C([NH:8][C:9]1[C:14]2[O:15][CH2:16][CH2:17][N:18]([C:19]([O:21][C:22]([CH3:25])([CH3:24])[CH3:23])=[O:20])[C:13]=2[CH:12]=[CH:11][N:10]=1)C1C=CC=CC=1>CO.[Pd]>[NH2:8][C:9]1[C:14]2[O:15][CH2:16][CH2:17][N:18]([C:19]([O:21][C:22]([CH3:25])([CH3:24])[CH3:23])=[O:20])[C:13]=2[CH:12]=[CH:11][N:10]=1A mixture of tert-butyl 5-(benzylamino)-2,3-dihydropyrido[3,4-b][1,4]oxazine-1-carboxylate (3.6 g, 10.56 mmol) and 10% Pd on carbon (1.12 g, 1.06 mmol) in MeOH (100 mL) was stirred under hydrogen atmosphere (2 L) at 35° C. for 48 h. The mixture was then filtered through Celite and washed with MeOH (3×25 mL). The combined organic layer was concentrated under reduced pressure. The residue was re-dissolved in EtOAc (100 mL) and washed with brine (2×50 mL). The combined organic layer was dried over sodium sulfate, filtered, and the solvent removed under reduced pressure. The residue was purified by reverse phase column chromatography (eluting with 22% acetonitrile in water, with 0.1% NH3.H2O) to give tert-butyl 5-amino-2,3-dihydropyrido[3,4-b][1,4]oxazine-1-carboxylate (2.1 g, 79% yield) as a yellow solid. ESI MS: m/z 252 [M+H]+.
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