[CH3:1][N:2]1[C:10]2[C:5](=[CH:6][C:7]([O:12][CH3:13])=[CH:8][C:9]=2Br)[CH:4]=[CH:3]1.C([Li])(C)(C)C.[C:19](OC)(=[O:24])[C:20]([O:22][CH3:23])=[O:21]>C1COCC1>[CH3:23][O:22][C:20](=[O:21])[C:19]([C:9]1[CH:8]=[C:7]([O:12][CH3:13])[CH:6]=[C:5]2[C:10]=1[N:2]([CH3:1])[CH:3]=[CH:4]2)=[O:24]A solution of 1-methyl-5-methoxy-7-bromoindole (1.6 g, 6.66 mmol) in THF (44.5 mL) was cooled to −78° C. and a solution of tert-butyl lithium in pentanes (1.7 M, 8.62 mL, 14.7 mmol) added dropwise over 30 min. After 30 min at −78° C., the mixture was treated with dimethyl oxalate (1.96 g, 16.7 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 extracts washed with brine, dried (Na2SO4) and concentrated. Flash chromatography (EtOAc/hexanes) afforded the title compound (0.9 g, 54.7%) as bright yellow oil. 1HNMR (400 MHz, CDCl3) 3.83 (s, 3H), 3.87 (s, 3H), 4.00 (s, 3H), 6.51 (d, J=3.12 Hz, 1 H), 7.07 (d, J=3.13 Hz, 1H), 7.21 (d, J=2.35 Hz, 1H), 7.7.40 (d, J=2.34 Hz, 1H); MS (ES, m/z): C13H13NO4: 188.06 (M++1).
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