Sodium Hydroxide → 10H-pyrazino[2,3-b][1,4]benzothiazine-8-carboxylic acid

Participants

Reaction Steps

To 50 ml of a solution of 2 g of methyl 10H-pyrazino[2,3-b][1,4]benzothiazine-8-carboxylate in methanol was added 0.8 g of sodium hydroxide and the resulting mixture was heated under reflux for 1 hour. After distilling off the methanol under reduced pressure, a 1 N aqueous solution of hydrochloric acid was added thereto so as to adjust the pH value to 5 to 6. Then the mixture was extracted with ethyl acetate/dichloromethane and the organic layer was dried over anhydrous magnesium sulfate. After distilling off the solvent under reduced pressure, 1.9 g of the title compound was obtained as a yellow solid.

Provenance & Evidence