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Stereoelectronic effects in vinyl sulfoxides
Roland Ulshöfer1, Joachim Podlech
1Karlsruher Institut für Technologie, Fritz-Haber-Weg 6, 76131 Karlsruhe, Germany.
Journal of the American Chemical Society
|November 6, 2009
Summary
Vinyl sulfoxides exhibit unique electronic stabilization through orbital alignment, affecting UV absorbance and nucleophilic attack stereoselectivity. This study quantifies these differences in vinyl sulfoxide reactions.
Area of Science:
- Organic Chemistry
- Spectroscopy
- Reaction Mechanisms
Background:
- Vinyl sulfoxides share similarities with alpha,beta-unsaturated carbonyl compounds but possess distinct stabilization mechanisms.
- The electronic interaction between the C=C double bond and the S=O bond is crucial for vinyl sulfoxide properties.
Purpose of the Study:
- To investigate the electronic interactions and conformational effects on vinyl sulfoxides.
- To elucidate the impact of S=O bond orientation on UV-Vis spectroscopy and nucleophilic addition reactions.
Main Methods:
- Comparative analysis of UV-Vis spectra for conformationally constrained and flexible vinyl sulfoxides.
- Stereochemical analysis of nucleophilic attack on vinyl sulfoxides with varying S=O bond orientations.
- Kinetic studies using competition experiments to determine reaction rates.
Main Results:
- Maximum UV absorbance wavelengths are higher (2-14 nm) when the S=O bond is collinear with the C=C p orbitals.
- Nucleophilic attack is favored when the developing lone pair is anti to the S=O bond, influencing stereoselectivity.
- Differing reaction rates were observed for differently configured vinyl sulfoxides, quantified via competition experiments.
Conclusions:
- The orientation of the S=O bond significantly impacts the electronic properties and reactivity of vinyl sulfoxides.
- Orbital alignment dictates stabilization, affecting spectroscopic properties and reaction pathways.
- Understanding these principles is key to controlling stereoselectivity and reaction rates in vinyl sulfoxide chemistry.
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