Gold-Catalyzed Cascade and Divergent Synthesis of Indolobenzazepines and Indoloquinolines from Nitrogen-Tethered 1,8-Diynes

We describe the divergent construction of two nitrogen-containing polycyclic systems by gold-catalyzed cycloisomerizations. The gold-catalyzed cascade hydroamination and 7-endo-dig-selective cycloisomerization of nitrogen-tethered 1,8-diynes yielded indolo[1,7-ab]benzazepines in one pot. In contrast, when Johnphos-coordinated gold catalyst was used, the same 1,8-diynes were transformed into indolo[1,2-a]quinolines by 6-endo-dig-selective cycloisomerization along with rearrangement of the substituent on one of the alkynes. The reaction of a naphthalene-tethered substrate provided a helically chiral aza[6]helicene.