119825-27-3

107575-60-0

The experimental procedure for the synthesis of ethyl 6-amino-5-methoxyindole-2-carboxylate using pyrroloquinoline impurity 1 as starting material was as follows: the experiment was divided into six groups, each using a different sample solution of heteropolyacid as catalyst. The procedure was as follows: compound 6 (0.524 g, 2 mmol) and benzylamine (0.321 g, 0.328 ml, 3 mmol) were placed in a 10 ml flask, and heteropolyacid ionic liquids (0.04 mmol) were added as catalysts, respectively. The reaction mixture was heated by microwave heating at 140 °C for 90 min. After completion of the reaction, 20 ml of ethyl acetate was added to the mixture and stirred thoroughly for 30 minutes. Subsequently, the mixture was filtered and the filtrate was concentrated to dryness by evaporation and finally purified by recrystallization to obtain the target product compound 7.