A diversity-oriented synthesis of pyrazolo[4,3-f]quinoline derivatives with potential bioactivities via microwave-assisted multi-component reactions

Six new series of pyrazolo[4,3-f]quinoline derivatives with potential bioactivities were synthesized by the three-component reactions of aromatic aldehydes, 5-aminoindazole, and various cyclic 1,3-dicarbonyl compounds under microwave irradiation. This protocol has the valuable features of structural diversity of products, broader substrate scope, operational simplicity, high yields, and short reaction time. Moreover, the structure of compound 88a was confirmed by an X-ray crystallographic analysis and attested to the chemoselectivity of reaction where 1-methyl barbituric acid participated.