General procedure for the synthesis of 7-bromo-3,4-dihydro-2H-isoquinolin-1-one from 6-bromoindanone: preparation of intermediate 23-1 (7-bromo-3,4-dihydroisoquinolin-1(2H)-one). Sodium azide (0.431 g, 6.63 mmol) was slowly added to a solution of 6-bromo-2,3-dihydro-1H-inden-1-one (1 g, 4.74 mmol) and methanesulfonic acid (15 mL, 231 mmol) in dichloromethane (30 mL) at 0 °C. The reaction mixture was stirred for 15 h at room temperature and then carefully quenched with 1 M aqueous sodium hydroxide solution (50 mL). The aqueous layer was extracted with dichloromethane (3 x 50 mL) and the combined organic layers were washed sequentially with water (20 mL) and brine (20 mL), dried over anhydrous sodium sulfate and concentrated. The residue was purified by column chromatography using a 90:10 gradient elution of hexane-ethyl acetate to pure ethyl acetate to afford 7-bromo-3,4-dihydroisoquinolin-1(2H)-one as a white solid (650 mg, 61% yield). The product was confirmed by 1H NMR (400 MHz, chloroform-d): δ 8.35 (1H, br.s.), 7.08-7.17 (1H, m), 6.98-7.06 (1H, m), 6.95 (1H, d, J=1.98 Hz), 2.93 (2H, t, J=7.59 Hz), 2.49-2.68 (2H, m). Mass spectral analysis showed m/z 226,228 (M+H)+.
