[CH2:1]([NH:8][CH2:9][C@H:10]1[CH2:15][O:14][C:13]2[CH:16]=[CH:17][C:18]([N+:23]([O-:25])=[O:24])=[C:19]([CH2:20][C:21]#N)[C:12]=2[O:11]1)[C:2]1[CH:7]=[CH:6][CH:5]=[CH:4][CH:3]=1.S(=O)(=O)(O)O.[OH-:31].[NH4+].[CH2:33]([OH:35])[CH3:34]>>[CH2:33]([O:35][C:21](=[O:31])[CH2:20][C:19]1[C:12]2[O:11][C@@H:10]([CH2:9][NH:8][CH2:1][C:2]3[CH:7]=[CH:6][CH:5]=[CH:4][CH:3]=3)[CH2:15][O:14][C:13]=2[CH:16]=[CH:17][C:18]=1[N+:23]([O-:25])=[O:24])[CH3:34]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)+.
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