Abstract
We report counter‐intuitive axial preferences in non‐stereochemically biased, selectively fluorinated methoxycyclohexanes. These pseudo‐anomeric effects are apparent when electronegative CF2 groups are placed at the C‐2, C‐4 and C‐6 positions of the cyclohexane ring to render the C‐3/5 axial hydrogen atoms electropositive. The electrostatic interaction between these axial hydrogen atoms and the ‐OMe oxygen is stabilising. The effect is explored using high‐level ab initio and DFT calculations in the framework of NBO, QTAIM and NCI analysis across a range of derivatives, and experimentally (19F{1H}‐NMR at −80 °C) for some illustrative examples. The effect is significant in energy terms for a weak interaction, and illustrates a new stereoelectronic aspect attributed to selective fluorine substitution in organic chemistry.
Original language | English |
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Pages (from-to) | 11989-11994 |
Number of pages | 7 |
Journal | Chemistry - A European Journal |
Volume | 26 |
Issue number | 52 |
Early online date | 18 Aug 2020 |
DOIs | |
Publication status | Published - 16 Sept 2020 |
Keywords
- Organofluorine
- Anomeric effect
- Conformational analysis
- Stereoelectronic effects
- Computational chemistry