[C:1]([O:5][C:6]([N:8]1[C@@H:12](/[CH:13]=[CH:14]/[C:15]2[CH:20]=[CH:19][C:18]([N+:21]([O-])=O)=[CH:17][CH:16]=2)[CH2:11][O:10][C:9]1([CH3:25])[CH3:24])=[O:7])([CH3:4])([CH3:3])[CH3:2].C([O-])=O.[NH4+]>CO.[Pd]>[C:1]([O:5][C:6]([N:8]1[C@@H:12]([CH2:13][CH2:14][C:15]2[CH:16]=[CH:17][C:18]([NH2:21])=[CH:19][CH:20]=2)[CH2:11][O:10][C:9]1([CH3:25])[CH3:24])=[O:7])([CH3:4])([CH3:2])[CH3:3]To a stirred suspension of (S)-2,2-dimethyl-4-[(E)-2-(4-nitro-phenyl)-vinyl]-oxazolidine-3-carboxylic acid tert-butyl ester (2.08 g) in methanol (140 ml) were added ammonium formate (5.66 g) and palladium on charcoal (0.51 g, 10 wt %) and the mixture was heated at 60° C. for 90 min. The mixture was then cooled to room temperature, filtered through celite and the filtrate was concentrated in vacuo. The residue was purified by column chromatography (SiO2; gradient: heptane/EtOAc) to give (S)-4-[2-(4-amino-phenyl)-ethyl]-2,2-dimethyl-oxazolidine-3-carboxylic acid tert-butyl ester (1.58 g, 82%) as a yellow oil. MS (ISP): 321.4 ([M+H]+).
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