Hydrogen Peroxide → 6-Chloro-2-fluoropyridin-3-ol

Temperature

0 °C

A solution of i-Pr2NH (828 mL, 5.85 mol) in anhydrous THF (1.3 L) was cooled to −10° C. n-BuLi (1.6 M in hexanes, 3660 mL, 5.85 mol) was added and the solution was stirred for 10 min at 0° C. The reaction mixture was cooled to −78° C. and a solution of 2-chloro-6-fluoropyridine (700 g, 5.32 mol) in anhydrous THF (1.3 L) was slowly added keeping the internal temperature below −60° C. After the addition was complete, the reaction mixture was stirred for an additional hour and then a solution of triisopropyl borate (1221 mL, 5.32 mol) in anhydrous THF (620 mL) was added drop wise keeping the internal temperature below −60° C. After the addition, the reaction mixture was warmed to RT and stirred over night. Water (3 L) was added and the mixture was stirred vigorously. The reaction mixture was concentrated under reduced pressure. The residue was treated with a cold aqueous solution of NaOH (10 M, 1610 mL, 16.0 mol) and 50% H2O2 (392 mL, 6.92 mol) and stirred over night (Note: the internal temperature increased slowly from 5 to 60° C.). The reaction mixture was quenched with ice and 4N HCl until pH of the mixture was ˜5. EtOAc (5 L) was added and stirred well. After phase separation, the aqueous layer was extracted with EtOAc (1.5 L×2). The combined organic layers were washed with brine, dried over anhydrous Na2SO4, and concentrated under reduced pressure to provide 6-chloro-2-fluoropyridin-3-ol as an off white solid.

1. additionwas added
2. temperatureThe reaction mixture was cooled to −78° C.
3. customthe internal temperature below −60° C
4. additionAfter the addition
5. stirringthe reaction mixture was stirred for an additional hour
6. customthe internal temperature below −60° C
7. additionAfter the addition
8. temperaturethe reaction mixture was warmed to RT
9. stirringstirred over night
10. stirringthe mixture was stirred vigorously
11. concentrationThe reaction mixture was concentrated under reduced pressure
12. stirringstirred over night (
13. temperaturethe internal temperature increased slowly from 5 to 60° C.)
14. customThe reaction mixture was quenched with ice and 4N HCl until pH of the mixture
15. additionEtOAc (5 L) was added
16. stirringstirred well
17. customAfter phase separation
18. extractionthe aqueous layer was extracted with EtOAc (1.5 L×2)
19. washThe combined organic layers were washed with brine
20. dry with materialdried over anhydrous Na2SO4
21. concentrationconcentrated under reduced pressure

ORD record

ord-bbb760b349f74d81bdf243cabb90f0b1

Source dataset

uspto-grants-2016_03

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US09296759B2