Sydnone

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 Template:Ill and Template:Ill 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.Template:RpTemplate:Rp

Chemical structure

Sydnones have the following resonance structures. The exocyclic oxygen atom (O6) has a significant negative charge. File:Sydnone Resonance Structures.svg

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

• Cefanone (Cephanone)
• Ipramidil
• 3-Thiomorpholino-sydnonimine U.S. patent 4332801
• The reaction between methyl 3-benzyl-sydnone-4-acetate and diphenylacetylene is described in Ex1 of Template:Citation/make link  gives an analog of Bufezolac.
• Synthesis and Biological Evaluation of Coumarinyl Sydnone Derivatives.

Related compounds

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

• Chemical compounds with unusual names
• Montréalone
• Münchnone
• Sydnone imine

References

• 88, 178 (1961);
• , ();

External links

• IUPAC Goldbook entry
• Dictionary of Organic Compounds