Hexane → 3-Amino-4-(2,4,5-trifluorophenyl)but-2-enoic acid ethyl ester

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Reaction Steps

Ethyl 3-oxo-4-(2,4,5-trifluoro-phenyl)-butyrate 1c (24.6 g, 94.5 mmol) was dissolved in 240 mL of methanol, and ammonium acetate (36.4 g, 473 mmol) was added to the solution. The reaction mixture was heated to reflux for 3 hours. The reaction mixture was concentrated under reduced pressure, and then 100 mL of water was added to the residues. The mixture was extracted with ethyl acetate (200 mL×3), and the combined organic phase was washed with 200 mL of saturated brine, dried over anhydrous magnesium sulfate, filtered and concentrated under reduced pressure to obtain a light yellow solid. The resulting solid was dissolved in 50 mL of ethyl acetate at 80° C., and then 50 mL of n-hexane and seed-crystal were added to the solution. The mixture was cooled to room temperature, and half an hour later, 100 mL of n-hexane was added. The mixture was stored in refrigerator for 12 hours and then filtered to obtain the title compound ethyl 3-amino-4-(2,4,5-trifluoro-phenyl)-but-2-enoate 1d (19.5 g, yield 80%) as a white solid. MS m/z (ESI): 260.1 [M+1].

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