Ammonia → 5-Bromo-1-cyclopropyl-1H-benzo[d]imidazol-7-ol

Participants

Reaction Conditions

Reaction Steps

5-bromo-1-cyclopropyl-7-methoxy-1H-benzo[d]imidazole (0.54 g, 2.01 mmol) was dissolved in dichloromethane (12 mL) under N2. A 1M BBr3 solution in DCM (12 mL, 12 mmol) was added dropwise over 1 min. The resulting stirred suspension was heated to 35° C. After 5 h, the reaction mixture was cooled in an ice water bath. A 7M ammonia in MeOH solution (7.5 mL, 53 mmol) was then added over 2 min via syringe. The mixture was stirred 5 min and was removed from the ice bath. After an additional 10 min, the mixture was concentrated in vacuo, and the crude product was dissolved in MeOH (30 mL) and was concentrated in vacuo. The resulting crude solids were suspended in 20% MeOH in DCM (30 mL) and were filter through a short pad of silica, eluting with 20% MeOH in DCM. Filtrate was concentrated in vacuo, and the crude product was adsorbed onto silica gel. Purification by silica gel chromatography (0-20% MeOH in DCM) gave 5-bromo-1-cyclopropyl-1H-benzo[d]imidazol-7-ol (2.73). LCMS-ES r (m/z): [m+H]+ calcd for C10H10BrN2O: 253.00; found: 253.14.

Provenance & Evidence