[C:1]1(=[O:6])[CH2:5][CH2:4][CH:3]=[CH:2]1.C1(N(C)C2CCCCC2)CCCCC1.Br[C:22]1[C:23]([F:28])=[N:24][CH:25]=[CH:26][CH:27]=1.O1CCOCC1>O>[F:28][C:23]1[C:22]([C:3]2[CH2:4][CH2:5][C:1](=[O:6])[CH:2]=2)=[CH:27][CH:26]=[CH:25][N:24]=1To a round bottom flask was added bis(tri-t-butyl)phosphine palladium (0.591 g, 1.156 mmol) before sealing and evacuating and backfilling with nitrogen. Subsequently, cyclopent-2-enone (7.48 mL, 93 mmol), N-cyclohexyl-N-methylcyclohexanamine (14.73 mL, 69.4 mmol), and 3-bromo-2-fluoropyridine (4.07 g, 23.13 mmol) were added before adding dioxane (25 mL). The reaction mixture was stirred under nitrogen at 110° C. for 16 h. The reaction mixture was cooled to room temperature and diluted with water and extracted with ethyl acetate before drying over magnesium sulfate, filtering, and concentrating under reduced pressure. The crude compound was purified by column chromatography (ethyl acetate/dichloromethane) to give 3-(2-fluoropyridin-3-yl)cyclopent-2-enone was afforded as an orange solid. MS (ESI, pos. ion) m/z: 178.0 (M+1).
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