Imidazolidinone

Imidazolidinone is a heterocyclic organic compound that features a five‑membered ring containing two nitrogen atoms and a carbonyl group, forming a lactam known as imidazolidin-2-one. The core ring is often saturated at the 4 and 5 positions (4,5-dihydroimidazolidin-2-one), and many derivatives exist in which the nitrogens or ring carbons bear substituents. The parent compound is sometimes referred to as 2-imidazolidinone.

In its derivatives, the imidazolidinone ring can be N‑substituted or further functionalized at carbon atoms, giving a range of compounds with differing physical and chemical properties. The presence of the carbonyl group makes the ring a relatively polar lactam and a potential hydrogen bond acceptor, while the ring nitrogens can impart basicity that depends on substitution.

Synthesis of imidazolidinones typically involves cyclization to form the five‑membered lactam from suitable precursors, such as diamines with carbonyl partners or 2‑aminoalkanamides, using dehydration or cyclodehydration steps. Variants may arise from different substituents on nitrogen, on carbon, or by protection–deprotection strategies during assembly.

Applications and occurrence: Imidazolidinones are used as synthetic building blocks in medicinal chemistry and as scaffolds in the development of more complex heterocycles. They are structurally related to hydantoins (imidazolidine-2,4-diones), which are a closely studied class of compounds known for pharmacological activity. Imidazolidinones thus serve as versatile motifs in drug discovery and materials science, with properties tunable by substitution.