Ethyl 5-chloropyridine-2-carboxylate (146 mg, 76% yield) was obtained by reacting 5-chloropyridine-2-carboxylic acid (200 mg, 1.03 mmol) in ethanol (3 mL) and a dioxane solution (0.5 mL) of 4M HCl at 90 °C for 20 hours. Subsequently, ethyl 5-chloropyridine-2-carboxylate (146 mg, 0.786 mmol) was dissolved in dichloromethane (4.0 mL), to which a toluene solution of 1M DIBAL (1.74 mL, 1.74 mmol) was added and reacted for 20 min to give 5-chloropyridine-2-carbaldehyde (58 mg, 52% yield). The product was analyzed by GC-MS and the molecular ion peak (M+) was 141.
