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

A novel palladium-catalyzed cascade cyclization of alkene-tethered aryl halides with -bromobenzoic acids is described, which provides an efficient avenue for building various fused hexacyclic scaffolds containing indolo[2,1-]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[]naphthalene-fused indolo[2,1-]isoquinolines can be synthesized in moderate yield by constructing a seven-membered ring.