Aryne-mediated fluorination: Synthesis of fluorinated biaryls via a sequential desilylation–halide elimination–fluoride addition process

An unusual aryne-mediated fluorination of aromatic ring systems during the desilylation of ortho-bromo-biphenyl-trimethylsilanes with tetrabutylammonium fluoride (TBAF) is described. In situ formation of an aryne and addition of fluoride affords fluorinated biphenyls. The structures have been undoubtfully confirmed by synthesis of authentic samples via Suzuki–Miyaura cross-coupling and X-ray analysis. In situ trapping experiments with furan proved the transient formation of aryne by fluoride-induced displacement of the TMS group and subsequent bromide elimination.

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► In this study we describe an aryne-mediated carbon–fluorine bond formation.
► (o-Bromobiphenyl-3-yl)trimethylsilanes afford with TBAF fluorinated biphenyls.
► X-ray structure determination confirmed the regioselectivity of the reaction.
► We examined the reaction in presence of furan. Formation of the Diels–Alder cycloadduct undoubtfully proved the intermediate formation of arynes.