Boron tribromide → 4-Fluoro-2,3-dihydroxybenzaldehyde

Temperature

-78 °C

To a solution at −78° C. of 2,3-dimethoxy-4-fluorobenzaldehyde (7.0 g, 38.0 mmol) in dry dichloromethane (150 mL) was added dropwise BBr3 (23.8 g, 95.0 mmol) in dichloromethane (30 mL). Reaction mixture was allowed to attain room temperature and stirred for 18 h. Then reaction mixture was cooled to −78° C., and quenched with a mixture of methanol (10 mL) and water (50 mL) and stirred at room temperature for 30 min. Precipitated solid was separated by filtration and washed with cold dichloromethane. Dichloromethane layer was concentrated to yield the title compound as a solid (5.2 g, 88%). 1H NMR (400 MHz, CHLOROFORM-d) δ ppm: 11.38 (s, 1H), 9.84 (s, 1H), 7.15 (dd, J=8.6, 5.5 Hz, 1H), 6.81 (t, J=9.4 Hz, 1H), 5.47 (s, 1H); MS (ESI) m/z=155 (M−1, negative).

1. customReaction mixture
2. customto attain room temperature
3. customThen reaction mixture
4. customquenched with a mixture of methanol (10 mL) and water (50 mL)
5. stirringstirred at room temperature for 30 min
6. customPrecipitated solid
7. customwas separated by filtration
8. washwashed with cold dichloromethane
9. concentrationDichloromethane layer was concentrated

ORD record

ord-371f926d4f8d45c1a3a58391eead2d27

Source dataset

uspto-grants-2014_04

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US08703742B2