{{chembox | Verifiedfields = changed | Watchedfields = changed | verifiedrevid = 477215588 | Reference =<ref>[http://www.sigmaaldrich.com/catalog/search/ProductDetail/ALDRICH/463159 2H-Pyran-2-one] at Sigma-Aldrich</ref> | ImageFile =2-Pyranone.png | ImageSize =100px | PIN =2''H''-Pyran-2-one | OtherNames =α-Pyrone<br>2-Pyranone<br>Pyran-2-one |Section1={{Chembox Identifiers | ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}} | ChemSpiderID = 61462 | InChI = 1/C5H4O2/c6-5-3-1-2-4-7-5/h1-4H | InChIKey = ZPSJGADGUYYRKE-UHFFFAOYAI | StdInChI_Ref = {{stdinchicite|correct|chemspider}} | StdInChI = 1S/C5H4O2/c6-5-3-1-2-4-7-5/h1-4H | StdInChIKey_Ref = {{stdinchicite|correct|chemspider}} | StdInChIKey = ZPSJGADGUYYRKE-UHFFFAOYSA-N | CASNo_Ref = {{cascite|correct|CAS}} | CASNo =504-31-4 | UNII_Ref = {{fdacite|correct|FDA}} | UNII = 8WW45I202V | PubChem =68154 | ChEBI_Ref = {{ebicite|correct|EBI}} | ChEBI = 37965 | SMILES = O=C\1O\C=C/C=C/1 }} |Section2={{Chembox Properties | C=5|H=4|O=2 | Density =1.197 g/mL | BoilingPtC = 102 to 103 | BoilingPt_notes = at 20 mmHg }} }}
'''2-Pyrone''' ('''α-pyrone''' or '''pyran-2-one''') is an unsaturated cyclic chemical compound with the molecular formula C<sub>5</sub>H<sub>4</sub>O<sub>2</sub>. It is isomeric with 4-pyrone.
2-Pyrone is used in organic synthesis as a building block for more complex chemical structures because it may participate in a variety of cycloaddition reactions to form bicyclic lactones. For example, it readily undergoes Diels-Alder reactions with alkynes producing, upon loss of carbon dioxide, substituted benzenes.<ref>{{cite journal | author = Woodard BT, Posner G H | title = Recent Advances in Diels-Alder Cycloadditions Using 2-Pyrones | journal = Advances in Cycloaddition | year = 1999 | volume = 5 | pages = 47–83| doi = 10.1016/S1052-2077(99)80004-3}}</ref> The Gogte Synthesis (1938) is a method for the alkylation of certain pyrones with acid chlorides.{{Citation needed|date=March 2008}}
The parent 2-pyrone can be produced from decarboxylation of coumalic acid.<ref>{{cite book|first1=L. F.|last1=Fieser|author-link1=Louis Fieser|first2=M.|last2=Fieser|author-link2=Mary Peters Fieser|title=Lehrbuch der organischen Chemie|lang=de|trans-title=Textbook of Organic Chemistry|edition=3rd|publisher=Verlag Chemie|year=1957|page=943}}</ref>
==Derivatives== The most common natural products containing a 2-pyrone are the bufanolides and kavalactones. Oxovitisin A, a pyranoanthocyanin found in wine, also contains a 2-pyrone element.
6-Amyl-α-pyrone (6PP) is a derivative of 2-pyrone, found in animal foods and heated beef.<ref>{{PubChem|33960}}</ref> Due to its good organoleptic properties{{citation needed|date=July 2020}} with coconut aroma, it is used as flavor enhancer in the food industry. Biologically, it is produced by ''Trichoderma'' species via solid state fermentation.<ref>{{cite journal | doi = 10.1590/S1517-83822008000400022| pmid = 24031295| title = Production of 6-pentyl-α-pyrone by trichoderma harzianum in solid-state fermentation| journal = Brazilian Journal of Microbiology| volume = 39| issue = 4| pages = 712–717| year = 2008| last1 = Ramos| first1 = Aline de Souza| last2 = Fiaux| first2 = Sorele Batista| last3 = Leite| first3 = Selma Gomes Ferreira| pmc=3768464}}</ref>
Derivatives of 2-pyrone play a role as signalling molecules in bacterial communication, similar to quorum sensing. Cells with LuxR-type receptors, but lacking its homolog LuxI (and thus unable to produce ''N''-acylhomoserine lactone QS signaling molecules) are known as LuxR "solos", to which pyrones bind as ligands facilitating cell-cell communication.<ref>{{cite journal |last = Brachmann |first = Alexander |author2=Brameyer, S. |author3=Kresovic, D. |author4=Hitkova, I. |author5=Kopp, Y. |author6=Manske, C. |author7=Schubert, K. |author8=Bode, H. B. |author9=Heermann, R. |title = Pyrones as bacterial signaling molecules |journal=Nature Chemical Biology |volume = 9 |issue = 9 |pages = 573–578 | publisher=Nature Publishing Group |date=14 July 2013 |doi=10.1038/nchembio.1295 |pmid = 23851573}}</ref>
==See also== * Pyrone
== References == <references/>
{{DEFAULTSORT:Pyrone, 2-}} Category:2-Pyrones