Methyl 5-chloropyrazine-2-carboxylate

13924-95-3

33332-25-1

General procedure for the synthesis of methyl 5-chloropyrazine-2-carboxylate from methyl 5-hydroxypyrazine-2-carboxylate: Methyl 5-hydroxypyrazine-2-carboxylate (673 mg, 4.37 mmol) was dissolved in phosphorus trichloride (6.1 mL), and a few drops of N,N-dimethylformamide were added as catalyst. The reaction mixture was heated to reflux for 2 h under nitrogen protection. After completion of the reaction, the reaction solution was slowly poured into ice water and extracted three times with chloroform (30 mL). The organic layers were combined and washed sequentially with saturated aqueous sodium bicarbonate and saturated saline (100 mL each). The organic layers were dried over anhydrous sodium sulfate and concentrated under reduced pressure to remove the solvent to give methyl 5-chloropyrazine-2-carboxylate (611 mg, 81% yield) as a gray solid. The structure of the product was confirmed by 1H-NMR (CDCl3, 400 MHz): δ 4.05 (3H, s), 8.71 (1H, d, J = 1.6 Hz), 9.10 (1H, d, J = 1.2 Hz).