Azirines are three-membered heterocyclic unsaturated (i.e. they contain a double bond) compounds containing a nitrogen atom and related to the saturated analogue aziridine.

[1] They are highly reactive yet have been reported in a few natural products such as Dysidazirine.

[3] Due to the weak N-O bond, the isoxazole ring tends to collapse under UV irradiation, rearranging to azirine.

Photolysis of azirines (under 300 nm) is a very efficient way to generate nitrile ylides.

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