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101.
In this article we prove that the extended centroid of a nondegenerate Jordan system is isomorphic to the centroid (and to the center in the case of Jordan algebras) of its maximal Martindale-like system of quotients with respect to the filter of all essential ideals. 相似文献
102.
Esther von Grotthuss Felix Nawa Michael Bolte Hans-Wolfram Lerner Matthias Wagner 《Tetrahedron》2019,75(1):26-30
The 9,10-dimethyl-9,10-dihydro-9,10-diboraanthracene dianion salt Li2[1] instantaneously reacts with the dichalcogens O2(tBu)2, S2Me2, S2(pTol)2, Se2Ph2, and Te2Ph2 under reductive cleavage of the chalcogen–chalcogen bonds to give lithium chalcogenides and neutral 1. In solution, the products are involved in rapid association/dissociation equilibria. In the crystalline state, 1 and Li[O(tBu)] form a diadduct, whereas Li[SMe] gives a B?B-bridged monoadduct. In the three remaining cases, the crystal lattices contain monoadducts of 1 with one tri- and one tetracoordinate boron atom. 相似文献
103.
Halichonic acid,a new rearranged bisabolene-type sesquiterpene from a marine sponge Halichondria sp.
Kenta Raiju Yuki Hitora Hikaru Kato Yuji Ise Esther D. Angkouw Remy E.P. Mangindaan Sachiko Tsukamoto 《Tetrahedron letters》2019,60(15):1079-1081
A new compound, halichonic acid (1), was isolated from a marine sponge Halichondria sp., together with (6R,7S)-7-amino-7,8-dihydro-α-bisabolene (2). The structure of 1 was elucidated by spectroscopic analysis and ECD spectrum calculation to be a rearranged bisabolene-type sesquiterpene having a 3-azabicyclo[3.3.1]nonene moiety. Compound 2 was cytotoxic against HeLa cells with an IC50 value of 50?μM, whereas 1 did not show cytotoxicity even at 50?μM. It is possible that 1 is biosynthesized from farnesyl pyrophosphate and glycine, with rearrangement. 相似文献
104.
Martin Peng Esther Mittmann Lukas Wenger Prof. Dr. Jürgen Hubbuch Dr. Martin K. M. Engqvist Prof. Dr. Christof M. Niemeyer Dr. Kersten S. Rabe 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(70):15998-16001
Continuous flow systems for chemical synthesis are becoming a major focus in organic chemistry and there is a growing interest in the integration of biocatalysts due to their high regio- and stereoselectivity. Methods established for 3D bioprinting enable the fast and simple production of agarose-based modules for biocatalytic reactors if thermally stable enzymes are available. We report here on the characterization of four different cofactor-free phenacrylate decarboxylase enzymes suitable for the production of 4-vinylphenol and test their applicability for the encapsulation and direct 3D printing of disk-shaped agarose-based modules that can be used for compartmentalized flow microreactors. Using the most active and stable phenacrylate decarboxylase from Enterobacter spec. in a setup with four parallel reactors and a subsequent palladium(II) acetate-catalysed Heck reaction, 4-hydroxystilbene was synthesized from p-coumaric acid with a total yield of 14.7 % on a milligram scale. We believe that, due to the convenient direct immobilization of any thermostable enzyme and straightforward tuning of the reaction sequence by stacking of modules with different catalytic activities, this simple process will facilitate the establishment and use of cascade reactions and will therefore be of great advantage for many research approaches. 相似文献
105.
106.
