Synthesis 2024; 56(19): 3054-3062
DOI: 10.1055/a-2350-1323
paper

Silylium-Ion-Initiated Twofold Halodealkylation of Fully Alkylated Silanes

a   Institut für Chemie, Technische Universität Berlin, Straße des 17. Juni 115, 10623 Berlin, Germany
,
Tao He
a   Institut für Chemie, Technische Universität Berlin, Straße des 17. Juni 115, 10623 Berlin, Germany
b   School of Pharmacy, China Pharmaceutical University, 639 Longmian Avenue, Nanjing, 211198, P. R. China
,
a   Institut für Chemie, Technische Universität Berlin, Straße des 17. Juni 115, 10623 Berlin, Germany
,
a   Institut für Chemie, Technische Universität Berlin, Straße des 17. Juni 115, 10623 Berlin, Germany
› Author Affiliations
T. R. thanks the Fonds der Chemischen Industrie for a predoctoral fellowship (Kekulé scholarship, 2024–2026). 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 synthesis of silanes starting from multifunctionalized precursors often suffers from low chemoselectivity due to the similar kinetic reaction profiles, leading to the formation of difficult to separate side products. The opposite approach, which is an access based on unreactive tetraalkylsilanes as starting materials, is far less developed. Making use of the silylium-ion-initiated chemoselective halodealkylation of tetraalkylsilanes recently developed by our laboratory, an extension of this protocol, namely the direct synthesis of dihalosilanes from tetraalkylsilanes, is reported. Following a sequence of halodehydrogenation and halodealkylation, trialkylhydrosilanes can also be converted into dihalosilanes. Commercially available 1,2-dihaloethane acts as the halogen source and is involved in the generation of the catalytically active arenium ion by an SEAr substitution of the benzene solvent. The formation of an uncommon halogen-substituted silylium ion as an intermediate is assumed, likely accounting for the need of an elevated reaction temperature.

Supporting Information



Publication History

Received: 05 June 2024

Accepted after revision: 21 June 2024

Accepted Manuscript online:
21 June 2024

Article published online:
19 July 2024

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