Acetolactone

In organic chemistry, α'lactone refers to a functional group, the smallest possible lactone. It is a family of unstable, three-membered heterocycles, containing an epoxide ring fused with a carbonyl group.
The parent, acetolactone ', is an organic compound with formula, and has not been isolated in bulk. The compound was first described in 1997 as a transient species in mass spectrometry experiments.
Generally, αlactones are produced by the cryogenic, photochemical decarboxylation of peroxymalonic anhydrides. Even at 77 K, the products rapidly polymerize or decarbonylate to ketones or aldehydes.
An exception is bisacetolactone, stabilized by its two trifluoromethyl groups. That compound has a half-life of 8 hours at 25 °C.
Α-Thiolactones can be produced via oxygen transfer from a nitrone to a thioketene.