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551 results on '"KLEINPETER, E."'

22. Varia

Author

Calvete, J. J., Schäfer, W., Henschen, A., Gonzalez-Rodriguez, J., Sichtermann, W., Wenclawiak, B., Schipke, J., Benninghoven, A., Meese, C. O., Specht, D., Fischer, P., Hübner, D., Fischer, G., Ströhl, D., Kleinpeter, E., Hartrodt, B., Brandt, W., Gauglitz, G., Walz, R., Wälder, H., Lipinski, J., Stan, H. -J., Waidmann, E., Hilpert, K., Stoeppler, M., Welz, Bernhard, Sperling, Michael, Fang, Zhaolun, Fink, E., Hehlein-Fink, C., Nast-Kolb, D., Jochum, M., Ohlsson, K., Dietze, S., Auerswald, E. A., Fritz, H., Pfeilschifter, Josef, Leighton, Jonathan, Pignat, Werner, Märki, Fritz, Vosbeck, Klaus, Bachem, M. G., Meyer, D. H., Gressner, A. M., Ratge, D., Steegmüller, U., Wisser, H., Dargel, R., Schlag, B., Winkler, L., Müller, H., Oswald, B., Schumann, G., Petersen, D., Büttner, J., and Maurer, Hans H.

Published
1990
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30. 2-Substituted and 2,2-disubstituted adamantane derivatives as models for studying substituent chemical shifts and C-Hax⋯Yax cyclohexane contacts - results from experimental and theoretical NMR spectroscopic chemical shifts and DFT structures

Author

Kolocouris, A. Koch, A. Kleinpeter, E. Stylianakis, I.

Abstract

The complete 1H and 13C NMR chemical shifts assignment for various 2-substituted and 2,2-disubstituted adamantane derivatives 1-38 in CDCl3 solution was realized on the basis of NMR experiments combined with chemical structure information and DFT-GIAO (B3LYP/6-31+G(d,p)-GIAO) calculations of chemical shifts in solution. Substituent-induced 13C NMR chemical shifts (SCS) are discussed. C-Hax⋯Yax contacts are a textbook prototype of steric hindrance in organic chemistry. The nature of these contacts will be further investigated in this work on basis of new adamantane derivatives, which are substituted at C-2 to provide models for 1,4-C-Hax⋯Yax and 1,5-C-Hax⋯Yax contacts. The B3LYP/6-31+G(d,p) calculations predicted the presence of NBO hyperconjugative attractive interactions between C-Hax and Yax groups along C-Hax⋯Yax contacts. The 1H NMR signal separation, Δδ(γ-CH2), reflects the strength of the H-bonded C-Haxa⋯Yax contact. © Elsevier Ltd. All rights reserved.

Published
2015

31. Comparison of the electronic structures of imine and hydrazone side-chain functionalities with the aid of (super)13 C and (super)15 N NMR chemical shifts and PM3 calculations. The influence of C=N-substitution on the sensitivity to aromatic substitution

Author

Neuvonen, K., Fulop, F., Neuvonen, H., Koch, A., Kleinpeter, E., and Pihlaja, K.

Subjects
Schiff bases, Hydrazine, Chemical reactions -- Analysis, Nuclear magnetic resonance spectroscopy -- Usage, Aromatic compounds, Substitution reactions -- Analysis, Biological sciences, Chemistry
Abstract

Research has been conducted on C=N carbon resonances on hydrazones and imines. The characterization of the origin of the differences in substituent dependence of these resonances has been carried out, and the results are reported.

Published
2003

32. Conformational Analysis of (1,1′-Phenyl-1,1′-silacyclohex-1-yl)disiloxane. DFT and Low-Temperature 13C NMR Spectroscopy Study.

Author

Shainyan, B. A., Suslova, E. N., and Kleinpeter, E.

Subjects
SILOXANES, CONFORMATIONAL analysis, NUCLEAR magnetic resonance spectroscopy, DENSITY functional theory, LOW temperatures, HEXANE
Abstract

The DFT and MP2 theoretical conformational analysis of the recently synthesized (1,1′-phenyl-1,1′-silacyclohex-1-yl)disiloxane has revealed the energetic preference of the Phax,Phax conformer. The Phax,Phax: Phax,Pheq: Pheq,Pheq conformers ratio has been estimated as of 46.6: 33.1: 20.3 from the M062X/6-311G(d,p) free energy simulation, suggesting the possibility of detecting individual conformers experimentally, e.g., by low-temperature 1H and 13C NMR spectroscopy. However, only the presence of several conformers has been detected by means of 1H NMR spectroscopy at 113 K; determination of the Δν (Hz) and ΔG# (kcal/mol) parameters for the 6-membered ring interconversion has been impossible due to the signals broadening at low temperature, signal temperature shifts, and extremely low barrier of ring inversion at Tc < 113 K. [ABSTRACT FROM AUTHOR]

Published
2019
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35. Stereocontrolled synthesis of new tetrahydrofuro[2,3-d]thiazole derivatives via activated vinylogous iminium ions

Author

Markovic, R, Baranac-Stojanović, Marija, Steel, P, Kleinpeter, E, Stojanovic, M, Markovic, R, Baranac-Stojanović, Marija, Steel, P, Kleinpeter, E, and Stojanovic, M

Abstract

Heterocyclization of (Z)-5-(2-hydroxyethyl)-3-methyl-4-oxothiazolidines, bearing electron-withdrawing groups conjugated to an exocyclic double bond at C(2)-position, afforded under reductive conditions, cis-tetrahydroftiro[2,3-d]thiazole derivatives. The reactions of these functionalized push-pull beta-enamines occur in a stereocontrolled fashion via activated vinylogous N-methyliminium ions, which are trapped by an internal hydroxyethyl group.

Published
2005

36. Stereocontrolled synthesis of new tetrahydrofuro[2,3-d]thiazole derivatives via activated vinylogous iminium ions

Author

Marković, R., Baranac-Stojanović, Marija, Steel, P, Kleinpeter, E, Stojanović, Milovan, Marković, R., Baranac-Stojanović, Marija, Steel, P, Kleinpeter, E, and Stojanović, Milovan

Abstract

Heterocyclization of (Z)-5-(2-hydroxyethyl)-3-methyl-4-oxothiazolidines, bearing electron-withdrawing groups conjugated to an exocyclic double bond at C(2)-position, afforded under reductive conditions, cis-tetrahydroftiro[2,3-d]thiazole derivatives. The reactions of these functionalized push-pull beta-enamines occur in a stereocontrolled fashion via activated vinylogous N-methyliminium ions, which are trapped by an internal hydroxyethyl group.

Published
2005

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