A simple, green and efficient protocol for synthesis of dihydropyrano[2,3-c]pyrazole derivatives is developed by a four component reaction of various benzaldehydes, ethyl acetoacetate, hydrazine hydrate and malononitrile in the presence of 3-methyl-1-(4-sulphonic acid)butylimidazolium hydrogen sulphate [(CH 2) 4 SO 3 HMIM][HSO 4 ], an acidic ionic liquid and as a catalyst, under solvent-free conditions. The key advantages of this process are high yields, shorter reaction times, easy work-up, purification of products by non-chromatographic method and the reusability of the catalyst.

Nucleophilic substitution of hydrogen followed by intramolecular electrophilic aromatic substitution in nitro drevitavies of indazole has been used as a key step in the one pot synthesis of new fluorescent heterocyclic compounds 3H-pyrazolo[4,3-a]acridin-11-carbonitriles.

Biologically active substituted dihydropyrano[2,3‐c]pyrazole derivatives (IV) are obtained by a simple, green, and efficient four‐component reaction of various benzaldehydes (II), ethyl acetoacetate (I), malononitrile (III), and hydrazine hydrate using an acidic ionic liquid as catalyst.