Journal of the American Chemical Society, Vol.138, No.25, 7868-7871, 2016
Bronsted Acid-Promoted Formation of Stabilized Silylium Ions for Catalytic Friedel-Crafts C-H Silylation
A counterintuitive approach to electrophilic aromatic substitution with silicon electrophiles is disclosed. A strong Bronsted 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.