Pyrimidine is an organic compound with an aromatic and heterocyclic structure, closely resembling pyridine. It belongs to the class of diazines, which are heterocyclic compounds containing two nitrogen atoms in the six-membered ring. In pyrimidine, the nitrogen atoms are positioned at positions 1 and 3 within the ring.

The principal synthesis for the production of pyrimidines usually involves the cyclization of β-dicarbonyl compounds with N-C-N compounds. Typical reactions include the synthesis of 2-substituted pyrimidines by reacting the former with amidines, the synthesis of 2-pyrimidinones by reacting with urea, and the synthesis of 2-aminopyrimidines by reacting with guanidines.

Pyrimidines are typically utilized by cells as a source of energy, and they are crucial for synthesizing DNA and RNA, proteins, starch, regulating enzymes, signaling between cells, and other important biological functions.

Pyrimidines, also known as 1,3-diazines, consist of a six-membered heteroaromatic ring that contains two nitrogen atoms located at positions 1 and 3. This chemical compound is one of three isomeric forms of diazine, the other two being pyridazine and pyrazine.

Pyrimidines, similar to pyridines, exhibit a greater decrease in π-electron density. As a result, electrophilic aromatic substitution is hindered, while nucleophilic aromatic substitution is promoted.