Berylloles and Alumoles: Highly Unsaturated Antiaromatics at the Frontiers of Metallacyclopentadiene Chemistry
Final Report Abstract
Alumoles and berylloles are compounds containing rings of four carbon atoms and one aluminum or beryllium atom, respectively. In their simplest form, these rings contain four π electrons, making them "antiaromatic". In stark contrast to the well-known, stabilizing phenomenon known as "aromaticity", "antiaromaticity" destabilizes molecules and usually makes them highly reactive. These two families of compounds are poorly understood: little published work exists on alumoles, and berylloles were only introduced by our group shortly before this project began. Our aim in this project was to expand the scope of structures available for both families of molecule, as well as to explore their reactivity. Over the course of the project we have expanded these families of compounds in a number of ways, developing routes to examples with varied backbones, including bicyclic and tricyclic examples, and compounds with a range of exocyclic substituents and donor ligands. Initial reactivity profiles have been developed for all of these variations, uncovering a range of novel reactivity patterns and products, notably including the synthesis of larger heterocyclic species with multiple heteroatoms (rings with up to ten atoms and including up to five heteroatoms), and the second confirmed compound containing an olefin π-bound to a beryllium atom. Overall, the work has opened up a number of new molecular platforms that will form the basis of future synthetic work in our group and also likely other groups. This work has already formed the basis of five research articles, all of which were published in top general chemistry journals (e.g. Chemical Science, ChemComm) or high-quality specialist journals, with one manuscript in preparation, and a number of further publications predicted as ongoing work is completed.
Publications
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Synthesis of novel six-, seven- and eight-membered aluminum-containing rings by alumole ring expansion. Chemical Communications, 57(61), 7505-7508.
Drescher, Regina; Ritschel, Benedikt; Dewhurst, Rian D.; Deißenberger, Andrea; Hofmann, Alexander & Braunschweig, Holger
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Synthesis, structure and insertion reactivity of Lewis acidic 9-aluminafluorenes. Dalton Transactions, 50(30), 10400-10404.
Drescher, Regina; Wüst, Leonie; Mihm, Cornelius; Krummenacher, Ivo; Hofmann, Alexander; Goettel, James & Braunschweig, Holger
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Boroles from alumoles: accessing boroles with alkyl-substituted backbones via transtrielation. Chemical Science, 14(34), 9010-9015.
Bohlen, Josina L.; Endres, Lukas; Drescher, Regina; Radacki, Krzysztof; Dietz, Maximilian; Krummenacher, Ivo & Braunschweig, Holger
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Dibenzoberylloles: antiaromatic s-block fluorene analogues. Chemical Communications, 59(60), 9199-9202.
Tröster, Tobias; Endres, Franziska; Arrowsmith, Merle; Endres, Lukas; Fantuzzi, Felipe & Braunschweig, Holger
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Synthesis, Structural Characterization, and Bonding of Molecular Heavier Beryllium Chalcogenides. Chemistry – A European Journal, 29(44).
Czernetzki, Corinna; Tröster, Tobias; Endres, Lukas; Endres, Franziska; Arrowsmith, Merle; Gärtner, Annalena; Fantuzzi, Felipe & Braunschweig, Holger
