Boron‐Catalyzed Electrochemical Si−C Bond Formation for Safe and Controllable Benzylation and Allylation of Hydrosilanes

The range of possible applications of B(C 6 F 5 ) 3 extends into many areas of organic and inorganic chemistry. However, electrochemical synthesis with hydrosilanes using B(C 6 F 5 ) 3 to increase yield or scope has not yet been achieved. A comprehensive study on the use of Lewis acidic boron species, especially B(C 6 F 5 ) 3 , for the activation of hydrosilanes in presence of commercially available supporting electrolyte for Si−C bond formation was presented. The benzylation and allylation of hydrosilane species was successfully conducted in presence of catalytic amounts of B(C 6 F 5 ) 3 in yields up to 86 %. Screening of electrode materials revealed leaded bronzes as superior for cathodic conversion without contamination of the electrolyte by heavy metals. Supported by cyclic voltammetry studies, B(C 6 F 5 ) 3 activated the hydrosilane for easier nucleophilic access, leading to significant increase in yield and enrichment of the target product in the reaction mixture.