Photoinduced EDA Complex‐Enabled Radical Alkylation/Cyclization Reaction of N‐Arylacrylamides with Katritzky Salts

As important structural motifs among N ‐heterocycles, phenanthridines are ubiquitous in significant functional compounds. Herein, a visible‐light‐mediated radical alkylation/cyclization reaction between N ‐Arylacrylamides and Katritzky salts for the efficient construction of phenanthridines under mild conditions is reported. Triggered by photoexcitation of electron donor–acceptor complexes formed between salts and N, N ‐diisopropylethylamine, this strategy circumvents the requirement for photocatalysts and transition‐metal catalysts. A series of phenanthridine derivatives are smoothly synthesized in up to 86% yield, demonstrating excellent functional group compatibility.