Visible‐Light‐Induced Cascade Silylation of Activated Alkenes with Silylboronates via Radical Truce‐Smile Rearrangement ^†

Comprehensive Summary Organosilicon compounds have garnered significant attention due to their unique physicochemical properties and broad applications in pharmaceuticals, materials science, and synthetic chemistry. The construction of C–Si bonds represents a fundamental challenge in this field, with silylboronates emerging as particularly versatile reagents. Conventional catalytic systems heavily rely on precious transition metals ( e.g ., Pd, Pt, Au) to activate Si–B bonds through oxidative addition or transmetalation pathways. While effective, these methods suffer from limitations in sustainability, cost, and functional group compatibility. The emergence of photoredox and electrocatalytic approaches has opened new avenues for metal‐free Si–B bond activation. These strategies enable controlled generation of silyl radicals under mild conditions through single‐electron transfer processes, including anodic oxidation or photoinduced electron transfer. This paradigm shift has facilitated diverse radical silylation transformations, such as hydrosilylation and radical‐mediated functionalization. Despite these advancements, the integration of silylboronates with photocatalytic Truce‐Smiles rearrangements remains unexplored. Herein, we report a visible‐light‐promoted tandem silylation reaction that addresses this gap. Using silylboronates as silicon sources, our methodology proceeds via a novel Truce‐Smiles rearrangement pathway to efficiently construct two distinct types of silylated products from methacrylamide substrates. The optimized reaction conditions employ a photocatalyst and operate at ambient temperature without stoichiometric oxidants, demonstrating excellent functional group tolerance, broad substrate scope, and scalability. The practical utility of this protocol is further verified through successful late‐stage functionalization of complex drug molecules. This work not only provides a general strategy for C–Si bond construction but also underscores the potential of photoredox catalysis in expanding the toolbox for sustainable, metal‐free synthetic organic chemistry.