Lithium Hydroxide → 2-bromo-1-methyl-1H-imidazole-5-carboxylic acid

Participants

Reaction Steps

To a suspension of methyl 2-bromo-1-methyl-1H-imidazole-5-carboxylate (2.18 g, 10 mmol) in tetrahydrofuran (60 mL) and water (6 mL) was added lithium hydroxide (0.72 mg, 30 mmol) and the reaction mixture was allowed to stir at room temperature for 2.5 h. The solvent was removed under reduced pressure and water was added followed by formic acid, the resulting precipitate was filtered, washed with water and dried under vacuum overnight to afford the 2-bromo-1-methyl-1H-imidazole-5-carboxylic acid (82%). 1H-NMR (300 MHz, CDCl3): 7.79 (s, 1H), 3.91 (s, 3H). LCMS (ESI+) 205.0 (MH+). To a solution of the carboxylic acid (1.68 g, 8.2 mmol) in anhydrous tetrahydrofuran (24 mL) was added EDC (1.53 g, 9.9 mmol) followed by HOBt (1.22 g, 9.1 mmol) and the reaction mixture was allowed to stir for 1 h at room temperature. A solution of pyrrolidine (1.03 ml, 12.4 mmol) in tetrahydrofuran (8 mL) was added and the reaction mixture was allowed to stir overnight at room temperature. The solvent was removed under reduced pressure and residue partitioned between ethyl acetate and 1 M aqueous potassium carbonate. The organic layer was dried (Na2SO4) and solvent evaporated under reduced pressure. Purification by flash column chromatography (silica, EtOAc/MeOH 9:1) afforded the title compound (95%). 1H NMR (300 MHz, CDCl3): 7.79 (s, 1H), 3.92 (s, 3H), δ 3.35 (bs, 4H), δ 1.97 (bs, 4H). LCMS (ESI+) 257.0 (MH+).

Provenance & Evidence