Synthesis of Tetrahydro‐β‐carbolines via Cascade Sigmatropic Rearrangements

Abstract We have developed a synthesis for tetrahydro‐β‐carbolines involving cascade sigmatropic rearrangements. The substrates were conveniently prepared from parent anilines via a [2,3]‐sigmatropic rearrangement and cyanomethylation. Silver‐mediated decyanation afforded the corresponding iminium cation, which underwent a cascade consisting of an aza‐Cope rearrangement, an aza‐oxa‐Cope rearrangement, an aromatization, and a Pictet‐Spengler reaction, and tetrahydro‐β‐carbolines were obtained as the single product. The reaction involved seven bond scissions and four bond formations and was triggered by a single reagent.