N-Carbethoxyphthalimide → 3-(o-nitrophenyl)thio-2(R)-phthalimidopropionic acid

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Reaction Steps

In an aqueous solution (200 ml) of 1.4 g of sodium carbonate is dissolved 2.9 g of S-(o-nitrophenyl)-L-cysteine, and 3.5 g of N-ethoxycarbonylphthalimide is added to the solution under stirring. After the mixture is stirred at room temperature for 5 hours, the insoluble matter is removed by filtration, and the filtrate is made weakly acid with concentrated hydrochloric acid. The crystals which separate out are recovered by filtration, and recrystallized from 30 ml of ethanol to give 3.6 g of 3-(o-nitrophenyl)thio-2(R)-phthalimidopropionic acid as pale yellow needles, melting at 220°-222° C.

Provenance & Evidence