Boron tribromide → 3,5-Difluoro-1,2-benzenediol

Temperature

-25 °C

3,5-Difluoro-2-methoxyphenol (1.0 g, 6.3 mmol, prepared as described in Jones, Lyn H.; Randall, Amy; Barba, Oscar; Selby, Matthew D., Organic & Biomolecular Chemistry 2007, 5, 3431-3433) was dissolved in dry dichloromethane (11 mL), cooled to −20 to −30° C. and treated in portions with boron tribromide (BBr3) solution in dichloromethane (1.0 M; 13 mL, 13 mmol). The cooling bath was removed and the mixture was stirred for 20 h at 20° C. The mixture was cooled to −30° C., treated in portions with water (3 mL) and then warmed to 20° C. 6 M HCl (10 mL) and ethyl acetate (30 mL) were added, and the mixture was stirred for 20 min to produce two clear phases. The aqueous phase was extracted with ethyl acetate (20 mL), and the combined organic phases were washed with saturated NaCl (10 mL), dried (Na2SO4) and rotary evaporated to give the title compound as an oil which solidified upon standing (720 mg, 78%): 1H NMR (400 MHz, CDCl3) δ 6.51 (ddd, J=9.5, 2.8, 2.1 Hz, 1H), 6.45 (ddd, J=10.3, 8.7, 2.9 Hz, 1H), 5.71 (s, 1H), 5.06 (s, 1H); 19F NMR (376 MHz, CDCl3) δ −119.56, −136.16; EIMS m/z 146.

1. customThe cooling bath was removed
2. temperatureThe mixture was cooled to −30° C.
3. additiontreated in portions with water (3 mL)
4. temperaturewarmed to 20° C
5. addition6 M HCl (10 mL) and ethyl acetate (30 mL) were added
6. stirringthe mixture was stirred for 20 min
7. customto produce two clear phases
8. extractionThe aqueous phase was extracted with ethyl acetate (20 mL)
9. washthe combined organic phases were washed with saturated NaCl (10 mL)
10. dry with materialdried (Na2SO4)
11. customrotary evaporated

ORD record

ord-56342368d9034fa0b5344ce8c78cc365

Source dataset

uspto-grants-2015_10

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US09149038B2