# Sydnone
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{{more footnotes needed|date=August 2013}}
{{Chembox
|ImageFile=Sydnone circle structure.png
|ImageSize = 120px
|IUPACName=2''H''-Oxadiazol-5-one
|OtherNames=1,2,3-Oxadiazol-5(2''H'')-one
|Section1={{Chembox Identifiers
| CASNo = 534-24-7
| PubChem=12443168
| ChemSpiderID = 65792731
| StdInChI=1S/C2H2N2O2/c5-2-1-3-4-6-2/h1,4H
| StdInChIKey = BIGWXAGEQONZGD-UHFFFAOYSA-N
| SMILES = C1=NNOC1=O
}}
|Section2={{Chembox Properties
|C=2|H=2|N=2|O=2
}}
}}
'''Sydnones''' are [mesoionic](/source/mesoionic) [heterocyclic](/source/heterocyclic_compound) chemical compounds possessing a C5-oxygenated [1,2,3-oxadiazole](/source/Oxadiazole) core,[{{GoldBookRef|title=sydnones|file=S06207}}][{{cite journal|last1=Stewart|first1=F. H. C.|title=The Chemistry of the Sydnones|journal=Chemical Reviews|date=1 April 1964|volume=64|issue=2|pages=129–147|doi=10.1021/cr60228a004}}][{{cite journal|last1=Browne|first1=Duncan L.|last2=Harrity|first2=Joseph P.A.|title=Recent developments in the chemistry of sydnones|journal=Tetrahedron|date=January 2010|volume=66|issue=3|pages=553–568|doi=10.1016/j.tet.2009.10.085}}] named after the city of [Sydney](/source/Sydney), Australia. Like other mesoionic compounds they are [dipolar](/source/Dipolar_compound), possessing both positive and negative charges which are delocalized across the ring.
== Discovery ==
N-phenylsydnone was first prepared in 1935 by [John Campbell Earl](/source/John_Campbell_Earl) and {{ill|Alan W. Mackney|qid=Q112249660}} by cyclodehydration of N-Nitroso-[N-phenylglycine](/source/N-Phenylglycine) with [acetic anhydride](/source/acetic_anhydride).[{{cite journal|last1=Earl|first1=J. Campbell|last2=Mackney|first2=Alan W.|title=204. The action of acetic anhydride on N-nitrosophenylglycine and some of its derivatives|journal=Journal of the Chemical Society (Resumed)|date=1935|pages=899|doi=10.1039/jr9350000899}}] Later work showed that this could be applied fairly generally to the [nitrosamine](/source/nitrosamine)s of N-substituted [amino acid](/source/amino_acid)s.[
The parent compound '''sydnone''' is not synthetically accessible and may not exist.][{{rp|p=130}}][{{rp|p=554}}
== Chemical structure ==
Sydnones have the following [resonance structures](/source/resonance_structures).{{citation needed|date=December 2024}} The [exocyclic](/source/exocyclic) oxygen atom (O6) has a significant negative charge.][
Image:Sydnone Resonance Structures.svg
Recent computational studies have indicated that sydnones and other similar mesoionic compounds are [nonaromatic](/source/nonaromatic), "though well-stabilized in two separate regions by electron and charge delocalization."][{{cite journal|last1=Simas|first1=Alfredo|title=Are mesoionic compounds aromatic?|journal=Canadian Journal of Chemistry|date=1998|volume=76|issue=6 |pages=869–872|doi=10.1139/v98-065}}]
==Examples==
* [Cefanone](/source/Cefanone) ([Cephanone](/source/Cephanone))
* [Ipramidil](/source/Ipramidil)
* 3-Thiomorpholino-sydnonimine {{US patent|4332801}}
* The reaction between methyl 3-benzyl-sydnone-4-acetate and diphenylacetylene is described in Ex1 of {{Cite patent|country=GB|number=1387306}} gives an analog of [Bufezolac](/source/Bufezolac).
* Synthesis and Biological Evaluation of Coumarinyl Sydnone Derivatives.[{{cite journal|last1=Patel|first1=Keshav C.|last2=Patel|first2=Himanshu D.|title=Synthesis and Biological Evaluation of Coumarinyl Sydnone Derivatives|journal=e-Journal of Chemistry|volume=8|issue=1|year=2011|pages=113–118|issn=0973-4945|doi=10.1155/2011/705856|doi-access=free}}]
==Related compounds==
A [sydnone imine](/source/sydnone_imine) in which the [keto](/source/ketone) [group](/source/functional_group) of sydnone (=O) has been replaced with an [imino](/source/imine) (=NH) group can be found as a substructure in the stimulant drugs [feprosidnine](/source/feprosidnine) and [mesocarb](/source/mesocarb).
