[F:1][C:2]1[C:7]([C:8]2[CH2:12][CH2:11][C:10](=[O:13])[CH:9]=2)=[CH:6][CH:5]=[CH:4][N:3]=1.[CH3:14][Mg]Br>C1COCC1.O>[F:1][C:2]1[C:7]([C:8]2[CH2:12][CH2:11][C:10]([CH3:14])([OH:13])[CH:9]=2)=[CH:6][CH:5]=[CH:4][N:3]=1To a solution of 3-(2-fluoropyridin-3-yl)cyclopent-2-enone (1 g, 5.64 mmol) in THF (28.2 mL) was added methylmagnesium bromide (4.70 mL, 14.11 mmol) dropwise over 5 minutes. The dark brown solution was stirred for 3 h at room temperature before. slowly quenching with aqueous ammonium chloride. The crude reaction was diluted with water and extracted with ethyl acetate, drying over magnesium sulfate, filtering, and concentrating to a dark brown oil under reduced pressure. The crude compound was purified by column chromatography (ethyl acetate/dichloromethane) to afford 3-(2-fluoropyridin-3-yl)-1-methylcyclopent-2-enol as a clear oil. MS (ESI, pos. ion) m/z: 194.1 (M+1).
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