TY - JOUR A1 - Kleinpeter, Erich A1 - Kirpichenko, Svetlana V. A1 - Ushakov, Igor A. A1 - Shainyan, Bagrat A. T1 - Conformational analysis of 3-methyl-3-silathiane and 3-fluoro-3-methyl-3-silathiane N2 - The conformational equilibria of 3-methyl-3-silathiane 5, 3-fluoro-3-methyl-3-silathiane 6 and 1-fluoro-1- methyl-1-silacyclohexane 7 have been studied using low temperature 13C NMR spectroscopy and theoretical calculations. The conformer ratio at 103;K was measured to be about 5ax:5eq;=;15:85, 6ax:6eq;=;50:50 and 7ax:7eq;=;25:75. The equatorial preference of the methyl group in 5 (0.35;kcal;mol;1) is much less than in 3-methylthiane 9 (1.40;kcal;mol;1) but somewhat greater than in 1-methyl-1- silacyclohexane 1 (0.23;kcal;mol;1). Compounds 5-7 have low barriers to ring inversion: 5.65 (ax;;;eq) and 6.0 (eq;;;ax) kcal mol;1 (5), 4.6 (6), 5.1 (Meax;;;Meeq) and 5.4 (Meeq;;;Meax) kcal;mol;1 (7). Steric effects cannot explain the observed conformational preferences, like equal population of the two conformers of 6, or different conformer ratio for 5 and 7. Actually, by employing the NBO analysis, in particular, considering the second order perturbation energies, vicinal stereoelectronic interactions between the Si-X and adjacent C-H, C-S, and C-C bonds proved responsible. Y1 - 2011 SN - 0894-3230 ER - TY - JOUR A1 - Kleinpeter, Erich A1 - Koch, Andreas T1 - The anisotropic effect of functional groups in 1H NMR spectra is the molecular response property of spatial NICS-the frozen conformational equilibria of 9-arylfluorenes N2 - Rotation about the single bond adjoining the aryl and fluorene moieties in 9-arylfluorenes can be frozen out on the NMR timescale if methyl groups are located at either one or both of the ortho positions of the aryl substituent. In the ground-state of these rotamers, the planes of the aryl and fluorene moieties are perpendicular to each other and the methyl protons are either shielded or deshielded, respectively, due to the ringe current effect of the fluorene moiety. This anisotropic effect on the 1H chemical shifts of the methyl protons has been quantified on the basis of through- space NMR shieldings (TSNMRS) and subsequently _______ compared with the experimentally observed chemical shift differences _____. In this context, the experimental anisotropic effects of functional groups in the !H NMR have proven to quantitatively be the molecular response property of theoretical spatial nucleus independent chemical shieldings (NICS). Differences between _______ and _____ were, for the first time, also quantified as arising from steric compression. Y1 - 2011 UR - http://www.sciencedirect.com/science/article/pii/S0040402011008507 (13.9.13) SN - 0040-4020 ER - TY - JOUR A1 - Kleinpeter, Erich A1 - Lammermann, Anica A1 - Kühn, Heiner T1 - Synthesis and NMR spectra of the syn and anti isomers of substituted cyclobutanes-evidence for steric and spatial hyperconjugative interactions N2 - The syn and anti isomers of cis,cis-tricyclo[5.3.0.0(2.6)]dec-3-ene derivatives have been synthesized and their (1)H and (13)C NMR spectra unequivocally analyzed. Both their structures and their (1)H and (13)C NMR chemical shifts were calculated by DFT, the latter two calculations employing the GIAO perturbation method. Additionally, calculated NMR shielding values were partitioned into Lewis and non-Lewis contributions from the bonds and lone pairs involved in the molecules by accompanying NBO and NCS analyses. The differences between the syn and anti isomers were evaluated with respect to steric and spatial hyperconjugation interactions. Y1 - 2011 SN - 0040-4020 ER - TY - JOUR A1 - Csütörtöki, Renáta A1 - Szatmári, István A1 - Koch, Andreas A1 - Heydenreich, Matthias A1 - Kleinpeter, Erich A1 - Fulop, Ferenc T1 - Synthesis and conformational analysis of new naphth[1,2-e][1,3]oxazino[3,4-c]quinazoline derivatives Y1 - 2011 SN - 0040-4020 ER - TY - JOUR A1 - Kleinpeter, Erich A1 - Koch, Andreas T1 - Chelatoaromaticity-existing: yes or no? An answer given by spatial magnetic properties (through space NMR shieldings-TSNMRS) Y1 - 2011 SN - 1463-9076 ER - TY - JOUR A1 - Stojanovic, Milovan A1 - Markovic, Rade A1 - Kleinpeter, Erich A1 - Baranac-Stojanovic, Marija