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111.
Synthesis of Methyl ω-(5-Oxo-1-cyclopentenyl)alkanoates Starting from 2-Nitrocycloalkanones A convenient synthesis of methyl ω-(5-oxo-1-cyclopentenyl)alkanoates 1 is described. 2-Nitrocycloalkanones 2 are converted to 2-(3,3-dimethoxypropy1)-2-nitrocycloalkanones 4 . Treatment of 4 with MeOH/MeONa led to the ring-opened nitronates 5 which underwent a Nef reaction to form the corresponding oxo derivatives 6 . Partial hydrolysis of followed by base-catalyzed aldol reaction gave the desired products in high yields. 相似文献
112.
Zusammenfassung Es wird die Synthese von 6,11-Dihydro-dibenzo[be]oxepin-bzw.-thiepin-11-onen (IIa bzw. IIb) durch Dehydratisierung der o-(Phenoxymethyl)-benzoesäuren (IIIa) mit Polyphosphorsäureester bzw. der o-(Phenylmercaptomethyl)-benzoesäuren (IIIb) mit Polyphosphorsäure beschrieben. Eine weitere Darstellungsvariante für Oxepine (IIa) ist die Cyclisierung der o-(Phenoxymethyl)-benzoylchloride, erhalten aus den entsprechenden Säuren (IIIa) mit Thionylchlorid durch einfaches Erwärmen. Die Darstellung von 5,6,7,12-Tetrahydro-dibenzo[ad]cyclo-octen-12-on (Ia) erfolgt durch Cyclisierung von 2-(3-Phenylpropyl)-benzoesäure mit Polyphosphorsäure.In der vorliegenden Fassung: am 30. Mai 1962. 相似文献
113.
Quantification of structurally related aliphatic amino alcohols in l‐valinol by hydrophilic interaction liquid chromatography separation combined with postcolumn derivatization and fluorescence detection
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The amino alcohols in l‐ valinol were effectively separated and quantified using hydrophilic interaction chromatography with fluorescence detection. The influence of the mobile phase (salt type, buffer concentration, and pH) on retention was studied. A column TSKgel amide and mobile phase consisting of 10 mM acetate buffer pH 4.0 and acetonitrile (20:80, v/v) provided well‐ separated symmetric peaks of analytes. Fluorescence detection was performed using postcolumn derivatization with o‐phtaldialdehyde/2‐mercaptoethanol at an excitation and emission wavelength of 345 and 450 nm, respectively. Simple sample pretreatment and very high sensitivity represent the main advantages of the developed method. After validation, the method was successfully applied to the analysis of commercial samples of l‐ valinol. 相似文献
114.
115.
Jacek Mercik Barbara Gadysz Izabella Stach Jochen Staudacher 《Entropy (Basel, Switzerland)》2021,23(12)
The aim of the article is to propose a new method of valuation of a company, considering its ownership relations with other companies. For this purpose, the concept of the Shapley value from cooperative game theory is used as the basis for assessing such dependent companies. The paper presents proposals for Shapley value calculation algorithms for our model. We expand our model by discussing personal relations in addition to ownership relations and point out how intuitionistic fuzzy sets may be helpful in this context. As a result, we propose two new expanded models. In the first probabilistic model, we apply Pearson’s correlation coefficient, in the second, we use a correlation coefficient between intuitionistic fuzzy sets to determine the personal relationships. Finally, we present and interpret results for a real-world economic network with 17 companies. 相似文献
116.
117.
Stanislav Rádl Jan Stach Ondřej Píša Josef Cinibulk Jaroslav Havlíček Markéta Zajícová Tomáš Pekárek 《Journal of heterocyclic chemistry》2016,53(6):1738-1749
An improved process for the active pharmaceutical ingredient of a new HIV integrase inhibitor elvitegravir ( 1 ) has been developed. It starts from commercially available 2,4‐dimethoxyacetophenone, which is selectively halogenated into the position 5. The 5‐halo acetophenones are condensed with dialkyl carbonates to give the corresponding benzoylacetates. Their treatment with N,N‐dimethylformamide dimethyl acetal followed by (S)‐valinol then provided the corresponding intermediate benzoyl acrylates. Cyclization to the required 1,4‐dihydroquinolin‐4‐oxo derivatives by aromatic nucleophilic substitution of the 2‐methoxy group was achieved by treatment with N,O‐bis(trimethylsilyl)‐acetamide, which also protected the OH group as the trimethylsilyl derivative. Finally, the Negishi coupling with 2‐fluoro‐3‐chlorobenzylzinc bromide and the following hydrolysis provided elvitegravir ( 1 ). The preferred variant, the seven‐step procedure starting from 2,4‐dimethoxyacetophenone, provides elvitegravir in 29.3% yield. 相似文献
118.
C Kisielowski B Freitag M Bischoff H van Lin S Lazar G Knippels P Tiemeijer M van der Stam S von Harrach M Stekelenburg M Haider S Uhlemann H Müller P Hartel B Kabius D Miller I Petrov E A Olson T Donchev E A Kenik A R Lupini J Bentley S J Pennycook I M Anderson A M Minor A K Schmid T Duden V Radmilovic Q M Ramasse M Watanabe R Erni E A Stach P Denes U Dahmen 《Microscopy and microanalysis》2008,14(5):469-477
The ability of electron microscopes to analyze all the atoms in individual nanostructures is limited by lens aberrations. However, recent advances in aberration-correcting electron optics have led to greatly enhanced instrument performance and new techniques of electron microscopy. The development of an ultrastable electron microscope with aberration-correcting optics and a monochromated high-brightness source has significantly improved instrument resolution and contrast. In the present work, we report information transfer beyond 50 pm and show images of single gold atoms with a signal-to-noise ratio as large as 10. The instrument's new capabilities were exploited to detect a buried Sigma3 {112} grain boundary and observe the dynamic arrangements of single atoms and atom pairs with sub-angstrom resolution. These results mark an important step toward meeting the challenge of determining the three-dimensional atomic-scale structure of nanomaterials. 相似文献
119.
Shan ZW Wiezorek JM Stach EA Follstaedt DM Knapp JA Mao SX 《Physical review letters》2007,98(9):095502
It is believed that the dynamics of dislocation processes during the deformation of nanocrystalline materials can only be visualized by computational simulations. Here we demonstrate that observations of dislocation processes during the deformation of nanocrystalline Ni with grain sizes as small as 10 nm can be achieved by using a combination of in situ tensile straining and high-resolution transmission electron microscopy. Trapped unit lattice dislocations are observed in strained grains as small as 5 nm, but subsequent relaxation leads to dislocation recombination. 相似文献
120.
N. Hessler M. Dolch E. B. Kester E. J. Schneider F. W. Jung K. Drees G. Kowalski S. Hellmann F. Roll E. Stach N. N. Gawrilow L. A. Weissbrut R. A. Mott R. V. Wheeler K. Bunte W. Ludewig B. G. imek F. Coufalík und Z. Beránek 《Fresenius' Journal of Analytical Chemistry》1935,102(7-8):294-299
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