General procedure for the synthesis of 3-bromo-2-fluorobenzaldehyde from (3-bromo-2-fluorophenyl)methanol: Manganese dioxide (9.32 g, 107.31 mmol) was added to a solution of dichloromethane (50 mL) containing (3-bromo-2-fluorophenyl)methanol (2.750 g, 13.413 mmol). The reaction mixture was stirred at 45°C overnight. Upon completion of the reaction, the mixture was filtered through diatomaceous earth and the filter cake was washed with dichloromethane. The filtrate was collected and concentrated under reduced pressure to give 3-bromo-2-fluorobenzaldehyde as a white solid (2.24 g, 83% yield). The product was characterized by 1H NMR (400 MHz, DMSO-d6): δ10.19 (dt, J=1.3,0.7 Hz, 1H), 8.05 (tdd, J=6.8,3.1,1.5 Hz, 1H), 7.85 (ddt, J=7.9,6.4,1.5 Hz, 1H), 7.37 (tdt, J=7.8,1.6, 1H). 0.8 Hz, 1H).
