Hydrochloric Acid → 3,5-Dibromobenzeneboronic acid

To 9.44 g of 1,3,5-tribromobenzene in 200 mL of diethyl ether was added 19.4 mL of 1.55M n-butyllithium in hexane at -78° under nitrogen. The suspension was stirred for 30 min, then added to 30 mL of trimethyl borate in 300 mL of diethyl ether at the same temperature. The now clear solution was stirred at -78° for 30 min then warmed to room temperature overnight. Fifty mL of 1 N hydrochloric acid were added and allowed to react for 2 h. The aqueous layer was discarded and the ether layer was extracted with 2 N sodium hydroxide solution (5 times with 100 mL). The extract was washed once with 50 mL of ether, then acidified with 6N HCl to pH 2 at 0°. A white precipitate was collected by filtration after the solution had been kept at 0° for 2 h. After air drying, 8.49 g (95%) of the title product was obtained. Melting point was >300° and the purity was confirmed by chromatography.

1. stirringThe now clear solution was stirred at -78° for 30 min
2. customto react for 2 h
3. extractionthe ether layer was extracted with 2 N sodium hydroxide solution (5 times with 100 mL)
4. washThe extract was washed once with 50 mL of ether
5. customacidified with 6N HCl to pH 2 at 0°
6. filtrationA white precipitate was collected by filtration after the solution
7. waithad been kept at 0° for 2 h
8. customAfter air drying

ORD record

ord-e3b42ad2a75c4ae9ac652d1448d2643b

Source dataset

uspto-grants-1992_09

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US05145930