Synthesis of Benzocyclohepta[<i>b</i>]indoles by Lewis Acid Catalyzed Annulation of Two 3‑(1<i>H</i>‑Isochromen-1-yl)‑1<i>H</i>‑indoles

A novel Lewis acid catalyzed annulation reaction has been established for the synthesis of benzocyclohepta­[b]­indoles. This method represents a new annulation strategy to a seven-membered carbocyclic ring system from two 3-(1H-isochromen-1-yl)-1H-indole molecules using Cu­(OTf)2 catalyst; moreover, the products, benzocyclohepta­[b]­indoles, can be used as the rapid mercuric ion colorimetric detection reagents.