An efficient, step-economical synthesis of β-carboline tethered imidazopyrido[3,4-b]indoles from acetals†

An efficient one-pot pseudo three component cascade annulation reaction has been devised to generate the fluorescent β-carboline tethered imidazopyrido[3,4-b]indole derivatives. These scaffolds were afforded in high yields via one-pot cascade reaction of diversified β-carboline acetals with NH₄Cl through the formation of three C–N bonds in a single operation. The current protocol is step-economical and offers high atom-economy, short reaction time and high structural diversity with excellent yields (57–90%). The synthesized compounds displayed promising photophysical properties and delivered luminescence quantum yield (Φ_F) up to 55%.