C([C:5]1[N:6]([CH2:17][C@@H:18]2[CH2:22][O:21][C:20]([CH3:24])([CH3:23])[O:19]2)[C:7]2[C:12]([CH:13]=1)=[CH:11][C:10]([N+:14]([O-])=O)=[CH:9][CH:8]=2)(C)(C)C.C([O-])=O.[NH4+]>C(O)C.O.[Pd]>[CH3:23][C:20]1([CH3:24])[O:19][CH:18]([CH2:17][N:6]2[C:7]3[C:12](=[CH:11][C:10]([NH2:14])=[CH:9][CH:8]=3)[CH:13]=[CH:5]2)[CH2:22][O:21]1
To a stirred solution of (R)-2-tert-butyl-1-((2,2-dimethyl-1,3-dioxolan-4-yl)methyl)-5-nitro-1H-indole (1.0 g, 3.0 mmol) in ethanol (20 mL) and water (5 mL) was added ammonium formate (0.76 g, 12 mmol) followed by slow addition of 10% palladium on carbon (0.4 g). The mixture was stirred at room temperature for 1 h. The reaction mixture was filtered through a plug of celite and rinsed with ethyl acetate. The filtrate was evaporated under reduced pressure and the crude product was dissolved in ethyl acetate. The organic layer was washed with water (2×5 mL) and brine (2×5 mL). The organic layer was dried over Na2SO4, filtered and evaporated under reduced pressure to give (R)-2-tert-butyl-1-((2,2-dimethyl-1,3-dioxolan-4-yl)methyl-1H-indol-5-amine (0.89 g, 98%). 1H NMR (400 MHz, CDCl3) δ 7.04 (d, J=4 Hz, 1H), 6.70 (d, J=2.2 Hz, 1H), 6.48 (dd, J=2.2, 8.6 Hz, 1H), 6.05 (s, 1H), 4.38-4.1 (m, 2H), 4.21 (dd, J=7.5, 16.5 Hz, 1H), 3.87 (dd, J=6.0, 8.6 Hz, 1H), 3.66 (dd, J=6.0, 8.6 Hz, 1H), 3.33 (br s, 2H), 1.40 (s, 3H), 1.34 (s, 9H), 1.25 (s, 3H).
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