At -40 °C, 4-chloropyridin-2-yl chloride (9.0 g, 51.1 mmol) was dissolved in 1,2-dichloroethane (60 mL) and added slowly and dropwise to a mixed solution containing tert-butanol (25 mL), pyridine (20 mL) and 1,2-dichloroethane (80 mL). The reaction mixture was heated at 50°C for 24 hours. After completion of the reaction, the reaction mixture was diluted with dichloromethane and washed sequentially with 5% aqueous citric acid solution and saturated aqueous NaHCO3 solution. The organic layer was dried with anhydrous MgSO4, filtered and concentrated. Purification by fast column chromatography (silica gel as stationary phase, 20% ethyl acetate/dichloromethane as eluent) afforded tert-butyl 4-chloropyridine-2-carboxylate (9.8 g, 90% yield) as a clarified oil. m/z 213 (M+), 158 (M-Bu+) by LC-MS.
