General procedure for the synthesis of 5-amino-1(2H)-isoquinolinone from 5-nitro-1(2H)-isoquinolinone: To a reaction flask was added 378.3 mg (1.51 mmol) of 5-nitroisoquinolin-1(2H)-one, 376.5 mg of ammonium chloride, 2.6 mL of water and a solvent mixture of 14 mL of ethanol and 5.4 mL of tetrahydrofuran. 1.23 g of zinc powder was added in batches at 30 to 35 °C and the reaction was stirred continuously for 2 hours. Upon completion of the reaction, the reaction mixture was filtered by pumping through a glass fiber filter and the filter cake was washed with ethyl acetate. The filtrates were combined and washed sequentially with water and saturated sodium chloride solution, and then the organic phase was treated as usual. Finally, the desiccant was removed by filtration and the solvent was removed by concentration under reduced pressure to afford 196.5 mg (88.1% yield) of the target product 5-amino-1(2H)-isoquinolinone. The product was characterized by 1H-NMR (300 MHz, DMSO-d6): δ=5.6 (2H), 6.68 (1H), 6.87-7.45 (1H), 7.00 (1H), 7.17 (1H), 7.39 (1H), 11.7 (1H).
