Synthesis of Tricyclic Quinoline Derivatives from 5- and 6-Aminoindazoles and 5-Aminoindole under Conventional Way and Microwave System

Targeted tricyclic quinolines were prepared from the corresponding aminoindazolic and indolic derivatives as starting materials using two comparative methods; conventional heating and microwave irradiation. We noticed that the syntheses of 5-amino-1-methylindazole and 5-aminoindole were abandoned due to their conversion to fluorescent products one week after free contact with air and acetone. As a result of this finding, we decided to condense the relevant amine with acetone or mesityl oxide to confirm our hypothesis. We show that the amine is converted to the derived quinoline through these condensation processes. Subsequently, this reaction was extended to the aminoindazole derivatives of positions 5 and 6, yielding the appropriate quinoline derivatives. Similarly, 5-aminoindole exhibited the same reactivity. By applying the corresponding NMR and centesimal techniques, the resulting structures were identified.