Dr. Dominique T. Thielemann Anna T. Wagner Dr. Yanhua Lan Dr. Pascual Oña‐Burgos Prof. Dr. Ignacio Fernández Prof. Dr. Esther S. Rösch Dr. Dominik K. Kölmel Prof. Dr. Annie K. Powell Prof. Dr. Stefan Bräse Prof. Dr. Peter W. Roesky 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(7):2813-2820
A new family of pentadecanuclear coordination cluster compounds (from now on simply referred to as clusters) [{Ln15(OH)20(PepCO2)10(DBM)10Cl}Cl4] (PepCO2=2‐[{3‐(((tert‐butoxycarbonyl)amino)methyl)benzyl}amino]acetate, DBM=dibenzoylmethanide) with Ln=Y and Dy was obtained by using the cell‐penetrating peptoid (CPPo) monomer PepCO2H and dibenzoylmethane (DBMH) as supporting ligands. The combination of an inorganic cluster core with an organic cell‐penetrating peptoid in the coordination sphere resulted in a core component {Ln15(μ3‐OH)20Cl}24+ (Ln=Y, Dy), which consists of five vertex‐sharing heterocubane {Ln4(μ3‐OH)4}8+ units that assemble to give a pentagonal cyclic structure with one Cl atom located in the middle of the pentagon. The solid‐state structures of both clusters were established by single‐crystal X‐ray crystallography. MS (ESI) experiments suggest that the cluster core is robust and maintained in solution. Pulsed gradient spin echo (PGSE) NMR diffusion measurements were carried out on the diamagnetic yttrium compound and confirmed the stability of the cluster in its dicationic form [{Y15(μ3‐OH)20(PepCO2)10(DBM)10Cl}Cl2]2+. The investigation of both static (dc) and dynamic (ac) magnetic properties in the dysprosium cluster revealed a slow relaxation of magnetization, indicative of single‐molecule magnet (SMM) behavior below 8 K. Furthermore, the χT product as a function of temperature for the dysprosium cluster gave evidence that this is a ferromagnetically coupled compound below 11 K. 相似文献
107.
Ayari Faouzi Mannei Emna Asedegbega-Nieto Esther Mhamdi Mourad Guerrero-Ruiz Antonio Ricardo Delahay Gérard Ghorbel Abdelhamid 《Journal of Thermal Analysis and Calorimetry》2018,131(2):1295-1306
Journal of Thermal Analysis and Calorimetry - Thermal decomposition (2 K min?1) of ammonium heptamolybdate tetrahydrate, performed between room temperature and... 相似文献
108.
Esther Beneish 《Transactions of the American Mathematical Society》1998,350(9):3571-3585
Following Procesi and Formanek, the center of the division ring of generic matrices over the complex numbers is stably equivalent to the fixed field under the action of , of the function field of the group algebra of a -lattice, denoted by . We study the question of the stable rationality of the center over the complex numbers when is a prime, in this module theoretic setting. Let be the normalizer of an -sylow subgroup of . Let be a -lattice. We show that under certain conditions on , induction-restriction from to does not affect the stable type of the corresponding field. In particular, and are stably isomorphic and the isomorphism preserves the -action. We further reduce the problem to the study of the localization of at the prime ; all other primes behave well. We also present new simple proofs for the stable rationality of over , in the cases and .
109.
Kilian Muñiz Prof. Dr. Claas H. Hövelmann Esther Campos‐Gómez José Barluenga Prof. Dr. José M. González Prof. Dr. Jan Streuff Martin Nieger Dr. 《化学:亚洲杂志》2008,3(4):776-788
The oxidative intramolecular diamination of alkenes with tethered ureas and related groups as the nitrogen source has been investigated both with the iodonium reagent IPy2BF4 (Py=pyridine) and under palladium catalysis in the presence of copper(II) bromide as a reoxidant. For terminal alkenes, the two procedures enable selective and high‐yielding transformations. Studies with deuterated material led to the conclusion that the reactions proceed through different stereochemical pathways. An advanced protocol for palladium‐catalyzed diamination through six‐membered‐ring annulation was also developed, and the first examples of the intramolecular diamination of internal alkenes are described. In this case, the same stereochemical outcome was observed for the iodonium‐promoted and palladium‐catalyzed transformations. On this basis, it was possible to determine the importance of aminohalogenated intermediates in both diamination reactions. Overall, the disclosed procedures broaden significantly the synthetic applicability of the oxidative intramolecular diamination of alkenes. 相似文献
110.
Sánchez A Millán S Sampedro MC Unceta N Rodríguez E Goicolea MA Barrio RJ 《Journal of chromatography. A》2008,1177(1):170-174
A sensitive and specific method for determining fenitrothion and its main metabolites, 3-methyl-4-nitrophenol and fenitrooxon, in poplar leaves using deuterated isotopes as the internal standard is described. The analytes and the labeled isotopes were extracted from leaves by solid-phase microextraction and subsequently analysed by gas chromatography coupled with mass spectrometry. The method had a chromatographic run time of 17.0 min and good linearity over the range 0.01-10 mg kg(-1). The detection limits ranged between 2.5 and 0.6 microg kg(-1). The isotopic dilution technique allowed improving significantly the repetitivity even using different fibers with the same coating (RSD<5.1%). The method was applied successfully to study the persistence of fenitrothion in forestal matrices in a poplar forest after cannon spray application of the insecticide. 相似文献