Trimethyl borate → 5-Bromo-2-chlorophenylboronic acid

4-Bromo-1-chloro-2-iodobenzene (10.35 g, 33 mmol) is dissolved in anhydrous tetrahydrofuran (60 ml) and the solution is cooled to −75° C. under an atmosphere of argon. Isopropylmagnesium chloride (17.1 ml, 34 mmol, 2M solution in tetrahydrofuran) is added dropwise over 30 minutes, maintaining the internal temperature below −70° C. by external cooling. Once the addition is complete, the reaction mixture is stirred at approximately −70° C. for 30 minutes and then allowed to warm to room temperature and stirred for 1 hour. The reaction mixture is then cooled to −78° C. and trimethyl borate (7.3 ml, 65 mmol) is added dropwise. The mixture is stirred at −78° C. for 30 minutes and then the cooling bath is removed and the mixture is stirred at room temperature for 1.5 hours. 2M Aqueous hydrochloric acid (30 ml) is added, and the crude product is extracted with ethyl acetate. The organic phase is washed with water and brine, dried over anhydrous magnesium sulfate, filtered and the filtrate evaporated in vacuo. Trituration with hexane gives 5-bromo-2-chlorophenylboronic acid (6.16 g) as an off-white solid.

1. temperaturemaintaining the internal temperature below −70° C. by external cooling
2. additionOnce the addition
3. temperatureto warm to room temperature
4. stirringstirred for 1 hour
5. temperatureThe reaction mixture is then cooled to −78° C.
6. stirringThe mixture is stirred at −78° C. for 30 minutes
7. customthe cooling bath is removed
8. stirringthe mixture is stirred at room temperature for 1.5 hours
9. addition2M Aqueous hydrochloric acid (30 ml) is added
10. extractionthe crude product is extracted with ethyl acetate
11. washThe organic phase is washed with water and brine
12. dry with materialdried over anhydrous magnesium sulfate
13. filtrationfiltered
14. customthe filtrate evaporated in vacuo

ORD record

ord-32389e2238464edc91c2cbfc2098ed62

Source dataset

uspto-grants-2014_09

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US08828908B2