Cyanogen Bromide → 5-Bromo-1H-1,3-benzodiazol-2-amine

Participants

Reaction Steps

4-bromobenzene-1,2-diamine (1.02 g, 5.45 mmol) was taken into 50% aqueous methanol (25 mL) followed by slow addition of cyanogen bromide (1.73 g, 16.35 mmol) and the mixture was allowed to stir at room temperature over 12 h. The mixture was then concentrated to approximately 50% volume, diluted with water and brought to neutral pH by addition of 2 M aqueous sodium hydroxide. The aqueous mixture was then partitioned with ethyl acetate and the organic solution washed with brine, dried over anhydrous sodium sulfate, filtered and concentrated to give 6-bromo-1H-benzimidazol-2-amine (1.67 g) as a red amorphous residue. MS (EI) for C7H6BrN3: 213 (MH+).

Provenance & Evidence