A facile, superacid-promoted, domino, one-pot synthesis of novel spirotetracyclic indanones through intramolecular Friedel-Crafts acylation/alkylation of α,β-unsaturated cinnamic acid esters is presented. Interestingly, when the β-aryl group contained electron-withdrawing substituents such as fluoro, chloro, or bromo, the reaction took a different mechanistic path and afforded arylindenes as the end products. © Georg Thieme Verlag Stuttgart.New York.