Trifluoroacetic acid → 2-(3-Bromo-5-fluoro-phenyl)-3,3-dimethyl-1,2,3,4-tetrahydro-quinoline-6-carboxylic acid ethyl ester

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Reaktionsschritte

To a mixture of 2-(3-bromo-5-fluoro-phenyl)-4-hydroxy-3,3-dimethyl-1,2,3,4-tetrahydro-quinoline-6-carboxylic acid ethyl ester (3.3 g, 7.9 mmol) and triethylsilane (5 mL) at 25° C. was added trifluoroacetic acid (5 mL) dropwise. The resulting mixture was stirred at 25° C. for 1 h. Then the reaction mixture was concentrated in vacuo and the residue was extracted with ethyl acetate (2×20 mL), washed with saturated aqueous sodium bicarbonate solution (2×10 mL), dried over anhydrous sodium sulfate and concentrated in vacuo. Purification on flash silica gel chromatography (silica gel from QingDao, 200-300 mesh, glass column from Shanghai SD company) (10% ethyl acetate/hexanes) to afford 2-(3-bromo-5-fluoro-phenyl)-3,3-dimethyl-1,2,3,4-tetrahydro-quinoline-6-carboxylic acid ethyl ester (1.2 g, 16%) as a white solid: LC/MS m/e calcd for C20H21BrFNO2 M+: 406.3, observed: 406.2, 408.2.

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