GENERAL METHOD: To an anhydrous ethanol solution of 3-cyanoindole (15 mmol) was added 40% aqueous NaOH (5 mL) under stirring conditions. The reaction process was monitored by thin layer chromatography (TLC). Subsequently, 30% aqueous H2O2 solution (10.5 mL, 104.7 mmol) was slowly added dropwise to the reaction mixture. Upon completion of the reaction, the precipitated solid was collected by filtration, washed with water and recrystallized with anhydrous ethanol. Finally, the product was dried under vacuum to give 1H-indole-3-carboxamide (20a). The product was a white solid in 75% yield with a melting point of 195-197 °C (literature value 197-199 °C [31]).1H NMR (δ, ppm): 6.84 (s, 1H, NH), 7.13-7.21 (m, 2H, ArH), 7.47 (d, J = 8.0 Hz, 2H, ArH), 8.08 (s, 1H, NH), 8.20 (d, J = 7.5 Hz, 1H, ArH), 11.60 (s, 1H, NH).
