4-Bromo-2-fluoro-1-iodobenzene → Rac-[2-(4-bromo-2-fluoro-phenyl)-1-(3,4-dichloro-phenyl)-2-oxo-ethyl]-carbamic acid tert-butyl ester

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To a stirred solution of 1.75 g (5.78 mmol) 1-bromo-3-fluoro-4-iodo-benzene in 12 ml dry tetrahydrofuran were added at −78° C. 3.61 ml (5.78 mmol) of a 1.6M butyl lithium solution in hexanes. After 1 h 0.600 g (1.65 mmol) rac-[(3,4-dichloro-phenyl)-(methoxy-methyl-carbamoyl)-methyl]-carbamic acid tert-butyl ester (Intermediate 9) were added and stirred at −78° C. fur further 4 h. Then the reaction mixture was quenched by addition of saturated aqueous ammonium chloride solution, warmed to ambient temperature and extracted with ethyl acetate. The combined extracts were washed with brine, dried over Na2SO4, filtered and evaporated. The crude product was purified by flash-chromatography over silica gel with a heptane/AcOEt gradient starting with pure heptane: rac-[2-(4-bromo-2-fluoro-phenyl)-1-(3,4-dichloro-phenyl)-2-oxo-ethyl]-carbamic acid tert-butyl ester was obtained as a colorless viscous oil: MS (ISP): 476.0 and 477.9 (M+H)+.

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