The Pd/Cu-cocatalyzed one-pot reaction of 2-allyl-3-iodo-1-tosyl-1H-indoles and terminal alkynes afforded carbazoles highly efficiently via sequential carbon carbon coupling, isomerization, cyclization, and aromatization forming a benzene ring. Both Pd and Cu are responsible for the coupling step, while K2CO3 was observed to be critical for the subsequent cyclization.
Zhu C,Ma SM. Efficient Carbazole Synthesis via Pd/Cu-Cocatalyzed Cross-Coupling/Isomerization of 2-Allyl-3-iodoindoles and Terminal Alkynes[J]. Org. Lett.,2014,16(6):1542-1545.