Synonyms: 5-Methyl-4-oxo-3,4-dihydrothieno[2,3-d]pyrimidine-6-carboxylic acid;Thieno[2,3-d]pyrimidine-6-carboxylic acid, 3,4-dihydro-5-methyl-4-oxo-;thieno[2,3-d]pyrimidine-6-carboxylic acid, 4-hydroxy-5-methyl-;5-methyl-4-oxo-3,4-dihydrothieno[2,3-d]pyrimidine-6-carboxylate