T1 - endo-Mode cyclizations of vinylogous N-acyliminium ions as a route to the synthesis of condensed thiazolidines Y1 - 2011 SN - 0040-4020 ER - TY - JOUR A1 - Csuetoertoeki, Renata A1 - Szatmari, Istvan A1 - Koch, Andreas A1 - Heydenreich, Matthias A1 - Kleinpeter, Erich A1 - Fueloep, Ferenc T1 - Synthesis and conformational analysis of new naphth[1,2-e][1,3]oxazino[3,4-c]quinazoline derivatives JF - Tetrahedron N2 - A new highly functionalized aminonaphthol derivative, 1-(amino(2-aminophenyl)methyl)-2-naphthol (4), was synthesized by the reaction of 2-naphthol, 2-nitrobenzaldehyde and tert-butyl carbamate or benzyl carbamate, followed by reduction and/or removal of the protecting group. The aminonaphthol derivative thus obtained was converted in ring-closure reactions with formaldehyde. benzaldehyde and/or phosgene to the corresponding naphth[1,2-e][1,3]oxazino[3,4-c]quinazoline derivatives. The conformational analysis of some derivatives by NMR spectroscopy and accompanying molecular modelling are also reported. KW - Naphthoxazinoquinazolines KW - NMR KW - Conformational analysis KW - DFT calculations KW - Hammett-Brown plots Y1 - 2011 U6 - https://doi.org/10.1016/j.tet.2011.08.074 SN - 0040-4020 VL - 67 IS - 44 SP - 8564 EP - 8571 PB - Elsevier CY - Oxford ER - TY - JOUR A1 - Kramer, Markus A1 - Kleinpeter, Erich T1 - A conformational study of N-acetyl glucosamine derivatives utilizing residual dipolar couplings JF - Journal of magnetic resonance N2 - The conformational analyses of six non-rigid N-acetyl glucosamine (NAG) derivatives employing residual dipolar couplings (RDCs) and NOEs together with molecular dynamics (MD) simulations are presented. Due to internal dynamics we had to consider different conformer ratios existing in solution. The good quality of the correlation between theoretically and experimentally obtained RDCs show the correctness of the calculated conformers even if the ratios derived from the MD simulations do not exactly meet the experimental data. If possible, the results were compared to former published data and commented. KW - NMR KW - Residual dipolar couplings KW - Molecular dynamics KW - N-acetyl glucosamine derivatives KW - Carbohydrates Y1 - 2011 U6 - https://doi.org/10.1016/j.jmr.2011.06.029 SN - 1090-7807 VL - 212 IS - 1 SP - 174 EP - 185 PB - Elsevier CY - San Diego ER - TY - GEN A1 - Kramer, Markus A1 - Kleinpeter, Erich T1 - A conformational study of N-acetyl glucosamine derivatives utilizing residual dipolar couplings (vol 212, pg 174, 2011) T2 - Journal of magnetic resonance Y1 - 2011 U6 - https://doi.org/10.1016/j.jmr.2011.09.017 SN - 1090-7807 VL - 213 IS - 1 SP - 210 EP - 211 PB - Elsevier CY - San Diego ER - TY - JOUR A1 - Marsat, Jean-Noel A1 - Heydenreich, Matthias A1 - Kleinpeter, Erich A1 - Berlepsch, Hans V. A1 - Boettcher, Christoph A1 - Laschewsky, André T1 - Self-Assembly into multicompartment micelles and selective solubilization by Hydrophilic-Lipophilic-Fluorophilic block copolymers JF - Macromolecules : a publication of the American Chemical Society N2 - Amphiphilic linear ternary block copolymers (ABC) were synthesized in three consecutive steps by the reversible addition fragmentation chain transfer (RAFT) method. Using oligo(ethylene oxide) monomethyl ether acrylate, benzyl acrylate, and 1H,1H-perfluorobutyl acrylate monomers, the triblock copolymers consist of a hydrophilic (A), a lipophilic (B), and a fluorophilic (C) block. The block sequence of the triphilic copolymers was varied systematically to provide all possible variations: ABC, ACB, and BAC. All blocks have glass transition temperatures below 0 degrees C. Self-assembly into spherical micellar aggregates was observed in aqueous solution, where hydrophobic cores undergo local phase separation into various ultrastructures as shown by cryogenic transmission electron microscopy (cryo-TEM). Selective solubilization of substantial quantities of hydrocarbon and fluorocarbon low molar mass compounds by the lipophilic and fluorophilic block, respectively, is demonstrated. Y1 - 2011 U6 - https://doi.org/10.1021/ma200032j SN - 0024-9297 VL - 44 IS - 7 SP - 2092 EP - 2105 PB - American Chemical Society CY - Washington ER -