Azirine

Azirine
Names
IUPAC name
2H-Azirine
Identifiers
3D model (JSmol)
1633516
ChEBI
ChemSpider
  • InChI=1S/C2H3N/c1-2-3-1/h1H,2H2
    Key: NTJMGOWFGQXUDY-UHFFFAOYSA-N
  • C1C=N1
Properties
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).

Azirines are heterocyclic organic compounds containing a three-membered ring with two carbon atoms and one nitrogen atom, the unsaturated analogs of aziridines. Azirine, the parent compound, has two isomers: the antiaromatic 1H-azirine, containing a carbon–carbon double bond, is not stable and rearranges to the tautomeric 2H-azirine, containing a carbon–nitrogen double bond, which is at least 30 kcal·mol−1 lower in energy. 2H-Azirines can be considered strained imines and are isolable. They are highly reactive yet have been reported in a few natural products such as dysidazirine.

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.

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.

See also

References

  1. ↑ Januar, Lawrence A.; Molinski, Tadeusz F. (17 May 2013). "Acremolin from Acremonium strictum is N2,3-Etheno-2'-isopropyl-1-methylguanine, not a 1H-Azirine. Synthesis and Structural Revision". Organic Letters. 15 (10): 2370–2373. doi:10.1021/ol400752s. PMC 3957326.
  2. ↑ Pinho e Melo, Teresa M. V. D.; d'A. Rocha Gonsalves, António M. "Exploiting 2-Halo-2H-Azirine Chemistry" (PDF). Current Organic Synthesis. 1 (3): 275–292. doi:10.2174/1570179043366729. Archived from the original (PDF) on 2026-04-22.
  3. ↑ Palacios F, Ochoa de Retana AM, Martinez de Marigorta E, de los Santos JM (2001). "2H-Azirines as synthetic tools in organic chemistry". Eur. J. Org. Chem. 2001 (13): 2401–2414. doi:10.1002/1099-0690(200107)2001:13<2401::AID-EJOC2401>3.0.CO;2-U.
  4. ↑ Ullman, Edwin F.; Singh, Balwant (April 1966). "Photochemical Transposition of Ring Atoms in Five-Membered Heterocycles. The Photorearrangement of 3,5-Diphenylisoxazole". J. Am. Chem. Soc. 88 (8): 1844–1845. Bibcode:1966JAChS..88.1844U. doi:10.1021/ja00960a066.
  5. ↑ Cheng, K.; Qi, J.; Ren, X.; Zhang, J.; Li, H.; Xiao, H.; Wang, R.; Liu, Z.; Meng, L; Ma, N.; Sun, H. (2022). "Developing Isoxazole as a Native Photo-Cross-Linker for Photoaffinity Labeling and Chemoproteomics". Angew. Chem. Int. Ed. 61 (47) e202209947. doi:10.1002/anie.202209947. hdl:2031/8f64b6a6-b7a5-44e1-919c-e000ffe424f0. PMID 36151600.