Sonochemical Synthesis of Schiff Base of Substituted Benzoxazolone: A Quantum Chemical, Antibacterial Evaluation and Molecular Docking Study

The derivatives of benzoxazolone (BOA) have attracted a lot of interest because of their diverse pharmacological potential as therapeutic agents. In this work, we report an environmentally friendly synthetic method based on ultrasonication(US) as well as conventional method to prepare new BOA derivatives (M1-M4). Furthermore, the BOA derivatives were reacted with p-nitro, p-chloro, and p-hydroxy anilines to get Schiff bases compounds (M5-M16). The results demonstrated that, in comparison to traditional approaches, the ultrasonication method had higher reaction kinetics and energy efficiency. Additionally, quantum chemical calculations and molecular docking studies were performed to understand the reaction mechanisms and evaluate the antibacterial potential of the synthesized compounds. The presence of electron-withdrawing group at the para position of substituted anilines follows the trend & horbar;NO2 > & horbar;Cl > & horbar;OH, leading to higher formation energies of the corresponding products as reflected in the progression of the reactions in the mechanistic studies. Further, the presence of a methyl group in benzoxazolone (BOA) enhances the binding interaction affinity with Escherichia coli, however on the basis of docking scores of nitro group containing (M5, M8, M11, and M14) compounds exhibited stronger interactions with the protein of E. coli, compared to the chlorine and hydroxyl groups. The docking results were also found consistent with in vitro results.