3-Trimethylsilylcyclobutylidene. The γ-effect of silicon on carbenes.

doi:10.1021/ja400747u

Paper

3-Trimethylsilylcyclobutylidene. The γ-effect of silicon on carbenes.

Published Apr 16, 2013 · X. Creary

Journal of the American Chemical Society

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Abstract

3-Trimethylsilylcyclobutylidene was generated by pyrolysis of the sodium salt of the tosylhydrazone derivative of 3-trimethylsilylcyclobutanone. This carbene converts to 1-trimethylsilylbicyclobutane as the major product. A labeling study shows that this intramolecular rearrangement product comes from 1,3-hydrogen migration to the carbenic center and not 1,3-silyl migration. Computational studies show two carbene minimum energy conformations, with the lower energy conformation displaying a large stabilizing interaction of the carbene center with the rear lobe of the C3-Si bond. In this conformation, the trimethylsilyl group cannot migrate to the carbene center, and the most favorable process is 1,3-hydrogen migration. When the carbene is generated photochemically in methanol, it reacts by a protonation mechanism giving the highly stabilized 3-trimethylsilylcyclobutyl carbocation as an intermediate. When generated in dimethylamine as solvent, the carbene undergoes preferred attack of this nucleophilic solvent from the back of this C-Si rear lobe stabilized carbene.

Study Snapshot

3-Trimethylsilylcyclobutylidene exhibits the -effect of silicon on carbenes, with the lower energy conformation stabilizing the carbene center and preventing 1,3-hydrogen migration.

PopulationOlder adults (50-71 years)

Sample size24

MethodsObservational

OutcomesBody Mass Index projections

ResultsSocial networks mitigate obesity in older groups.

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3-Trimethylsilylcyclobutylidene. The γ-effect of silicon on carbenes.

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References

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Citations

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