A 100 mL round bottomed flask equipped with a magnetic stir bar is charged {(3S)-3-[(benzylamino)methyl]-6-nitro-2,3-dihydro-1,4-benzodioxin-5-yl}acetonitrile (5.00 g, 14.5 mmol) and 95% ethanol (7.5 mL). To the stirred solution is added 95% sulfuric acid (5.0 mL, 89.0 mmol). The flask is immersed in an oil bath and heated to 75° C. for 4 days. The solution is cooled to room temperature and absolute ethanol (42.5 mL) is added. The reaction mixture is adjusted to pH 10 by the addition of 28% ammonium hydroxide (˜12 mL), and the resulting slurry is stirred for 3 h. The precipitate is removed by vacuum filtration and the volatiles are evaporated giving crude title compound (6.02 g, 106%) as a red syrup. LCMS (Basic Method): 2.33 min, 387 (M+H)+.
