One-pot Synthesis of Functionalized Benzimidazole-quinazolinone Derivatives

Introduction/Objective: Quinazolinone and aldehyde derivatives have emerged as important molecules in recent studies because of their wide spectrum of pharmacological and biological effects. They have recently attracted attention in synthesis and research. Combinatorial synthesis for this type of heterocycle has emerged in the literature over the last decade. In one-pot processes, atypical intermediates often play key roles in the overall transformation. An unusual coupling sequence occurs through nucleophilic addition to an in situ-formed Michael intermediate. This is followed by an electrocyclic cyclization step. Motivated by these findings, we focused on designing a convenient synthetic method for the preparation of benzimidazole-quinazolinone and heteroaryl aldehyde derivatives. This study aimed to create efficient MCR pathways using common starting materials to build benzimidazole and quinazolinone scaffolds. Methods: In this study, we performed a one-pot, three-component reaction. We reacted 2- aminobenzimidazole, various substituted heteroaryl aldehydes, and dimedone in absolute ethanol. Analytical and spectroscopic data (NMR, GC-MS, IR, and UV) were used to characterize and verify the structures of the synthesized complexes. Results: The lead was compound 4a (88% yield). This route enables efficient heterocycle assembly. GC-MS analysis confirmed that compounds 4e and 4f share the same base peak (m/z 266), suggesting a common fragmentation pathway due to structural similarities. Discussion: An efficient one-pot method for the synthesis of benzimidazole[2,1-b]quinazolinone derivatives was developed, avoiding multi-step procedures, and spectroscopic analyses confirmed the successful formation of the target compounds, demonstrating the practicality of the method. conclusion: A series of benzimidazole[2,1-b]quinazolinone derivatives (4a–4f) were successfully synthesized via a one-pot three-component reaction involving 2-aminobenzimidazole, various heteroaryl aldehydes, and dimedone in ethanol. This method proved efficient, providing moderate to excellent yields under mild conditions without the need for catalysts. The one-pot strategy demonstrated good functional group tolerance and offers a valuable approach for generating structurally diverse heterocycles with potential for biological screening and further derivatization. Conclusion: The compounds obtained represent promising starting points for structural modification, which could lead to the development of more active quinazoline-based derivatives.