Sulfuric Acid → Methyl 8-bromo-4,5-dihydro-4-oxo-1-(tetrahydro-2H-pyran-4-yl)[1,2,4]triazolo[4,3-a]quinoxaline-7-carboxylate

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Reaction Steps

To a mixed liquid of 360 mg of 8-bromo-4-oxo-1-(tetrahydro-2H-pyran-4-yl)-4,5-dihydro[1,2,4]triazolo[4,3-a]quinoxaline-7-carboxylic acid and 10 mL of methanol was added 2 mL of concentrated sulfuric acid, followed by stirring overnight under a refluxing condition. After cooling to room temperature, the pH was adjusted to about 8 by the addition of a saturated aqueous sodium hydrogen carbonate solution, followed by extraction with a mixed liquid of chloroform and isopropanol. The organic layer was washed with saturated brine and dried over anhydrous magnesium sulfate. The solvent was evaporated under reduced pressure to obtain 320 mg of methyl 8-bromo-4-oxo-1-(tetrahydro-2H-pyran-4-yl)-4,5-dihydro[1,2,4]triazolo[4,3-a]quinoxaline-7-carboxylate as an orange solid.

Provenance & Evidence