3-(3,5-Dichloro-phenyl)-acrylic acid tert butyl ester → 3-(3,5-Dichlorophenyl)-propionic acid tert-butyl ester

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Reaktionsschritte

3,5-dichloro-iodo-benzene (5 g, 18 mmol) was stirred at room temperature as a solution in DMF (50 mL) containing tert butyl acrylate (6.5 mL, 2.5 eq), tetrabutyl ammonium chloride hydrate (5.1 g, 1 eq), potassium acetate (5.4 g, 3 eq) and palladium (II) acetate (˜200 mg, 30 mol %) for 5 hours. Reaction mixture was reduced in vacuo, partitioned between water and ethyl acetate. Ethyl acetate fractions were dried over magnesium sulfate, filtered over a small plug of silica gel. Silica gel plug washed with 10% Ethyl acetate/n-heptanes to afford 3-(3,5-Dichloro-phenyl)-acrylic acid tert butyl ester after evaporation as a white solid. 1H NMR (400 MHz, DMSO-D6) δ ppm 1.46 (s, 9H) 6.69 (d, J=16.04 Hz, 1H) 7.49 (d, J=16.04 Hz, 1H) 7.59 (t, J=1.89 Hz, 1H) 7.81 (d, J=1.77 Hz, 2H). A solution of 3-(3,5-Dichloro-phenyl)-acrylic acid tert butyl ester (4 g, 14 mmol) in ethanol (100 mL) was charged with platinum oxide (800 mg), after purging reaction mixture with nitrogen. Attached balloon of hydrogen and stirred vigorously at room temperature over night. After removal of excess hydrogen, catalyst was removed by filtering mixture over a pad of celite and the resulting solution was evaporated to afford 3-(3,5-dichloro-phenyl)-propionic acid tert-butyl ester as an oil (3.8 g; 94% isolated yield). 1H NMR (400 MHz, CHLOROFORM-D) δ ppm 1.41 (s, 9H) 2.52 (s, 2H) 2.85 (s, 2H) 7.08 (s, 2H) 7.18 (s, 1H).

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