Bromine → Methyl 3-bromopyrazine-2-carboxylate

Participants

Reaction Conditions

Reaction Steps

To a rapidly stirring heterogeneous mixture of 3-aminopyrazine-2-carboxylic acid methyl ester (2.00 g, 13.1 mmol) in 48% hydrobromic acid (7.9 mL) cooled to 0° C. was added bromine (2.00 mL, 6.2 g, 38.8 mmol) dropwise over 5 minutes. Then a solution of sodium nitrite (2.27 g, 32.8 mmol) in 9.5 mL of water was added dropwise over 10 minutes. The reaction mixture was stirred at 0° C. for 15-30 minutes and then basified with 60 mL of saturated sodium bicarbonate solution and extracted with ethyl acetate followed by chloroform. The combined organic extracts were dried over magnesium sulfate and concentrated under reduced pressure. The residue obtained was flash chromatographed on silica gel eluting with mixtures of hexane and ethyl acetate to afford the title compound (1.265 g, 46%). m.p. 43.5°-44° C. 1H NMR (CDCl3, 300 MHz) δ 4.04 (s, 3H), 8.50 (bs, 1H), 8.60 (bs, 1H). MS (DCl/NH3) m/e 217/219 (M+H)+, 234/236 (M+H+NH3)+.

Provenance & Evidence