General procedure for the synthesis of 6-amino-isoindolin-1-one from 6-nitro-isoindolin-1-one: A suspension of intermediate 6B (1.6 g, 8.98 mmol) and Pd/C (0.18 g) in methanol (100 mL) was stirred for 4 hr under hydrogen (1 atm) atmosphere. After completion of the reaction, the reaction mixture was filtered and the filter cake was washed with methanol. After combining the filtrates, the solvent was removed by concentration under reduced pressure. The crude product was ground with methanol (10 mL) and subsequently dried under reduced pressure to afford intermediate 6 (800 mg, 5.40 mmol, 60.1% yield) as a beige solid. The structure of the product was confirmed by 1H NMR (400 MHz, DMSO-d6): δ 4.15 (s, 2H), 5.26 (s, 2H), 6.77 (dd, J = 8.25, 2.20 Hz, 1H), 6.80 (s, 1H), 7.16 (d, J = 8.79 Hz, 1H), 8.29 (s, 1H). The mass spectrum (ESI) showed m/z 149.2 ([M + H]+).
