[Synthesis]
General procedure for the synthesis of ethyl 2-bromo-5-nitrobenzoate from ethanol and 2-bromo-5-nitrobenzoic acid: To a solution of 2-bromo-5-nitrobenzoic acid (1.50 g, 6.12 mmol) in methylene chloride (10 mL) was added oxaloyl chloride (1.10 g, 12.24 mmol), and the resultant solution was stirred for 30 min at room temperature. The reaction mixture was concentrated and the residue was dissolved in ethanol and the resulting solution was continued to be stirred for 2 hours at room temperature. Subsequently, the reaction solution was concentrated and the residue was dissolved in ethyl acetate. Water was added to this solution and the organic layer was washed with brine, separated, dried, filtered and concentrated to give 1.0 g of the target product ethyl 2-bromo-5-nitrobenzoate. The structure of the product was confirmed by 1H NMR (300 MHz, DMSO-d6): δ 8.50 (d, J = 3.0 Hz, 1H), 8.27-8.23 (dd, J = 3.0, 8.7 Hz, 1H), 8.06-8.03 (d, J = 8.7 Hz, 1H), 4.41-4.34 (q, J = 6.9 Hz, 2H), 1.37 -1.32 (t, J = 7.2 Hz, 3H). |