A Catalyst-Free Facile Synthesis of 2-(dihydropyridyl)benzothiazoles from (Benzothiazol-2-yl)acrylonitriles: A Green Route

Abstract

An efficient, metal-free and catalyst-free, atom-economical green route for the synthesis of C-2-(dihydropyridyl)benzothiazoles is described. The synthesis is achieved by [3+3] cycloaddition reaction of (benzo[d]thiazol-2yl)acrylonitriles with cyclic 1,1-enediamines under mild conditions to furnish imidazo[1,2-a]pyridine, pyrimidino[1,2-a]pyridine, and diazapino[1,2-a]pyridine incorporated benzothiazole moieties. The protocol is operationally simple and affords products directly by filtration, oviates any other purification techniques for the isolation of the scaffolds. Furthermore, the strategy tolerates a wide range of substrates, as well as the gram-scale synthesis, yielding the product in good to excellent yields, demonstrating its practicality and versatility. Absorption behaviour of the benzothiazole hybrid was also analysed. Further, the applied methodology also aligns with the principles of green chemistry by offering high atomeconomy and excellent environmental compatibility.