pyrimidin2one

Pyrimidin-2-one, also referred to as 2-pyrimidinone, is a heterocyclic compound that features a six‑membered pyrimidine ring with a carbonyl group at the 2‑position. The ring contains nitrogen atoms at the 1 and 3 positions, and the carbonyl converts the ring into a lactam-like framework. The unsubstituted parent is a relatively small, polar heterocycle that serves as a versatile building block in organic synthesis and medicinal chemistry.

Isomerism and tautomerism are common considerations for pyrimidinones. In addition to the 2‑one isomer, other carbonyl‑containing isomers of the pyrimidine ring (notably 4‑one) exist as distinct compounds. Substitution on the ring (for example at C-4, C-5, or C-6) creates a variety of 2‑one derivatives with different physicochemical properties and reactivity. Depending on the substituents and environment, the molecule can participate in enol–keto or lactam–lactim tautomerism in some cases, influencing hydrogen-bonding patterns and reactivity.

Synthesis and use in chemistry. Pyrimidin-2-one derivatives are typically prepared through cyclization strategies that assemble the pyrimidine ring from amidine or guanidine precursors and β‑dicarbonyl components, followed by selective oxidation to install the 2‑carbonyl. They can also arise from oxidation of related dihydropyrimidine systems. In practice, these compounds are explored as scaffolds in drug discovery and as linkable cores for the development of enzymes, receptor ligands, and nucleoside‑like analogs due to their hydrogen-bonding capabilities and planar aromatic structure.

See also: uracil, pyrimidin-4-one, dihydropyrimidinone.