Pyrrolidinium Acetate (PyrrIL) as a Green and Recyclable Catalyst: Synthesis of 2-Phenyl Benzimidazoles and 2-Phenyl Benzothiazoles under Solvent-Free Conditions at Room Temperature

Benzimidazoles and benzothiazoles are a class of pharmacologically potential compounds, which exhibited anti-microbial, anticancer, and anti-inflammatory activities. These can be obtained by simple condensation of o-phenylenediamine or o-aminothiophenol with aromatic aldehydes. The synthetic protocol can be accomplished/improved by varying reaction parameters such as temperature, solvents, and catalysts. To develop such condensation reactions in a sustainable way, non-toxic solvents and eco- friendly catalysts are presently used. In this study, we proposed a novel and interesting strategy for obtaining diversely substituted 2-phenyl benzimidazole and 2-phenyl benzothiazole derivatives via a one-pot protocol, employing pyrrolidinium ionic liquid as a green and environmentally benign catalyst under solvent-free conditions at room temperature in an open atmosphere. The resulting products were obtained in good to excellent yields within a short reaction time (3-20 min). A plausible mechanism was also discussed.