White/Sun/Red‐Light Mediated Oxidative Cyclization from Formyl Acetates: Application to Ester Substituted N ‐Doped PAHs

Comprehensive Summary Quinoxalines are privileged scaffolds in medicinal chemistry and materials science, yet their synthesis from sterically hindered and electron‐deficient ketones remains challenging. Herein, we report a mild, photochemical strategy for the direct oxidative annulation of readily available formyl acetates with o ‐diamines. This operationally simple protocol, devoid of external photocatalysts, efficiently proceeds under ambient conditions using white light, sunlight, or remarkably, low‐energy red light ( λ = 700–710 nm) as the sole energy source. The reaction exhibits exceptional functional group tolerance, enabling the incorporation of diverse (hetero)aryl, alkyl, and ester groups onto the quinoxaline core in up to 90% yield. Its synthetic utility is demonstrated through gram‐scale synthesis, facile downstream transformations, and the construction of novel ester‐functionalized, nitrogen‐doped polycyclic aromatic hydrocarbons ( N ‐doped PAHs). The photophysical characterization of the obtained N ‐doped PAHs revealed excellent optical properties across FMO and ESP analysis, UV‐vis absorption, fluorescence, and phosphorescence emission spectra. Mechanistic studies support a pathway involving initial condensation followed by a light‐mediated oxygen capture and radical cyclization.