[Cl:1][C:2]1[CH:3]=[C:4]([S:8][C:9]2[NH:13][CH:12]=[C:11]([C:14]([O:16]C)=[O:15])[CH:10]=2)[CH:5]=[CH:6][CH:7]=1.[OH-].[Na+]>CO>[Cl:1][C:2]1[CH:3]=[C:4]([S:8][C:9]2[NH:13][CH:12]=[C:11]([C:14]([OH:16])=[O:15])[CH:10]=2)[CH:5]=[CH:6][CH:7]=1Methyl 5-(3-chlorophenylthio)pyrrole-3-carboxylate (1.5 g.) was refluxed with 10 ml. of 1N sodium hydroxide and 20 ml. of methanol, at which time thin layer chromatography (silica gel with hexane-5/ethyl acetate-1/5% acetic acid as eluant) indicated hydrolysis was complete. The methanol was allowed to evaporate. The aqueous residue was diluted with approximately one volume of water and extracted twice with ether. The aqueous phase was acidified with 6N hydrochloric acid and product extracted multiply into ethyl acetate. The combined ethyl acetate extracts were back-washed with water and then with saturated brine, dried over anhydrous sodium sulfate and evaporated to an oil. Trituration of the oil with hexane gave 5-(3-chlorophenylthio)pyrrole-3-carboxylic acid (1.32 g., m.p. 134°-137° C., m/e 253).
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