Reductive Coupling of Aryl Halides via C—H Activation of Indene

Main observation and conclusion This paper describes the first case of a reductive coupling reaction with indene, a non‐heteroatom olefin used as a reducing agent. The scope of the substrate is wide. The homo‐coupling, cross‐coupling, and synthesis of 12 and 14‐membered rings were realized. The control experiment, indene‐product curve and density functional theory calculations showed that the η 3 ‐palladium indene intermediate was formed by C—H activation in the presence of cesium carbonate. We speculate that the final product was obtained through a Pd (IV) intermediate or aryl ligand exchange. In addition, we excluded the formation of palladium anion (Pd(0) − ) intermediates.