TY  - JOUR
A1  - Shainyan, Bagrat A.
A1  - Kirpichenko, Svetlana V.
A1  - Kleinpeter, Erich
T1  - Stereochemistry of 3-isopropoxy-3-methyl-1,3-oxasilinane-the first 3-silatetrahydropyran with an exo-cyclic RO-Si bond
JF  - Tetrahedron
N2  - Molecular structure and conformational behavior of 3-isopropoxy-3-methyl-3-oxasilinane is studied by low temperature C-13 NMR spectroscopy and theoretical calculations (DFT, MP2). Two conformers, 1-ROax and 1-ROeq, were found experimentally and located on the potential energy surface. LT C-13 NMR spectroscopy gives almost equal population of the two conformers at 98 K with Delta G(98K)degrees=0.02 kcal/mol in favor of 1-ROax and Delta G(98K)(#)=4.5 kcal/mol. The corresponding DFT calculated values (Delta G(98K)degrees=0.03 kcal/mol, Delta G(98K)(#)=5.1 kcal/mol) are in excellent agreement with the experiment. Detailed DFT and MP2 calculations of the solvent effect on the conformational equilibrium were performed and highlighted the leveling out of the two conformers when transferred from gas to solution. (C) 2015 Published by Elsevier Ltd.
KW  - 1,3-Oxasilinanes
KW  - Conformational equilibrium
KW  - Barrier to ring inversion
KW  - Solvent effects
KW  - Assignment of stereochemistry
Y1  - 2015
U6  - https://doi.org/10.1016/j.tet.2015.07.047
SN  - 0040-4020
VL  - 71
IS  - 38
SP  - 6720
EP  - 6726
PB  - Elsevier
CY  - Oxford
ER  - 
TY  - JOUR
A1  - Shainyan, Bagrat A.
A1  - Moskalik, Mikhail Yu
A1  - Heydenreich, Matthias
A1  - Kleinpeter, Erich
T1  - Conformational equilibrium and dynamic behavior of bis-N-triflyl substituted 3,8-diazabicyclo[3.2.1]octane
JF  - Magnetic resonance in chemistry
N2  - Restricted rotation about the N-S partial double bonds in a bis-N-triflyl substituted 3,8-diazabicyclo[3.2.1]octane derivative 1 has been frozen at low temperature (Delta G* = 11.6 kcal mol(-1)), and the existence of all four rotamers about the two N-S bonds, 3-in, 8-in, 3-in, 8-out, 3-out, 8-in, and 3-out, 8-out, respectively, proved experimentally by NMR spectroscopy and theoretically by DFT and MP2 calculations. Copyright (C) 2014 John Wiley & Sons, Ltd.
KW  - NMR
KW  - H-1
KW  - C-13
KW  - F-19
KW  - Dynamic NMR
KW  - Conformational equilibrium
KW  - restricted N-S rotation
Y1  - 2014
U6  - https://doi.org/10.1002/mrc.4086
SN  - 0749-1581
SN  - 1097-458X
VL  - 52
IS  - 8
SP  - 448
EP  - 452
PB  - Wiley-Blackwell
CY  - Hoboken
ER  - 
TY  - JOUR
A1  - Shainyan, Bagrat A.
A1  - Kleinpeter, Erich
T1  - Silacyclohexanes and silaheterocyclohexanes-why are they so different from other heterocyclohexanes?
JF  - Tetrahedron
N2  - Stereochemical studies on silaheterocyclohexanes is a 'hot topic' as evidenced by the growing number of publications. During last 10 years a substantial number of substituted silacyclohexanes and heterocyclohexanes containing sulfur, oxygen or nitrogen as the second (or third) heteroatom have been synthesized and studied by variable temperature dynamic NMR spectroscopy, gas-phase electron diffraction, variable temperature IR, Raman, microwave spectroscopy with respect to thermodynamic (frozen conformational equilibria) and kinetic (barrier to ring inversion) information. As the stereochemistry of cyclohexane and its N-, O-, P-, S-hetero analogues is one of keystones of modern theoretical and synthetic organic and heterocyclic chemistry, the stereochemistry of silacyclohexane and its hetero analogs is an important element of theoretical and synthetic organosilicon chemistry. The various classes of saturated six-membered rings were critically compared and studied in detail with respect to differences in their stereochemistry and dynamic behavior.
KW  - Silacyclohexanes
KW  - Silaheterocyclohexanes
KW  - Conformational equilibrium
KW  - Barrier to ring inversion
KW  - Steric effects
KW  - Electrostatic effects
Y1  - 2013
U6  - https://doi.org/10.1016/j.tet.2013.04.126
SN  - 0040-4020
VL  - 69
IS  - 29
SP  - 5927
EP  - 5936
PB  - Elsevier
CY  - Oxford
ER  -