Hydrochloric Acid → (3-Ethylphenyl)boronic acid

Temperature

-70 °C

n-Butyllithium (11 ml of a 2.5M solution in hexane, 28 mmol) was added to a stirred solution of 3ethylbromobenzene (Chem. Pharm. Bull., 1968, 16, 2456; 4.6 g, 25 mmol) in anhydrous tetrahydrofuran (50 ml), whilst keeping the internal temperature below −60° C. The mixture was stirred at about −70° C. for 1 hour, then trimethylborate (4.4 ml, 38 mmol) added dropwise, again whilst keeping the internal temperature below −60° C. The reaction mixture was stirred at −70° C. for 30 minutes, then slowly allowed to warm to room temperature. 2M Hydrochloric acid was added, the mixture was extracted with dichloromethane (3×50 ml) and the combined extracts concentrated under reduced pressure The residue was dissolved in ether (50 ml), the solution extracted with 1M aqueous sodium hydroxide solution (2×30 ml) and the aqueous phase acidified with 2M hydrochloric acid, then extracted with ether (3×50 ml). The combined extracts were dried (MgSO4) and evaporated under reduced pressure to give the title compound as a white solid (0.9 g, 24%). δ(DMSOd6): 1.17 (t,3H), 2.57 (q,2H), 7.22 (t,2H), 7.57 (t,1H), 7.61 (s,1H), 7.93 (s,2H).

1. customthe internal temperature below −60° C
2. customthe internal temperature below −60° C
3. stirringThe reaction mixture was stirred at −70° C. for 30 minutes
4. temperatureto warm to room temperature
5. extractionthe mixture was extracted with dichloromethane (3×50 ml)
6. concentrationthe combined extracts concentrated under reduced pressure The residue
7. dissolutionwas dissolved in ether (50 ml)
8. extractionthe solution extracted with 1M aqueous sodium hydroxide solution (2×30 ml)
9. extractionextracted with ether (3×50 ml)
10. dry with materialThe combined extracts were dried (MgSO4)
11. customevaporated under reduced pressure

ORD record

ord-3e2a625a15244e998ca435854ec8639b

Source dataset

uspto-grants-2002_12

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US06495568B1