Electrosynthesis of Highly Functionalized Polycyclic N‑Heteroaromatics through Cascade Radical Cyclization and Alkoxylation in Batch and Continuous-Flow

Electrochemical
radical cascade cyclization has been recognized
as a powerful, straightforward, and environmentally-friendly synthetic
tool to give highly functionalized polycyclic aromatic compounds but
remains challenging and difficult because of the instability of the
radical intermediates under the electrolysis conditions, especially
using a user-friendly undivided cell. Herein, we report a novel electrosynthesis
of pyridine-fused N-heteroaromatics through dehydrogenative cascade
cyclization and alkoxylation under oxidant-free conditions. This electrochemical
synthesis methodology features green and mild reaction conditions,
good functional group tolerance, and the use of readily available
substrates. Moreover, attributed to the use of flow electrolysis cells,
the steady production and large-scale preparation can be conveniently
achieved using only small amounts of electrolytes.