Catalytic Ring Expansion of Furyl Hydrosilanes: Synthesis of 1,2‐Oxasilines as Diels‐Alder Diene Components

The development of new methods for aromatic ring-expansion offers a strategic means of transforming abundant aromatic feedstocks into intricate structures via skeletal editing, thereby unlocking valuable avenues for organic synthesis. We report herein a mild and efficient ruthenium-catalyzed ring-expansion of 2-silylfurans to form 1,2-oxasilines with wide substrate scope and excellent functional group tolerance. Density functional theory (DFT) calculations suggest the reaction proceeds through regioselective insertion of furan double bond into a Ru─H bond, followed by skeletal rearrangement, 1,2-hydride transfer, and elimination steps. The resulting 1,2-oxasilines are electron-rich cyclic dienes with an extrudable and transformable Si─O linker, which exhibit unique and versatile reactivity in Diels-Alder cyclization with electron-deficient dienophiles, enabling modular assembly of molecular skeletons with higher complexity.