Triethylamine → 1H-Benzimidazole-5-carboxylic acid, 7-bromo-2,3-dihydro-2-oxo-, methyl ester

Participants

Reaction Steps

A solution of 3,4-diamino-5-bromobenzoate (1 g, 4.0 mmol) and triethylamine (0.4 g, 4.0 mmol) in dichloromethane (6 mL) was cooled to 0° C. A solution of triphosgene (1.2 g, 4.08 mmol) in dichloromethane (15 mL) was added to this solution. The reaction mixture was allowed to warm to ambient temperature and maintained for 18 hours. The reaction mass was quenched with water (3 mL) and extracted with ethyl acetate (3×10 mL). The combined organic layers were washed with aqueous saturated sodium chloride (50 mL), dried over anhydrous sodium sulfate and concentrated to obtain methyl 7-bromo-2-oxo-2,3-dihydro-1H-benzo[d]imidazole-5-carboxylate as an off-white solid (500 mg, 45%). 1HNMR (CDCl3+DMSO-d6): δ 11.35 (s, 1H), 11.05 (s, 1H), 7.75 (s, 1H), 7.52 (s, 1H) and 3.85 (s, 3H).

Provenance & Evidence