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

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 %)/AgSbF6 (10 mol %) catalytic system to produce the corresponding 1-aryl-N-tosyl-2,3,4,5-tetrahydropyrido­[4,3-b] indole derivatives in good yields. This is the first report on the synthesis of tetrahydro pyrido­[4,3-b]­indole scaffolds through as tandem 5-endo-dig cyclization and Pictect–Spengler reaction.