Hydrochloric Acid → 4-bromo-1-(3-chloro-2-methylbenzyl)-2-(difluoromethyl)-1H-benzo[d]imidazol-6-amine

Participants

Reaction Steps

To a 250 mL rb flask containing MeOH (50 mL) was added 4-bromo-1-(3-chloro-2-methylbenzyl)-2-(difluoromethyl)-6-nitro-1H-benzo[d]imidazole (4.0 g, 9.29 mmol), tin(II) chloride dihydrate (12.58 g, 55.7 mmol) and concentrated hydrochloric acid (6.97 ml, 84 mmol). The resultant suspension was heated to 50° C. and monitored by LC/MS. By LC/MS the reaction was complete in 45 minutes. After the reaction had cooled to room temperature and was filtered to remove insoluble tin salts, 6N NaOH (0.8 ml, 4.00 mmol) was added to adjust the pH to about 11 and the mixture was concentrated to remove any MeOH. The sticky mixture was extracted with EtOAC; however, because it was difficult to extract from the tin-salt containing aqueous the entire mixture of two phases was filtered then the layers were separated. The organic was dried over MgSO4 and concentrated in vacuo to provide and the organic was washed with H2O and brine and dried over MgSO4 and filtered. The solvent was removed in-vacuo leaving light brown solid 4-bromo-1-(3-chloro-2-methylbenzyl)-2-(difluoromethyl)-1H-benzo[d]imidazol-6-amine (2.25 g, 5.62 mmol, 60.5% yield) as crude material. LC/MS: MS (ES+) m/e 402.4 [M+H]+; 1H NMR (400 MHz, CHLOROFORM-d) δ ppm 7.33 (d, J=7.83 Hz, 1H), 6.80-7.13 (m, 3H), 6.33 (d, J=7.83 Hz, 1H), 6.25 (d, J=2.02 Hz, 1H), 5.46 (s, 2H), 3.81 (s, 2H), 2.49 (s, 3H)

Provenance & Evidence