[H 2 -DABCO][HSO 4 ] 2 Ionic Liquid as a Catalyst for the Synthesis of Quinazolinone Derivatives

An efficient and recyclable Brønsted acidic ionic liquid (BAIL) [[H2-DABCO][HSO4]2 was employed as a catalyst for the synthesis of quinazolinone derivatives through the cyclocondensation of anthranilamide with structurally diverse aromatic aldehydes. The reaction conditions were systematically optimized by investigating the effects of solvent, temperature, and catalyst loading. Among the conditions examined, an ethanol-water (1:1) solvent system containing 10 mol% of [H2-DABCO][HSO4]2 at 80°C provided the optimal results. Under these conditions, a series of fifteen quinazolinone derivatives was synthesized in good to excellent isolated yields (80-98%) within 25–120 min. The catalyst could be recovered and reused for four consecutive reaction cycles with only a gradual decrease in catalytic performance. Furthermore, the environmental performance of the protocol was assessed using selected green chemistry metrix, including atom economy, reaction mass efficiency, mass intensity, and E-factor, which indicated favorable reaction efficiency and relatively low waste generation within the defined calculation boundaries. The methodology combines a recoverable Brønsted acidic catalyst, an ethanol-water reaction medium, and straightforward product isolation without column chromatography, providing a useful approach for the synthesis of quinazolinone derivatives under the investigated laboratory-scale conditions.