[CH2:1]([C:3]1[S:7][C:6]([NH:8][C:9]2[CH:14]=[CH:13][CH:12]=[CH:11][C:10]=2[N+:15]([O-:17])=[O:16])=[C:5]([C:18]([O:20]CC)=[O:19])[CH:4]=1)[CH3:2].[OH-].[Na+]>C(O)C.O>[CH2:1]([C:3]1[S:7][C:6]([NH:8][C:9]2[CH:14]=[CH:13][CH:12]=[CH:11][C:10]=2[N+:15]([O-:17])=[O:16])=[C:5]([C:18]([OH:20])=[O:19])[CH:4]=1)[CH3:2]Ethyl 5-ethyl-2-(2-nitroanilino)-thiophene-3-carboxylate (6.0 g) dissolved in ethanol (100 ml) and water (50 ml) and heated to 60° C. with stirring. Sodium hydroxide (5N, 50 ml) was then added and the temperature maintained for 16 hours. The reaction mixture was cooled and diluted with water (500 ml), and solid title product filtered off, m.p. 189°-191° C. (EtOAc).
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