Dimethylformamide → 4-Bromopyridine-3-carbaldehyde

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To a stirred solution of diisopropylamine (9.02 mL, 63.3 mmol) in THF (75 mL) at −78° C. was added n-butyllithium (1.6 M in hexane) (30 mL, 76 mmol) dropwise under nitrogen atmosphere. After complete addition the solution was stirred for 30 min at −78° C. 4-Bromopyridine HCl (5 g, 31.6 mmol) was added portionwise and the resultant solution stirred at −78° C. for 1 h. DMF (2.94 mL, 38.0 mmol) was then added dropwise at −78° C. to the solution. The reaction mixture was warmed to room temperature slowly and stirred for 12 h. The reaction mixture was quenched with 3 N HCl and stirred for 2 h. The solution was neutralized with saturated sodium bicarbonate solution, extracted with EtOAc (75 mL), dried over sodium sulfate and concentrated under reduced pressure to give 4-bromonicotinaldehyde (3.75 g, 20.16 mmol, 64% yield). The crude product was used without purification in the next step. 1H NMR (400 MHz, CDCl3) δ 10.39 (s, 1H), 9.00 (s, 1H), 8.56 (d, J=5.2 Hz, 1H), 7.62 (d, J=5.2 Hz, 1H).

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