Redox Approaches to Carbene Generation in Catalytic Cyclopropanation Reactions
Mingxin Liu1, Christopher Uyeda1
1Department of Chemistry, Purdue University, 560 Oval Dr., West Lafayette, IN 47907, USA.
Angewandte Chemie (International Ed. in English)
|May 16, 2024
Summary
This review explores new catalytic methods for synthesizing cyclopropanes using transition metal-catalyzed carbene transfer reactions. Emerging strategies utilize gem-dihaloalkanes, carbonyl compounds, or direct methylene dehydrogenation for broader carbene precursor scope.
Area of Science:
- Organic Chemistry
- Catalysis
- Synthetic Methodology
Background:
- Transition metal-catalyzed carbene transfer reactions are vital for cyclopropane synthesis.
- Traditional methods using diazo compounds have limitations in carbene scope, especially for unstabilized carbenes.
- Expanding precursor options is crucial for advancing cyclopropanation chemistry.
Purpose of the Study:
- To review emerging catalytic reductive cyclopropanation reactions.
- To discuss novel carbene transfer strategies beyond traditional diazo precursors.
- To highlight recent advancements in generating carbenes from alternative sources.
Main Methods:
- Discussion of catalytic reductive cyclopropanation using gem-dihaloalkanes and carbonyl compounds.
- Exploration of transition metal carbene/carbenoid formation inspired by stoichiometric reactions (e.g., Simmons-Smith, Clemmensen).
- Presentation of methods for direct carbene generation from methylene groups via dehydrogenation.
Main Results:
- Emerging catalytic reductive cyclopropanation expands the scope of carbene precursors.
- Novel strategies enable carbene transfer from gem-dihaloalkanes and carbonyl compounds.
- Direct generation of carbenes from methylene groups is feasible for specific substrates.
Conclusions:
- Catalytic reductive cyclopropanation offers a powerful alternative to traditional carbene transfer methods.
- New approaches broaden the accessibility of diverse cyclopropane structures.
- Future work may focus on expanding the substrate scope for direct methylene functionalization.
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