A solution of BOC-Ser-OH (981 mg, 4.78 mmol) in DMF (5.00 mL) was added to a suspension of NaH (60% in mineral oil, 402 mg, 10.0 mmol) in DMF (5 mL). The mixture was stirred at 0° C. for 1 h and a solution of 2-fluoro-1-nitro-3-(trifluoromethyl)benzene (1 g, 4.78 mmol) in DMF (5 mL) was added. After 2 h the mixture was diluted with H2O and acidified to pH 3 with 1 N HCl. The mixture was extracted with EtOAc, the combined extracts dried over MgSO4, filtered and the filtrate concentrated to give a residue that was purified by silica gel chromatography to afford (S)-2-(tert-butoxycarbonylamino)-3-(2-nitro-6-(trifluoromethyl)phenoxy)propanoic acid (1.53 g, 81%) as a light yellow solid. MS m/z 417 (M+Na)′
