[C:1]([O:5][C:6]([N:8]1[CH2:13][CH2:12][O:11][CH:10]([C:14]2[CH:19]=[CH:18][C:17]([N:20]=C(C3C=CC=CC=3)C3C=CC=CC=3)=[C:16]([F:34])[CH:15]=2)[CH2:9]1)=[O:7])([CH3:4])([CH3:3])[CH3:2].C([O-])=O.[NH4+]>CO>[C:1]([O:5][C:6]([N:8]1[CH2:13][CH2:12][O:11][CH:10]([C:14]2[CH:19]=[CH:18][C:17]([NH2:20])=[C:16]([F:34])[CH:15]=2)[CH2:9]1)=[O:7])([CH3:4])([CH3:2])[CH3:3]To a stirred solution of (RS)-2-[4-(benzhydrylidene-amino)-3-fluoro-phenyl]-morpholine-4-carboxylic acid tert-butyl ester (2.21 g) in methanol (40 ml) was added ammonium formate (4.54 g). The reaction mixture was degassed by bubbling argon into the mixture for several minutes. 10% Palladium on activated charcoal (255 mg) was then added and the reaction mixture was stirred at 60° C. for 1 hour. The reaction mixture was then filtered through celite and the filtrate was poured into 1 M aq. NaOH and extracted twice with EtOAc. The combined organic layers were dried over Na2SO4 and concentrated in vacuo. The residue was purified by flash column chromatography (silica gel; gradient: 0% to 30% EtOAc in hexanes) to afford (RS)-2-(4-amino-3-fluoro-phenyl)-morpholine-4-carboxylic acid tert-butyl ester (1.42 g, 74%) as a white solid. MS (ISP): 319.2 ([M+Na]+), 297.3 ([M+H]+), 241.2 ([M+H—C4H8]+), 197.2 ([M+H—C4H8—CO2]+).
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