Visible Light-Driven Brønsted Acid-Catalyzed Annulation of Enaminones Enables Modular Access to Imidazo[1,2- a ]azaarenes

Imidazo[1,2-a]pyridines are privileged heterocyclic motifs in pharmaceuticals and functional materials, yet densely substituted azaarenyl-containing variants remain difficult to access. We report a visible-light-driven, Brønsted acid-catalyzed annulation of readily accessible N-(2-azaarenyl)enaminones. The reaction proceeds under mild, transition-metal- and photocatalyst-free conditions, providing modular access to structurally diverse imidazo[1,2-a]azaarenes, including C2/C3 azaarenyl-substituted architectures that are difficult to obtain by conventional methods.