‘On Water’ Synthesis of Indolyl-Substituted Benzo[b]carbazoles via LiCl-Promoted HBF₄-Catalyzed Annulation of ortho-Formylaryl Ketones with Indoles

Abstract

A LiCl-promoted, HBF₄-catalyzed intermolecular cascade cyclization of indoles and ortho-formylaryl ketones has been developed, utilizing saturated aqueous 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.

Key words

lithium chloride - Lewis acids - Brønsted acids - on water - benzo[b]carbazoles

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