Hydrochloric Acid → (4-Bromophenyl)boronic acid

A solution of butyllithium (21.2 mmol, 15%, 13.3 ml) in hexane was slowly added to a solution of 1,4-dibromobenzene (21.2 mmol, 5.0 g) in ether (86 ml) at -40° C. under argon. The mixture was allowed to warm to room temperature and was stirred for further 2 h. The mixture was transferred into a solution of freshly distilled trimethyl borate (63.3 mmol, 7.2 ml) in ether (172 ml) at -60° C. under argon. The mixture was allowed to warm to room temperature and refluxed for further 20 h. Aqueous hydrochloric acid (2M, 127 ml) was added, and the aqueous phase was separated and extracted with ether (90 ml). The solvent was removed from the combined organic layers and petroleum ether was added. A colourless solid was recovered by filtration (ca 5 g). Further purification was carried out by column chromatography over silica (64 g), with toluene (200 ml) as an eluent to remove by-products. Elution with ether (300 ml) produced a pure product.(2.0 g, 48%); m.p. 282°-283° C., Rf (ether), 0.42; νmax (KBr, cm-1) 3020 (Ph), 1580 (Ph), 830 (Ph); δH (250 MHz, CDCl3) 4.63 (2H, s, OH), 7.64 (2H, d, J 6.6, 3,5-PhH), 8.05 (2H, d, J 6.6, 2,6-PhH).

1. temperatureto warm to room temperature
2. temperaturerefluxed for further 20 h
3. customthe aqueous phase was separated
4. extractionextracted with ether (90 ml)
5. customThe solvent was removed from the combined organic layers and petroleum ether
6. additionwas added
7. filtrationA colourless solid was recovered by filtration (ca 5 g)
8. customFurther purification
9. customto remove by-products
10. washElution with ether (300 ml)
11. customproduced a pure product

ORD record

ord-851f6fdaf7ef4a9fa2b594b7f08b59b9

Source dataset

uspto-grants-1997_08

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US05653914