Acetic Acid → 3,4-Dichloropyridine-2-carboxamide

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To a mixture of 2,2,6,6-tetramethylpiperidine (6.2 mL, 37.2 mmol) in diethylether (50 mL) was added n-BuLi in hexane (2.5M, 23 mL, 57.5 mmol) at 0° C. via syringe over 15 min. The mixture was stirred at 0° C. for 0.5 hour, then cooled to −78° C. A solution of 3,4-dichloropyridine (5.00 g, 33.8 mmol) in diethylether (20 mL) was added to the mixture via a syringe over 15 minutes. The reaction was stirred at −78° C. for 2 hours, then isocyanatotrimethylsilane (94% pure, 6.7 mL, 50.7 mmol) was added. The mixture was warmed up to rt and further stirred for 2 hours, quenched with acetic acid (6.76 g, 112.6 mmol) in 35 mL of water. The mixture was further stirred overnight. The titled product was precipitated overnight as a white solid, which was collected through filtration. More products were recovered from the filtrate. Thus, the filtrate was extracted with ethyl acetate (50 mL×3) and the combined organic phases were washed with brine (50 mL), dried over anhydrous Na2SO4, and concentrated in vacuo. The solid was combined and washed with 35 mL of Et2O to give the title compound as a pale yellow solid (2.20 g, 34.0%).

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