Gold-catalyzed domino cycloisomerization/Pictet-Spengler reaction of 2-(4-aminobut-1-yn-1-yl)anilines with aldehydes: synthesis of tetrahydropyrido[4,3-b]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 %)/AgSbF(6) (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.