Dynamic-dependent selectivity in a bisphosphine iron spin crossover C–H insertion/π-coordination reaction

Davenport, Michael T.; Kirkland, Justin K.; Ess, Daniel H.

doi:10.1039/d3sc02078a

Cited by 1 publication

(1 citation statement)

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“…They found that π-complexation of the alkene is thermodynamically favored with respect to the oxidative addition of vinylic sp 2 C–H bonds. Moreover, the π-complex was found to be not an intermediate in the lowest energy C–H activation process. , Computational studies support the conclusions and suggest that π-coordination and C–H activation of the alkene are separate and competitive pathways. − …”

Section: Introductionmentioning

confidence: 99%

Vinylic C–H Activation of Styrenes by an Iron–Aluminum Complex

Gorgas,

Stadler,

White

et al. 2024

J. Am. Chem. Soc.

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The oxidative addition of sp 2 C−H bonds of alkenes to single-site transition-metal complexes is complicated by the competing πcoordination 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 sp 2 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.

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