5-Bromo-1-methyl-1H-benzo[d]imidazole

122-51-0

69038-76-2

53484-15-4

To a solution of triethyl orthoformate (10 mL) of 4-bromo-N'-methylbenzene-1,2-diamine (1.7 g, 8 mmol) was added p-toluenesulfonic acid monohydrate (PTSA-H2O, 152 mg, 0.8 mmol). The reaction mixture was stirred at 85 °C for 2 hours. After completion of the reaction, the mixture was poured into water (50 mL) and extracted with ethyl acetate (EA, 40 mL × 2). The organic layers were combined, dried with anhydrous sodium sulfate (Na2SO4), filtered and concentrated under reduced pressure. The crude product was purified by silica gel column chromatography (eluent: petroleum ether/ethyl acetate = 50/1 to 10/1) to afford 5-bromo-1-methyl-1H-benzo[d]imidazole (1.5 g, 89% yield) as a yellow solid.LC-MS m/z: 211.1 [M + H]+. Retention time (tR) = 1.90 min.