# Azete

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> Markdown URL: https://mediated.wiki/source/Azete.md
> Source: https://en.wikipedia.org/wiki/Azete
> Source revision: 1307288608
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{{chembox
| verifiedrevid = 462576477
| ImageFile=Azete structure.svg
| ImageSize=80px
| PIN = Azete
| SystematicName = Azacyclobutadiene
| OtherNames=Azetine
|Section1={{Chembox Identifiers
| CASNo_Ref = {{cascite|correct|??}}
| CASNo=287-24-1
| PubChem=20185374
| SMILES=C1=CN=C1
| ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}}
| ChemSpiderID = 14804701
| InChI = 1/C3H3N/c1-2-4-3-1/h1-3H
| InChIKey = LKSPYOVNNMPMIZ-UHFFFAOYAS
| StdInChI_Ref = {{stdinchicite|correct|chemspider}}
| StdInChI = 1S/C3H3N/c1-2-4-3-1/h1-3H
| StdInChIKey_Ref = {{stdinchicite|correct|chemspider}}
| StdInChIKey = LKSPYOVNNMPMIZ-UHFFFAOYSA-N
  }}
|Section2={{Chembox Properties
| C=3|N=1|H=3
| Appearance=
| Density=
| MeltingPt=
| BoilingPt=
| Solubility=
  }}
|Section3={{Chembox Hazards
| MainHazards=
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'''Azete''', also known as '''azacyclobutadiene''', is a [heterocyclic](/source/heterocycle) compound consisting of an [unsaturated](/source/Saturated_and_unsaturated_compounds) four-membered ring with three [carbon](/source/carbon) atoms and one [nitrogen](/source/nitrogen) atom.<ref name = "Didier_2018">{{cite journal | vauthors = Didier D, Baumann AN, Eisold M | title = Unsaturated four-membered N-heterocycles: From synthesis to applications. | journal = Tetrahedron Letters | date = November 2018 | volume = 59 | issue = 45 | pages = 3975–3987 | doi = 10.1016/j.tetlet.2018.09.055 }}</ref><ref name = "Davies_1984">{{cite book | vauthors = Davies DE, Storr RC | chapter = Azetidines, azetines and azetes | veditors = Katritzky AR, Rees CW | title = Comprehensive Heterocyclic Chemistry | volume = 7 | date = 1984 | pages = 237–284 | doi = 10.1016/B978-008096519-2.00115-6 | isbn = 978-0-08-096519-2 }}</ref> It is inherently unstable due to its 4π-electron [antiaromatic](/source/antiaromatic) character and the [strain](/source/ring_strain) of the four-membered ring.

Azete is the most unsaturated four-membered nitrogen heterocycle and is formally the nitrogen analogue of [cyclobutadiene](/source/cyclobutadiene). Its parent structure is highly strained and antiaromatic, accounting for its pronounced instability and reactivity. Azetes occur in unfused forms, where the ring is isolated, and in benzo-fused variants, which gain stability from aromatic conjugation with a benzene ring.<ref name = "Davies_1984" /><ref name = "Didier_2018" />

== Structure and electronic properties ==

Azete features a four-membered ring, with one atom replaced by nitrogen. [Quantum chemical calculation](/source/Ab_initio_quantum_chemistry_methods)s indicate the molecule is antiaromatic, possessing negative [resonance energy](/source/resonance_energy) and a [ground state](/source/ground_state) that leans towards [Singlet state](/source/Singlet_state) stabilization, though less antiaromatic than cyclobutadiene. The nitrogen atom breaks degeneracy of the [non-bonding orbital](/source/non-bonding_orbital)s, which helps mitigate some of the instability seen in cyclobutadiene itself. Experimental attempts confirm azete’s fleeting existence: isolable examples such as tris(dimethylamino)azete (a red solid, stable only at very low temperatures) and various benzo-fused azetes, which can be manipulated and trapped below freezing, have been documented.<ref name = "Davies_1984" /><ref name = "Didier_2018" />

== Synthesis ==

Azetes are typically generated via [ring contraction](/source/ring_contraction) or extrusion of small molecules (often nitrogen) from larger heterocyclic precursors. For example, vapor-phase [pyrolysis](/source/pyrolysis) of substituted benzo-[triazine](/source/triazine)s yields benzo-fused azetes in up to 60% yield as the major compound at −80 °C. [Thermolysis](/source/Thermolysis) of tertiary-alkyl [cyclopropene](/source/cyclopropene) [azide](/source/azide)s is another efficient route, exploiting the heightened stability conferred by bulky substituents and [London dispersion](/source/London_dispersion) forces. These strategies underscore the challenges posed by the inherent strain and antiaromaticity of the azete ring.<ref name = "Didier_2018" />

== Reactivity ==

Due to their antiaromaticity and strain, azetes are extraordinarily reactive. They readily undergo fragmentation into [acetylene](/source/acetylene)s and [nitrile](/source/nitrile)s, even in inert conditions, by [cycloreversion](/source/cycloreversion) processes. They are also prone to rapid [dimerization](/source/dimerization), acting as [diene](/source/diene)s or [dienophile](/source/dienophile)s in [cycloaddition](/source/cycloaddition) reactions. Benzo-fused azetes, in particular, exhibit useful chemical behavior, dimerizing via a Diels-Alder-type mechanism and participating in a range of cycloadditions with reactive partners such as [isobenzofuran](/source/isobenzofuran) and tetraphenylcyclopentenone, yielding structurally diverse and complex organic compounds.<ref name = "Davies_1984" /><ref name = "Didier_2018" />

== Applications ==

Although azetes themselves are rarely isolated in pure form and lack direct practical applications due to instability, their reactivity has been harnessed in [synthetic organic chemistry](/source/synthetic_organic_chemistry) to access various intermediates and fused ring systems. The use of azete precursors and azete-based reactions enables the construction of complex molecular architectures relevant to [medicinal chemistry](/source/medicinal_chemistry) and [material sciences](/source/material_sciences).<ref name = "Didier_2018" />

==See also==
* [Azetidine](/source/Azetidine), the saturated analog
* [Cyclobutadiene](/source/Cyclobutadiene), the homocyclic analog

==References==
{{reflist}}

Category:Nitrogen heterocycles
Category:Four-membered rings

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Adapted from the Wikipedia article [Azete](https://en.wikipedia.org/wiki/Azete) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Azete?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.