[CH3:1][C:2]1[NH:6][C:5]([C:7]([O:9][CH2:10][CH3:11])=[O:8])=[C:4]([C:12]2[CH:17]=[CH:16][CH:15]=[CH:14][CH:13]=2)[C:3]=1[C:18]([O:20][CH2:21][CH3:22])=[O:19].[H-].[Na+].[CH3:25]I>O1CCCC1>[CH3:25][N:6]1[C:2]([CH3:1])=[C:3]([C:18]([O:20][CH2:21][CH3:22])=[O:19])[C:4]([C:12]2[CH:17]=[CH:16][CH:15]=[CH:14][CH:13]=2)=[C:5]1[C:7]([O:9][CH2:10][CH3:11])=[O:8]A solution of diethyl 5-methyl-3-phenyl-1H-pyrrole-2,4-dicarboxylate (85 g, 0.28 mol) in dry tetrahydrofuran (240 mL) was added to a suspension of sodium hydride (60% w/w; 17 g, 0.425 mol) in dry tetrahydrofuran (200 mL) at 0° C. over 45 min. The mixture was warmed to room temperature and stirred for 1 h before cooling back to 0 C. Methyl iodide (71 mL, 1.13 mol) was added dropwise over 30 min and the reaction mixture and then stirred at room temperature for 18 h. The mixture was quenched with ice-water (100 mL) and concentrated in vacuo to remove volatile organics. The aqueous phase was decanted off and the residual solid was extracted with dichloromethane (350 mL). The aqueous phase was extracted with dichloromethane (2×100 mL) and the combined extracts were washed successively with water (2×200 mL), brine (2×100 mL), dried over anhydrous sodium sulfate and concentrated to afford diethyl 1,5-dimethyl-3-phenyl-pyrrole-2,4-dicarboxylate (80 g, 90%) as a yellow solid.
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