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Catalytic metal-free Si-N cross-dehydrocoupling
Lutz Greb1, Sergej Tamke, Jan Paradies
1Institute for Organic Chemistry, Karlsruhe Institute of Technology (KIT), Fritz-Haber-Weg 6, D-76131 Karlsruhe, Germany. jan.paradies@kit.edu.
Chemical Communications (Cambridge, England)
|January 22, 2014
Summary
Metal-free boron catalysis enables efficient dehydrocoupling of hydrosilanes with nitrogen-containing compounds like anilines and indoles. This reaction yields valuable silylated products with high selectivity, offering a green synthetic route.
Area of Science:
- Organometallic Chemistry
- Catalysis
- Synthetic Organic Chemistry
Background:
- Metal-free catalysis is gaining traction as a sustainable alternative in organic synthesis.
- Boron-based Lewis acids offer unique reactivity profiles for various transformations.
- Efficient methods for forming silicon-nitrogen (Si-N) bonds are crucial for synthesizing diverse organic molecules.
Purpose of the Study:
- To report a novel metal-free catalytic system for the dehydrocoupling of hydrosilanes with N-H containing compounds.
- To investigate the scope and limitations of this catalytic system with anilines, carbazoles, and indoles.
- To elucidate the mechanism of the observed Si-N coupling and subsequent transformations.
Main Methods:
- Utilizing tris(pentafluorophenyl)borane (B(C6F5)3) as a metal-free catalyst.
- Reacting various hydrosilanes with anilines, carbazoles, and indoles under optimized conditions.
- Analyzing reaction products using standard spectroscopic techniques (NMR, Mass Spectrometry).
- Proposing a reaction mechanism based on experimental observations.
Main Results:
- Successful dehydrocoupling of hydrosilanes with anilines and carbazoles, liberating H2 as the sole byproduct.
- Formation of N-silyl indolines from indoles and diphenyl(methyl)hydrosilane with high diastereoselectivity (10:1 d.r.) and excellent yields.
- Demonstration of the catalytic activity of B(C6F5)3 in Si-N bond formation.
Conclusions:
- Tris(pentafluorophenyl)borane is an effective metal-free catalyst for Si-N bond formation.
- The developed method offers a selective and efficient route to silylated anilines, carbazoles, and particularly N-silyl indolines.
- The proposed mechanism provides insights into the Si-N coupling and hydrogenation sequence.
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