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101.
Anikó Nemes Tamás Csóka Szabolcs Béni Zsófia Garádi Dénes Szabó József Rábai 《Helvetica chimica acta》2020,103(8):e2000081
Four new chiral α-(nonafluoro-tert-butoxy)carboxylic acids were synthesized from naturally occurring α-amino acids (alanine, valine, leucine and isoleucine, respectively), and tested in 1H- and 19F-NMR experiments as chiral NMR shift reagents. The NMR studies were carried out at room temperature, using CDCl3 and C6D6 as solvents, and (RS)-α-phenylethylamine and (RS)-α-(1-naphthyl)ethylamine as racemic model compounds. To demonstrate the applicability of the reagents, the racemic drugs ketamine and prasugrel were also tested. 相似文献
102.
Mt Mikls Major Gerg Rvid Szabolcs Balogh Attila Bnyei Gyrgy Lendvay Dvid Frigyes Jzsef Bakos Gergely Farkas 《应用有机金属化学》2019,33(2)
A series of chiral pentane‐2,4‐diyl‐based thioether‐amine ligands [ 4 and 5 ; (R,S)‐ and (S,S)‐R1SCH(CH3)CH2CH(CH3)NHR2, respectively, where 4a R1 = iPr, R2 = Ph; 4b R1 = tBu, R2 = Ph; 4c R1 = 1‐Ad, R2 = Ph; 5a R1 = iPr, R2 = Ph; 5b R1 = tBu, R2 = Ph; 5c R1 = 1‐Ad, R2 = Ph; 5d R1 = iPr, R2 = 4‐MeOC6H4; 5e R1 = iPr, R2 = 4‐MeC6H4; 5f R1 = iPr, R2 = 3,5‐Me2C6H3] with stereogenic S‐ and N‐donor atoms has been prepared starting from cyclic sulfates via optically pure γ‐aminoalcohol or 2,4‐dimethylazetidine intermediates. The synthesis of the novel diastereomerically related ligand sets 4 and 5 was accomplished starting from the same source of chirality. The modular ligand structure and the novel synthetic strategies developed for their synthesis allowed the easy modification of the ligands’ (i) S‐ and (ii) N‐substituents, as well as (iii) the relative stereochemistry within the ligand backbone. Six‐membered [Pd(N,S)Cl2]‐type chelate complexes of the diastereomerically related ligands 4a and 5a were synthesized and characterized by X‐ray crystallography in the solid phase, by density functional theory calculations and in solution by NMR spectroscopy. The coordination of 5a resulted in the formation of a single chair conformation by the stereospecific locking of both stereolabile (N and S) donor atoms. In contrast, compound 4a forms rapidly equilibrating palladium species due to the fast inversion of the sulfur donor. Ligands with stereochemically fixed donor atoms provided robust and efficient catalytic systems that can be effectively applied in alkylene carbonates as green reaction media. Remarkably, the phosphine‐free catalysts are air‐stable, and at room temperature in the presence of moisture gave excellent ee’s (up to 93%) in asymmetric allylation processes thanks to the double stereoselective coordination. 相似文献
103.
Bérczes Attila Dujella Andrej Hajdu Lajos Tengely Szabolcs 《Monatshefte für Mathematik》2016,180(3):469-484
Monatshefte für Mathematik - Diophantine sets, i.e. sets of positive integers A with the property that the product of any two distinct elements of A increased by 1 is a perfect square, have a... 相似文献
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Tölgyesi A Fekete J Fekete S Sharma VK Békési K Tóth E 《Journal of chromatographic science》2012,50(3):190-198
A fast liquid chromatography-tandem mass spectrometry (LC-MS-MS) method is developed to determine lincomycin (LM) in honey, muscle, milk, and egg. Samples are cleaned-up at pH 4.7 using Strata-X-C mixed-mode polymeric strong cation exchange solid-phase extraction (SPE) cartridges, which could selectively adsorb the lincomycin from matrices under the acidic condition. LM is separated on the recently introduced Kinetex XB core-shell type HPLC column using isocratic elution mode with a mobile phase containing 0.1% formic acid in water/acetonitrile (93/7, v/v, pH 2.6) at a flow rate of 0.7 mL/min. The subsequent MS/MS detection has decreased ion effect, which allows the limit of detection (LOD) of LM for honey to be 0.05 μg/kg for honey and 0.5 μg/kg for muscle, milk, and egg. These LODs are much lower than those reported previously. The other main advantage of the developed method is the analysis time of only 3.5 min, which is about three times shorter than other reported LC-MS-MS methods. Recoveries varies between 94.2% and 125.2% and in-house reproducibility ranges from 3.7% to 28.7%. The developed method is validated according to European Union (EU) Commission Decision 2002/657/EC using a matrix-comprehensive validation strategy. All studied analytical parameters fulfills the EU guidelines. 相似文献
106.
Farkas G Balogh S Madarász J Szöllősy Á Darvas F Ürge L Gouygou M Bakos J 《Dalton transactions (Cambridge, England : 2003)》2012,41(31):9493-9502
A series of new phosphine-phosphite ligands P(C)(n)OP (n = 1-4) have been synthesized and used for rhodium-catalyzed asymmetric hydrogenation of prochiral olefins in order to study the effect of the chelate ring size. Excellent ees (up to 97.5%) were obtained in the hydrogenation of dimethyl itaconate and an increase of activity and enantioselectivity was observed in the hydrogenation of (Z)-α-acetamidocinnamic acid methyl ester with the increasing length of the backbone of the ligands. 相似文献
107.
Szabolcs Borsányi Ydalia Delgado Stephan Dürr Zoltán Fodor Sándor D. Katz Stefan Krieg Thomas Lippert Dániel Nógrádi Kálmán K. Szabó 《Physics letters. [Part B]》2012
We study QCD thermodynamics using two flavors of dynamical overlap fermions with quark masses corresponding to a pion mass of 350 MeV. We determine several observables on Nt=6 and 8 lattices. All our runs are performed with fixed global topology. Our results are compared with staggered ones and a nice agreement is found. 相似文献
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