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Hindered Brønsted bases as Lewis base catalysts
Sobia Tabassum1, Oksana Sereda, Peddiahgari Vasu Govardhana Reddy
1Institute of Organic Chemistry, Clausthal University of Technology, Leibnizstr. 6, 38678 Clausthal-Zellerfeld, Germany.
Organic & Biomolecular Chemistry
|September 19, 2009
Summary
Potassium bis(trimethylsilyl)amide (KHMDS) and potassium tert-butoxide (KOtBu), known strong bases, are now proven highly active Lewis base catalysts. They effectively catalyze the [2+2] cycloaddition reactions of ketenes with aldehydes and imines.
Area of Science:
- Organic Chemistry
- Catalysis
- Reaction Mechanisms
Background:
- Potassium bis(trimethylsilyl)amide (KHMDS) and potassium tert-butoxide (KOtBu) are recognized as potent, sterically hindered, non-nucleophilic Brønsted bases.
- Their catalytic applications have primarily focused on their Brønsted basicity.
Purpose of the Study:
- To explore and demonstrate the utility of KHMDS and KOtBu as Lewis base catalysts.
- To investigate their efficacy in catalyzing the formal [2+2] cycloaddition of ketenes with aldehydes and imines.
Main Methods:
- Utilizing KHMDS and KOtBu as catalysts in the presence of ketenes, aldehydes, and imines.
- Characterization of reaction products to confirm cycloaddition pathways.
Main Results:
- KHMDS and KOtBu exhibit high catalytic activity in the formal [2+2] cycloaddition reactions.
- Successful cycloaddition of ketenes with both aldehydes and imines was achieved under catalysis by these bases.
Conclusions:
- KHMDS and KOtBu function as effective Lewis base catalysts, expanding their known reactivity profile.
- This work establishes a novel catalytic application for these commonly used strong bases in cycloaddition chemistry.
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