50743-01-6

3034-50-2

50743-01-6

General procedure for the synthesis of 5-bromo-1H-imidazole-4-carbaldehyde from 4-imidazolecarboxaldehyde: Anhydrous acetic anhydride (40 mL) solution of bromine (8.0 g, 50 mmol, 2.3 eq.) was added dropwise to a solution of 4-imidazolecarboxaldehyde (2.08 g, 21.7 mmol) and sodium acetate (18.7 g, 228 mmol, 10.5 eq.) in anhydrous acetic acid (200 mL) The dropwise addition to the solution in was controlled to be completed within 1 h at room temperature. The reaction mixture was continued to be stirred at room temperature for 2.5 hours, followed by concentration. The concentrated residue was partitioned with ether (200 mL) and water (200 mL), and after separating the layers, the aqueous layer was then extracted with ether (200 mL). All organic phases were combined, concentrated after drying and finally purified by column chromatography (eluent: ethyl acetate) to afford the target product 5-bromo-1H-imidazole-4-carboxaldehyde (1.00 g, 26% yield) as white crystals.