Azirine

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title: "Azirine" type: doc version: 1 created: 2026-02-28 author: "Wikipedia contributors" status: active scope: public tags: ["azirines"] topic_path: "general/azirines" source: "https://en.wikipedia.org/wiki/Azirine" license: "CC BY-SA 4.0" wikipedia_page_id: 0 wikipedia_revision_id: 0

| ImageFile = Azirin.svg | ImageSize = 100px | IUPACName = 2H-Azirine | OtherNames = | Section1 = {{Chembox Identifiers | CASNo = 157-16-4 | Beilstein = 1633516 | ChEBI = 30971 | ChEMBL = | ChemSpiderID = 119750 | DrugBank = | EC_number = | KEGG = | MeSHName = | PubChem = 135972 | InChI = 1S/C2H3N/c1-2-3-1/h1H,2H2 | InChIKey = NTJMGOWFGQXUDY-UHFFFAOYSA-N | SMILES = C1C=N1 | Section2 = {{Chembox Properties | C=2 | H=3 | N=1 | Appearance = | Density = | MeltingPt = | BoilingPt = | Solubility = | Section3 = {{Chembox Hazards | MainHazards = | FlashPt = | AutoignitionPt = Azirine is three-membered heterocyclic unsaturated (i.e. it contain a double bond) compound containing a nitrogen atom and related to the saturated analogue aziridine. Azirines are highly reactive yet have been reported in a few natural products such as Dysidazirine. There are two isomers of azirine: 1H-Azirines with a carbon-carbon double bond are not stable and rearrange to the tautomeric 2H-azirine, a compound with a carbon-nitrogen double bond. 2H-Azirines can be considered strained imines and are isolable.

Preparation

2H-Azirine is most often obtained by the thermolysis of vinyl azides. During this reaction, a nitrene is formed as an intermediate. Alternatively, they can be obtained by oxidation of the corresponding aziridine. Azirine can be generated during photolysis of isoxazole. Due to the weak N-O bond, the isoxazole ring tends to collapse under UV irradiation, rearranging to azirine. :[[File:Synth-Azirin.svg|350px|Azirine synthesis]]

Substituted azirines can be produced via the Neber rearrangement.

Reactions

Photolysis of azirines (under 300 nm) is a very efficient way to generate nitrile ylides. These nitrile ylides are dipolar compounds and can be trapped by a variety of dipolarophiles to yield heterocyclic compounds, e.g. pyrrolines.

The strained ring system also undergoes reactions that favor ring opening and can act as a nucleophile or an electrophile.

Azirines readily hydrolyse to give aminoketones which are themselves susceptible to self-condensation.

References

References

  1. Teresa M. V. D. Pinho e Melo and Antonio M. d'A. Rocha Gonsalves. (2004). "Exploiting 2-Halo-2H-Azirine Chemistry". Current Organic Synthesis.
  2. (2001). "2''H''-Azirines as synthetic tools in organic chemistry". Eur. J. Org. Chem..
  3. Edwin F. Ullman. (1966). "Photochemical Transposition of Ring Atoms in Five-Membered Heterocycles. The Photorearrangement of 3,5-Diphenylisoxazole". J. Am. Chem. Soc..
  4. (2022). "Developing Isoxazole as a Native Photo-Cross-Linker for Photoaffinity Labeling and Chemoproteomics.". Angew. Chem. Int. Ed..

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azirines