HCl-mediated silylation of C-H bonds in (hetero)arenes with trialkylsilanes

Direct C-H silylation of (hetero)arenes provides a straightforward route for synthesizing valuable organosilicon molecules. Contrasting with traditional methods that rely on costly photocatalysts, toxic metal reagents, excess strong oxidants, and high temperatures. Herein, our study presents a practical, eco-friendly electron donor-acceptor (EDA) strategy that enables highly efficient C-H silylation of (hetero)arenes by using affordable and readily available HCl as the only additive under visible-light excitation. Substrate classes previously challenging to activate are efficiently silylated with high yields and excellent regioselectivity. Furthermore, this protocol enables the direct silylation of active pharmaceutical ingredients. The resulting heteroarylsilane products undergo versatile transformations, enabling advanced synthetic strategies for heteroaromatic functionalization. This synthetic strategy shows great potential for industrial-scale applications, attributed to readily available raw materials, simple reaction conditions, air and water tolerance, broad substrate scope, and excellent scalability. Notably, this reaction system facilitates other versatile functionalizations of heteroarenes, including trifluoromethylation, acylation, and alkylation. More significantly, the quinoline salt derived from quinoline and hydrochloric acid serves as a novel photocatalyst, converting silanes or alkyl trifluoroborates into corresponding radicals for diverse chemical bond construction. In future studies, these results provide valuable insights for achieving new chemical transformations with quinoline hydrochloride, an EDA complex, as a photocatalyst or additive.