Citric Acid → (S)-2-Amino-3-(3-bromo-4-fluoro-phenyl)-propionic acid tert-butyl ester

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Reaction Steps

A solution of (S)-2-(benzhydrylidene-amino)-3-(3-bromo-4-fluoro-phenyl)-propionic acid tert-butyl ester (300 mg, 0.622 mmol) in THF (3 mL) was treated with 10% citric acid (3 mL). The mixture was stirred overnight, diluted with water, and extracted with Et2O (2×). The aqueous layer was basified to pH=10 with satd. aq. K2CO3 and extracted with EtOAc (3×). The combined organic layers were dried (MgSO4) and concentrated to give the title compound (247 mg, 64%). MS (ESI+): mass calcd. for C13H17BrFNO2, 318.18; m/z found, 262.2 [M-t-Bu]+. 1H NMR (400 MHz, CDCl3): 7.42 (dd, J=6.6, 2.1 Hz, 1H), 7.16-7.11 (m, 1H), 7.08-7.02 (m, 1H), 3.56 (dd, J=7.3, 5.9 Hz, 1H), 2.85-2.78 (m, 1H), 2.99-2.92 (m, 1H), 1.43 (m, 9H).

Provenance & Evidence