Sydnone

Sydnone
Names
IUPAC name
2H-Oxadiazol-5-one
Other names
1,2,3-Oxadiazol-5(2H)-one
Identifiers
3D model (JSmol)
ChemSpider
  • InChI=1S/C2H2N2O2/c5-2-1-3-4-6-2/h1,4H
    Key: BIGWXAGEQONZGD-UHFFFAOYSA-N
  • C1=NNOC1=O
Properties
C2H2N2O2
Molar mass 86.050 g·mol−1
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).

Sydnones are mesoionic heterocyclic chemical compounds possessing a C5-oxygenated 1,2,3-oxadiazole core, named after the city of Sydney, Australia. Like other mesoionic compounds they are dipolar, possessing both positive and negative charges which are delocalized across the ring.

Discovery

N-Phenylsydnone was first prepared in 1935 by John Campbell Earl and Alan W. Mackney [Wikidata] by cyclodehydration of N-nitroso-N-phenylglycine with acetic anhydride. Later work showed that this could be applied fairly generally to the nitrosamines of N-substituted amino acids.

The parent compound sydnone is not synthetically accessible and may not exist.: 130 : 554 

Chemical structure

Sydnones have the following resonance structures.[citation needed] The exocyclic oxygen atom (O6) has a significant negative charge.

Recent computational studies have indicated that sydnones and other similar mesoionic compounds are nonaromatic, "though well-stabilized in two separate regions by electron and charge delocalization."

Examples

A sydnone imine in which the keto group of sydnone (=O) has been replaced with an imino (=NH) group can be found as a substructure in the stimulant drugs feprosidnine and mesocarb.

See also

References

  1. ↑ IUPAC, Compendium of Chemical Terminology, 5th ed. (the "Gold Book") (2025). Online version: (2006–) "sydnones". doi:10.1351/goldbook.S06207
  2. 1 2 3 Stewart, F. H. C. (1 April 1964). "The Chemistry of the Sydnones". Chemical Reviews. 64 (2): 129–147. doi:10.1021/cr60228a004.
  3. 1 2 3 Browne, Duncan L.; Harrity, Joseph P.A. (January 2010). "Recent developments in the chemistry of sydnones". Tetrahedron. 66 (3): 553–568. doi:10.1016/j.tet.2009.10.085.
  4. ↑ Earl, J. Campbell; Mackney, Alan W. (1935). "204. The action of acetic anhydride on N-nitrosophenylglycine and some of its derivatives". Journal of the Chemical Society (Resumed): 899. doi:10.1039/jr9350000899.
  5. ↑ Simas, Alfredo (1998). "Are mesoionic compounds aromatic?". Canadian Journal of Chemistry. 76 (6): 869–872. Bibcode:1998CaJCh..76..869S. doi:10.1139/v98-065.
  6. ↑ U.S. patent 4,332,801
  7. ↑ GB 1387306
  8. ↑ Patel, Keshav C.; Patel, Himanshu D. (2011). "Synthesis and Biological Evaluation of Coumarinyl Sydnone Derivatives". e-Journal of Chemistry. 8 (1): 113–118. doi:10.1155/2011/705856. ISSN 0973-4945.

Further reading