Phenyl glycine (SRL), Di-tert-butyl pyrocarbonate (Spectrochem), Sodium hydroxide (S.D. Fine), Hydrochloric acid (Rankem), Dioxane (Rankem), Ethyl acetate (Spectrochem)

Phenyl glycine (10 g, 66.2 mmol) was dissolved with stirring in a mixture of dioxane (50 ml), water (25 ml) and 1N NaOH (10 ml). The reaction mixture was cooled using ice bath, and Di-tert-butyl pyrocarbonate (BOC anhydride, 15.8 g, 72.4 mmol) was added dropwise to the above solution. The cooled reaction mixture was stirred for 30 min, then reaction brought to rt and stirred for further 30 min. The solution was concentrated under vacuum to about 25-30 ml. The reaction mixture was again cooled using an ice bath, covered with a layer of ethyl acetate (75 ml) and then acidified with a 1N HCl solution to pH 2-3. The aqueous layer was extracted with ethyl acetate (3 x 50 ml), the combined extracts washed with water (2 x 50 ml), dried over anhydrous sodium sulphate and concentrated under vacuum. The resulting crude product was chromatographed on silica gel (100-200 mesh size) column using 20% EtOAc/hexane as eluent to give the pure product as white solid (12 g, yield 72%).

In this procedure 1N HCl has been used to extract the amino acid in ethylacetate in place of KHSO₄ as described in the literature.

m.p. 88-90^oC; Rf 0.5 (50% EtOAc/ Hexane); ¹HNMR (CDCl₃) 1.16-1.22 (m, 9H), 5.12 (d, 1H, J = 4.7 Hz), 7.29-7.43 (m, 5H), 8.03 (d, 1H, J = 4.2 Hz); MS (ES⁺) m/z 274 (M+H+Na); HPLC purity = 99.2%

The Practice of Peptide Synthesis, 2nd edition, M. Bodanszky, A. Bodanszky, 1994, page 17, Springer-Verlag Publications.