Photochemical Decarboxylative Radical Alkylation/Cyclization Reaction to Fused Nitrogen Heterocycles by LiI/PPh3 Catalysis

Abstract

Comprehensive SummaryA visible‐light‐induced decarboxylative radical cascade cyclization reaction between N‐(2‐cyanoaryl)‐acrylamides and alkyl N‐(acyloxy)phthalimide (NHPI esters) for the construction of phenanthridine derivatives has been developed. This approach utilizes lithium iodide (LiI) and triphenylphosphine (PPh3) as the redox catalysts and the alkyl radical is produced through the photoactivation of the electron donor‐acceptor (EDA) complex. A series of primary, secondary, and tertiary alkyl‐substituted phenanthridines are prepared in up to 82% yield without transition‐metal catalysts, chemical oxidants, or metal‐/organic dye‐based photocatalysts.