Imidazolidinones or imidazolinones are a class of 5-membered ring

heterocycle A heterocyclic compound or ring structure is a cyclic compound that has atoms of at least two different elements as members of its ring(s). Heterocyclic chemistry is the branch of organic chemistry dealing with the synthesis, properties, and ...

s structurally related to

imidazole Imidazole (ImH) is an organic compound with the formula C3N2H4. It is a white or colourless solid that is soluble in water, producing a mildly alkaline solution. In chemistry, it is an aromatic heterocycle, classified as a diazole, and has non ...

. Imidazolidinones feature a saturated C₃N₂ nucleus, except for the presence of a

urea Urea, also known as carbamide, is an organic compound with chemical formula . This amide has two amino groups (–) joined by a carbonyl functional group (–C(=O)–). It is thus the simplest amide of carbamic acid. Urea serves an important ...

amide In organic chemistry, an amide, also known as an organic amide or a carboxamide, is a compound with the general formula , where R, R', and R″ represent organic groups or hydrogen atoms. The amide group is called a peptide bond when it is ...

functional group In organic chemistry, a functional group is a substituent or moiety in a molecule that causes the molecule's characteristic chemical reactions. The same functional group will undergo the same or similar chemical reactions regardless of the res ...

in the 2 or 4 positions.

2-Imidazolidinones

The 2-imidazolidinones are cyclic derivatives of

. 1,3-Dimethyl-2-imidazolidinone is a polar solvent and

Lewis base A Lewis acid (named for the American physical chemist Gilbert N. Lewis) is a chemical species that contains an empty orbital which is capable of accepting an electron pair from a Lewis base to form a Lewis adduct. A Lewis base, then, is any sp ...

. Drugs featuring this ring system include emicerfont, imidapril, and

azlocillin Azlocillin is an acyl ampicillin antibiotic with an extended spectrum of activity and greater ''in vitro'' potency than the carboxy penicillins. Azlocillin is similar to mezlocillin and piperacillin. It demonstrates antibacterial activity again ...

. Dimethylol ethylene urea is the reagent used in permanent press clothing.

4-Imidazolidinones

4-Imidazolidinones can be prepared from phenylalanine in two chemical steps (amidation with methylamine followed by condensation reaction with acetone): Imidazolidinone catalyst work by forming an iminium ion with

carbonyl In organic chemistry, a carbonyl group is a functional group composed of a carbon atom double-bonded to an oxygen atom: C=O. It is common to several classes of organic compounds, as part of many larger functional groups. A compound containin ...

groups of α,β-unsaturated aldehydes ( enals) and enones in a rapid

chemical equilibrium In a chemical reaction, chemical equilibrium is the state in which both the reactants and products are present in concentrations which have no further tendency to change with time, so that there is no observable change in the properties of the ...

. This iminium activation lower the substrate's

LUMO In chemistry, HOMO and LUMO are types of molecular orbitals. The acronyms stand for ''highest occupied molecular orbital'' and ''lowest unoccupied molecular orbital'', respectively. HOMO and LUMO are sometimes collectively called the ''fronti ...

. Several 4-imidazolidinones have been investigated. Drugs featuring the 4-imidazolidinone ring include hetacillin, NNC 63-0532,

spiperone Spiperone (Spiroperidol; brand name: Spiropitan ( JP)) is a typical antipsychotic and research chemical belonging to the butyrophenone chemical class. It is licensed for clinical use in Japan as a treatment for schizophrenia. Additionally, spip ...

, and

spiroxatrine Spiroxatrine is a drug which acts as a selective antagonist at both the 5-HT1A receptor and the α2C adrenergic receptor. It is an analog of spiperone and also has some dopamine antagonist A dopamine antagonist, also known as an anti-dopa ...

Imidazolones

{{main, Imidazolone Imidazolones (also called imidazolinones) are oxo derivatives of

imidazoline Imidazoline is a class of heterocycles formally derived from imidazoles by the reduction of one of the two double bonds. Three isomers are known, 2-imidazolines, 3-imidazolines, and 4-imidazolines. The 2- and 3-imidazolines contain an imine In ...

(dihydroimidazoles). Examples include

imidazol-4-one-5-propionic acid Imidazol-4-one-5-propionic acid is an intermediate in the metabolism of histidine. It is a colorless compound that is sensitive to light in air. The compound features an imidazolone ring. Occurrence It arises via the action of urocanase on ur ...

, a product of the catabolism of

histidine Histidine (symbol His or H) is an essential amino acid that is used in the biosynthesis of proteins. It contains an α-amino group (which is in the protonated –NH3+ form under biological conditions), a carboxylic acid group (which is in the ...

, and imazaquin, a member of the imidazolinone class of herbicide.

2-Imidazolidinones

4-Imidazolidinones

Imidazolones

References