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51.
Rodríguez Rivero M De La Rosa JC Carretero JC 《Journal of the American Chemical Society》2003,125(49):14992-14993
The first asymmetric version of intermolecular Pauson-Khand reactions of unstrained alkenes is described. Generally simple acyclic alkenes exhibit low reactivity and regioselectivity in intermolecular Pauson-Khand reactions; however, o-(dimethylamino)phenyl vinyl sulfoxide reacts under very mild conditions with a wide variety of terminal alkynes in a completely regioselective and highly stereoselective manner. The utility of the resulting 5-sulfinyl-2-cyclopentenones in asymmetric synthesis is illustrated by a very short enantioselective synthesis of the antibiotic (-)-pentenomycin I. 相似文献
52.
Electrospray ionization mass spectrometry (MS) has been widely used to detect noncovalent interactions in supramolecular compounds, especially in biological systems. In our work, we present the application of the electrospray ionization MS technique to characterize the metallamacrocycles, known as metallacrowns. This project involves investigations of the aminohydroxamic acids structure and chirality influence on formation of ternary 12‐metallacrown‐4 complexes. For our experiments, we used a series of β‐aminohydroxamic acids and derivatives of histidinehydroxamic acid. A high stability of the studied supramolecular systems in the gas phase was confirmed by MS/MS experiments. We also proposed the fragmentation pathways for the studied compounds. Obtained results reveal that the ternary 12‐metallacrown‐4 formation process is not selective, and ligands of various structures and chiralities can be incorporated into these systems. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
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54.
Lavilla R Bernabeu MC Brillas E Carranco I Díaz JL Llorente N Rayo M Spada A 《Chemical communications (Cambridge, England)》2002,(8):850-851
One-electron reduction of pyridinium salts (NAD+ analogues) generates dihydropyridyl radicals which may then be engaged in radical addition processes to regioselectively form gamma-substituted dihydropyridines. 相似文献
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56.
The coordination number of percolating clusters and their backbones, on the square and simple cubic lattices, is investigated numerically. At the percolation threshold, the average coordination number of the clusters is 2.239 ± 0.012 and 2.079 ± 0.016 for d = 2 and d = 3, respectively. The corresponding numbers for the backbones are 2.402 ± 0.016 and 2.246 ± 0.034. 相似文献
57.
Martínez-Teipel B Teixidó J Pascual R Mora M Pujolà J Fujimoto T Borrell JI Michelotti EL 《Journal of combinatorial chemistry》2005,7(3):436-448
Heterocyclic demonstration libraries for agrochemical screening were prepared from the common intermediates 2-methoxy-6-oxo-1,4,5,6-tetrahydropyridine-3-carbonitriles (1), using standard solution-phase techniques. A total of 18 screening libraries were prepared in good to excellent yields. Several members of these libraries were active in the first level of agrochemical screening, especially in the fungicide screen. 相似文献
58.
The first one-step conversions of ketimines I into cyclized allylamine derivatives of types II and III are reported. 相似文献
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60.
Domínguez M Alvarez R Martras S Farrés J Parés X de Lera AR 《Organic & biomolecular chemistry》2004,2(22):3368-3373
Ring-oxidized retinoids have been synthesized stereoselectively using the Stille cross-coupling reaction. Kinetic constants of mouse class I alcohol dehydrogenase (ADH1) with these retinoids were determined. 相似文献