A superacid (triflic acid) promoted dual C-C bond formation via intermolecular Friedel-Crafts alkylation (Michael addition type) and intramolecular acylation for the efficient synthesis of 3-substituted indan-1-ones is presented. This method was successful in activating ethyl cinnamates towards dual aromatic electrophilic substitution. Moreover, it enabled us to synthesize novel spirotetracyclic systems. © Georg Thieme Verlag Stuttgart · New York.