| With sodium carbonate; In water; | L-2-tert-Butoxycarbonylamino-3-(3-fluoro-phenyl)-propionic acid A mixture of L-2-amino-3-(3-fluoro-phenyl)-propionic acid (20.0 g, 110 mmol, 1 eq) in H2O (100 mL) was treated with Na2CO3 (16.2 g, 153 mmol, 1.4 eq) in H2O (40 mL) followed by 1,4-dioxane (100 mL) and cooled to 0° C. The BOC2O was added and the reaction mixture was stirred at ambient temperature for 5 h after which the dioxane was evaporated. H2O (125 mL) was then added and the mixture then washed with Et2O (2*100 mL). The aqueous phase was acidified with 10percent citric acid followed by extraction with EtOAc (2*300 mL). The combined EtOAc layers were washed with H2O (2*150 mL), brine (150 mL), dried (Na2SO4) and concentrated to give the acid as a colorless, viscous oil which slowly solidified upon standing (31 g, quant). 1H NMR (CDCl3) 7.33-7.26 (m,1H), 7.00-6.91 (m,3H), 4.96 (s, 1H), 4.62 (bs, 1H), 3.23 (dd, J=14, 5.3, 2H), 1.44 (s, 9H); Anal Calcd for C14H18NO4F: C, 5936; H, 6.40; N, 4.94. Found: C, 59.29; H, 6.34; N, 4.90. |