Catalytic Alkoxysilylation of (Hetero)Aryl Bromides with tert-Butyl Alkoxysilyldiazenes

Aryl(alkoxy)silanes are valuable building blocks in organic synthesis and materials science, yet their preparation often relies on stoichiometric organometallic reagents or transition metal-catalyzed methods. Herein, we report a catalytic and transition metal-free alkoxysilylation of (hetero)aryl bromides using tert -butyl-substituted alkoxysilyldiazenes ( t Bu–N=N–SiMe 2 (OR)) as silylating reagents and t BuONa as catalytic initiator. The reaction proceeds under mild conditions and provides direct access to a broad range of functionalized aryl(alkoxy)silanes. Competition experiments and DFT calculations reveal that increasing the electrophilicity of silicon through alkoxy substitution accelerates the key C(sp 2 )–Si bond-forming step relative to SiMe 3 transfer. This enhanced reactivity significantly broadens the substrate scope, enabling the efficient alkoxysilylation of challenging hindered aryl bromides and those bearing electrophilic functional groups.