Methanol → methyl 2-bromo-5H-pyrrolo[2,3-b]pyrazine-7-carboxylate

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Reaction Steps

To a stirred solution of 2-bromo-5H-pyrrolo[2,3-b]pyrazine-7-carboxylic acid (0.527 g, 2.18 mmol) in 50 ml, of methanol was added H2SO4 (1.5 mL) slowly at room temperature. The reaction mixture was stirred at reflux for 16 h. The solvent was evaporated at 40° C. under reduced pressure then the residue was suspended in 5 mL of water and treated with solid NaHCO3 until pH=7. The solution was extracted with ethyl acetate (90 mL), then the organics were washed with water (20 mL), brine (20 mL) and dried over anhydrous sodium sulfate. The drying agent was removed by filtration and the solvent was evaporated at 40° C. under reduced pressure to give a crude product, which was purified by column chromatography (silica gel, 200-300 mesh, eluting with a mixture of petroleum ether and ethyl acetate (1:1, v/v) to give 2-bromo-5H-pyrrolo[2,3-b]pyrazine-7-carboxylic acid methyl ester (0.24 g, 43%) as a white solid.

Provenance & Evidence