Combinatorial Synthesis of Pyrazoloquinoline and Pyrazoloacridine Derivatives with High Regioselectivity

Three-component reaction of aldehyde, 1H-indazol-6-amine and 1,3-dicarbonyl compounds in EtOH under catalyst-free conditions, generates the corresponding pyrazolo[3,4-a]acridine, cyclopenta[b]pyrazolo[3,4-f]quinoline, indeno[1,2-b]pyrazolo[3,4-f]quinoline and benzo[h]pyrazolo[3,4-a]acridine derivatives in high yields and regioselectivity, respectively. The dicarbonyl compounds include 5,5-dimethylcyclohexane-1,3-dione, cyclopentane-1,3-dione, 2H-indene- 1,3-dione and 2-hydroxynaphthalene-1,4-dione.