Rapid and Green Synthesis of Schiff Bases Using Sulfo-octahydroimidazo[1,2-a]azepin-4-ium Chloride as an Efficient Catalyst

In the present research work, a novel and efficient method has been developed for the synthesis of Schiff bases using a newly designed organic catalyst, 4-sulfo-2,3,4,5,6,7,8,9-octahydroimidazo[1,2-a]azepin-4-ium chloride complex (DBUST-Cl). This catalyst effectively facilitates the condensation reaction between aromatic aldehydes and aniline in a green solvent system, leading to the formation of Schiff bases in high yields. The synthesized products were thoroughly characterized using ¹H NMR, ¹³C NMR, and FT-IR spectroscopy. The DBUST-Cl catalyst is believed to function via forming an iminium intermediate, which promotes the efficient synthesis of the Schiff base. This methodology presents several advantages, including cost-effectiveness, scalability, a simple workup process, minimal side reactions, shorter reaction times, and broad substrate applicability. Compared to conventional methods, it provides a superior alternative, especially for acyl derivatives that typically do not proceed efficiently without catalysis. This innovative protocol holds great promise and has the potential to revolutionize the industrial-scale synthesis of Schiff bases and related compounds.