Photoredox-Catalyzed [2 + 1 + 2] Cyclization of Alkenes, Carbyne Equivalents, and Nitriles

We present an unprecedented light-driven three-component [2 + 1 + 2] cyclization that integrates carbyne equivalents with readily available nitriles and alkenes. Mechanistic validation through the isolation of a key intermediate reveals a cascade sequence: photoinduced diazomethyl radical generation, concerted cyclization, and subsequent acid-promoted aromatization. This catalytic paradigm enables modular synthesis of unprotected tetrasubstituted pyrroles with complete regioselectivity, eliminating traditional multistep manipulations. Furthermore, we developed a skeletal editing strategy that overcomes the challenge of converting pyrrole cores into polysubstituted naphthalenes. Combined with established skeletal diversification protocols (pyrrole-to-benzene/pyridine conversions), these transformations collectively demonstrate the remarkable plasticity of pyrrole cores in the construction of highly functionalized aromatic systems.