18666-43-8Relevant articles and documents
Friedel-Crafts-Type Intermolecular C-H Silylation of Electron-Rich Arenes Initiated by Base-Metal Salts
Yin, Qin,Klare, Hendrik F. T.,Oestreich, Martin
supporting information, p. 3204 - 3207 (2016/03/12)
An electrophilic aromatic substitution (SEAr) with a catalytically generated silicon electrophile is reported. Essentially any commercially available base-metal salt acts as an initiator/catalyst when activated with NaBArF4. The thus-generated Lewis acid then promotes the SEAr of electron-rich arenes with hydrosilanes but not halosilanes. This new C-H silylation was optimized for FeCl2 /NaBArF4, affording good yields at catalyst loadings as low as 0.5 mol %. The procedure is exceedingly straightforward and comes close to typical Friedel-Crafts methods, where no added base is needed to absorb the released protons.
Br?nsted acid-promoted formation of stabilized silylium ions for catalytic friedel-crafts C-H silylation
Chen, Qing-An,Klare, Hendrik F. T.,Oestreich, Martin
supporting information, p. 7868 - 7871 (2016/07/07)
A counterintuitive approach to electrophilic aromatic substitution with silicon electrophiles is disclosed. A strong Br?nsted acid that would usually promote the reverse reaction, i.e., protodesilylation, was found to initiate the C-H silylation of electron-rich (hetero)arenes with hydrosilanes. Protonation of the hydrosilane followed by liberation of dihydrogen is key to success, fulfilling two purposes: to generate the stabilized silylium ion and to remove the proton released from the Wheland intermediate.
