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. 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 extrusable 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.