63071-13-6

24484-93-3

63071-13-6

General procedure for the synthesis of 4-chloro-2-pyridinecarboxaldehyde from methyl 4-chloropyridinecarboxylate: to a solution of methyl 4-chloropyridinecarboxylate (2.5 g, 14.6 mmol) in anhydrous THF (100 mL) was added slowly and dropwise diisobutylaluminum hydride (1.0 M solution in THF, 29.1 mmol) at -78 °C and the reaction was stirred in an argon atmosphere at that temperature mixture for 2 hours. Upon completion of the reaction, the reaction was quenched with methanol (MeOH) at -78 °C, followed by the addition of potassium sodium tartrate solution (1.0 M, 180 mL), and the mixture was stirred and gradually warmed to room temperature over a period of 1 hour. The reaction mixture was diluted with ethyl acetate (EtOAc, 60 mL) and the organic layer was separated, washed with saturated saline and dried with anhydrous sodium sulfate. The solvent was removed by mild decompression distillation at room temperature to afford the target product 4-chloro-2-pyridinecarboxaldehyde (1.87 g, 91% yield), which solidified to light yellow crystals after standing at room temperature.