Step 4: (S)-2-phenoxymethylamino-3-(2,6-difluorophenyl)propanoic acid (2.2 g, 11 mmol) was dissolved in ethanol (25 mL) and 5% activated carbon loaded palladium catalyst (600 mg) was added. The hydrogenation reaction was carried out at 50 psi hydrogen pressure for 24 hours. Upon completion of the reaction, the catalyst was removed by Celite filtration and the solvent was evaporated under reduced pressure to give the crude product. The crude product was recrystallized from ether to give (S)-2-amino-3-(2,6-difluorophenyl)propionic acid (2.2 g, 80% yield). The product was identified by NMR hydrogen spectrum (DMSO-d6): δ 7.28 (m, 1H), 7.0 (t, J=7.6Hz, 2H), 2.77 (m, 2H). Mass spectrometry analysis showed: 202.2 (M+1), 199.7 (M-1).
