Bromine → Methyl 3-bromopyrazine-2-carboxylate

HRID 1655587Notes

Reaction equation

[CH3:1][O:2][C:3]([C:5]1[C:10](N)=[N:9][CH:8]=[CH:7][N:6]=1)=[O:4].[Br:12]Br.N([O-])=O.[Na+].C(=O)(O)[O-].[Na+]>Br.O>[Br:12][C:10]1[C:5]([C:3]([O:2][CH3:1])=[O:4])=[N:6][CH:7]=[CH:8][N:9]=1

Participants

Conditions

Temperature: 0 °C

Procedure

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)+.

Workup

stirringThe reaction mixture was stirred at 0° C. for 15-30 minutes
extractionextracted with ethyl acetate
dry with materialThe combined organic extracts were dried over magnesium sulfate
concentrationconcentrated under reduced pressure
customThe residue obtained
customchromatographed on silica gel eluting with mixtures of hexane and ethyl acetate

Sources & evidence

ORD record: ord-78181a2919d845e28601c0d06eeda450
Source dataset: uspto-grants-1993_10
DOI: 10.6084/m9.figshare.5104873.v1
Patent number: US05250548

Reaction notes

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