Azirine

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.^[1] 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.

Azirine

Names
IUPAC name 2H-Azirine
Identifiers
CAS Number	157-16-4
3D model (JSmol)	Interactive image
Beilstein Reference	1633516
ChEBI	CHEBI:30971
ChemSpider	119750
PubChem CID	135972
InChI InChI=1S/C2H3N/c1-2-3-1/h1H,2H2 Key: NTJMGOWFGQXUDY-UHFFFAOYSA-N
SMILES C1C=N1
Properties
Chemical formula	C2H3N
Molar mass	41.053 g·mol−1
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Infobox references

Preparation

2H-Azirine is most often obtained by the thermolysis of vinyl azides.^[2] 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.^[3] Due to the weak N-O bond, the isoxazole ring tends to collapse under UV irradiation, rearranging to azirine. ^[4]

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.

See also

• Dysidazirine, one of only a few naturally occurring azirines