3H‐indolium salts efficiently prepared from N‐substituted anilines and α‐branched ketones by an one‐pot synthesis

Abstract Starting with the N ‐substituted anilines 4/12 and the α‐branched ketones 3 the 3 H ‐indolium salts 1 and their fused derivatives 13 are prepared by combining a sodium nitrite nitrosation, a zinc dust reduction, a hydrazone formation and a Fischer indolization to a reaction sequence in which the isolation and purification of intermediates is not necessary. The scope and limitations of this effective one‐pot synthesis are discussed.