Environmental Friendly Synthesis of 3-(1H-Tetrazol-5-yl) Coumarins (3-(1H-Tetrazol-5-yl)-2H-1-benzopyran-2-ones) Employing a Heterogeneous Catalyst in Solvent-free Conditions

Coumarins are extensively found in the field of biology, medicine, and polymer sciences. The most well-known and important coumarin is Warfarin , which is prescribed in low doses as a blood thinner. Numerous coumarins are used as a drug in contemporary and recent medicine. Tetrazoles are among important heterocyclic systems. Several tetrazole derivatives illustrate various biological potencies, such as antibacterial, antiinflammatory, antifungal, antiviral, antitubercolous, cyclo-oxygenase inhibitors, antinociceptive, hypoglycemic and anticancer activities.A multi-component, one-pot and environmentally friendly synthesis of 3-(1H-Tetrazol-5-yl)coumarins(3-(1H-Tetrazol-5-yl)-2H-1-benzopyran-2-ones) was successfully synthesized via domino Knoevenagel condensation, Pinner reaction, and 1,3-dipolar cycloaddition of substituted salicylaldehydes (2-hydroxybenzaldehydes), malononitrile (propanedinitrile), and [BMIm]N3 (as the relatively green source in organic synthesis and reactions, especially those based on imidazolium cations) in condition of solvent-free. This reaction is catalyzed by ionic liquid which functionalized on HY-Zeolite and characterized by different methods such as: FT-IR, XRD, SEM, EDX. In conclusion, an efficient, plain, and convenient method for the preparation of new 3-(1H-tetrazol-5-yl) coumarins in condition of solvent-free is reported. The FT-IR data of Ionic liquid/HY zeolite compound indicate an intense band about ca. 1050 cm-1 attributable to the asymmetric stretching of Al–O–Si chain of zeolite. The symmetric stretching and bending frequency bands of Al–O–Si framework of zeolite appear at ca.751 and 455 cm-1, respectively. The FT-IR data of coumarin-tetrazole compound indicate absorption bands for the N-H and C=O groups at 3346 and 1710 cm-1, respectively.