Palladium-Catalyzed Cascade Cyclization of Alkene-Tethered Aryl Halides with o -Bromobenzoic Acids: Access to Diverse Fused Indolo[2,1- a ]isoquinolines

A novel palladium-catalyzed cascade cyclization of alkene-tethered aryl halides with o -bromobenzoic acids is described, which provides an efficient avenue for building various fused hexacyclic scaffolds containing indolo[2,1- a ]isoquinoline in moderate to excellent yield. The method enables the construction of three C–C bonds through an intramolecular carbopalladation, C–H activation, and a decarboxylation sequence. Furthermore, dihydrocyclohepta[ de ]naphthalene-fused indolo[2,1- a ]isoquinolines can be synthesized in moderate yield by constructing a seven-membered ring.