Beilstein J Org Chem. 2017 Aug 24;13:1781-1787. doi: 10.3762/bjoc.13.172. eCollection 2017.

Conformational impact of structural modifications in 2-fluorocyclohexanone.

Beilstein journal of organic chemistry

Francisco A Martins, Josué M Silla, Matheus P Freitas

PMID: 28904621 PMCID: PMC5588668 DOI: 10.3762/bjoc.13.172

Abstract

2-Haloketones are building blocks that combine physical, chemical and biological features of materials and bioactive compounds, while organic fluorine plays a fundamental role in the design of performance organic molecules. Since these features are dependent on the three-dimensional chemical structure of a molecule, simple structural modifications can affect its conformational stability and, consequently, the corresponding physicochemical/biological property of interest. In this work, structural changes in 2-fluorocyclohexanone were theoretically studied with the aim at finding intramolecular interactions that induce the conformational equilibrium towards the axial or equatorial conformer. The interactions evaluated were hydrogen bonding, hyperconjugation, electrostatic and steric effects. While the gauche effect, originated from hyperconjugative interactions, does not appear to cause some preferences for the axial conformation of organofluorine heterocycles, more classical effects indeed rule the conformational equilibrium of the compounds. Spectroscopic parameters (NMR chemical shifts and coupling constants), which can be useful to determine the stereochemistry and the interactions operating in the series of 2-fluorocyclohexanone derivatives, were also calculated.

Keywords: 2-fluorocyclohexanone; classical effects; conformational analysis; hyperconjugation

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