Simultaneous gauche and anomeric effects in α-substituted sulfoxides
1Department of Chemistry, Federal University of Lavras, 37200-000 Lavras, MG, Brazil. matheus@dqi.ufla.br
The Journal of Organic Chemistry
|August 11, 2012
Summary
α-Substituted sulfoxides exhibit gauche and anomeric effects. Fluorine-19 NMR coupling constants in α-fluoro sulfoxides are not solely dependent on dipolar interactions, limiting their use in conformational analysis.
Area of Science:
- Organic Chemistry
- Computational Chemistry
Background:
- α-Substituted sulfoxides possess structural features enabling gauche and anomeric effects.
- These effects are crucial for understanding molecular conformations and reactivity.
Purpose of the Study:
- To investigate the influence of gauche and anomeric effects on α-substituted sulfoxides.
- To evaluate the utility of fluorine-19 NMR coupling constants for probing conformations in α-fluoro sulfoxides.
Main Methods:
- Computational calculations were performed to analyze the electronic and geometric requirements for hyperconjugative effects.
- Nuclear Magnetic Resonance (NMR) spectroscopy, specifically (1)J(CF) coupling, was used to study the rotational dependence in (fluoromethyl)methyl sulfoxide.
Main Results:
- Calculations confirmed the presence of gauche and anomeric effects in 1,3-oxathiane 3-oxide and the gauche effect in 2-fluorothiane 1-oxide.
- (1)J(CF) coupling in (fluoromethyl)methyl sulfoxide showed a nonmonotonic dependence on the dihedral angle, indicating factors beyond dipolar interactions or hyperconjugation.
- The (1)J(CF) rotational profile was found to be of limited diagnostic value for determining α-fluoro sulfoxide conformations.
Conclusions:
- The study elucidates the interplay of electronic and steric effects in α-substituted sulfoxides.
- Fluorine-19 NMR coupling constants are not exclusively governed by dipolar interactions or hyperconjugation in these systems.
- The conformational analysis of α-fluoro sulfoxides using (1)J(CF) is limited due to its complex rotational behavior.
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