Sydnones are

mesoionic In chemistry, mesoionic compounds are one in which a heterocyclic structure is dipolar and where both the negative and the positive charges are delocalized. A completely uncharged structure cannot be written and mesoionic compounds cannot be repre ...

heterocyclic A heterocyclic compound or ring structure is a cyclic compound that has atoms of at least two different elements as members of its ring(s). Heterocyclic chemistry is the branch of organic chemistry dealing with the synthesis, properties, and ...

chemical compounds possessing a 1,2,3-oxadiazole core with a keto group in the 5 position. Like other mesoionic compounds they are di-polar, possessing both positive and negative charges which are delocalized across the ring. Recent computational studies have indicated that sydnones and other similar mesoionic compounds are

nonaromatic In chemistry, aromaticity is a chemical property of cyclic ( ring-shaped), ''typically'' planar (flat) molecular structures with pi bonds in resonance (those containing delocalized electrons) that gives increased stability compared to saturate ...

, "though well-stabilized in two separate regions by electron and charge delocalization." Sydnones are heterocyclic compounds named after the city of Sydney, Australia. A

sydnone imine Sydnone imine is a mesoionic heterocyclic aromatic chemical compound. Sydnone imine is the imine of sydnone where the keto functional group of sydnone (=O) has been replaced with an imine (=NH) group. A sydnone imine substructure can be found i ...

in which the keto

group A group is a number of persons or things that are located, gathered, or classed together. Groups of people * Cultural group, a group whose members share the same cultural identity * Ethnic group, a group whose members share the same ethnic iden ...

of sydnone (=O) has been replaced with an

imino In organic chemistry, an imine ( or ) is a functional group or organic compound containing a carbon–nitrogen double bond (). The nitrogen atom can be attached to a hydrogen or an organic group (R). The carbon atom has two additional single bon ...

(=NH) group can be found as a substructure in the stimulant drugs

feprosidnine Feprosidnine (Sydnophen) is a stimulant drug which was developed in the USSR in the 1970s. It is structurally related to another Russian drug mesocarb but unlike mesocarb, was withdrawn earlier from production. In comparison with mesocarb it has ...

and

mesocarb Mesocarb (brand names Sidnocarb, Sydnocarb) is a drug that is currently being developed for Parkinson's disease. The drug was originally developed in the USSR in the 1970s for a variety of indications including asthenia, apathy, adynamia and so ...

Discovery

Sydnone was first prepared in 1935 by Earl & Mackney by cyclodehydration of N-Nitroso-

N-phenylglycine ''N''-Phenylglycine is an organic compound with the formula C6H5NHCH2CO2H. This white solid achieved fame as the industrial precursor to indigo dye. It is a non-proteinogenic amino acid, non-proteinogenic alpha amino acid related to sarcosine, ...

with

acetic anhydride Acetic anhydride, or ethanoic anhydride, is the chemical compound with the formula (CH3CO)2O. Commonly abbreviated Ac2O, it is the simplest isolable anhydride of a carboxylic acid and is widely used as a reagent in organic synthesis. It is a col ...

. Later work showed that this could be applied fairly generally to the

nitrosamine In organic chemistry, nitrosamines (or more formally ''N''-Nitrosamines) are organic compounds with the chemical structure , where R is usually an alkyl group. They feature a nitroso group () bonded to a deprotonated amine. Most nitrosamines are ...

s of N-substituted

amino acid Amino acids are organic compounds that contain both amino and carboxylic acid functional groups. Although hundreds of amino acids exist in nature, by far the most important are the alpha-amino acids, which comprise proteins. Only 22 alpha am ...

Chemical structure

Examples

* Cefanone ( Cephanone) * Ipramidil *3-Thiomorpholino-sydnonimine *The reaction between methyl 3-benzyl-sydnone-4-acetate and diphenylacetylene is described in Ex1 of gives an analog of Bufezolac. *Synthesis and Biological Evaluation of Coumarinyl Sydnone Derivatives.

References

* * * * * 88, 178 (1961); * *, (); * * *{{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

IUPAC Goldbook entry

Dictionary of Organic Compounds
Oxadiazoles Simple aromatic rings Lactones

Discovery

Chemical structure

Examples

See also

References

External links