Hydrogen Bromide → 7-amino-4-bromo-9H-carbazole-1-carboxamide hydrobromide

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Reaction Steps

A suspension of benzyl 5-bromo-8-carbamoyl-9H-carbazol-2-ylcarbamate (Example 50-3, 2.18 g, 4.97 mmol) in hydrogen bromide (30-35% in acetic acid, 11.9 mL, 59.7 mmol) was stirred at rt for 30 min. The mixture was diluted with ether (100 mL) and the precipitate was collected by filtration, washed with ether and dried to provide 7-amino-4-bromo-9H-carbazole-1-carboxamide, hydrobromide salt, as a light yellow solid (2.20 g). 1H NMR (400 MHz, DMSO-d6) δ 12.02 (1H, s), 8.69 (1H, d, J=8.5 Hz), 8.28 (1H, br. s.), 7.91 (1H, d, J=8.0 Hz), 7.84 (1H, d, J=1.8 Hz), 7.65 (1 H, br. s.), 7.51 (1H, d, J=8.3 Hz), 7.25 (1H, dd, J=8.4, 1.9 Hz). Mass spectrum m/z 304, 306 (M+H)+. The salt was partitioned between EtOAc and NaHCO3 (aq). Residual solid was collected by filtration, washed with EtOAc and water and dried. The organic phase of the filtrate was separated, washed with brine, and dried and concentrated. The solid residue was combined with the filtered solid, dissolved in acetone, filtered to remove undissolved solid, and the filtrate was concentrated to provide 7-amino-4-bromo-9H-carbazole-1-carboxamide, hydrobromide salt, as a light yellow solid (1.62 g, 96%).

Provenance & Evidence