General procedure for the synthesis of 5-amino-6-bromo-2,3-dihydro-1H-inden-1-one from N-(6-bromo-1-oxo-2,3-dihydro-1H-inden-5-yl)acetamide: N-(6-bromo-1-oxo-2,3-dihydro-1H-inden-5-yl)acetamide (13.1 g, 48.9 mmol) was reacted with 6 M aqueous hydrochloric acid solution (260 mL. 1.560 mol) were mixed and the reaction was stirred at 100 °C for 1 hour. After completion of the reaction, the reaction solution was cooled to 0 °C and the pH was adjusted to 8 with 10 M aqueous sodium hydroxide.The precipitated solid was collected by filtration, washed with water and dried in vacuum to afford the light brown powdery product 5-amino-6-bromo-2,3-dihydro-1H-inden-1-one (10.8 g, 98% yield). The structure of the product was confirmed by 1H NMR (400 MHz, CDCl3): δ 7.86 (s, 1H), 6.74 (s, 1H), 4.68 (s, 2H), 2.98 (t, J = 6.0 Hz, 2H), 2.64 (t, J = 6.0 Hz, 2H).
