4,5-Dichlorophthalic anhydride → 3-(5,6-dichloro-1,3-dioxo-1,3-dihydro-2H-isoindole-2-yl)thiophene-2-carboxamide

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Reaktionsschritte

3-aminothiophene-2-carboxamide was added to an acetic acid solution of 4,5-dichlorophthalic anhydride and stirred all night heated to reflux to give 3-(5,6-dichloro-1,3-dioxo-1,3-dihydro-2H-isoindole-2-yl)thiophene-2-carboxamide. 1M NaOH aq was added to THF-MeOH solution of the obtained 3-(5,6-dichloro-1,3-dioxo-1,3-dihydro-2H-isoindole-2-yl)thiophene-2-carboxamide and stirred for 2.5 hours at 80° C. to give 4,5-dichloro-2-(4-oxo-3,4-dihydrothieno[3,2-d]pyrimidine-2-yl)benzoic acid. Sulfuric acid was added to a MeOH-1,4-dioxane solution of the obtained 4,5-dichloro-2-(4-oxo-3,4-dihydrothieno[3,2-d]pyrimidine-2-yl)benzoic acid and stirred for three days at 70° C. to give methyl 4,5-dichloro-2-(4-oxo-3,4-dihydrothieno[3,2-d]pyrimidine-2-yl)benzoate.

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