Iodine → (4-Fluoro-2-methylphenyl)boronic acid

To dry magnesium (113 g, 46.4 mmol) in 25 mL THF was added a small amount of 1,2-dibromoethane (2 drops) and iodine (2crystals). 1-Bromo-4-fluoro-2-methylbenzene (4.95 mL, 39.15 mmol) was added the resulting solution was refluxed for 4 h. The solution was cooled to RT and transferred by syringe to a solution of trimethylborate (4.5 mL, 40 mmol) in 20 mL THF at −78° C. The solution was warmed to RT and stirred for 2 days. Water (200 mL) was added and the mixture was concentrated (to remove most of the organics). The mixture was then treated with 2N HCl (200 mL) and stirred 2 hrs. The suspension was extracted with ethyl ether, dried over MgSO4, filtered and concentrated to give 2-methyl-4-fluoro-phenylboronic acid. LC1: 1.72 min.

1. temperaturewas refluxed for 4 h
2. temperatureThe solution was warmed to RT
3. concentrationthe mixture was concentrated (
4. customto remove most of the organics)
5. additionThe mixture was then treated with 2N HCl (200 mL)
6. stirringstirred 2 hrs
7. extractionThe suspension was extracted with ethyl ether
8. dry with materialdried over MgSO4
9. filtrationfiltered
10. concentrationconcentrated

ORD record

ord-c7fae732d76c4a3dad9f0f48169dab72

Source dataset

uspto-grants-2004_10

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US06809199B2