2-Pyrone (α-pyrone or pyran-2-one) is an unsaturated cyclic chemical compound with the

molecular A molecule is a group of two or more atoms that are held together by attractive forces known as chemical bonds; depending on context, the term may or may not include ions that satisfy this criterion. In quantum physics, organic chemistry, ...

formula C₅H₄O₂. It is

isomer In chemistry, isomers are molecules or polyatomic ions with identical molecular formula – that is, the same number of atoms of each element (chemistry), element – but distinct arrangements of atoms in space. ''Isomerism'' refers to the exi ...

ic with

4-pyrone 4-Pyrone (γ-pyrone or pyran-4-one) is an unsaturated cyclic chemical compound with the molecular formula C5H4O2.It is isomeric with 2-pyrone. Preparation 4-Pyrone is prepared via the thermal decarboxylation of chelidonic acid. Reactions 4-Pyr ...

. 2-Pyrone is used in

organic synthesis Organic synthesis is a branch of chemical synthesis concerned with the construction of organic compounds. Organic compounds are molecules consisting of combinations of covalently-linked hydrogen, carbon, oxygen, and nitrogen atoms. Within the gen ...

as a building block for more complex chemical structures because it may participate in a variety of

cycloaddition reaction In organic chemistry, a cycloaddition is a chemical reaction in which "two or more unsaturated molecules (or parts of the same molecule) combine with the formation of a cyclic adduct in which there is a net reduction of the bond multiplicity". T ...

s to form bicyclic

lactone Lactones are cyclic carboxylic esters. They are derived from the corresponding hydroxycarboxylic acids by esterification. They can be saturated or unsaturated. Lactones are formed by lactonization, the intramolecular esterification of the corresp ...

s. For example, it readily undergoes Diels-Alder reactions with

alkyne \ce \ce Acetylene \ce \ce \ce Propyne \ce \ce \ce \ce 1-Butyne In organic chemistry, an alkyne is an unsaturated hydrocarbon containing at least one carbon—carbon triple bond. The simplest acyclic alkynes with only one triple bond and n ...

s producing, upon loss of

carbon dioxide Carbon dioxide is a chemical compound with the chemical formula . It is made up of molecules that each have one carbon atom covalent bond, covalently double bonded to two oxygen atoms. It is found in a gas state at room temperature and at norma ...

, substituted

benzene Benzene is an Organic compound, organic chemical compound with the Chemical formula#Molecular formula, molecular formula C6H6. The benzene molecule is composed of six carbon atoms joined in a planar hexagonal Ring (chemistry), ring with one hyd ...

s. The Gogte Synthesis (1938) is a method for the alkylation of certain pyrones with acid chlorides. The parent 2-pyrone can be produced from

decarboxylation Decarboxylation is a chemical reaction that removes a carboxyl group and releases carbon dioxide (CO2). Usually, decarboxylation refers to a reaction of carboxylic acids, removing a carbon atom from a carbon chain. The reverse process, which is ...

coumalic acid Coumalic acid is an organic compound with the molecular formula C6H4O4. Its melting point is around 210 °C. In laboratory coumalic acid may be obtained by self-condensation of malic acid Malic acid is an organic compound with the molecul ...

Derivatives

The most common natural products containing a 2-pyrone are the

bufanolide Bufanolide is a C24 steroid and, indirectly, a parent structure of bufadienolide. Its derivatives was found in ''Bufo'' and ''Scilla'', as an aglycone of cardiac glycosides and is usually toxic Toxicity is the degree to which a chemical subs ...

s and

kavalactone Kavalactones are a class of lactone compounds found in kava roots and ''Alpinia zerumbet'' (shell ginger) and in several Gymnopilus, Phellinus and Inonotus fungi. Some kavalactones are bioactive. They are responsible for the psychoactive, analges ...

s. Oxovitisin A, a pyranoanthocyanin found in wine, also contains a 2-pyrone element.

6-Amyl-α-pyrone 6-Amyl-α-pyrone, also 6-pentyl-2-pyrone or 6PP, is an unsaturated lactone molecule. It contains two double bonds in the ring and a Pentyl group, pentyl substituent at carbon adjacent to the ring oxygen. It is a colorless liquid which possesses ch ...

(6PP) is a derivative of 2-pyrone, found in animal foods and heated beef. Due to its good organoleptic properties with coconut aroma, it is used as flavor enhancer in the food industry. Biologically, it is produced by ''

Trichoderma ''Trichoderma'' is a genus of fungi in the family Hypocreaceae that is present in all soils, where they are the most prevalent culturable fungi. Many species in this genus can be characterized as opportunistic avirulent plant symbionts. This re ...

'' species via solid state fermentation. Derivatives of 2-pyrone play a role as signalling molecules in bacterial communication, similar to

quorum sensing In biology, quorum sensing or quorum signaling (QS) is the process of cell-to-cell communication that allows bacteria to detect and respond to cell population density by gene regulation, typically as a means of acclimating to environmental disadv ...

. 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.

References

{{DEFAULTSORT:Pyrone, 2-

Derivatives

See also

References