[Na].[Cl:2][C:3]1[CH:28]=[CH:27][C:6]([C:7]([C:9]2[N:13]([CH2:14][CH2:15][CH:16]3[C:21](=[O:22])[O:20][C:19](C)(C)[O:18][C:17]3=[O:25])[C:12]([Cl:26])=[CH:11][CH:10]=2)=[O:8])=[CH:5][CH:4]=1.[CH3:29]O>Cl>[Cl:2][C:3]1[CH:28]=[CH:27][C:6]([C:7]([C:9]2[N:13]([CH2:14][CH2:15][CH:16]([C:21]([O:20][CH3:19])=[O:22])[C:17]([O:18][CH3:29])=[O:25])[C:12]([Cl:26])=[CH:11][CH:10]=2)=[O:8])=[CH:5][CH:4]=1The 5-(4-chlorobenzoyl)-2-chloro-1-[2-(2,2-dimethyl-4,6-dioxo-1,3-dioxan-5-yl)ethyl]pyrrole sodium salt from Example 3A was dissolved in methanol saturated with hydrogen chloride (30 mL) and stirred at 0° C. for three hours. The solution was diluted with methanol (30 mL) and allowed to warm to room temperature, and was then stirred for another four hours. The solvent was then evaporated under reduced pressure at 10°-20° C. The residue was partitioned between ether and water (150 mL+50 mL), and the water was extracted with ether (2×150 mL). The combined ether extracts were dried over anhydrous sodium sulfate and evaporated to dryness. The residue was chromatographed on Florisil® (50 g/g mixture), eluting the product with hexane/ethyl acetate, 7:3. The product so obtained (1.912 g, 68%) was a colorless crystalline solid, which was recrystallized from dichloromethane/hexane to afford 5-(4-chlorobenzoyl)-2-chloro-1-[3,3-di(methoxycarbonyl)propyl]pyrrole, having the following properties:
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