The general procedure for the synthesis of (S)-2-amino-3-(3-bromo-4-hydroxyphenyl)propionic acid from L-tyrosine was as follows: reaction of D- or L-tyrosine (1.0 g) with N-bromosuccinimide (NBS, 1.5 g, 8.3 mmol) in anhydrous THF (15 mL). The reaction mixture was stirred overnight at room temperature. Upon completion of the reaction, the solution was concentrated under reduced pressure and purified by rapid column chromatography on silica gel to afford D- or L-3-bromotyrosine (100 mg). The product was analyzed by electrospray mass spectrometry (positive ion mode) and showed m/z 260/262 (1:1).1H NMR (500 MHz, CD3OD) data were as follows: δH 7.46 (s, H-2); 7.13 (d, J = 8.2 Hz, H-6); 6.91 (d, J = 8.2 Hz, H-5); 3.97 (m, H-8); 3.22 (dd, J = 4.6, 14.6 Hz, H-7a); 3.03 (dd, J = 7.8, 14.6 Hz, H-7b).
