An acid-promoted novel skeletal rearrangement is described. Using trifluoroacetic acid as the acid promoter, an intramolecular ipso-Friedel–Crafts-type addition of phenols to 3-alkylidene indolenium cations, formation of iminium cations through rearomatization of the spirocyclohexadienone units, and intramolecular Pictet–Spengler reaction proceeded sequentially, producing tricyclic indole derivatives.