Abstract A multi-component, one pot and regio-selective synthesis of different 5-substituted 1H-tetrazoles was successfully accomplished via a click reaction. In this respect, we have performed the reaction of either isatins or various aromatic aldehydes with malononitrile and ionic liquid, 1-butyl-3-methylimidazolium azide ([BMIM]N3), as a relatively green source of azide mediated by o-phthalimide-N-sulfonic acid (OPNSA). The calculated thermodynamic results demonstrate a reliable agreement with our experimentally observed regio-selectivity. From the electronic viewpoint, we have also assessed the nature of regio-selectivity via quantum theory of atoms in molecule analysis.
