Abstract
4,4-Dialkyl 3,3-dichloro oxetan-2-ones rearrange under Lewis acid catalysis, accompanied by loss of HC1, to afford 4,5-dialkyl 3-chloro butenolides.
We have recently been investigating the reactions of beta lactones under the influence of Lewis acid catalysis.1 When the lactone ring oxygen is bonded to a secondary carbon atom, a rearrangement occurs in which the beta lactone 1 expands to a butyrolactone 4 with the concommitant migration of a hydrogen or carbon atom into the lactone ring.2 If the oxygen is bonded to a tertiary carbon, an ionization/elimination sequence ensues, producing a β, γ-unsaturated carboxylic acid