A LiCl-promoted, HBF4-catalyzed intermolecular cascade cyclization of indoles and ortho-formylarylketones has been developed, utilizing saturated LiCl solutions as the solvent for the rapid synthesis of indolyl benzo[b]carbazoles. This 'on-water' synthetic approach exhibits excellent functional group tolerance, a broad substrate scope, and scalability, making it suitable for practical applications. Additionally, the fluorescence emission properties of the synthesized indolyl benzo[b]carbazole compounds were systematically investigated.
