Synthesis 2023; 55(10): 1602-1612
DOI: 10.1055/a-2009-8114
paper

Silylium Ion Initiated Intramolecular Friedel–Crafts-Type Cyclization of 1,1-Difluoroalkenes with Subsequent Hydrodefluorination of C(sp3)–F Bonds

Avijit Roy
,
Haopeng Gao
,
,
A.R. and H.G. thank the Berlin Graduate School of Natural Sciences and Engineering for predoctoral fellowships (2018–2021 and 2020–2023, respectively). Generous funding by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) under Germany’s Excellence Strategy (EXC 2008/1 – 390540038, UniSysCat) is gratefully acknowledged. M.O. is indebted to the Einstein Foundation Berlin for an endowed professorship.


Abstract

The strong electrophilicity of silylium ions has been leveraged to probe an intramolecular Friedel–Crafts-type cyclization of aryl-tethered 1,1-difluoroalkenes. The reaction is presumed to be initiated by a preferential electrophilic silylation of the carbon–carbon double bond over the activation of one of the vinylic C(sp2)–F bonds. Subsequent cyclization followed by hydrodefluorination of the resulting C(sp3)–F bonds leads to the final product. The resulting tetraline derivatives were obtained in moderate to good yields. Distinct from earlier reports, the reaction proceeds with the perfluorinated tetraphenylborate counteranion under ambient conditions without the prerequisite of a carborate counteranion associated with the silylium ion intermediates.

Supporting Information



Publikationsverlauf

Eingereicht: 21. Dezember 2022

Angenommen nach Revision: 09. Januar 2023

Accepted Manuscript online:
09. Januar 2023

Artikel online veröffentlicht:
08. Februar 2023

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