Hydrogen Bromide → Methyl 4-(2-oxoacetyl)benzoate

Participants

Reaction Steps

To a solution of methyl 4-acetylbenzoate (1.00 g, 5.61 mmol) in DMSO (5 mL) was slowly added 40% HBr (1.5 mL) at 20° C. under stirring. The mixture was stirred at 60° C. for 12 hours. The mixture was diluted with water (10 mL) and the resulting mixture was extracted with DCM (10 mL×3), washed with brine, dried over anhydrous Na2SO4, filtered and concentrated in vacuo to give methyl 4-(2-oxoacetyl)benzoate (150 mg), which was taken forward without further purification. To a solution of 4-methoxybenzene-1,2-diamine (107 mg, 0.78 mmol) in 5 mL of acetic acid was added the crude methyl 4-(2-oxoacetyl)benzoate (150 mg). The mixture was refluxed for 2.5 hours. The solvent was removed in vacuo. The crude product was purified by prep-TLC (PE/EA: 1/1) to separate the desired methyl 4-(6-methoxyquinoxalin-2-yl)benzoate (more polar) from the undesired methyl 4-(7-methoxyquinoxalin-2-yl)benzoate. The two structures were confirmed by HMBC spectra.

Provenance & Evidence