Introduction of a novel Brønsted acidic ionic liquid as a recyclable catalyst in the green production of dihydropyrano-pyrazoles

In this work, a novel, comprehensive, and eco-friendly protocol for the production of biologically active dihydropyrano-pyrazole derivatives in aqueous medium at room temperature using 1,3,5-trimethyl-2,4,6-tris(4-pyridinium sulfonic acid)benzene tri-chloride (TMTPSBTC) as a capable, recyclable, and homogeneous Brønsted acidic ionic liquid catalyst is described. The results from carbon, hydrogen and nitrogen elemental analysis, mass spectrometry, thermal analysis, nuclear magnetic resonance, and Fourier transform infrared techniques characterized the TMTPSBTC skeleton. The high yields of products in reasonable times during a one-pot multicomponent domino operation (1a-16a, 85–98%, 5–20 min), the introduction of novel products to the literature (5a and 16a), the non-metallic nature of the catalysis, the simple preparation of the catalyst, and its reusability (four runs) without significant loss of activity are attractive benefits of the present methodology.

Graphical abstract