Synergistic Catalytic Effect of the Combination of Deep Eutectic Solvents and Hierarchical H-TiO₂ Nanoparticles toward the Synthesis of Benzimidazole-Linked Pyrrolidin-2-One Heterocycles: Boosting Reaction Yield

Synthesis of bioactive heterocyclic compounds comprising pyrrolidinone linked to a benzimidazole moiety by an eco-friendly and efficient route was investigated. The targeted scaffolds were synthesized from substituted arylamines and available o-phenylenediamine under ultrasonic irradiation in the presence of a mixture of a deep eutectic solvent (DES) and hierarchical TiO₂ (H-TiO₂) microspheres as a green catalytic system. Two DESs were synthesized by separately mixing FeCl₂ and CuCl₂ with urea. On the other hand, hierarchical TiO₂ (H-TiO₂) was synthesized by a solvothermal route and characterized by XRD, SEM, Raman spectroscopy, and XPS. The results demonstrate that the best reaction yields are obtained by using H-TiO₂ microspheres in the DES. Besides, the synthesized compounds were screened for their antibacterial activity against different bacteria. Overall, eight derivatives were confirmed to exhibit antibacterial activity.