Acetic Anhydride → 1-(2-Methoxy-5-trifluoromethylphenyl)ethanone
Reaction equation
FC(F)(F)S(O)(=O)=O.[F:9][C:10]([F:20])([F:19])[C:11]1[CH:16]=[CH:15][C:14]([O:17][CH3:18])=[CH:13][CH:12]=1.[C:21](OC(=O)C)(=[O:23])[CH3:22]>>[CH3:18][O:17][C:14]1[CH:13]=[CH:12][C:11]([C:10]([F:19])([F:20])[F:9])=[CH:16][C:15]=1[C:21](=[O:23])[CH3:22]Participants
4
Procedure
2′-methoxy-5′-trifluoromethyl-acetophenone was prepared as follow (US2003/0109574): In a water bath at room temperature, to a solution of trifluoromethane sulfonic acid (5 ml, 56.7 mmol) under argon was slowly added a solution of 4-trifluoromethyl-anisol (2.0 g, 11.35 mmol) in acetic anhydride (2.15 ml, 22.7 mmol). The resulting dark mixture was stirred for 3 hours at room temperature then poured onto ice water (26 ml). The product was extracted several times with ether. The ethereal layer was washed with a 10% solution of sodium hydrogenocarbonate, water, dried over sodium sulfate and concentrated to dryness. The residue was purified by flash chromatography over silica gel (gradient cyclohexane/dichloromethane: 0-50%) to yield 2′-methoxy-5′-trifluoromethyl-acetophenone (1.7 g, 67%) as a white solid.