Quinolizinium

Quinolizinium
Names
	Other names pyrido[1,2-a]pyridinium
Identifiers
CAS Number	255-59-4 ;
3D model (JSmol)	Interactive image;
Beilstein Reference	1423269
ChEBI	CHEBI:36646;
ChemSpider	107593;
PubChem CID	120516;
CompTox Dashboard (EPA)	DTXSID60276229 ;
	InChI InChI=1S/C9H8N/c1-3-7-10-8-4-2-6-9(10)5-1/h1-8H/q+1 Key: GUOHRXPYGSKUGT-UHFFFAOYSA-N;
	SMILES C1=CC=[N+]2C=CC=CC2=C1;
Properties
Chemical formula	C9H8N+
Appearance	colorless
Related compounds
Related compounds	4H-Quinolizine
	Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Infobox references

Quinolizinium refers to the heterocyclic cation with the formula C₉H₈N⁺. The cation is isoelectronic and nearly isostructural with naphthalene, the difference being the replacement of one of the two carbons at the fusion positions with N⁺. The parent quinolizine has not been isolated but salts of these aromatic quinolizinium compounds are well known. Several syntheses begin with 2-substituted pyridines and involve N-alkylation and various dehydrogenation reactions.^[1] The quinolizinium core is represented in the berberine family of natural products.^[2] It is formally derived from the elusive quinolizines by hydrde abstraction. According to X-ray crystallography of the hexafluorophosphate salt, which is colorless, C₉H₈N⁺ is planar.^[3]

Reactions

Being a cation, quinolinizium resists electrophilic attack, although it can be brominated. Catalytic hydrogenation gives quinolizidine.^[1]

References

^ ^a ^b Julio Alvarez-Builla; Juan Jose Vaquero; José Barluenga, eds. (2011). Modern Heterocyclic Chemistry. Wiley-VCH.
^ Grycová, Lenka; Dostál, Jiří; Marek, Radek (2007). "Quaternary protoberberine alkaloids". Phytochemistry. 68 (2): 150–175. Bibcode:2007PChem..68..150G. doi:10.1016/j.phytochem.2006.10.004. PMID 17109902.
^ Sato, Kiyoshi; Arai, Sadao; Yamagishi, Takamichi; Tanase, Tomoaki (2001). "Quinolizinium Hexafluorophosphate". Acta Crystallographica Section C Crystal Structure Communications. 57 (2): 174–175. doi:10.1107/S0108270100015742. PMID 11173443.

[Mod-1] Julio Alvarez-Builla; Juan Jose Vaquero; José Barluenga, eds. (2011). Modern Heterocyclic Chemistry. Wiley-VCH.

[2] Grycová, Lenka; Dostál, Jiří; Marek, Radek (2007). "Quaternary protoberberine alkaloids". Phytochemistry. 68 (2): 150–175. Bibcode:2007PChem..68..150G. doi:10.1016/j.phytochem.2006.10.004. PMID 17109902.

[3] Sato, Kiyoshi; Arai, Sadao; Yamagishi, Takamichi; Tanase, Tomoaki (2001). "Quinolizinium Hexafluorophosphate". Acta Crystallographica Section C Crystal Structure Communications. 57 (2): 174–175. doi:10.1107/S0108270100015742. PMID 11173443.

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