Gorgas, N., Stadler, B., White, A. J. P., & Crimmin, M. (2024). Vinylic C-H activation of styrenes by an iron-aluminum complex. Journal of the American Chemical Society, 146(6), 4252–4259. https://doi.org/10.1021/jacs.3c14281
E163-01-1 - Forschungsgruppe Organometallische Chemie und Katalyse
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Journal:
Journal of the American Chemical Society
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ISSN:
0002-7863
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Date (published):
14-Feb-2024
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Number of Pages:
8
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Publisher:
AMER CHEMICAL SOC
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Peer reviewed:
Yes
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Keywords:
Iron; C-H Activation; Aluminium
en
Abstract:
The oxidative addition of sp2 C-H bonds of alkenes to single-site transition-metal complexes is complicated by the competing π-coordination of the C═C double bond, limiting the examples of this type of reactivity and onward applications. Here, we report the C-H activation of styrenes by a well-defined bimetallic Fe-Al complex. These reactions are highly selective, resulting in the (E)-β-metalation of the alkene. For this bimetallic system, alkene binding appears to be essential for the reaction to occur. Experimental and computational insights suggest an unusual reaction pathway in which a (2 + 2) cycloaddition intermediate is directly converted into the hydrido vinyl product via an intramolecular sp2 C-H bond activation across the two metals. The key C-H cleavage step proceeds through a highly asynchronous transition state near the boundary between a concerted and a stepwise mechanism influenced by the resonance stabilization ability of the aryl substituent. The metalated alkenes can be further functionalized, which has been demonstrated by the (E)-selective phosphination of the employed styrenes.