Hydrochloric Acid → (5-Bromo-2-methylphenyl)boronic acid

Temperature

-78 °C

To a solution of 2-methyl-5-bromo-iodobenzene (12 g, 40.4 mmol) in tetrahydrofuran (75 ml), cooled to −78° C., was added a solution of isopropylmagnesium chloride (4.6 g, 44.5 mmol) in tetrahydrofuran (22.2 ml) dropwise over 20 minutes. After stirring at −78° C. for 30 minutes, the mixture was warmed slowly to −20° C. and stirred for 1 hour. After cooling again to −78° C., trimethylborate (8.4 g, 80.8 mmol) was added dropwise. After warming to 0° C., the mixture was stirred for 2 hours, treated with 1 M hydrochloric acid (35 ml), and extracted with ethyl acetate (2×50 ml). The combined extracts were washed with water (50 ml), dried over sodium sulfate, and concentrated under reduced pressure. The residual solid was suspended in hexane (50 ml), filtered, washed with hexane (30 ml) and dried under reduced pressure to provide 2-methyl-5-bromo-phenylboronic acid (7.32 g, 84% yield) as a white solid. 1H NMR (DMSO-d6) δ 7.92 (s, 1H), 7.46 (d, J=8.1 Hz, 1H), 7.13 (d, J=8.1 Hz, 1H), 2.59 (s, 3H).

1. temperaturethe mixture was warmed slowly to −20° C.
2. stirringstirred for 1 hour
3. temperatureAfter cooling again to −78° C.
4. temperatureAfter warming to 0° C.
5. stirringthe mixture was stirred for 2 hours
6. extractionextracted with ethyl acetate (2×50 ml)
7. washThe combined extracts were washed with water (50 ml)
8. dry with materialdried over sodium sulfate
9. concentrationconcentrated under reduced pressure
10. filtrationfiltered
11. washwashed with hexane (30 ml)
12. customdried under reduced pressure

ORD record

ord-19ea2f73420e4be0b4efc8764e85e883

Source dataset

uspto-grants-2008_09

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US07419984B2