Gold-Catalyzed Domino Cycloisomerization/Pictet–Spengler Reaction of 2‑(4-Aminobut-1-yn-1-yl)anilines with Aldehydes: Synthesis of Tetrahydropyrido[4,3‑<i>b</i>]indole Scaffolds V. Subba ReddyB. SwainManisha ReddyS.Madhusudana YadavJ. S. SridharB. 2012 A domino cycloisomerization/Pictet–Spengler reaction of 2-(4-aminobut-1-yn-1-yl)­aniline with aldehydes has been achieved using a AuIPrCl (5 mol %)/AgSbF<sub>6</sub> (10 mol %) catalytic system to produce the corresponding 1-aryl-<i>N</i>-tosyl-2,3,4,5-tetrahydropyrido­[4,3-<i>b</i>] indole derivatives in good yields. This is the first report on the synthesis of tetrahydro pyrido­[4,3-<i>b</i>]­indole scaffolds through as tandem 5-<i>endo</i>-<i>dig</i> cyclization and Pictect–Spengler reaction.