To a tetrahydrofuran (THF, 180 mL) solution of diisopropylamine (iPr2NH, 21.2 mL, 150 mmol) was slowly added n-butyllithium (n-BuLi, 1.6 M, 94 mL, 150 mmol) at 0 °C. The reaction mixture was stirred at 0 °C for 30 min and then cooled to -78 °C. Subsequently, a solution of 1,3-dibromobenzene (17.6 g, 74.6 mmol) in THF (80 mL) was slowly added over 20 min. The mixture was continued to be stirred at -78 °C for 30 min and then N,N-dimethylformamide (DMF, 11.6 mL, 150 mmol) was added. The reaction mixture was stirred at -78 °C for 1 h. The reaction was quenched with 2.5 M sulfuric acid (H2SO4, 350 mL) and extracted with a solvent mixture of ethyl acetate/ether (50/50, 3 x 300 mL). The organic phases were combined, dried with anhydrous magnesium sulfate (MgSO4), filtered and the filtrate was concentrated to give 2,6-dibromobenzaldehyde (17.6 g, 89% yield). The product was characterized by 1H NMR (250 MHz, CDCl3): δ 10.3 (s, 1H), 7.65 (d, J = 8.0 Hz, 2H), 7.23 (t, J = 8.1 Hz, 1H).
