Trifluoroacetic anhydride → 5-Chloro-3-(methoxycarbonyl)-2-methylpyrazine 1-oxide

Participants

Reaction Steps

To a solution of methyl 6-chloro-3-methylpyrazine-2-carboxylate (8.6 g, 46.1 mmol) and hydrogen peroxide urea adduct (8.1 g, 86 mmol) in dichloromethane (100 mL) was added 2,2,2-trifluoroacetic anhydride (10.9 ml, 78 mmol) dropwise. The resulting mixture was stirred at room temperature for 2 h. The reaction mixture was diluted with DCM and quenched with water. The aqueous layer was extracted with DCM. The combined organic extracts were dried (MgSO4), filtered and concentrated in vacuo to give the crude product 5-chloro-3-(methoxycarbonyl)-2-methylpyrazine 1-oxide (8.83 g, 43.6 mmol, 95% yield) which was used without further purification. 1H NMR (300 MHz, CDCl3) δ ppm 8.31 (1H, s), 4.02 (3H, s), 2.65 (3H, s).

Provenance & Evidence