Visible Light-Induced Intermolecular Dearomatization for Constructing Angularly Fused Tetracyclic Scaffolds

Visible light-induced dearomative cycloaddition has emerged as a powerful strategy for constructing complex polycyclic frameworks from simple aromatic precursors. Angularly fused polycyclic systems, which exhibit distinctive structural rigidity and tunable physicochemical properties, represent privileged scaffolds in bioactive natural products and pharmaceuticals. Herein, we report a robust photocatalytic protocol for the direct assembly of angularly fused tetracyclic scaffolds through intermolecular dearomatization of benzothiophene/indole derivatives with N-aryl cyclopropylamines. This transformation is achieved via a mechanistically intriguing cascade involving photocatalytic dearomative [3 + 2] cycloaddition and subsequent cyclization. This work demonstrates the synthetic feasibility of photocatalytic intermolecular dearomative [3 + 2] processes, providing direct access to structurally distinct angularly fused tetracyclic cores. Visible light-driven dearomative cycloadditions have become a powerful tool for building complex polycyclic frameworks from simple aromatics. Here, the authors report a photocatalytic strategy to assemble angularly fused tetracycles via intermolecular [3 + 2] dearomatization cascades.