Citric Acid → (2S)-2-((((9H-fluoren-9-yl)methoxy)carbonyl)amino)-3-(4-hydroxyphenyl)propanoic acid

참여 물질

반응 단계

L-Tyrosine (9.06 g, 50 mmol) was dissolved in 100 ml of water and 150 ml of tetrahydrofuran (THF) with 50 ml of 1 N NaOH. To this solution was added Fmoc-OSu (16.87 g, 50 mmol); with rapid stirring. The suspension was adjusted to pH 7 with 1N NaOH and then stirred overnight, after which a small amount of solid tyrosine still remained. Solid citric acid (15 g) was added with stirring followed by 300 ml of ethyl acetate (EtOAc). The EtOAc layer was collected washed with 3×50 ml of 10% citric acid, 4×50 ml of saturated NaCl, and dried over MgSO4. Evaporation of the EtOAc solution gave a light tan syrup which was crystallized from 200 ml of dichloromethane (DCM) to give 18.04 g (89.4% yield) of product (mp 126°-130°).

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