[CH3:1][N:2]1[CH:6]=[CH:5][C:4]([C:7]2[CH:12]=[CH:11][N:10]=[CH:9][CH:8]=2)=[N:3]1.[Br:13]Br.CO>C(Cl)(Cl)Cl.C(OCC)(=O)C>[Br:13][C:5]1[C:4]([C:7]2[CH:12]=[CH:11][N:10]=[CH:9][CH:8]=2)=[N:3][N:2]([CH3:1])[CH:6]=1To a solution of 4-(1-methyl-1H-pyrazol-3-yl)pyridine 2.98 g; Example 3, Step 2) in 50 mL chloroform cooled in ice, was added dropwise, a solution of 1.15 mL bromine in 30 mL chloroform. About 15 mL methanol was added to help dissolution of the yellow precipitate that formed. After 4 hours, the reaction mixture was quenched with saturated aqueous sodium bicarbonate and diluted with dichloromethane. The dichloromethane layer was washed with saturated aqueous sodium bicarbonate, brine, dried over magnesium sulfate, filtered, and evaporated to yield the crude product as a yellow semisolid. The crude material was slurried in ethyl acetate and filtered through celite. The filtrate was evaporated to yield 4.18 g product as a yellow solid. 1H NMR (CDCl3) was consistent with the desired structure. LC/MS showed one peak with a M+1 molecular ion of m/z 240.5 by positive ESI.
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