To a mixture of glycine tert butyl ester hydrochloride salt (5.9 g, 18 mmol) and DMF (20 mL) at 0° C. was added triethylamine (6.5 mL, 45 mmol) and 4-(4-fluoro-benzyloxy)-benzenesulfonyl chloride. After stirring for 1 h, the mixture was warmed to room temperature and stirred for an additional hour. The mixture was diluted with ethyl acetate, washed with 1M HCl, saturated aqueous NaHCO3 and brine, dried over Na2SO4, filtered and concentrated in vacuo. Trituration of the residue with ether-hexane afforded 10.8 g of [4-(4-fluoro-benzyloxy)-benzenesulfonylamino]-acetic acid tert-butyl ester as colorless crystals.
