Hydrogen Bromide → (R)-1-bromo-1-[3,5-bis(trifluoromethyl)phenyl]ethane

Temperature

2.5 °C

Under an argon atmosphere, a suspension of (S)-1-[3,5-bis(trifluoromethyl)-phenyl]ethanol (1.0 g, 3.87 mmol, >99.5% ee) in heptane (2 mL) was added dropwise with phosphorus tribromide (0.52 g, 1.94 mmol) at 0 to 5° C., and the mixture was stirred at 0 to 5° C. for 30 minutes. The reaction mixture was added dropwise with hydrogen bromide (30% solution in acetic acid, 0.76 mL, 3.87 mmol) at 0 to 5° C., and the mixture was stirred at 10° C. for 17 hours. The reaction mixture was poured into ice water, and the mixture was extracted with n-hexane (15 mL×2). The organic layers were combined, washed with saturated aqueous sodium hydrogencarbonate (15 mL×1) and then with saturated brine (15 mL×1), dried over anhydrous sodium sulfate, and then concentrated under reduced pressure. The resulting crude product was purified by column chromatography (silica gel, 8 g; developing solvent, n-hexane) to obtain 1.12 g of (R)-1-bromo-1-[3,5-bis(trifluoromethyl)phenyl]ethane as colorless oil.

1. stirringthe mixture was stirred at 10° C. for 17 hours
2. extractionthe mixture was extracted with n-hexane (15 mL×2)
3. washwashed with saturated aqueous sodium hydrogencarbonate (15 mL×1)
4. dry with materialwith saturated brine (15 mL×1), dried over anhydrous sodium sulfate
5. concentrationconcentrated under reduced pressure
6. customThe resulting crude product was purified by column chromatography (silica gel, 8 g; developing solvent, n-hexane)

ORD record

ord-54fcd0c2cf4743a8806d5324048d15e0

Source dataset

uspto-grants-2016_03

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US09272966B2