D-Phenylalanine → D-Phenylalanine 1,1-dimethylethyl ester

Participants

Reaction Steps

To a solution of D-phenylalanine (1.651 g, 10.0 mmol) in tert-butyl acetate (20 mL) at 0° C., was slowly added HClO4 (0.85 mL, 15 mmol). The reaction mixture was stirred at room temperature for 12 h then washed with H2O (25 mL) and 1.0 M HCl solution (15 mL). The resultant aqueous solution was adjusted to pH 9 by addition of 10% K2CO3 solution, and then extracted with dichloromethane (3×10 mL). The combined organic phases were dried with anhydrous Na2SO4, filtered and concentrated to give an oil. This was purified by flash chromatography on silica gel, using a grading of ethyl acetate/hexane ((1:5) to (2:5)), to give A1 as a colorless oil; (2.020 g, 89.3%). Spectral data were in accordance with those published. [α]D25: −39.5 (c=0.33, CHCl3); 1H-NMR (300 MHz, CDCl3): δ 7.35-7.29 (m, 2H), 7.27-7.22 (m, 3H), 3.63 (dd, J=6.0, 9.0 Hz, 1H), 3.09-3.02 (m, 1H), 2.89-2.82 (m, 2H), 1.47 (s, 2H), 1.44 (s, 9H); 13C NMR (300 MHz, CDCl3): δ 174.34, 137.57, 129.39, 128.41, 126.65, 81.12, 56.33, 41.29, 28.00; LRMS (ESI): calcd for: C13H19NO2 [M+H]+=222.1, obsd [M+H]+=222.1, [M+Na]+=244.1, obsd [M+Na]+=244.1.

Provenance & Evidence