Synthesis and Crystal Structure of a Silyl-Stabilized Allyl Cation Formed by Disruption of an Arene by a Protonation–Hydrosilylation Sequence


  • We thank the Swiss and US National Science Foundation for research support.


Sly silyl caught in the act: Protonation of a mesitylene ring by the strongly acidic arenium carborane [CH3C6H6]- [CHB11Me5Br6] initiates a cascade reaction that results in a stable β-silyl allyl cation (see picture, H yellow, C blue, silyl allyl group red). Remarkably, the driving force in the reaction suffices to disrupt a stable aromatic ring in favor of a cationic reactive intermediate.

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