[OH-].[Na+].[C:3]([C:7]1[NH:11][C:10]([C:12]([O:14][CH3:15])=[O:13])=[C:9]([N+:16]([O-:18])=[O:17])[CH:8]=1)([CH3:6])([CH3:5])[CH3:4].S(OC)(O[CH3:23])(=O)=O>[Br-].C([N+](CCCC)(CCCC)CCCC)C1C=CC=CC=1.ClCCl>[C:3]([C:7]1[N:11]([CH3:23])[C:10]([C:12]([O:14][CH3:15])=[O:13])=[C:9]([N+:16]([O-:18])=[O:17])[CH:8]=1)([CH3:6])([CH3:4])[CH3:5]
Sodium hydroxide (0.21 g, 2.65 mmol, 50% aqueous, 6 equiv) is added to a cold (0-−10° C.) solution of methyl 5-t-butyl-3-nitropyrrole-2-carboxylate (100 mg, 0.44 mmol), benzyltributyl ammonium bromide (158 mg, 0.44 mmol, 1 equiv), and dimethyl sulfate (46 mL, 0.49 mmol, 1.1 equiv) in dichloromethane (1 mL). After 5 min, the cooling bath is removed and the mixture is stirred for 4 h at rt. The reaction mixture is diluted with dichloromethane, washed with water (1×), 10% ammonium acetate (2×), dried (Na2SO4), and concentrated in vacuo to give a bright yellow oil. The residue is purified by flash chromatography (30% hexane in dichloromethane) to give 61 mg of methyl 5-t-butyl-1-methyl-3-nitropyrrole-2-carboxylate as a pale yellow oil which solidifies upon standing (62%). 1H NMR (CDCl3) d 6.47 (s, 1H), 3.92 (s, 3H), 3.80 (s, 3H), 1.38 (s, 9H).
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