One‐Step Synthesis of 3,4‐Diphenyl‐2‐pyrrolinones by Solvent‐Free and Bi2O3‐Catalyzed Approaches and Cytotoxicity Screening Against Glioma Cells

Multifunctionalized 2‐pyrrolinones were synthesized from the formal aza‐3 + 2] cycloaddition reaction of acyclic enaminones and diphenylcyclopropenone. For primary enaminones, solventless reaction under microwave heating was developed. On the other hand, catalysis by Bi₂O₃ under conventional heating was the more suitable strategy when secondary enaminones were employed. These conditions allowed the synthesis of a set of 2‐pyrrolinones with two vicinal phenyl substituents, which were evaluated for cytotoxicity against U251 and C6 glioblastoma cells. In general, all tested 2‐pyrrolinones with two vicinal phenyl rings were more active than those without this structural moiety, and 1‐butyl‐5‐methyl‐5‐(2‐oxopropyl)‐3,4‐diphenyl‐1,5‐dihydro‐2H‐pyrrol‐2‐one was the most cytotoxic and appears to be a new possibility as an antitumor scaffold to this aggressive brain tumor.