General procedure for the synthesis of 4-aminoisoindolin-1-one from 4-nitro-isoindolin-1-one: A mixture of 4-nitro-2,3-dihydro-1H-isoindolin-1-one (20 g), ammonium formate (35 g), and 7.5% Pd/C (0.6 g) in methanol (60 ml) was stirred for 2 hr at 35° C. The reaction was completed by filtration to remove the catalyst. After completion of the reaction, the Pd/C catalyst was removed by filtration and the filtrate was concentrated under reduced pressure. The residue was recrystallized by water to give 15.3 g of light yellow solid product in 92% yield. Melting point: 195.6-197°C. 1H-NMR (300 MHz, DMSO-d6) δ: 4.31 (s, 2H), 6.76 (d, 1H), 7.14 (t, 1H), 6.86 (d, 1H), 5.30 (s, 2H), 8.26 (s, 1H). 1H-NMR (300 MHz, DMSO-d6/D2O 1H-NMR (300MHz, DMSO-d6/D2O) δ: 4.14 (s, 2H), 6.79 (d, 1H), 6.93 (d, 1H), 7.16 (t, 1H) FAB (M + 1): 149 Elemental analysis: theoretical value (%): C 64.85, H 5.44, N 18.91; measured value (%): C 64.96, H 5.61, N 19.02. HPLC test conditions: Chromatography Column: Phenomenex Luna 5u C18 (250 mm×4.6 mm); Flow rate: 1.0 ml/min; Detection wavelength: 230 nm; Mobile phase: Acetonitrile/0.1% Phosphate=15/85 or Acetonitrile/0.01M Ammonium Acetate=10/90; Retention time of the target product: 3.580 min; 4.790 min. Purity of target product: 99.66%.
