Boron trifluoride → (2R)-1-(5-fluoro-2-methylphenyl)propan-2-ol

Beteiligte Stoffe

Reaktionsschritte

An oven dried 3-necked round bottom flask (rbf), which contained a magnetic stirring bar, was sealed with rubber septum having a thermometer. While cooling to rt, the flask was evacuated and backfilled with argon. This sequence was repeated 3 times. In the flask, a solution of 4-fluoro-2-iodo-1-methylbenzene (25 g, 105.9 mmol) in anhydrous THF (800 mL) was stirred at −78° C. in a dry ice/acetone bath under argon gas. After 30 min, 1.4 M sec-BuLi in hexane (83.2 mL, 116.5 mmol) was added dropwise at that temperature for 20 min. After adding, the mixture was stirred at −78° C. in the dry ice/acetone bath for 30 min, and stirred more for 30 min without the bath. And then, the solution was cooled again in the dry ice/acetone to −78° C. and a solution of R-(+)-propylene (8 g, 137.7 mmol) in 50 mL anhydrous THF was added dropwise at the temperature for 10 min. And then, the mixture was cooled to −105° C. and 46.5% solution of BF3 in diethyletherate (19.6 mL) was added dropwise. And the mixture was stirred at −78° C. for 2 h, and then quenched slowly by sat. NH4Cl at −78° C. and stirred at ambient temperature for overnight. Water (20 mL) was added and extracted with EtOAc, dried over anhydrous MgSO4, evaporated and purified by column chromatography (DCM/hexane 9/1) to give (R)-1-(5-fluoro-2-methylphenyl)propan-2-ol (F-1) as pale yellowish oil.

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