4-bromo-5-methoxybenzene-1,2-diamine

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: To a stirred mixture of 4-bromo-5-methoxybenzene-1,2-diamine (3.8 g, 18 mmol) from Step 1 of this Example and triethyl orthoformate (50 mL) was added formic acid (1 mL). The mixture was heated at reflux for 3 h, then concentrated under reduced pressure. The residue was partitioned between EtOAc (200 mL) and a 1 N aq Na2CO3 (100 mL). The EtOAc layer was separated, washed with brine (100 mL), dried over Na2SO4, filtered, and concentrated under reduced pressure to afford 5-bromo-6-methoxy-1H-benzo[d]imidazole (4.0 g) as a brown oil. The material was used in the next step without further purification. LCMS (ESI) m/z 228 and 230 (M+H)+. The mixture was heated at reflux for 3 h concentrated under reduced pressure The residue was partitioned between EtOAc (200 mL) The EtOAc layer was separated washed with brine (100 mL) dried over Na2SO4 filtered concentrated under reduced pressure

Conditions: temp:0.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: To a stirred mixture of 4-bromo-5-methoxy-2-nitroaniline (5 g, 20 mmol) in MeOH (50 mL) and HOAc (20 mL) at 0° C. under argon was added zinc powder (5.3 g, 80 mmol) portionwise. The mixture was stirred for 2 h, then filtered, and the filtrate was cooled to 0° C. The pH of the filtrate was adjusted to pH˜9 by addition of solid Na2CO3. The mixture was then partitioned between EtOAc (250 mL) and water (200 mL). The EtOAc layer was separated, dried over Na2SO4, filtered, and concentrated under reduced pressure to afford 4-bromo-5-methoxybenzene-1,2-diamine (3.8 g, 88%) as a dark purple solid. The material was used in the next step without further purification. 1H NMR (300 MHz, DMSO-d6) δ 6.66 (s, 1H), 6.34 (s, 1H), 4.08-4.83 (m, 4H), 3.63 (s, 3H). LCMS (ESI) m/z 217 and 219 (M+H)+. filtered The pH of the filtrate was adjusted to pH˜9 by addition of solid Na2CO3 The mixture was then partitioned between EtOAc (250 mL) and water (200 mL) The EtOAc layer was separated dried over Na2SO4 filtered concentrated under reduced pressure