Deformylative Intramolecular Hydroarylation: Synthesis of Benzo[<i>e</i>]pyrido[1,2‑<i>a</i>]indoles

Attempted cyclization of indolizines bearing both formyl and alkyne groups under acid catalysis provided benzo­[e]­pyrido­[1,2-a]­indoles with an aryl substituent at the C6 position as major products, along with the expected C5-acylated benzo­[e]­pyrido­[1,2-a]­indoles as minor ones, which resulted from preferential deformylative intramolecular hydroarylation instead of intended alkyne-carbonyl metathesis.