Conformational rivalry of geminal substituents in silacyclohexane derivatives: 1-Phenyl vs. 1-OR, R=H or Me
| Autor: | E. N. Suslova, Bagrat A. Shainyan, Tran Dinh Phien, Liubov E. Kuzmina, Sergey A. Shlykov |
|---|---|
| Rok vydání: | 2019 |
| Předmět: |
Geminal
010405 organic chemistry Chemistry Gas electron diffraction Organic Chemistry Substituent 010402 general chemistry Mass spectrometry Ring (chemistry) 01 natural sciences Biochemistry 0104 chemical sciences Crystallography chemistry.chemical_compound Drug Discovery Atom Molecule Conformational isomerism |
| Zdroj: | Tetrahedron. 75:3038-3045 |
| ISSN: | 0040-4020 |
| DOI: | 10.1016/j.tet.2019.04.044 |
| Popis: | Molecular structure and conformational equilibria of 1-methoxy- 1 and 1-hydroxy-1-phenylsilacyclohexanes 2 were studied by quantum chemical (QC) calculations and combined gas electron diffraction/mass spectrometry (GED/MS). Both molecules may exist in 5 or 6 forms, differing from each other by the substituents' position: (i) axial or equatorial and (ii) rotational orientation relative to the six-membered ring frame. The contribution of axial forms of both compounds varies from 35 to 60% depending on the theoretical method applied. From the GED data, the summarized molar fractions of the conformers were found to be Phax:Pheq = 70(15):30(20) and 50(20):50(20)% which corresponds to ΔG = Gax–Geq = −0.55(46) and 0.00(56) kcal/mol, for compound 1 and 2, respectively. The concentration of the Phax forms of 1-phenyl-1-(X)-silacyclohexanes (X = H, HO, Me, MeO and Me2N) increases with the size of the second substituent at the silicon atom: 38(10) |
| Databáze: | OpenAIRE |
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