Intramolecular C-H Alkenylation of N-Alkynylindoles: Exo and Endo Selective Cyclization According to the Choice of Metal Catalyst

The intramolecular reaction of 3-acetyl-N-alkynylindoles proceeded via C-H bond cleavage at the C2 position. Iridium and rhodium catalysts selectively promoted 6-exo-dig and 7-endo-dig cyclization, respectively, and N-fused tricyclic compounds were obtained.