An Ultrasound-Assisted Solvent and Catalyst-Free Synthesis of Structurally Diverse Pyrazole Centered 1,5-disubstituted Tetrazoles via One-Pot Four-Component Reaction

1,5-Disubstituted tetrazoles are vital drug-like scaffolds usually encountered as valuable bioisosteres of the cis-amide bond. In this article, we reported the synthesis of some novel medicinally relevant pyrazole centered 1,5-disubstituted tetrazoles using ultrasound irradiation via a one-pot 4-C reaction from various pyrazole originated aldehyde, amine, isocyanide, and sodium azide. All the synthesized derivatives were characterized by IR, ¹H NMR, ¹³C NMR, spectroscopic techniques, and mass analysis. This ultrasound-assisted green protocol has several advantages like mild reaction condition, high yield, catalyst and solvent-free reaction protocol, 15 minutes reaction time and easy workup.