2-Pyrone

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2-Pyrone (α-pyrone or pyran-2-one) is an unsaturated cyclic chemical compound with the molecular formula C₅H₄O₂. 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.^[1]. The Gogte Synthesis (1938) is a method for the alkylation of certain pyrones with acid chlorides ^{[citation needed]}.

2-Pyrone also forms the core structure of a variety of natural organic compounds. For example, the coumarins are an important class of compounds which are benzo-fused derivatives of 2-pyrone.

4-Pyrone
Coumarin

References

^ Woodard BT, Posner G H. "Recent Advances in Diels-Alder Cycloadditions Using 2-Pyrones." Advances in Cycloaddition. 1999, 5, 47-83.

[1] Woodard BT, Posner G H. "Recent Advances in Diels-Alder Cycloadditions Using 2-Pyrones." Advances in Cycloaddition. 1999, 5, 47-83.

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