2pyridone

2-Pyridone, also known as pyridin-2-one, is a heteroaromatic lactam. It features a six-membered ring containing a nitrogen atom at position 1 and a carbonyl group at position 2, giving the pyridinone framework. This compound is the lactam tautomer of 2-hydroxypyridine, and it commonly exists in equilibrium with its hydroxylated form.

Structure and tautomerism: 2-Pyridone and 2-hydroxypyridine are tautomers that interconvert through proton transfer. The relative abundance of the two forms varies with solvent, temperature, and substituents; in the solid state the lactam form is often favored, while solution equilibria can show appreciable amounts of either form depending on conditions.

Synthesis: Multiple routes exist to access 2-pyridone and its derivatives. Common strategies include oxidation of 2-hydroxypyridines to the corresponding lactams and cyclization reactions from suitable amidating or 1,3-dicarbonyl precursors. Protective-group strategies and functionalization at various positions allow access to substituted pyridin-2-ones for broader applications.

Properties and applications: 2-Pyridone is a polar, aromatic lactam that can act as a hydrogen-bond acceptor and, depending on tautomeric form, may participate in hydrogen-bond donation. The ring nitrogen imparts basic character in certain contexts, though the carbonyl reduces basicity relative to a parent amine. Derivatives of 2-pyridone are widely used as building blocks in organic synthesis, medicinal chemistry, and coordination chemistry, where the heteroaromatic lactam core serves as a versatile scaffold for target molecules and ligands.