Gold-Catalyzed Intramolecular Alkyne Cycloisomerization Cascade: Direct Synthesis of Aryl-Annulated[a]carbazoles from Aniline-Substituted Diethynylarenes

Aniline-substituted diethynylarenes, which are readily synthesized through Sonogashira coupling reactions from commercially available 1,2-dihaloarenes, directly produce aryl- and heteroaryl-annulated[a]carbazoles by the gold-catalyzed intramolecular cascade hydroamination/cycloisomerization without producing theoretical by-products. This new atom-economical route is easily applicable to various aryl-annulated[a]carbazoles containing an alkyl, aryl or ester substituent.