15965-57-8

19190-68-2

15965-57-8

Step A: Synthesis of 2-chloro-4-methyl-1H-benzo[d]imidazole To 4-methyl-1H-benzo[d]imidazol-2(3H)-one (1.5 g, 10 mmol) was added trichlorophosphorus (POCl3, 19 mL). The reaction mixture was heated to 135 °C and kept for 3 hours. Upon completion of the reaction, the mixture was cooled to room temperature and the excess phosphorous trichloride was removed under vacuum. The residue was carefully diluted with water and subsequently slowly neutralized with saturated sodium bicarbonate (NaHCO3) solution to a pH of about 7-8. The mixture was extracted with ethyl acetate (2 x 150 mL) and the organic phases were combined. The organic phase was dried with anhydrous magnesium sulfate (MgSO4), filtered and concentrated under reduced pressure to give the crude product. The crude product was purified by fast column chromatography (Biotage system) to afford 2-chloro-7-methyl-1H-benzo[d]imidazole (1.1 g, 6.3 mmol, 62% yield) as a light yellow powder. Mass spectrum (LC/MS) retention time (R.T.) = 2.61 min; [M+H]+ = 166.93.