[CH3:1][N:2]1[C:10]2[C:5](=[CH:6][C:7]([F:12])=[CH:8][C:9]=2Br)[CH:4]=[CH:3]1.C([Li])(C)(C)C.[C:18](OC)(=[O:23])[C:19]([O:21][CH3:22])=[O:20]>C1COCC1>[CH3:22][O:21][C:19](=[O:20])[C:18]([C:9]1[CH:8]=[C:7]([F:12])[CH:6]=[C:5]2[C:10]=1[N:2]([CH3:1])[CH:3]=[CH:4]2)=[O:23]A solution of 1-methyl-5-fluoro-7-bromoindole (8.3 g, 36.4 mmol) in THF (250 mL) was cooled to −78° C. and a solution of tert-butyl lithium in pentanes (1.7 M, 47 mL, 80.1 mmol) added dropwise over 30 min. After 30 min at −78° C., the mixture was treated with dimethyl oxalate (10.75 g, 91 mmol) in one portion. After 15 min, the mixture was allowed to warm to room temperature and stirred 4 h. The reaction mixture was quenched with water, extracted with ethyl acetate and the extract washed with brine, dried (Na2SO4) and concentrated. Flash chromatography (EtOAc/hexanes) afforded the title compound (4.2 g, 49%). 1H NMR (400 MHz, CDCl3) 3.83(s, 3H), 4.01 (s, 3H), 6.56 (d, J=3.13 Hz, 1H), 7.15 (d, J=3.13 Hz, 1H), 7.35 (dd, J1=2.0 Hz, J2=9.4 Hz, 1H), 7.57 (dd, J1=2.34 Hz, J2=8.21 Hz, 1H); MS (ES, m/z): C12H10FNO3: 235.22 (M++1).
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