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The electron is a catalyst

Nature Chemistry volume 6, pages 765–773 (2014)Cite this article

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Abstract

The electron is an efficient catalyst for conducting various types of radical cascade reaction that proceed by way of radical and radical ion intermediates. But because electrons are omnipresent, catalysis by electrons often passes unnoticed. In this Review, a simple analogy between acid/base catalysis and redox catalysis is presented. Conceptually, the electron is a catalyst in much the same way that a proton is a catalyst. The 'electron is a catalyst' paradigm unifies mechanistically an assortment of synthetic transformations that otherwise have little or no apparent relationship. Diverse radical cascades, including unimolecular radical substitution reactions (SRN1-type chemistry), base-promoted homolytic aromatic substitutions (BHAS), radical Heck-type reactions, radical cross-dehydrogenative couplings (CDC), direct arene trifluoromethylations and radical alkoxycarbonylations, can all be viewed as electron-catalysed reactions.

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Figure 1: A simple mechanistic analogy between base catalysis and hole catalysis.
Figure 2: A simple mechanistic analogy between acid catalysis and electron catalysis.
Figure 3: C–C and C–N bond formations by SRN1 type reactions.
Figure 4: Base-promoted homolytic aromatic substitution (BHAS) reactions.
Figure 5: Transition-metal-free Heck-type arylations.
Figure 6: Cross-dehydrogenative coupling reactions.
Figure 7: Trifluoromethylarene synthesis by base-promoted homolytic aromatic substitution.
Figure 8: Alkoxycarbonylation of aryl halides.

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Acknowledgements

D.P.C. thanks the NIH and NSF for funding. A.S. thanks the Deutsche Forschungsgemeinschaft and the programme 'Sustainable Chemical Synthesis (SusChemSysc)' which is co-financed by the European Regional Development Fund (ERDF) and the state of North Rhine-Westphalia, Germany, under the Operational Programme 'Regional Competitiveness and Employment' 2007–2013.

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  1. Organisch-Chemisches Institut, Westfälische Wilhelms-Universität, Corrensstrasse 40, Münster, 48149, Germany

    Armido Studer

  2. Department of Chemistry, University of Pittsburgh, Pittsburgh, 15260, Pennsylvania, USA

    Dennis P. Curran

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Correspondence to Armido Studer or Dennis P. Curran.

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Studer, A., Curran, D. The electron is a catalyst. Nature Chem 6, 765–773 (2014). https://doi.org/10.1038/nchem.2031

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