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

Temperature

25 °C

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).

1. customthe solvents were removed on a rotary evaporator (the trimethylborate
2. customwas removed)
3. additionTo it was added 40 mL of methanol and methanol and trimethyl borate
4. customwere removed by evaporation on a rotary evaporator
5. additionThe residue was diluted with dichloromethane
6. filtrationfiltered
7. washwashed with a small amount of dichloromethane

ORD record

ord-3b235bc7739d417cb7bb5a86fb37d370

Source dataset

uspto-grants-2004_04

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US06727277B1