2-Amino-3-[(4-methoxybenzyl)thio]propanoic acid

52-90-4

824-94-2

2544-31-2

(Step 1) Add 1-(chloromethyl)-4-methoxybenzene (280 g, 1780 mmol) dissolved in ether (400 mL) and concentrated hydrochloric acid to a mixture of ether (400 mL) and concentrated hydrochloric acid dropwise for 2 hours. After the dropwise addition was completed, the mixture was continued to be stirred for 1 hour. The organic layer was separated and added to a solution prepared from L-cysteine (197 g, 1625 mmol) and 2N aqueous sodium hydroxide (980 mL) dissolved in ethanol (1890 mL). The mixture was stirred at room temperature for 2 hours. Upon completion of the reaction, the mixture was cooled to 0 °C and neutralized with aqueous 3N hydrochloric acid to pH 7. The resulting solid was collected by filtration and dried to afford S-(4-methoxybenzyl)-L-cysteine (250 g, 1035 mmol, 64% yield).