A series of 1,6-dihydropyrrolo[2,3-g]indazole derivatives have been obtained by a three-component domino reaction of 1H-indazol-6-amine, arylglyoxal monohydrates, and cyclic 1,3-dicarbonyl compounds in ethanol medium at 60°C catalyzed by acetic acid. The notable features of this synthesis are excellent regioselectivity, operational simplicity, relative mild reaction conditions, and good yields.

A new series of pyrazino[2,3‐a]acridine derivatives were prepared, via three‐component reaction of quinoxalin‐6‐amine, aromatic aldehydes and 5,5‐dimethyl cyclohexane‐1,3‐dione or cyclohexane‐1,3‐dione in ethanol as a solvent at reflux. The advantages of this protocol include mild reaction conditions, easy purification, high yields, and catalyst‐free approach.

An efficient procedure for the synthesis of novel spiro[indoline‐3,11′‐pyrazolo[3,4‐f]pyrimido[4,5‐b]quinoline] derivatives has been developed by one‐pot condensation of 1H‐indazol‐6‐amine, isatin and barbituric acid or 2‐thiobarbituric acid, in the presence of L‐proline in refluxing EtOH. This method has the advantages of operational simplicity, high yield of products via a simple experimental and work‐up procedure. IR, 1H NMR, 13C NMR, 19F NMR and HRMS were used to identify the structures of all the synthesized compounds.

A concise and efficient synthetic approach was developed for the synthesis of functionalized 2,3‐disubstituted 1,6‐dihydropyrrolo[2,3‐g]indazole via a one‐pot, three‐component reaction of 1H‐indazol‐6‐amine, arylglyoxal monohydrates, and 4‐hydroxy‐2H‐chromen‐2‐one or 4‐hydroxyquinolin‐2(1H)‐one promoted by acetic acid in ethanol under reflux conditions. The attractive features of this protocol are operational simplicity, short reaction time, easy purification of products, and good to excellent yields.

An efficient and novel method for the synthesis of pyrazolo[3,4-f]quinoline derivatives by an efficient in situ reduction and cyclization reaction of 6-nitro-1H-indazole, aromatic aldehydes, and 4-hydroxy-2H-chromen-2-one or barbituric acid has been developed. Compared with amino compounds, nitro compounds are easier to obtain and more stable. The synthesis was achieved by using a multicomponent procedure under Fe/H 2 O medium. The advantages of this method are mild conditions, operational simplicity, high yields, and wide range of substrates.