P(Cl)(Cl)(Cl)=O.[CH3:6][N:7]1[C:15]2[C:10](=[CH:11][CH:12]=[CH:13][CH:14]=2)[C:9]([CH3:16])=[CH:8]1.[OH-].[Na+].CN([CH:22]=[O:23])C>O>[CH3:6][N:7]1[C:15]2[C:10](=[CH:11][CH:12]=[CH:13][CH:14]=2)[C:9]([CH3:16])=[C:8]1[CH:22]=[O:23]To a stirred solution of phosphorus oxychloride (7.0 mL, 75 mmole) in DMF (25 mL) was added dropwise a solution of 1,3-dimethylindole (12.0 g, 83 mmole) in dry DMF (6.0 mL). The reaction was stirred at RT for 2 hr then was poured onto ice. The mixture was basified with a solution of NaOH (13.2 g, 330 mmole) in H2O (44 mL), then was extracted with Et2O (2×50 mL). The combined organic layers were washed with brine, dried (MgSO4), and concentrated under vacuum. Flash chromatography on silica gel (10% ethyl acetate/hexanes) gave the title compound (13.03 g, 91%) as an off-white solid: LCMS (ES) m/e 174.2 (M+H)+; 1H NMR (400 MHz, CDCl3) δ 10.16 (s, 1 H), 7.68 (d, J=8.1 Hz, 1 H), 7.42 (t, 1 H), 7.32 (d, J=8.5 Hz, 1 H), 7.15 (t, 1 H), 4.04 (s, 3 H), 2.63 (s, 3 H).
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