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08:12
A Two-Step Protocol for Umpolung Functionalization of Ketones Via Enolonium Species
Published on: August 16, 2018
From cationic to anionic helicenes: new reactivity through umpolung
David Conreaux1, Nathalie Mehanna, Christelle Herse
1Department of Organic Chemistry, University of Geneva, 30 Quai Ernest Ansermet, CH-1211 Geneva 4, Switzerland.
The Journal of Organic Chemistry
|March 23, 2011
Summary
Highly stable chiral carbenium ions are converted into reactive carbanions using a novel two-step reduction/metalation method. This process enables umpolung reactions, yielding polar ketone and thioamide products while preserving helical backbone configuration.
Area of Science:
- Organic Chemistry
- Stereochemistry
Background:
- Chiral carbenium ions are typically electrophilic.
- Generating nucleophilic species from stable carbocations is challenging.
Purpose of the Study:
- To develop a method for transforming stable chiral carbenium ions into reactive carbanion intermediates.
- To achieve umpolung reactivity with retention of stereochemical configuration.
Main Methods:
- A two-step reduction/metalation sequence was employed.
- The reaction was applied to highly stable chiral carbenium ions.
Main Results:
- Reactive carbanion intermediates were successfully generated.
- Umpolung was achieved, leading to the formation of polar ketone and thioamide products.
- Complete retention of the helical backbone's configuration was observed.
Conclusions:
- The developed method provides a novel route to carbanions from carbenium ions.
- This strategy allows for umpolung reactivity with excellent stereochemical control.
- The findings have implications for the synthesis of complex chiral molecules.
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