2-Furanone

2-Furanone, also furan-2-one, is a heterocyclic chemical compound classified as a lactone. It is a common component of natural products synthesized by biochemical pathways in organisms, especially plants of the genus Angelica. 2-Furanone is also known as γ-crotonolactone or β-angelica lactone. It is the simplest butenolide compound and is colloquially called "butenolide" in the context of natural product synthesis.

Tautomerism
The tautomer of 2-furanone is known as 2-hydroxyfuran. It is unstable and rarely detected in solution, but serves as a reactive intermediate in the interconversion between the β and α lactones. The β form is the more stable but interconversion can be catalyzed by the addition of base.

Reduction to furan
2-Furanones can be converted to furans by a two-step process of reduction followed by dehydration. First the carbon-oxygen double bond is reduced by the attachment of a trimethylsilyl functional group to the oxygen atom. The dehydration reaction introduces two carbon-carbon double bonds in the ring.

Natural uses
Compounds derived from butenolides are generated by some plants exposed to high heat in brush fires and trigger seed germination in plants whose reproduction depends on exposure to fire.