Green and Efficient Synthesis of 1H-Pyrazole-Conjugated 5,6,7,9-Tetrahydrotetrazolo[5,1-b]quinazolin-8(4H)-ones

Abstract

1H-Pyrazole-conjugated tetrazoloquinazolinone scaffolds represent crucial structural motifs in various novel chemical entities with medicinal potential. 9-(1H-pyrazol-5-yl)-5,6,7,9-tetrahydrotetrazolo­[5,1-b]­quinazolin-8(4H)-one derivatives were efficiently synthesized in 85–90% yields by the reaction of methyl- and dimethyl-substituted 1H-pyrazole-5-carbaldehydes, 1H-tetrazol-5-amine, and dimedone or cyclo­hexane-1,3-dione using the ionic liquid [BMIM][OH] as a green reaction medium at 75–80°C for 40–60 min. The synthesized compounds were characterized by NMR and mass spectra. This synthetic methodology offers several advantages, including high yields, a straightforward protocol, environmental compatibility, short reaction times, and mild reaction conditions. Notably, the use of a catalytically active ionic liquid as reaction medium obviates the necessity for additional catalysts and solvents, thus streamlining the synthetic process and aligning with principles of green chemistry. Overall, this approach holds promise for the efficient and sustainable synthesis of 1H-pyrazole-conjugated tetrazoloquinazolinone derivatives.