General procedure for the synthesis of N-Boc-4-methoxy-D-phenylalanine from methyl (S)-2-((tert-butoxycarbonyl)amino)-3-(4-methoxyphenyl)propionate: in the presence of 1 mL of water, K2CO3 (0.089 g, 0.608 mmol) was added to a (S)-2-((tert-butoxycarbonyl)amino)-3-(4-methoxyphenyl) Methyl propionate (0.100 g, 0.323 mmol) was added to a solution in methanol (4 mL). The reaction mixture was stirred at room temperature for 12 hours. After completion of the reaction, methanol was removed by rotary evaporation. The reaction mixture was diluted with water and the aqueous layer was extracted with ethyl acetate. The organic layers were combined, dried with anhydrous Na2SO4, filtered and concentrated under reduced pressure. The crude product was purified by column chromatography using ethyl acetate and petroleum ether (1:1) as eluent to give pure N-Boc-4-methoxy-D-phenylalanine.
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