Dimethyl Ether → (2-Hydroxy-5-(trifluoromethyl)phenyl)boronic acid

Temperatur

0 °C

To a suspension of 2-methoxy-5-(trifluoromethyl)phenylboronic acid (24.93 g, 0.1133 mol) in dichloromethane (150 mL) cooled to 0° C. was added dropwise boron tribromide (11.0 mL, 0.116 mol) over 30 minutes. After stirring for 5 hours, more boron tribromide (2.0 mL, 0.021 mol) was added. After stirring for 2 more hours, the reaction mixture was added to ice water and stirred for 20 minutes. The resulting white precipitate was filtered and washed with water to give a white solid that contained product. The layers of the filtrate were separated and extracted with dichloromethane (2×). The combined organics were dried over anhydrous magnesium sulfate, filtered, and concentrated to give a white solid which also contained product. It was determined by NMR that there was some methyl ether remaining, so all the material recovered was suspended in dichloromethane (100 mL) and cooled to 0° C. To this was added boron tribromide (7.0 mL, 0.074 mol) dropwise over 10 minutes and then boron tribromide (1M in dichloromethane, 11.0 mL, 0.0110 mol) dropwise over 10 minutes. After stirring for 5 hours, the reaction was complete as indicated by TLC. The reaction mixture was added to ice water, filtered, and washed with water to provide product (15.24 g, 65%) as a white solid. The layers of the filtrate were separated and extracted with dichloromethane (2×) and 4:1 dichloromethane:isopropyl alcohol. The combined organics were dried over anhydrous magnesium sulfate, filtered, and concentrated to give additional product (5.7 g, 24%) as a white solid.

1. stirringAfter stirring for 2 more hours
2. stirringstirred for 20 minutes
3. filtrationThe resulting white precipitate was filtered
4. washwashed with water
5. customto give a white solid
6. customThe layers of the filtrate were separated
7. extractionextracted with dichloromethane (2×)
8. dry with materialThe combined organics were dried over anhydrous magnesium sulfate
9. filtrationfiltered
10. concentrationconcentrated
11. customto give a white solid which also contained product
12. customso all the material recovered
13. temperaturecooled to 0° C
14. stirringAfter stirring for 5 hours
15. filtrationfiltered
16. washwashed with water

ORD-Eintrag

ord-5f99de60ab4949e690dd087fa3144473

Quelldatensatz

uspto-grants-2013_09

DOI

10.6084/m9.figshare.5104873.v1

Patentnummer

US08541588B2