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Opportunities with calcium Grignard reagents and other heavy alkaline-earth organometallics

Nature Reviews Chemistry volume 7, pages 843–853 (2023)Cite this article

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Abstract

More than a century old, magnesium Grignard reagents remain essential to the toolbox of organic chemists. Although similar reagents with the neighbouring group 2 metal Ca have been explored, the considerably higher polarity and reactivity of the Ca–C bond result in undesired decomposition pathways. Ca Grignard reagents have found academic interest but have never fully developed into an established synthetic tool. Recent research activities, however, provide facile access to these highly reactive organocalcium species, including in situ preparation and ball milling approaches to tackle the challenge of controlling their extreme sensitivity. Heavier Grignard reagents are not just more reactive but profit from unique chemical transformations. Insight into the transition metal-like properties of Ca, Sr and Ba is only just emerging. Considering the rapidly developing field of alkaline-earth metal-mediated catalysis, heavy Grignard reagents will probably have a bright future.

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Fig. 1: Ether cleavage.
Fig. 2: Syntheses and structures of Ca Grignard reagents.
Fig. 3: Synthesis of Ca reagents and the Barbier reaction.
Fig. 4: Syntheses and reactivity of low-valent Mg complexes and Grignard reagents.
Fig. 5: Activation of π systems by Ae2+ metal cations.
Fig. 6: Experimental observations hinting to d-orbital participation in heavier Ae metal chemistry.

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Acknowledgements

The Friedrich-Alexander University Erlangen-Nürnberg is acknowledged for support.

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  1. Inorganic Chemistry, Friedrich-Alexander Universität Erlangen-Nürnberg, Erlangen, Germany

    Sjoerd Harder & Jens Langer

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Both authors researched data for the article, contributed substantially to the discussion of the content and reviewed and/or edited the manuscript before submission. S.H. wrote the article.

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Harder, S., Langer, J. Opportunities with calcium Grignard reagents and other heavy alkaline-earth organometallics. Nat Rev Chem 7, 843–853 (2023). https://doi.org/10.1038/s41570-023-00548-0

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