Guanidine hydrochloride (GuHCl)-catalysed microwave-mediated solvent- and metal-free synthesis of pyrimido[1,2-]benzimidazole from aryl aldehyde and aryl methyl ketone

A novel microwave-mediated synthesis method was developed for the rapid and eco-friendly production of pyrimido[1,2- a ]benzimidazole in high yields utilizing simple and cost-effective starting materials. This reaction was facilitated by the green organocatalyst guanidine hydrochloride. This protocol offers a metal-free and organocatalysed technique to afford a library of highly fluorescent pyrimido[1,2- a ]benzimidazole derivatives. Key features of this synthetic method include its broad compatibility with functional groups, operational simplicity, and scalability, making it a promising technique for various applications. The rapid, eco-friendly, solvent- and metal-free microwave-assisted synthesis of pyrimido[1,2- a ]benzimidazole in high yields was achieved using the green organocatalyst guanidine hydrochloride using simple and inexpensive starting materials.