C(NC(C)C)(C)C.[Li]CCCC.[Br:13][C:14]1[CH:19]=[CH:18][C:17]([F:20])=[CH:16][CH:15]=1.[CH3:21][CH2:22][O:23]C(C(F)F)=O>C1COCC1>[Br:13][C:14]1[CH:19]=[CH:18][C:17]([F:20])=[C:16]([C:22](=[O:23])[CH3:21])[CH:15]=1A solution of 17.78 ml (126 mmol) diisopropyl amine in 375 ml THF was cooled to −78° C. A 1.6 M solution of BuLi in hexanes (79 ml, 126 mmol) was added drop wise. After 15 minutes 20 g of 4-bromo-1-fluoro benzene (114 mmol) was added dropwise while keeping the temperature below −60° C. After stirring for 2.5 h at −70° C. 13.22 ml ethyl difluoro acetate were added. The mixture was warmed to −40° C. and then quenched by pouring the mixture onto 1M HCl. The mixture was extracted with ligroine, dried with MgSO4.H2O, concentrated and purified by column chromatography (silica gel; hexane/5-15% TBME) to give the desired product as a yellow liquid. 1H-NMR (CDCl3, 360 MHz): 8.09 (dd, 1H), 7.82-7.77 (m, 1H), 7.17 (t, 1H), 6.45 (t, 1H, CHF2)
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