== See also ==
* [Chemical compounds with unusual names](/source/List_of_chemical_compounds_with_unusual_names)
* [Montréalone](/source/Montr%C3%A9alone)
* [Münchnone](/source/M%C3%BCnchnone)
* [Sydnone imine](/source/Sydnone_imine)
==References==
{{reflist}}
* {{cite journal
| title = Sydnone anions and abnormal N-heterocyclic carbenes of O-ethylsydnones. Characterizations, calculations and catalyses.
|author1=S. Wiechmann |author2=T. Freese |author3=M. H. H. Drafz |author4=E. G. Hübner |author5=J. C. Namyslo |author6=M. Nieger |author7=A. Schmidt | journal = Chem. Commun.
| volume = 50
| pages = 11822–11824
| year = 2014
|issue=80 | doi = 10.1039/C4CC05461J |pmid=25156208 | doi-access =free|hdl=10138/224668 |hdl-access=free }}
* {{cite journal
| title = Synthesis of Sydnones and Sydnone Imines
|author1=Claude V. Greco |author2=Wayne H. Nyberg |author3=C. C. Cheng | journal = Journal of Medicinal Chemistry
| volume = 5
| issue = 4
| pages = 861–865
| year = 1962
| doi = 10.1021/jm01239a022 |pmid=14056419 }}
* {{cite journal
| title = Meso-ionic compounds
|author1=Wilson Baker |author2=W. D. Ollis | journal = Quarterly Reviews, Chemical Society
| volume = 11
| pages = 15–30
| year = 1957
| doi = 10.1039/QR9571100015 |s2cid=96888271 }}
* {{cite journal
| title = The Preparation of Substituted Hydrazines. I. Alkylhydrazines via Alkylsydnones
|author1=Joseph Fugger |author2=Jack M. Tien |author3=I. Moyer Hunsberger | journal = [J. Am. Chem. Soc.](/source/J._Am._Chem._Soc.)
| volume = 77
| issue = 7
| pages = 1843–1848
| year = 1955
| doi = 10.1021/ja01612a039 }}
* {{cite journal
| title = The Preparation of Substituted Hydrazines. II.1 3-Pyridylhydrazine via the Phototropic N-(3-Pyridyl)-sydnone
|author1=Jack M. Tien |author2=I. Moyer Hunsberger
| journal = [J. Am. Chem. Soc.](/source/J._Am._Chem._Soc.)
| volume = 77
| issue = 24
| pages = 6604–6607
| year = 1955
| doi = 10.1021/ja01629a052 }} 88, 178 (1961);
* {{cite journal
| title = Sydnones. III. Preparation and Interconversion of Mercurated Derivatives of N-(3-Pyridyl)-sydnone1-3a
|author1=Jack M. Tien |author2=I. Moyer Hunsberger
| journal = [J. Am. Chem. Soc.](/source/J._Am._Chem._Soc.)
| volume = 83
| issue = 1
| pages = 178–182
| year = 1961
| doi = 10.1021/ja01462a035 }}
* {{cite journal
| author = [Alan R. Katritzky](/source/Alan_R._Katritzky)
| journal = Chem. Ind.
| pages = 521
| year = 1955
}}, ();
* {{cite journal
| title = Some new mesoionic compounds
|author1=Alexander Lawson |author2=D. H. Miles
| journal = J. Chem. Soc.
| pages = 2865–2871
| year = 1959
| doi = 10.1039/JR9590002865 }}
* {{cite journal
| title = A Kinetic Study of the Reaction of a "Meso-ionic" Compound (Dehydrodithizone) with Haloacetates
|author1=J. Ogilvie |author2=V. K. Miyamoto |author3=Thomas C. Bruice | journal = [J. Am. Chem. Soc.](/source/J._Am._Chem._Soc.)
| volume = 83
| issue = 11
| pages = 2493–2495
| year = 1961
| doi = 10.1021/ja01472a017 }}
* {{cite journal
| title = A New Class of Central Nervous System Stimulants
| author = LEMONT B. KIER, LAURETTA E. FOX, D. DHAWAN & I. W. WATERS
| journal = Nature
| volume = 195
| issue = 4843
| pages = 817–818
| year = 1962
| doi = 10.1038/195817a0
| pmid = 14455827 |bibcode = 1962Natur.195..817K | s2cid = 1683698
}}
== External links ==
* [https://goldbook.iupac.org/terms/view/S06207 IUPAC Goldbook entry]
* [https://books.google.com/books?id=OQrIk2rlduAC&dq=mesoionic+sydnone&pg=PA86 Dictionary of Organic Compounds]
{{Authority control}}
Category:Oxadiazoles
Category:Simple aromatic rings
Category:Lactones
---
Adapted from the Wikipedia article [Sydnone](https://en.wikipedia.org/wiki/Sydnone) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Sydnone?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.