[C:1]([O:5][C:6]([N:8]1[CH2:13][CH2:12][N:11]([C:14]2[C:19]([CH3:20])=[CH:18][C:17](Br)=[CH:16][N:15]=2)[CH2:10][CH2:9]1)=[O:7])([CH3:4])([CH3:3])[CH3:2].[CH3:22]B(O)O.[F-].[K+].O1CCCC1>O>[C:1]([O:5][C:6]([N:8]1[CH2:13][CH2:12][N:11]([C:14]2[C:19]([CH3:20])=[CH:18][C:17]([CH3:22])=[CH:16][N:15]=2)[CH2:10][CH2:9]1)=[O:7])([CH3:4])([CH3:3])[CH3:2]To a mixture of 4-(5-bromo-3-methylpyridin-2-yl)piperazine-1-carboxylic acid tert-butyl ester (25 g), methylboronic acid (8.4 g), [1,1′-bis(diphenylphosphino)ferrocene]palladium (II) dichloride dichloromethane complex (1:1)(2.9 g) and potassium fluoride (16 g) was added tetrahydrofuran (140 mL), and the mixture was refluxed for 8 hr. After cooling, water was added to the reaction mixture, and the mixture was extracted with ethyl acetate. The organic layer was washed with saturated brine, and the solvent was evaporated. The residue was purified by column chromatography (hexane:ethyl acetate) to give 4-(3,5-dimethylpyridin-2-yl)piperazine-1-carboxylic acid tert-butyl ester (16 g). 4-(3,5-Dimethylpyridin-2-yl)piperazine-1-carboxylic acid tert-butyl ester (16 g) was dissolved in chloroform (100 mL), 4N hydrogen chloride/ethyl acetate (50 mL) was added, and the mixture was stirred at room temperature overnight. Ethyl acetate (200 mL) was added, and the mixture was filtered to give the title compound (10 g).
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