1,3-Dihydroimidazol-2-one

1,3-Dihydroimidazol-2-one
Names
	Other names 2-Hydroxyimidazole
Identifiers
CAS Number	5918-93-4 ;
3D model (JSmol)	Interactive image;
Beilstein Reference	105774
ChEBI	CHEBI:51022;
ChemSpider	20850;
ECHA InfoCard	100.302.640
EC Number	852-506-3;
KEGG	C20382;
PubChem CID	22208;
UNII	C658O375NL;
CompTox Dashboard (EPA)	DTXSID40207910 ;
	InChI InChI=1S/C3H4N2O/c6-3-4-1-2-5-3/h1-2H,(H2,4,5,6) Key: AICIYIDUYNFPRY-UHFFFAOYSA-N;
	SMILES C1=CNC(=O)N1;
Properties
Chemical formula	C3H4N2O
Molar mass	84.078 g·mol−1
Hazards
	GHS labelling:
Pictograms
Signal word	Danger
Hazard statements	H302, H314, H315, H319, H335, H360D
Precautionary statements	P203, P260, P264, P264+P265, P270, P271, P280, P301+P317, P301+P330+P331, P302+P352, P302+P361+P354, P304+P340, P305+P351+P338, P305+P354+P338, P316, P317, P318, P319, P321, P330, P332+P317, P337+P317, P362+P364, P363, P403+P233, P405, P501
	Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Infobox references

1,3-Dihydroimidazol-2-one is a chemical compound belonging to the group of unsaturated compounds nitrogen heterocycles. It is classified as a lactam and is a derivative of imidazoline and urea.

Representation

1,3-Dihydroimidazol-2-one (2) is obtained by reduction of hydantoin (1) with diisobutylaluminum hydride (DIBAH) in tetrahydrofuran.^[2]

Reduction of hydantoin to 1,3-dihydroimidazol-2-one

The Schwartz reagent can be used as an alternative reducing agent.^[3]

Another synthetic route is based on 2,2-diethoxyethylamine (1). Reaction with potassium cyanate yields 2,2-diethoxyethylurea (2), which undergoes cyclization under acidic conditions with sulfuric acid to form 1,3-dihydroimidazol-2-one (3).^[4]

text=Synthesis of 1,3-dihydroimidazol-2-one from 2,2-diethoxyethylamine

Properties

Several tautomeric forms of 1,3-dihydroimidazol-2-one are possible due to keto-enol tautomerism. In addition to 1,3-dihydroimidazol-2-one (1), these include 1H-imidazol-2-ol (2), 4H-imidazol-2-ol (3), and 1,5-dihydroimidazol-2-one (4). The preferred tautomer is 1,3-dihydroimidazol-2-one.^[5]

keto-enol tautomerism of synthesis at 1,3-dihydroimidazol-2-one

Use

In organic synthesis, 1,3-dihydroimidazol-2-one serves as a versatile building block for the preparation of substituted vicinal diamines or compounds featuring a cyclic urea structure.^[6]

1,3-Dihydroimidazol-2-one undergoes [2+2]-cycloadditions, for which the diacetylated derivative is typically employed due to solubility considerations. This reaction represents, for example, a key step in a total synthesis of biotin (5). Upon treatment with acetic anhydride, 1,3-dihydroimidazol-2-one (1) is first converted into 1,3-diacetyl-1,3-dihydroimidazol-2-one (2). A subsequent photochemical reaction with 3,4-dihydro-2-methoxy-2H-pyran (3) yields the tricyclic cyclobutane derivative 4, which can be transformed into biotin through several subsequent steps.^[7]

Total synthesis of biotin starting from 1,3-dihydroimidazol-2-one

References

↑ PubChem. "2-Hydroxyimidazole". pubchem.ncbi.nlm.nih.gov. Retrieved 2026-05-02.
↑ Ralph A. Whitney (1981). "Cycloaddition reactions of 1,3-diacetylimidazolin-2-one". Tetrahedron Letters. 22 (22): 2063–2066. doi:10.1016/S0040-4039(01)93277-0.
↑ Srinivasa Reddy Dandepally, Radouane Elgoummadi, Alfred L. Williams (2013). "Schwartz reagent mediated synthesis of thiazolones and imidazolones from thiazolidine-2,4-diones and imidazolidine-2,4-diones". Tetrahedron Letters. 54 (8): 925–928. doi:10.1016/j.tetlet.2012.12.015.{{cite journal}}: CS1 maint: multiple names: authors list (link)
↑ John W. Fischer, Richard A. Hollins, Charlotte K. Lowe-Ma, Robin A. Nissan, Robert D. Chapman (1996). "Synthesis and Characterization of 1,2,3,4-Cyclobutanetetranitramine Derivatives". Journal of Organic Chemistry. 61 (26): 9340–9343. doi:10.1021/jo9613040.{{cite journal}}: CS1 maint: multiple names: authors list (link)
↑ Klaus Ebel (1994). 1H-Imidazole (Struktur, Stabilität, Reaktivität) (4. ed.). Thieme Verlag. doi:10.1055/b-0035-110513. ISBN 978-3-13-797804-6.
↑ Alexis Archambeau (2019). "1,3-Dihydroimidazolone". Encyclopedia of Reagents for Organic Synthesis. John Wiley & Sons. pp. 1–3. doi:10.1002/047084289X.rn02225. ISBN 978-0-470-84289-8.
↑ Ralph Allen Withney (1983). "A total synthesis of (±)-biotin". Canadian Journal of Chemistry. 61 (6): 1158–1160. doi:10.1139/v83-206.

[1] PubChem. "2-Hydroxyimidazole". pubchem.ncbi.nlm.nih.gov. Retrieved 2026-05-02.

[2] Ralph A. Whitney (1981). "Cycloaddition reactions of 1,3-diacetylimidazolin-2-one". Tetrahedron Letters. 22 (22): 2063–2066. doi:10.1016/S0040-4039(01)93277-0.

[3] Srinivasa Reddy Dandepally, Radouane Elgoummadi, Alfred L. Williams (2013). "Schwartz reagent mediated synthesis of thiazolones and imidazolones from thiazolidine-2,4-diones and imidazolidine-2,4-diones". Tetrahedron Letters. 54 (8): 925–928. doi:10.1016/j.tetlet.2012.12.015.{{cite journal}}: CS1 maint: multiple names: authors list (link)

[4] John W. Fischer, Richard A. Hollins, Charlotte K. Lowe-Ma, Robin A. Nissan, Robert D. Chapman (1996). "Synthesis and Characterization of 1,2,3,4-Cyclobutanetetranitramine Derivatives". Journal of Organic Chemistry. 61 (26): 9340–9343. doi:10.1021/jo9613040.{{cite journal}}: CS1 maint: multiple names: authors list (link)

[5] Klaus Ebel (1994). 1H-Imidazole (Struktur, Stabilität, Reaktivität) (4. ed.). Thieme Verlag. doi:10.1055/b-0035-110513. ISBN 978-3-13-797804-6.

[EROS-6] Alexis Archambeau (2019). "1,3-Dihydroimidazolone". Encyclopedia of Reagents for Organic Synthesis. John Wiley & Sons. pp. 1–3. doi:10.1002/047084289X.rn02225. ISBN 978-0-470-84289-8.

[7] Ralph Allen Withney (1983). "A total synthesis of (±)-biotin". Canadian Journal of Chemistry. 61 (6): 1158–1160. doi:10.1139/v83-206.

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