Electrochemical Synthesis of Polycyclic N‑Heteroaromatics through Cascade Radical Cyclization of Diynes

An electrochemical cyclization reaction of easily available urea-tethered diynes has been developed for the synthesis of nitrogen-doped polycyclic aromatic hydrocarbons (PAHs). The employment of ferrocene as a mild and selective redox catalyst allows access to a variety of electron-rich PAHs including helicene-like structures without overoxidation. The electrosynthetic method involves an unprecedented amidyl radical cascade cyclization process to form three rings in a single operation.