Hydrochloric Acid → (5-Phenylthiophen-2-yl)boronic acid

n-Butyllithium (1.6M in hexanes) (24 ml, 38.1 mmol) was added drop wise to a solution of 2-phenylthiophene (6.1 g, 38.1 mmol) in anhydrous THF (150 ml), at 0° C., under nitrogen. The ice-bath was removed, and the mixture heated to reflux for 20 min. After cooling, the reaction mixture was added drop wise to a solution of trimethyl borate (8.7 ml, 76.25 mmol) in anhydrous THF (100 ml), at −78° C., under nitrogen. This was allowed to warm to room temperature overnight, then was acidified with concentrated HCl, stirred for 1 h, then extracted with Et2O (3×100 ml). The combined extracts were washed with water (2×100 ml), dried (Na2SO4), and the solvent removed. The resulting grey solid was recrystallised from ethanol/water (50:50), then dissolved in aqueous NaOH (2M, 500 ml), Et2O (250 ml) added, the aqueous layer precipitated with concentrated HCl, extracted with Et2O (300 ml), dried (Na2SO4) and the solvent removed under pressure to give the title compound (2.72 g, 35%) as an off white solid.

1. customat 0° C.
2. customThe ice-bath was removed
3. temperaturethe mixture heated
4. temperatureto reflux for 20 min
5. temperatureAfter cooling
6. customat −78° C.
7. extractionextracted with Et2O (3×100 ml)
8. washThe combined extracts were washed with water (2×100 ml)
9. dry with materialdried (Na2SO4)
10. customthe solvent removed
11. customThe resulting grey solid was recrystallised from ethanol/water (50:50)
12. dissolutiondissolved in aqueous NaOH (2M, 500 ml)
13. additionEt2O (250 ml) added
14. customthe aqueous layer precipitated with concentrated HCl
15. extractionextracted with Et2O (300 ml)
16. dry with materialdried (Na2SO4)
17. customthe solvent removed under pressure

ORD record

ord-5f4801cefec1482cb9c90576be8281b5

Source dataset

uspto-grants-2014_04

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US08703978B2