C([NH:4][C:5]1[C:9]([Cl:10])=[CH:8][S:7][C:6]=1[C:11]([O:13][CH3:14])=[O:12])(=O)C>CO.Cl>[NH2:4][C:5]1[C:9]([Cl:10])=[CH:8][S:7][C:6]=1[C:11]([O:13][CH3:14])=[O:12]In a mixture of 50 ml of methanol and 50 ml of concentrated hydrochloric acid, 7 g of methyl 3-acetylamino-4-chlorothiophene-2-carboxylate are stirred at 60° C. for 4 hours, under reflux for 5 hours and at room temperature for another 3 days. Any precipitate that has formed is removed by filtration, and about ⅓ of the volume of the solvent is removed by distillation under reduced pressure. Following addition of about 100 ml of water, the mixture is stirred at room temperature for another 15 minutes and the colorless crystals are filtered off and dried in a stream of air. M.p.: 62-64° C.
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