Boron tribromide → 3-Chloro-4,5-dihydroxybenzaldehyde

Participants

Reaction Conditions

Reaction Steps

To a solution 2.00 g (10.7 mmol) of benzaldehyde 12 in 20 mL of dichloromethane under argon at 0° C. was added 1.20 mL (11.8 mmol) of boron tribromide. The solution was stirred at 0° C. for 0.3 h and 25° C. for 4 h, diluted with 40 mL of methanol, and the solvents were removed on a rotary evaporator (the trimethylborate was removed). To it was added 40 mL of methanol and methanol and trimethyl borate were removed by evaporation on a rotary evaporator, and this process was repeated three times. The residue was diluted with dichloromethane and filtered and washed with a small amount of dichloromethane to give 1.722 g (94% yield) of pure 5-chloro-3,4-dihydroxybenzaldehyde. This material was used in next step without purification. 1H NMR (CDCl3) δ 10.43 (s, 2H, OH), 9.70 (s, 1H, CHO), 7.42 (d, J=2.0Hz, 1H, C6-H), 7.22 (d, J=2.0Hz, 1H, C2-H); 13C NMR (DMSO-d6) δ 190.6 (C═O), 148.3 (s), 146.9 (s), 128.4 (d), 124.2 (d), 120.3 (s), 112.5 (s).

Provenance & Evidence