Dimethylformamide → tert-Butyl 6-chloropyridine-2-carboxylate

6-Chloropyridine-2-carboxylic acid (5.00 g, 31.7 mmol) was dissolved in DCM (150 mL) and oxalyl chloride (5.45 mL, 63.5 mmol) and DMF (1 mL) were added. The reaction mixture was stirred for 3 h, concentrated in vacuo and azeotroped with DCM. The residue was dissolved in THF (150 mL) and potassium tert-butoxide (3.39 mg, 47.6 mmol) was added. The reaction mixture was stirred for 18 h, quenched with water (250 mL) and extracted with DCM (3×150 mL). The combined organic fractions were washed with sat aq NaHCO3 (150 mL), dried (MgSO4) and concentrated in vacuo. The residue was purified by column chromatography to give the title compound (3.11 g, 46%) as a white solid. LCMS (ES+): 236.1 [MNa]+.