Hydrochloric Acid → 2-Chloro-4-fluorobenzeneboronic acid

To 1.05 g Mg in THF (20 mL) was added catalytic I2 and then a 1 mL portion of the 2-Chloro-4-fluoro-iodobenzene (10 g total, 39 mmol) was added. The mixture was stirred, slowly warmed, and an exothermic reaction began. The remainder of the 2-Chloro-4-fluoro-iodobenzene was added at a rate to maintain the exotherm and then the reaction was heated to THF reflux for 2.5 h, then cooled to 23°. The resulting mixture was added with rapid stirring to a −70° solution of trimethyl borate (4.53 mL, 40 mmol) in THF (40 mL). The reaction was stirred at <0° for 20 min and at 23° for 16 h, then poured into 2N HCl (150 mL), stirred 2 h, and the THF was removed under vacuum. The residual aqueous solution was extracted with Et2O (3×200 mL) and the combined extracts were dried (Na2SO4) and concentrated to afford a red solid. Trituration with hexane and drying afforded the title compound as a tan solid. (1.89 g, 28%). 1H-NMR CD3OD δ 7.09 (m, 1H), 7.21 (m, 1H), 7.38 (m, 1H).

1. temperatureslowly warmed
2. customan exothermic reaction
3. temperatureto maintain the exotherm
4. temperaturereflux for 2.5 h
5. temperaturecooled to 23°
6. additionThe resulting mixture was added
7. stirringThe reaction was stirred at <0° for 20 min and at 23° for 16 h
8. stirringstirred 2 h
9. customthe THF was removed under vacuum
10. extractionThe residual aqueous solution was extracted with Et2O (3×200 mL)
11. dry with materialthe combined extracts were dried (Na2SO4)
12. concentrationconcentrated
13. customto afford a red solid
14. dry with materialTrituration with hexane and drying

ORD record

ord-6940d7a340ad42f0b2008bb6a1793aca

Source dataset

uspto-grants-2009_12

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US07629350B2