N-bromobutanimide → Methyl 6-((4-bromo-2-chlorophenyl)amino)-7-fluoro-1H-benzo[d]imidazole-5-carboxylate

Participants

Reaction Conditions

Reaction Steps

6-(2-Chloro-phenylamino)-7-fluoro-3H-benzoimidazole-5-carboxylic acid methyl ester 7b (55 mg, 0.172 mmol) is dissolved in 1:1 THF/MeOH (2 mL) and cooled to −78° C. under an atmosphere of nitrogen. TsOH.H2O (49 mg, 0.258 mmol) is added followed by NBS (31 mg, 0.174 mmol). After 10 minutes, the reaction mixture is warmed to 0° C. and then 2 hours later warmed to room temperature. After 16 hours, the reaction mixture is quenched by the addition of 10% Na2S2O3 and diluted with ethyl acetate and water. The layers are separated and the aqueous layer is extracted with ethyl acetate. The combined organic extracts are dried (MgSO4) and concentrated under reduced pressure. The crude product is triturated with methylene chloride to give 58 mg (85%) of pure desired product as a tan solid.

Provenance & Evidence