymers of α-aminoisobutyric acid NCA obtained in the presence of l-acetyl-3-methylhydantoin and triethyl amine or sodium methoxide initiators, whereas the additives influenced variously the kinetics of polymerization according to the nature of the initiator used. The results were interpreted in the light of a multiple mechanism supposing the simultaneous presence of the initiator anion, its conjugate acid, and NCA anion for basic salt initiation. Thus, the observed effect has to be considered as the sum of an elementary acceleration due to NCA anion and of an elementary deceleration due to the initiator anion. Predominance of the pathways involving NCA anion could be shown this way. This conclusion could be extended to γ-benxyl-L-glutamate NCA which is a more reactive NCA. However, the deceleration observed with some additives led us to believe that a nonnegligible participation of initiator anion during initiation cannot be excluded. 相似文献
227.
Sizwe J. Zamisa Patrick Ndungu Bernard Omondi 《Acta Crystallographica. Section C, Structural Chemistry》2013,69(10):1100-1103
The reaction of 4,4′‐bipyridine with copper acetate in the presence of 4‐nitrophenol led to the formation of the title compound, {[Cu(CH3COO)2(C10H8N2)]·C6H5NO3·2H2O}n. The complex forms a double‐stranded ladder‐like coordination polymer extending along the b axis. The double‐stranded polymers are separated by 4‐nitrophenol and water solvent molecules. The two CuII centres of the centrosymmetric Cu2O2 ladder rungs have square‐pyramidal coordination environments, which are formed by two acetate O atoms and two 4,4′‐bipyridine N atoms in the basal plane and another acetate O atom at the apex. The ladder‐like double strands are separated from each other by one unit‐cell length along the c axis, and are connected by the water and 4‐nitrophenol molecules through a series of O—H...O and C—H...O hydrogen‐bonding interactions and two unique intermolecular π–π interactions. 相似文献
228.
Benoît Driesschaert Philippe Levêque Bernard Gallez Jacqueline Marchand-Brynaert 《Tetrahedron letters》2013
A stable RGD-conjugated triarylmethyl (TAM) radical 3 has been synthesized in a straightforward three-step sequence. CT-03 ‘the Finland trityl’ which is a very popular contrast agent for electron paramagnetic resonance imaging has been covalently bound to the NH2-ending of a pentapeptide commonly used to target integrins and confers tissue selectivity. Moreover, this new TAM radical is stable and sensitive to molecular oxygen. 相似文献
229.
230.
Proteome analysis involves separating proteins as a preliminary step toward their characterization. This paper reports on the translational migration of a model transmembrane protein (α‐hemolysin) in supported n‐bilayers (n, the number of bilayers, varies from 1 to around 500 bilayers) when an electric field parallel to the membrane plane is applied. The migration changes in direction as the charge on the protein changes its sign. Its electrophoretic mobility is shown to depend on size and charge. The electrophoretic mobility varies as 1/R2, with R the equivalent geometric radius of the embedded part of the protein. Measuring mobilities at differing pH in our system enables us to determine the pI and the charge of the protein. Establishing all these variations points to the feasibility of electrophoretic transport of a charged object in this medium and is a first step toward electrophoretic separation of membrane proteins in n‐bilayer systems. 相似文献