2-Pyrone is an unsaturated

Saturation (chemistry)

In chemistry, saturation has six different meanings, all based on reaching a maximum capacity...

 cyclic chemical compound with the molecular

Molecule

A molecule is an electrically neutral group of at least two atoms held together by covalent chemical bonds. Molecules are distinguished from ions by their electrical charge...

 formula C₅H₄O₂. It is isomer

Isomer

In chemistry, isomers are compounds with the same molecular formula but different structural formulas. Isomers do not necessarily share similar properties, unless they also have the same functional groups. There are many different classes of isomers, like stereoisomers, enantiomers, geometrical...

ic with 4-pyrone

4-Pyrone

4-Pyrone is an unsaturated cyclic chemical compound with the molecular formula C5H4O2. It is isomeric with 2-pyrone....

.

2-Pyrone is used in organic synthesis

Organic synthesis

Organic synthesis is a special branch of chemical synthesis and is concerned with the construction of organic compounds via organic reactions. Organic molecules can often contain a higher level of complexity compared to purely inorganic compounds, so the synthesis of organic compounds has...

 as a building block for more complex chemical structures because it may participate in a variety of cycloaddition reactions to form bicyclic lactone

Lactone

In chemistry, a lactone is a cyclic ester which can be seen as the condensation product of an alcohol group -OH and a carboxylic acid group -COOH in the same molecule...

s. For example, it readily undergoes Diels-Alder reaction

Diels-Alder reaction

The Diels–Alder reaction is an organic chemical reaction between a conjugated diene and a substituted alkene, commonly termed the dienophile, to form a substituted cyclohexene system. The reaction can proceed even if some of the atoms in the newly formed ring are not carbon...

s with alkyne

Alkyne

Alkynes are hydrocarbons that have a triple bond between two carbon atoms, with the formula CnH2n-2. Alkynes are traditionally known as acetylenes, although the name acetylene also refers specifically to C2H2, known formally as ethyne using IUPAC nomenclature...

s producing, upon loss of carbon dioxide

Carbon dioxide

Carbon dioxide is a naturally occurring chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom...

, substituted benzene

Benzene

Benzene is an organic chemical compound. It is composed of 6 carbon atoms in a ring, with 1 hydrogen atom attached to each carbon atom, with the molecular formula C6H6....

s. The Gogte Synthesis (1938) is a method for the alkylation of certain pyrones with acid chlorides.
The most common natural products containing a 2-pyrone are the bufanolides and kavalactone

Kavalactone

Kavalactones are a class of lactone compounds found in the kava shrub.-Compounds:At least 18 different kavalactones have been identified to date, with methysticin being the first identified.Analogues, such as ethysticin, have also been isolated....

s.