Diethyl Ether → (2R)-1-(3,4-difluoro-2-methylphenyl)propan-2-ol

Participants

Reaction Conditions

Reaction Steps

A solution of 1-bromo-3,4-difluoro-2-methylbenzene (4.14 g, 20 mmol) in 100 mL of anhydrous THF was cooled to −100° C. (liquid nitrogen/EtOH) under nitrogen. Then 1.4M solution of sec-BuLi in cyclohexane (15 mL, 21 mmol) was added dropwise at −100° C. to −90° C. The mixture was stirred at −100° C. to −90° C. for 10 min, then a solution of R-(+)-propylene oxide (1.51 g, 1.8 mL, 26 mmol) in 15 mL of THF was added dropwise at −100° C. to −90° C., then the mixture was cooled to −105° C. and a 46.5% solution of BF3 in diethyl ether (4.18 mL, 30 mmol) was added dropwise. The mixture was stirred at −100° C. to −90° C. for 2 h, then the reaction was quenched with 20 mL of sat. aq. NH4Cl at −90° C. The mixture was stirred and warmed to 0° C. overnight. Then 20 mL of water was added and mixture was extracted with EtOAc (2×60 mL), the extract was dried over Na2SO4 and evaporated to give crude oil, which was purified by column (silica gel, EtOAc/hexane 1:9, Rf=0.37 in EtOAc/hexane 3:7) to give (2R)-1-(3,4-difluoro-2-methylphenyl)propan-2-ol (2.64 g, 71%) as pale oil. 1H NMR (300 MHz, CDCl3): δ 6.85-7.26 (m, 2H), 3.98 (m, 1H), 2.73 (m, 2H), 2.25 (m, 3H), 1.45 (d, J=3.75 Hz, 1H), 1.26 (d, J=6.21 Hz, 3H).

Provenance & Evidence