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Single-electron transmetalation: an enabling technology for secondary alkylboron cross-coupling
David N Primer1, Idris Karakaya, John C Tellis
1Roy and Diana Vagelos Laboratories, Department of Chemistry, University of Pennsylvania , Philadelphia, Pennsylvania 19104-6323, United States.
Journal of the American Chemical Society
|February 5, 2015
Summary
A new single-electron transfer mechanism enables mild cross-coupling reactions. This method efficiently links secondary alkyl groups to aryl halides using iridium and nickel catalysts.
Area of Science:
- Organic Chemistry
- Catalysis
- Synthetic Methodology
Background:
- Transmetalation is crucial for cross-coupling reactions.
- Traditional methods often require harsh conditions or specific substrates.
- Developing milder, more general cross-coupling protocols is an ongoing challenge.
Purpose of the Study:
- To introduce a novel single-electron-mediated alkyl transfer mechanism.
- To establish general conditions for cross-coupling secondary alkyl groups with aryl halides.
- To demonstrate the utility of photoredox and nickel catalysis in this transformation.
Main Methods:
- Utilizing an iridium photoredox catalyst in conjunction with a nickel cross-coupling catalyst.
- Employing secondary alkyltrifluoroborates as alkylating agents.
- Reacting with a diverse range of aryl bromides under mild conditions.
Main Results:
- Successful cross-coupling of secondary alkyltrifluoroborates with various aryl bromides.
- Demonstration of a novel single-electron transfer pathway for transmetalation.
- Achieved cross-coupling under mild, broadly applicable conditions.
Conclusions:
- Single-electron-mediated alkyl transfer provides an efficient new route for cross-coupling.
- The developed method offers a mild and general approach for C(sp3)-C(sp2) bond formation.
- This work expands the scope of catalytic cross-coupling reactions.
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