General procedure for the synthesis of (S)-2-amino-3-(4-hydroxyphenyl)propionamide from L-tyrosine methyl ester hydrochloride: L-tyrosine methyl ester hydrochloride (1.16 g, 5 mmol) was added to a 50 mL reaction vessel with concentrated ammonia (40 mL), and the reaction was stirred for 4 hours at room temperature. Upon completion of the reaction, the ammonia was removed by rotary evaporation followed by rotary drying. The crude product was washed with anhydrous ethanol (20 mL x 2) followed by water. Finally, it was purified by column chromatography (silica gel, 200-300 mesh; unfolding agent ratio of ethyl acetate:methanol:ammonia = 300:10:15) to afford L-tyrosine amide in 86% yield.
