[Na].[I:2]Cl.[O:4]=[C:5]1[CH:10]([CH2:11][CH2:12][N:13]2[CH:17]=[CH:16][CH:15]=[C:14]2[C:18](=[O:25])[C:19]2[CH:24]=[CH:23][CH:22]=[CH:21][CH:20]=2)C(=O)O[C:7](C)(C)[O:6]1.S([O-])([O-])=O.[Na+:33].[Na+]>CO.O1CCCC1.ClCCl>[CH3:5][O-:4].[Na+:33].[CH3:7][O:6][C:5](=[O:4])[CH:10]([I:2])[CH2:11][CH2:12][N:13]1[CH:17]=[CH:16][CH:15]=[C:14]1[C:18](=[O:25])[C:19]1[CH:24]=[CH:23][CH:22]=[CH:21][CH:20]=1Sodium methoxide solution was prepared by dissolving metallic sodium (1.38 g, 60 mmol) in methanol (30 mL). This solution was diluted with anhydrous tetrahydrofuran (100 mL) and cooled to -30° C. A solution of iodine monochloride (8.97 g, 55.3 mmol) in dichloromethane (30 mL) was added dropwise to the stirred alkoxide solution. The resulting solution was stirred for 2 minutes, then the sodium salt of 1-[2-(4,6-dioxo-2,2-dimethyl-1,3-dioxan-5-yl)ethyl]-2-benzoylpyrrole (VI, 18.15 g, 50 mmol) was added as a solid. The mixture was stirred for 90 minutes at -30° C., then allowed to warm to 22° C. and stirred for an additional 18 hours. The reaction mixture was poured into 150 mL of 2% aqueous sodium sulfite solution in a separatory funnel, and the reaction flask was washed with 10 mL of diethyl ether, which was added to the separatory funnel. The mixture was shaken thoroughly, and the phases were separated. The aqueous phase was extracted with diethyl ether (2×20 mL), and the combined organic phase was washed with brine, dried over magnesium sulfate, and evaporated to afford 4-(2-benzoylpyrrol-1-yl)-2-iodobutyric acid methyl ester (IV, 18.16 g, 91.5%), identical to the material prepared by the method described above.
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