3-Nitro-5- -pyridinone

An alternative method for the synthesis of amrinone from 3-cyano-5-(4-piridyl)-2(l//)-pyridinone (17.2.2) is based on it s acidic hydrolysis to the corresponding acid, 3-carboxy-5-(4-piridyl)-2(l//)-pyridinone (17.2.5), nitration of which with nitrous acid in the presence of sulfuric acid forms 3-nitro-5-(4-piridyl)-2(l//)-pyridinone (17.2.6). Reducing the nitro group of this product with hydrogen gives the desired amrinone (17.2.4) [19, 20]. 

A mixture containing lOg of 3-nitro-5-(4-pyridinyl)-2(lH)-pyridinone, 200 ml of dimethylformamide and 1.5 g of 10% palladium-on-charcoal was hydrogenated under pressure (50 psi) at room temperature until the uptake of hydrogen ceased (about 30 minutes). The reaction mixture was filtered through infusorial earth and the filtrate was heated in vacuum to remove the solvent. The residual material was crystallized from dimethylformamide, washed successively with ethanol and ether, and dried in a vacuum oven at 80°C for 8 hours to yield 6 g of 3-amino-5-(4-pyridinyl)-2(lH)-pyridinone, melting point 294° to 297°C with decomposition. 

Displacement of a nitro group by a side-chain amine-derived anion can lead to the formation of a pyridinone derivative which may have antibacterial properties. 

Nitromethylideneimidazolidines (42.14) [synthesized from l-nitro-2,2-bis(methylthio)ethene and ethyienediamines] react at room temperature with diketene (reviews [116, 2018]) to form a new fused pyridinone ring [3816]. The readily available chalcones may be cyclized in hot mineral acid to form a fused pyran-4-one ring in moderate yield [3517]. 

A nitro group attached to a pyrimidinone or pyridinone ring may be displaced by a nucleophile such as an azide ion. On heating the azide in DMF, a fused triazole ring is formed. 

---