TY  - JOUR
A1  - Kirpichenko, Svetlana
A1  - Shainyan, Bagrat A.
A1  - Kleinpeter, Erich
A1  - Shlykov, Sergey A.
A1  - Tran Dinh Phien, 
A1  - Albanov, Alexander
T1  - Synthesis of 3-fluoro-3-methyl-3-silatetrahydropyran and its conformational preferences in gas and solution by GED, NMR and theoretical calculations
JF  - Tetrahedron
N2  - The 3,3-disubstitued 3-silaheterocyclohexane with an electronegative substituent at silicon, 3-fluoro-3-methyl-3-silatetrahydropyran 1, was synthesized, and its molecular structure and conformational properties studied by gas-phase electron diffraction (GED) and low temperature C-13 and F-19 NMR spectroscopy. Quantum-chemical calculations were carried out both for the isolated species and Hcomplexes in gas and in polar medium. The predominance of the 1-FeqMeax conformer (1-F-eq:1-F-ax ratio of 65:35, Delta G degrees = 0.37 kcal/mol) determined from GED is close to the theoretically estimated conformational equilibrium, especially at the DFT level. In solution, low temperature NMR spectroscopy showed no decoalescence of the signals in C-13 (down to 95 K) and F-19 NMR spectra (down to 123 K). However, the calculated F-19 chemical shift of -173.6 ppm for the 1-FeqMeax conformer practically coincides with the experimentally observed value (-173 to -175 ppm) as distinct from that for the 1-FaxMeeq conformer (-188.8 ppm), suggesting compound 1 to be anancomeric in solution, in compliance with its theoretical and experimental preference in the gas phase.
KW  - 3-Fluoro-3-methyl-3-silatetrahydropyran
KW  - Conformational analysis
KW  - Gas phase electron diffraction
KW  - Low-temperature NMR
KW  - DFT
KW  - MP2 and CCSD(T) calculations
Y1  - 2018
U6  - https://doi.org/10.1016/j.tet.2018.02.055
SN  - 0040-4020
VL  - 74
IS  - 15
SP  - 1859
EP  - 1867
PB  - Elsevier
CY  - Oxford
ER  -