Abstract This paper reports the synthesis of new pyrido [2, 3-d] pyrimidin-4-one derivatives as diuretic agents. Starting with 1, 2-dihydro-5-nitro-2-oxo-3-pyridinecarboxylic acid 1, ethyl 2-ethoxy-5-nitro-3-pyridincarboxylate 4 was obtained. Compound 4 reacts with ammonia, methylamine or S-methylpseudothiourea to give the respective 2-amino-5-nitro-3- pyridinecarboxamide derivatives 5 and 6 or 2-methylthio-6-nitro-3H-pyrido [2, 3-d] ...
