Formic Acid → 6-bromo-1-phenyl-1H-benzo[d]imidazole

Participants

Reaction Steps

To a stirred mixture of 4-bromo-N2-phenyl-benzene-1,2-diamine (step A) (420 mg, 1.6 mmol) and trimethyl orthoformiate (4.8 g, 5 ml, 45.2 mmol), formic acid (1.2 g, 1 ml, 26.1 mmol) was added at room temperature, and afterwards the reaction mixture was allowed to stir at for 2 h under reflux conditions. The reaction mixture was cooled to room temperature, evaporated and extracted with ethyl acetate (2×40 ml). The combined organic layers were washed with sat. sodium bicarbonate solution (20 ml) and brine (20 ml), dried (MgSO4) and evaporated. The crude product (400 mg) was purified by flash chromatography on silica gel (heptane/ethyl acetate 3:2) to yield the title compound as an off-white solid (358 mg, 82%), MS (ISP) m/z=275.0 [(M+H)+].

Provenance & Evidence